**1. Introduction**

*Artemisia* genus (Asteraceae family) comprise more than 2290 plant name records in the "The Plant List" database, being only 530 of these taxa with accepted Latin botanical name [1], which shows how challenging the taxonomy of this genus is. In this review, the complete accepted Latin botanical name, according to the "The Plant List" database, is presented in the first species citation, with an indication of any synonym when the latter is the one mentioned in the original publication. In the remaining citations, the genre name is abbreviated to *A.* and omitted the authority name. The *Artemisia* species are herbs and shrubs, which could be perennial, biennial and annual plants, distributed on all continents except Antarctica, mainly on Northern Hemisphere, with only 25 species on the Southern Hemisphere [2], being the Asian the zone where higher species diversity is concentrated [3,4]. They exhibit a great ability to grow on different ecosystems from the sea level to the mountains and from arid areas to wet regions, but the majority of the species live on temperate zones [2]. This ability contributed very significantly to the fact

**Citation:** Trendafilova, A.; Moujir, L.M.; Sousa, P.M.C.; Seca, A.M.L. Research Advances on Health Effects of Edible *Artemisia* Species and Some Sesquiterpene Lactones Constituents. *Foods* **2021**, *10*, 65. https://doi.org/ 10.3390/foods10010065

Received: 27 November 2020 Accepted: 25 December 2020 Published: 30 December 2020

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**Copyright:** © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

that some species of *Artemisia*, although originating in a specific zone, are now widely distributed. For example, *Artemisia vulgaris* L. is native to Europe and Asia but has now a large distribution in natural habitats worldwide, can be found in abundance in very distant areas ranging from Africa, North America to the Himalayas and Australia [5]. Some *Artemisia* species exhibit so high ability to adapt to new habitats that they become invasive species in these environments, posing a significant threat to biodiversity. This is the case of *Artemisia princeps* L. which, being native to Japan, China and Korea, is currently classified as an invasive species in Belgium and Netherlands [6] while *Artemisia verlotiorum* Lamotte is an alien invasive species in Croatia [7].

The use of *Artemisia* species in traditional medicine is well-documented [5,8–17] and demonstrates the great ethnopharmacological value of this genus. *Artemisia annua* L. and *Artemisia absinthium* L. are the best known for their uses in traditional medicine around of the World. For example, *A. annua* is cited in several ancient books as being suitable for the treatment of consumptive fever, jaundice, summer heat wounds, tuberculosis, lice, scabies, dysentery, and hemorrhoids in addition to pain relievers, while in Iran is used as antispasmodic, carminative, or sedative remedy for children [9,16,18]. In turn, *A. absinthium* has been traditionally used to treat mainly gastrointestinal diseases and as anthelmintic although for example in Italy it is also used as an antiparasitic, antihypertensive and anti-inflammatory, while in France it is also used to stimulate appetite, as an antipyretic, and emmenagogue [17,19]. However, many other species are used on each continent. For example, *Artemisia afra* Jacq. ex Willd. is one of the most widely used herbal remedies in South Africa to treat inflammation and pain [20]. It is also used to treat various ailments including coughs, colds, asthma, fever, influenza, diabetes and malaria [20], and by certain South African traditional healers to treat rhinitis [21]. *Artemisia dracunculus* L. is widely used in North America, for example by the Chippewa and Costanoan Indians as abortifacient and medicine to treat chronic dysentery, heart palpitations, wounds, colic in babies, and also to strengthen hair and make it grow [22]. In the Iranian Traditional Medicine *A. vulgaris* is used to treat cervicitis [23], while this species is reported in the ethnobotany of Karok, Kiowa, Miwok Paiute, Pomo and Tlingit areas, as a drug with several applications such as in childbirth, steam bath for pleurisy, gonorrheal sore, cold, rheumatism, headache, a 'worm' medicine, pains of afterbirth [24]. The traditional use of *Artemisia* species in Europe is mainly as food, spices and beverages (discussed in more detail in Section 2). However, *Artemisia* species are also used in the treatment of various diseases, as for example *Artemisia umbelliformis* Lam. and *Artemisia genipi* Weber ex Stechm. also known as Alpine wormwoods and génépis species, that are used traditionally to fight cold fever, fatigue, dyspepsia and respiratory infections, as wound-healing agents and to treat bruises, while wines aromatized with these species stimulate appetite, promote digestion, and fight the mountain sickness [10].

Even some *Artemisia* species less scientifically known such as *Artemisia ordosica* Krasch, have significant ethnomedicinal applications. This species was recorded on the traditional Mongolian and Chinese medicine books, as having a beneficial effect on the nasal bleeding, rheumatoid arthritis, headache, sore throat and carbuncle [25] and was used by Mongolian "barefoot" doctors for nasosinusitis treatment [26]. *Artemisia tripartita* (Nutt.) Rydb. was reported on Native American Ethnobotany database [27] as diaphoretic and remedy to treat cold and sore throats, while *Artemisia verlotiorum* Lamotte, distributed in all northern hemisphere, is used in Tuscany folk medicine to treat hypertension [28], and to alleviate stomach problems in Gilgit-Baltistan, Pakistan [29].

*Artemisia* species, as well as other herbal medicines, with proven pharmacological effects has been incorporated into conventional medicine. This incorporation is supported by the world health organization, which considers that traditional and complementary medicine can make a significant contribution to the goal of achieving universal health coverage by being included in the provision of essential health services [30]. Nevertheless, international research into traditional herbal medicines should be subject to the same ethical and methodological requirements as all research involving humans. Therefore, criteria to promote the safety, quality and effectiveness of the plants used in traditional medicine have been discussed and established [31,32].

Encouraged by this wide application in traditional medicine, the scientific community has dedicated itself to investigating in each *Artemisia* species evidence to support these applications. In the laboratory, the properties of the plant and extracts are tested using different models (in vitro, in vivo, clinical trial), and the active principles present in these species are wanted.

The result of this vast investigation showed the *Artemisia* species (extracts and essential oils) as exhibiting antiparasitic, anticancer and anti-inflammatory action in addition to antioxidant, wound healing, antinociceptive, immunoregulation, hepatoprotective, neuroprotective, anti-asthmatic, antidiabetic, antihypertensive, anti-adipogenic, anti-ulcerogenic, antiviral, antibacterial, antifungal, and anti-osteoporotic activities [10–13,18,19,33–39].

The search for bioactive compounds responsible for these biological activities has led to *Artemisia* species are privileged sources of compounds with highly diversified structures that exhibit a high level and diversity of biological activities, providing the basis for the development of new drugs, some of which are already used in clinical therapeutics [4,8,10, 13,40–47].

The *Artemisia* secondary metabolites belong to the several organic compounds families [44,47–49] such as terpenoids [14,44], mostly monoterpenes in essential oils [31,44] and sesquiterpene lactones [40,41,50], flavonoids [14,46,51,52], lignans [52–55], alkaloids [56], steroids [14,57], phenolic acids [37,47,58] and coumarins [14,53,59], all of them well known for their large range of biological activities.

Given the large number of papers published on the theme of health effects of products related to *Artemisia* species (plant, extracts, pure compounds, studies in vitro, in vivo and clinical trials), all publications related to in vitro studies were excluded from this review. In fact, although these studies are essential for a first assessment of the species' potential, they are the ones that are farthest from the final objective, which is, the application in patients. Thus, the results of these studies are those that weigh less in the realistic assessment of the therapeutic effects of the plant and/or its constituents.

This review is intended to gather and discuss the most impactful research concerning the health effects of edible *Artemisia* species, based on their applications as food, their nutritional composition and therapeutic applications supported by clinical studies. It is also discussed the therapeutic relevance of some sesquiterpene lactones constituents of *Artemisia* species and its derivatives.

The method consisted of searching the Scopus, Web of Science, PubMed and Google Scholar databases for original and review articles in English language, published from 2015 to 2020, while ClinicalTrials.gov was used to find registered clinical trials. For a systematic search, "Artemisia" as the primary keyword, associated with other keywords such as "chemical composition", "nutritional", "food", "adverse effects" and "covid-19" for Sections 2–4 and 7; "Artemisia" and "clinical trial" for Section 5; For Section 6 are used the name of each sesquiterpene lactone and terms like "biological activity", "cancer", "malaria". The in vitro studies were excluded (NOT "in vitro"). More than 300 references were considered, and the most significant results discussed and presented here.

#### **2. Use of** *Artemisia* **Species as Food, Spices, Condiments and Beverages**

In addition to the traditional medicine applications, *Artemisia* species exhibit high food value since many of them are species used in culinary.

The most extensive use of *Artemisia* species as food is found in the countries of Europe, Asia (Japan, Korea, China and India) as well as in North America. The literature data describing the utilization of *Artemisia* species as a food, spices, condiments and beverages are summarized in Table 1.


Application of *Artemisia* species as food, spices, condiments and beverages.

**Table 1.**



Taxa of the *A. vulgaris* is collected and cultivated for different alimentary purposes [60, 67,80]. Their leaves are one of the ingredients of kusa-mochi and hishi-mochi, two kinds of rice cakes or dumplings, one variant of which is called yomogi-mochi, yomogi being the Japanese name of these *Artemisia* species [80]. A type of soba, Japanese noodles used in soups and similar dishes, made with wheat and buckwheat also contains *A. princeps*, which gives it a green color. The young plants (leaves, stems, or shoot tips) of *A. dracunculus*, *A. dracunculoides*, *A. vulgaris*, *A. japonica*, *A. capillaris*, *A. carvifolia*, *A. indica*, *A. keiskeana*, *A. montana*, *A. schmidtiana*, *A. tilesii*, *A. tridentata*, *A. wrightii*, etc. (Table 1) can be eaten fresh in salads or cooked in soups and food supplements. *Sabzi khordan* is an Iranian (Persian) mixture of fresh herbs (served with lunch and dinner) that typically includes tarragon (*A. dracunculus*) [83]. Although the seeds of *A. dracunculoides* and *A. tridentata* are very small, they can be roasted, ground into a powder, and mixed with water or eaten raw [75]. Similarly, the seed of *A. wrightii* is crushed with water, made into balls and steamed [75].

On the other hand, the flavoring use of an *Artemisia* species is worldwide and especially of *A. dracunculus* (French tarragon, German tarragon, true tarragon or estragon) and closely related *A. dracunculoides* (Russian tarragon). The early culinary history is obscure, but the name "tarragon" is derived from *tarkhun, ¯* the Arabic name [83]. Tarragon became popular as a flavoring agent in the 16th century and is one of the most sought after herbs amongst gourmet chefs because of its delicate anise flavor, reminiscent of licorice. *Herbes vénitiennes* are a mixture of aromatic herbs (tarragon, chervil, parsley and sorrel) traditionally used in France to flavor butter. Tarragon vinegar is made by steeping a few fresh leafy twigs in a bottle of white wine vinegar. It is an essential ingredient of famous sauces such as béarnaise, hollandaise and tartare that classically accompany asparagus, green beans, peas and other vegetables (as tarragon cream) or chicken, meat and eggs. Leaves (preferably fresh) are used to flavor meat dishes, stews, fish dishes, salads, pickles and mustard sauces. Russian tarragon (*A. dracunculoides*) is very similar but more robust (and less aromatic). Tarragon is largely cultivated and commercialized as living plants in pots. Dried leaves of *A. argyi* are utilized as flavoring and colorant for the Chinese dish Qingtua [46], and *A. ludoviciana*—for sauces, gravies and as a garnish for pork and game [60,67]. Dried leaves of *A. vulgaris* (mugwort) make a bitter seasoning for poultry stuffing, especially for goose, and soups, and fresh leaves can be rubbed on fatty meats before roasting [61]. Some gourmands like cheese use seasoning with a mixture of wormwood (*A. absinthium*), thyme, and rosemary (at ratio 4:2:1) [84]. Small farmers in Lithuania are using a mix of wormwood and tansy (*Tanacetum vulgare*) for preservative purposes (to protect smoked meats from flies blow, other pests, and spoilage) as well as for flavoring (it gives a specific pleasant smell to the meat) [84]. The leaves of *A. frigida* are used by the Hopi Indians as a flavoring for sweet corn [68,76]. *A. abrotanum* is the sweetest *Artemisia* with slight lemon scent is a natural choice for seasoning cakes, pastries and vinegars [61]. Similarly, the leaves of *A. pallens* are delicately scented and the flowers yield a balsamic essential oil (davana) with application in baked goods, candy, chewing gum, and ice cream [61].

Many *Artemisia* species are applied in the preparation of different non-alcoholic beverages, giving them a bitter taste and alleged tonic properties. Thus, *A. absinthium*, *A. abrotanum*, *A. agryi*, *A. ludoviciana*, *A. montana*, *A. tridentata*, *A. granatensis*, etc. are consumed as herbal tea with digestive properties (Table 1). Silver wormwood (*A. arborescens*) and *A. herba-alba* are added to the green tea or the coffee in North Africa [67,78] and *A. carvifolia* has the same use in Asia [67]. Tarragon (*A. dracunculus*) is an ingredient of Georgian carbonated soft drink called *Tarkhuna* [75]. *A. maritima*, *A. abrotanum*, *A. absinthium, A. vulgaris*, etc. (Table 1) have been applied as a flavoring ingredient in beer production before the common application of hops.

Undoubtedly, the most famous *Artemisia* species employed in alcoholic drinks is *A. absinthium*, among which two are most noteworthy: vermouth and absinthe. Vermouth is a low alcoholic drink prepared from wine and a cocktail of botanical ingredients with *A. absinthium* as a principal component [85]. There are similar drinks in some countries of the Balkan Peninsula—pelin in Bulgaria [86] and vin pelin in Romania [87]. The spirit drink

absinthe was created in French-speaking Switzerland in the late eighteenth century [88] and is produced by macerating *A. absinthium* leaves, anise and fennel seeds in alcohol (85 vol%) [84,89]. Wormwood (*A. absinthium*) is also used for the preparation of a bitter liqueur with lower content of alcohol (28–35 vol%) called pelinkovac (pelinkovec, pelinovec, pelen or pelin) and popular in Croatia, Serbia, Montenegro, Bosnia-Herzegovina, North Macedonia as well as in Slovenia [71].

Another popular herbal liqueurs in which *Artemisia* species present are genepy or génépi (*A. genipi* and related taxa such as *A. glacialis* and *A. umbelliformis*) [10] and ratafia (*A. abrotanum*, *A. absinthium*, *A. arborescens* and *Artemisia chamaemelifolia* Vill. [65].

#### **3. Nutritional Value of** *Artemisia* **Species**

As demonstrated above *Artemisia* species are widely consumed by human as a traditional food, a tea and dietary supplements, owing to the fact that they are rich in fatty acids, carbohydrates, dietary fiber, protein, essential amino acids, vitamins and minerals as demonstrated in Table 2.






 Free (FAA), essential (EAA) and non-essential (NEAA) amino acids; total (TFA), saturated (SFA), unsaturated (UFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids;DW—dry weight; FW—fresh weight; DM—dry matter. \*\* Oil cake remaining after the extraction of essential oil.

Fatty acids (FA) have chemo-preventive effects and are pharmacologically active in chronic or degenerative diseases. Research has proved that diets rich in saturated fatty acids (SFA) are a risk factor for cardiovascular diseases unlike diets rich in monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA), which reduce or inhibit such cardiovascular disease [104]. Linoleic and linolenic acids are essential for human health growth health promotion and disease prevention [104–108]. They could not be synthesized endogenously in the human body and therefore they need to be supplied by food. The studies on the fatty acid profile of *Artemisia* species (Table 2) showed a very variable fatty acid content, ranging from 3.31 mg/g FW in *A. arborescens* [92] to 24.7 mg/g FW in *A. argyi* [46]. With exception of *A. jacutica* [99], *A. santolinifolia* [100] and *A. stelleriana* [92], unsaturated fatty acids (UFA) predominated in all investigated species, followed by polyunsaturated fatty acids (PUFA) and saturated fatty acids (SFA) (Table 2). Among individual compounds, linolenic and linoleic acids are the major fatty acids. These results determine *Artemisia* plants as a valuable source of unsaturated fatty acids with significance from both dietary and nutritional point of view. Palmitic acid was found to be the most abundant component in *A. stelleriana* (70%) [92], *A. princeps* (34.9%) [73] and *A. jacutica* (20.6–21.8%) [99].

Carbohydrates are important for keeping the body supply with energy and stamina. Recently, *A. sphaerocephala* carbohydrates have been the subject of a bibliographic review [109], showing their high nutritional value and versatility in terms of applications. For instance, the total amount of carbohydrates in *A. sphaerocephala* seed oil is 73% [83,110] while in *A. annua* is only 8% [93]. Recently, it has been found that the oil cake remaining after the extraction of essential oils from *A. absinthium* contains 9.4% of sugars [90]. The authors propose an application of the aqueous extracts of oil cake for the formulations of gelled desserts.

Dietary fiber possesses an ability to prevent or relieve constipation and foods containing fiber can provide other health benefits as well, such as helping to maintain a healthy weight and lowering your risk of diabetes, heart disease and some types of cancer [111]. Few *Artemisia* species have been studied for the content of dietary fiber (Table 2). The amount of crude fiber in the fresh *A. argyi* leaves, *A. annua*, *A. herba-alba* leaves and *A. sibieri* is 39.9 mg/g, 142 mg/g, 407.9 mg/g and 484 mg/g, respectively (Table 2).

Proteins play critical roles in cellular functions, structure and regulations of metabolic activities in all living organisms and have primary importance in the daily diets of consumers. Crude protein content was assessed in *A. argyi* and *A. princeps* [73], *A. herba-alba* [95–97], *A. campestris* [97], *A. sieberi* [101], *A. frigida* [96], *A. tridentata* ssp. *wyomingensis* [103] and *A. annua* [93]. It has been found that leaves and inflorescence of *A. annua* are rich in protein (27.1 and 18.4%, respectively) when compared to stems and roots (10.7 and 8.23%, respectively) [91]. The comparative study of the nutritional constituents of *A. princeps* and *A. argyi* showed significant difference in the content of free amino acids [73]. The content of the essential amino acids valine and phenylalanine is significantly higher in *A. argyi* (by approximately 63% and 41%, respectively) than in *A. princeps*. The amount of total essential amino acids is approximately 57% in *A. princeps* and 61% in *A. argyi*. γ-Aminobutyric acid is the main component in *A. argyi*. This acid is a natural non-protein amino acid with great therapeutic potential in neurological disorders and mental illnesses, because it acts as the major inhibitory neurotransmitter in the central nervous system [112]. Reflective of the protein content in the various tissues of *A. annua*, the highest concentration of amino acids was registered in the leaves and inflorescence and leucine was the most abundant one [91].

As can be seen in Table 2, few *Artemisia* species have been investigated for the presence of vitamins and minerals. Thus, the content of vitamin C (measured as ascorbic acid) in *A. argyi* was found to be twice higher than in *A. princeps* [73]. The content of vitamin E varies in the different plant parts of *A. annua*, from 1.19 mg/kg (stems) to 22.63 mg/kg (leaves) [91] and is significantly lower from that reported by Iqbal et al. [93]. The different values of vitamin E are probably due to the different methods used for the quantitative determination. The measured concentration of vitamin A in the different parts of *A. annua* was under

detection limit level (<0.3 μg/100 g) [91]. Among minerals, potassium was detected in the highest concentration in all studied *Artemisia* species so far (Table 2) followed by calcium and magnesium (Table 2). Potassium is important in a balance for cellular metabolism and regulating transfer of nutrients to cells, maintaining blood pressure and electrolyte balance, transmitting electrochemical impulses and for the correct functioning of blood, endocrine/digestive and nervous systems, heart, kidneys, muscles and skin [113]. High levels of phosphorous were found in aerial parts of *A. frigida* [96] and *A. sieberi* [101], in *A. annua* leaves and inflorescence [91]. Phosphorous is an essential component to maintain electrolyte balance, correct functioning of brain cells, circulatory and digestive systems, eyes, liver, muscles, nerves and teeth/bones. A balance of magnesium, calcium and phosphorus is required for these minerals to be used effectively [113]. Regarding the microelements, iron, manganese and zinc in different amounts dominated all studied samples (Table 2). Probably, the functions of all these macro- and microelements in the body to maintain water balance and to stimulate normal movement in the intestinal tract can explain the traditional use of the *Artemisia* plants as an herbal tonic.

#### **4. Adverse Effects Reported to** *Artemisia* **Species and Some Constituents**

Pollen from the various *Artemisia* species is one of the most frequent and serious pollinosis causes in many parts of the world [114–118]. It has been verified as an allergen by nasal challenge and bronchial provocation tests, and these allergens have been shown to occur not only in its pollen but also in its leaves and stems. Studies on the immunological changes from *Artemisia* pollen allergic subjects revealed that *Artemisia* pollen can trigger not only allergic rhinitis but also asthma alone or both [118,119]. Almost half of the patients with autumnal pollen allergic rhinitis developed seasonal allergic asthma within 9 years [118]. The immunoelectrophoretic comparison of the allergen extracts from pollen of six *Artemisia* species and morphological studies on the pollen grains showed an extensive degree of similarity and cross-reactivity between the studied species [120]. Screening of both Korean and Norwegian patient sera against extracts from *A. vulgaris* and *A. princeps* showed that both groups of patients had the same pattern of reactivity towards both extracts [120]. The mugwort (*A. vulgaris*) pollen contained allergenic substances with IgE reactivity [121], which can cause immediate Type I allergic reactions such as anaphylactic shock [122]. Another study on the pollen collected from plants across Europe has shown that the highest levels of endotoxin were detected on *A. vulgaris* pollen [123]. The investigation on *Artemisia* pollen allergenicity revealed significant daily, seasonal and species-specific variability [124]. The analysis of *Artemisia* pollen concentrations evidenced the presence of a bimodal curve with two peaks. The first peak was attributed to *A. vulgaris* (early flowering species) and the second one—to late flowering species *(A. campestris*, *A. annua*, *A. verlotiorum*, etc.) [115,124]. The authors supposed that the spread of these species could affect human health, increasing the length and severity of allergenic pollen exposure in autumn.

Skin contact with some members of the genus *Artemisia* can cause dermatitis or other allergic reactions in some people [125–128]. Several cases of contact dermatitis are described in the literature [129–132]. Mugwort (*A. vulgaris*) has demonstrated a medium sensitizing capacity in guinea pigs [133]. According to Park [134], nearly 43% of patients with allergic rhinitis and asthma have positive reactions to mugwort on skin prick testing. Wormwood tea (*A. absinthium*) induced positive patch test reactions in 13 of 19 Compositaeallergic patients [135]. Erythema multiforme, is probably an expression of a delayed hypersensitivity reaction and appears clinically as acute or chronic dermatitis of exposed sites [127,128]. Skin contact dermatitis caused by *Artemisia* species is attributed to the presence of sesquiterpene lactones [129,136,137].

Absinthe and the use of wormwood extracts (*A. absinthium*) for food purposes were prohibited around the years 1910–1920 in many countries as their consumption was associated with a range of severe adverse symptoms called absinthism, including convulsions, blindness, hallucinations and mental deterioration [89,138–140]. Padosch et al. [139] re-

viewed the available data concerning medical and toxicological aspects experienced and discovered before the prohibition of absinthe. Numerous studies did not give a clear answer whether the toxicity is due to thujone alone, to a combination of the alcohol and thujone or whether it can be traced back to toxic components used in the manufacture of absinthe liqueur [89,140]. Nowadays, *A. absinthium* is permitted in foods and alcoholic beverages according to the regulation of the European Parliament and Council [141]. In addition, European Food Safety Authority (EFSA) states that thujone content in alcoholic beverages, including absinthe, must not exceed 10 mg/kg [142], while the European Medicines Agency (EMA) also proposed a daily maximum intake of thujone in *Absinthii herba*, which was set at 3.0 mg thujone/day/person as acceptable for a maximum duration of 2 weeks in the wormwood monograph [143].

Some *Artemisia* species such as *A. vulgaris* [144], *A. herba-alba* [145], *A. annua* [146,147], *A. arborescens* and *A. douglasiana* Besser ex Besser [67] are used in regulating fertility and should be avoided in pregnancy. Thus, the consumption of *A. herba-alba* during pregnancy of mice offspring significantly decreased the fertility ratio and increased the weight and body size of preweaning offspring mice [148]. In addition, administration of *A. herba-alba* prolonged the time of completing the reflex response of surface righting, negative geotaxis, cliff avoidance and jumping test of mice offspring. In another study, treatment of pregnant rats with *A. kopetdaghensis* "Krasch, Popov & Lincz. ex Poljakov" hydroalcoholic extract (200 and 400 mg/kg) from the 2nd to 8th day of pregnancy led to 30 and 44% abortion in animals but had no significant effect on duration of pregnancy, average number of neonates, and weight of neonates [149]. The abortifacient effect of *A. kopetdaghensis* was attributed to the high content of camphor, for which is known that can crosses the placenta [150]. Gomes et al. [151] reviewed the results of non-clinical and clinical studies with artemisinin derivatives, their mechanisms of embryotoxicity and discussed the safety of their use during pregnancy. The mechanisms of embryotoxicity are not completely understood, but might not be so relevant for humans, considering the short time of treatment (3–7 days) compared with the longer period of target cell formation in the human embryo (~3 weeks).

The sesquiterpene lactone artemisinin isolated from the herb *A. annua* and its derivatives (artemether, arteether, and sodium artesunate) are successively applied in the malaria chemotherapy [152]. Extensive studies and meta-analyses of thousands of patients did not show serious side effects [152–156], although proper monitoring of adverse side effects in developing countries might not be a trivial task [155]. Common side effects were nausea, vomiting, and diarrhea, which are also symptoms of malaria itself. Efferth and Kaina [157] have summarized the available data on toxicity studies (neurotoxicity, embryotoxicity, genotoxicity, hemato- and immunotoxicity, cardiotoxicity, nephrotoxicity, and allergic reactions) in cell culture, animals (mice, rats, rabbits, dogs, monkeys) and in human clinical trials of artemisinin and its derivatives and concluded that artemisinin did not cause toxicity if are taken in appropriate doses for short periods.

#### **5. Therapeutic Uses of** *Artemisia* **Species Based on Clinical Trials**

Encouraged by long traditional use of many *Artemisia* species for treatment of various ailments, research into their pharmacological effects has been carried out and seem to support the traditional applications [5,12,15–17]. In this regard, *Artemisia* species and their biologically active compounds have already been introduced as antimalarial, antioxidant, cytotoxic, antispasmodic, anthelmintic, antinociceptive, neuroprotective, anti-inflammatory, and antimicrobial agents, among others [16,44]. It is noteworthy that although *Artemisia* species have been intensively studied in vitro as cytotoxic agents, there are no reports on their clinical evaluation for cancer therapy in humans [4]. However, one report by Saeed et al. showed that supplementing pet food with an *A. annua* formulation (Luparte®) clearly improved survival prognosis in veterinary treatment of small tumors [158].

Nevertheless, clinical evaluations of *Artemisia* species for a range of other diseases have been carried out [4]. The effect of *A. annua* in traditional medicine in China for treating fever, inflammation and malaria [9] have been evaluated in clinical trials for stiffness and functional limitation associated with osteoarthritis of the hip and knee, pain management, experimental heterophyid infection and treatment of malaria [159–161].

*Artemisia dracunculus* has been used for glycemic control, insulin sensitivity, and insulin secretion [162] and likewise, *A. princeps* was evaluated for the same effects in subjects with impaired fasting glucose and mild-type 2 diabetes [163] and *A. absinthium* in the control of diabetes type 2 [164].

Ointments and liniments of *A. absinthium* can be effective in the treatment of knee osteoarthritis [165]. Based on the suppressor activity of *A. absinthium* compounds on tumor necrosis factor alpha (TNF-α) and other interleukins [166], Krebs et al. [167] established the curative effect of this *Artemisia* species in patients with Crohn's disease. There was improvement in symptoms after treatment with dried powder of the plant together with a conventional therapy, and a cardamonin present in the plant was considered responsible for the anti-inflammatory activity.

In addition to being widely used clinically to treat itching in icteric and dialytic patients, owing to its anti-histaminic and anti-allergenic effects, *A. vulgaris* (mugwort) lotion has also provided good results in patients with post-burn hypertrophic scars [168].

Recently, the preventive effect on hepatitis B cirrhosis of *A. capillaris* decoction combined with the entecavir has been evaluate by a randomized, double-blind and placebo controlled clinical trial (Chinese Clinical Trial Registry: ChiCTR1900021521), to assess its efficacy and safety [169].

*Artemisia annua* and *A. vulgaris* are the species of the genus that produce the highest levels of allergens in their pollen, being one of the main causes of seasonal allergic rhinitis ("hayfever"). Lou et al. [170] carried out a phase III clinical trial (ClinicalTrials.gov identifier: NCT03990272) from March 2017 (approximately 4 months before the local natural *Artemisia* pollen season) to October 2017, involving patients from 13 centres across Northern China. The aim was to test the efficacy and safety of sublingual immunotherapy (SLI) with drops of *A. annua* for allergic rhinitis related to this plant. Results indicated that *A. annua* was a safe and significantly effective therapy. However, longer term follow-up is required, particularly to determine the mechanism of action.

Based in previous study where Xiao et al. [25] demonstrated using in vivo models, the ability of *A. ordosica* Krasch. extracts to control the allergic inflammatory response in rhinitis, clinical trials using nasal spray preparations of *A. abrotanum* containing its essential oils and flavonols have been performed with good results [171].

Munyangi et al. [172] published a randomized controlled clinical trial reporting far superior cure rates of *A. afra* and *A. annua* infusions than with artemisinin combination therapy (artesunate—amodiaquine), in the treatment of malaria. Contrastingly, a recent review by Toit and van der Kooy [15] concluded that tea infusions do not have in vitro activity, and in fact contain no artemisinin. Another randomized large-scale doubleblind controlled trial on *A. annua* and *A. afra* tea vs. praziquantel for the treatment of schistosomiasis was documented by Munyangi et al. [173]. Controversially, Gillibert found scientific and ethical issues such as the article on schistosomiasis referring to the same ethics committee registration number as the malaria article [174].

Sensitive skin was initially believed to be an unusual reaction occurring in only a small subset of individuals. However, during recent decades, it has been shown to affect half the population of the world [175]. Accordingly, extensive in vitro, preclinical, and clinical research with artemisinin and its derivatives has been undertaken, notably into their antiinflammatory, immunomodulatory and antioxidant properties [176]. Yu et al. [177] tested the effectiveness of cosmetics containing *A. annua* extract in repairing sensitive skin. In this study, the xylene-induced ear swelling and human clinical efficacy tests were used, and the authors found that applications containing *A. annua* extract can inhibit inflammation, repair the skin barrier, improve damaged skin, and reduce redness and other sensitive skin symptoms. Aside from this, its leaves are eaten in salads in some Asian countries and in the United States, and several companies currently sell ground leaves and their extracts as dietary supplements [178].

#### **6. Some Sesquiterpene Lactones Constituents of** *Artemisia* **Species with High Clinical Relevance**

The pharmaceutical industry has always been interested in the secondary metabolites produced by plants, for the treatment of diseases, in cosmetics, dyes, fragrances and flavorings [179]. The *Artemisia* species are well known by its content of sesquiterpene lactones [40,41,43,50]. These family of compounds have been studied and reveal high therapeutic potential [180,181]. Here are presented some of the most studied and promise sesquiterpene lactones constituents of edible *Artemisia* species (does not intent to be an exhaustive list) which, due to its medicinal properties discussed above, could contributes to the benefits effects of the *Artemisia* species. Sesquiterpene lactones such as arglabin parthenolide, cynaropicrin, helenalin, costunolide and thapsigargin identified in species of the genus *Artemisia* [40,41,50,180] and other genera, exhibit high pharmacological potential, including in in vivo studies and clinical trials, as demonstrated and discussed very recently [181]. So, they will not be considered in this work. The most recent and relevant experimental evidence of other sesquiterpene lactones medical potential will be highlighted discussed below. In this selection, was considerate mainly the in vivo and clinical studies, once they are the last steps of new drugs development and their results are the most significant to drug development.

The chemical structures of the selected sesquiterpene lactones discussed below are indicated in the Figure 1.

**Figure 1.** Chemical structures of some sesquiterpene lactones constituents of edible *Artemisia* sp. and derivatives with pharmacological relevance.

## *6.1. Artemisinin and Its Derivatives*

Artemisinin (**1**) is a sesquiterpene lactone with an unusual peroxide bridge (cadinene sub-group), that was discovered and isolated from the Chinese herb *A. annua* by Tu YouYou in the early 1970s [182], who was awarded the Nobel Prize in 2015, for discoveries concerning the novel artemisinin therapy against malaria.

Artemisinin (**1**) has low solubility in both water and oil, resulting in weak erratic absorption after oral administration. It also has a short half-life and high first-passage metabolism [183]. Therefore, preserving its pharmacophore, a series of derivatives were designed. The 5–10 times more potent hemiacetal, dihydroartemisinin (DHA, **1c**), also known as dihydroqinghaosu or artenimol, is produced by reducing the lactone. Alkylation of the hemiacetal yields arteether (artemotil) and artemether, while artesunate is reached by acylation of the hemiacetal with succinic acid [184]. In in vivo systems, artesunate (**1a**) and artemether (**1b**) are converted back to dihydroartemisinin (**1c**). The most clinical widely used derivative is artesunate [185]. These derivatives showed better efficacy, tolerability, and oral bioavailability (all well absorbed by mouth and rapidly eliminated) than artemisinin, as well as minimal adverse effects [186,187]. Artemisinin (**1**) and its derivatives have been highlighted for their potent activity against species of *Plasmodium* genus responsible for malaria, as well as in the treatment of leishmaniasis, schistosomiasis and trypanomiasis [188–190]. They have also shown efficacy on several cancer lines, along with anti-inflammatory activity, modulating the immune response by regulating cell proliferation and cytokine release [191–193]. They also have anti-ulcerous [194], antinociceptive [195], antiviral [196], antifungal [180], and antibacterial [197] activities, besides being effective in other disorders such as respiratory [198], and related to metabolic syndromes, including obesity, diabetes and atherosclerosis [199,200], being many of the effects mentioned evaluated in in vivo models

#### 6.1.1. Antiparasitic Activity In Vivo and Clinical Trials

Malaria is the most common tropical disease and is caused by protozoan parasites of the genus *Plasmodium* (*P. malariae*, quartan fevers; *P. vivax* and *P. ovale*, tertian fevers; *P. falciparum*, malignant tertians and *P. knowlesi*) [201]. Artemisinin (**1**) and its derivatives contain a 1,2,4-trioxane moiety responsible for the drug's action mechanism [193,202], which despite intensive study remains debatable. The compound is believed to act in two phases. Firstly, the haem iron attacks and breaks its endoperoxide linkage to produce oxy and carbon free radicals. In the second step, the latter free radical alkylates specific malarial proteins, killing the parasite. artemisinin (**1**) also has another target, the mitochondria and endoplasmic reticulum, where it inhibits PfATP6, the enzyme responsible for Ca++ delivery into vesicles. This is a parasite-encoded sarcoplasmic-endoplasmic reticulum calcium ATPase (SERCA), which is crucial for parasite development [193,201–205]. Furthermore, compound **1** exhibits a direct antiparasitic effect against several *Leishmania* species, by increasing NO production and iNOS expression in uninfected macrophages, and an indirect immunomodulatory effect. In addition, treatment with artemisinin (**1**) in a BALB/c mouse model led to significant reduction in splenic weight, a strong inhibition of parasites, and a restoration of Th1 cytokines such as interferon-γ and interleukin-2 (IL-2) [206].

The 11th World Malaria Report 2018 by the WHO estimated a 2 million increase in global malaria cases with respect to 2017. Examples of growing challenges are urban malaria, the parasite's drug resistance, malaria in pregnancy, resistance towards insecticides, etc. [207]. Artemisinin (**1**) and its analogues **1a**, **1b** and **1c** show marked activity against multidrug resistant strains of *Plasmodium* species and cerebral malaria both in vivo and in vitro. For this reason, the WHO recommends them as first choice treatment as part of artemisinin combination therapy (ACT) [208].

Artesunate (**1a**) is widely used to treat multidrug-resistant malaria [209,210]. The African Quinine Artesunate Malaria Trial multicenter study (AQUAMAT) conducted clinical trials with it in more than 5400 children under 15 years of age with severe malaria. As a result of these, the WHO revised the guidelines for malaria and recommended intravenous artesunate as a choice to treat severe malaria [211,212].

After a cluster-randomized trial carried out in several African countries, it was concluded that rectal derivative **1a** takes 4–6 h to reduce parasitemia and affect progression of the disease. Consequently, when malaria patients cannot be treated orally, rectal artesunate prior to hospital referral can prevent death and disability. In fact, the WHO recommends this, to reduce the risk of death or permanent disability [213].

In 2019, as part of a double-blind, randomized, placebo-controlled trial in Mozambique by Dobaño et al. [214], monthly chemoprophylaxis with sulfadoxine-pyrimethamine plus artesunate (**1a**) (ASSP) was tested to selectively control timing of malaria exposure during infancy. It was observed that a balanced proinflammatory and regulatory cytokine signature (probably by innate cells), around 2 years of age, is associated with a lower risk of clinical malaria. In addition, excellent results were obtained with ASSP therapy in patients affected with uncomplicated *P. falciparum* in India, obtaining an 84.1% cure rate. The 15% failure was due to an artemisinin-resistant isolate [215].

Recent reports highlight the capacity of iron oxide nanoparticles to enhance the efficacy of artesunate (**1a**). In fact, this combination was efficient to retard growth of *P. falciparum* at a reduced drug concentration, with significant damage to macromolecules mediated by enhanced ROS production. Its efficacy against the artemisinin-resistant strain of *P. falciparum* is noteworthy, which suggests artesunate can be developed into a potent therapeutic agent against multidrug-resistant strains [216]. Despite the success of artemisinin derivative artesunate (**1a**), the two major antimalarial policy options are dihydroartemisinin (**1c**)–piperaquine (DHA–PQP) and artemether (**1b**)–lumefantrine (AL) "first-line treatment of uncomplicated *P. falciparum* malaria worldwide" [217]. The benefits of DHA–PQP in children have been validated in endemic countries [218]. The AL combined therapy exerts its effects against the erythrocytic stages of *Plasmodium* spp. In the body, artemether (**1b**) is rapidly metabolized into the active metabolite dihydroartemisinin (**1c**). It is thought that **1b** derivative provides rapid symptomatic relief by reducing the number of malarial parasites. However, lumefantrine has a much longer half-life and is believed to clear residual parasites. Extensive clinical trials of the combination were carried out against *P. falciparum* in China and elsewhere, the success of which led to marketing the combination worldwide under the name "Coartem". This resulted in many independent comparative drug studies, which further confirmed its efficacy [219,220].

A prospective, open label, non-randomized, interventional clinical trial of artemether (**1b**)–lumefantrine (AL) combined therapy was conducted in Zambia. It involved 152 HIVinfected patients with uncomplicated falciparum malaria, who were on efavirenz-based anti-retro-viral therapy. They received a 3-day directly observed standard AL treatment and were followed up until day 63. The results showed that while AL was well tolerated and efficacious in treating uncomplicated falciparum malaria, 16.4% of the participants had a recurrent malaria episode by day 42. This highlights the need in this sub-population for additional malaria prevention measures after treatment [221].

Furthermore, a systematic review compared the efficacies of artemether (**1b**)–lumefantrine (AL) and dihydroartemisinin (**1c**)–piperaquine (DHA–PQP) with or without primaquine (PQ) on the risk of *P. vivax* recurrence [222]. It revealed that administration of DHA– PQP considerably reduced *P. vivax* recurrence by day 42, compared with AL, although at day 63 the risk of recurrence following DHA–PQP was also reduced substantially by co-administration of PQ.

Malaria causes serious maternal and fetal complications, for this reason control of infection in in pregnancy is very important. Centers for Disease Control and Prevention (CDC) recommended artemether (**1b**)–lumefantrine combined therapy as an additional option for treatment of pregnant women with uncomplicated malaria in the United States during the second and third trimesters of pregnancy, at the same doses recommended for non-pregnant adults [223,224].
