Search Results (16)

Three previously undescribed clerodane diterpenoids, including two cis-clerodanes, solidagolactone IX (1) and solidagoic acid K (2), and one trans-clerodane, solidagodiol (3), along with two known cis-clerodane diterpenoids, (−)-(5R,8R,9R,10S)-15,16-epoxy-ent-neo-cleroda-3,13,14-trien-18-ol (4) and solidagoic acid J (5), were isolated and comprehensively characterized from the ethanolic and ethyl acetate root extract of Solidago gigantea Ait. (giant goldenrod). Compound 4 has previously been reported from the roots of this species, whereas compound 5 was identified from the leaves of S. gigantea but not from the roots. The bioassay-guided isolation involved thin-layer chromatography–direct bioautography (TLC–DB) with a Bacillus subtilis antibacterial assay, preparative flash column chromatography, and TLC–mass spectrometry (MS). The chemical structures of the isolated compounds (1–5) were elucidated through extensive in-depth spectroscopic and spectrometric analyses, including one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy, high-resolution tandem mass spectrometry (HRMS/MS), and attenuated total reflectance Fourier-transform infrared (ATR–FTIR) spectroscopy. Their antimicrobial activities were evaluated using in vitro microdilution assays against B. subtilis and different plant pathogens. Compound 3 was the most active against the tested Gram-positive strains, exerting particularly potent effects against Clavibacter michiganensis with a minimal inhibitory concentration (MIC) value of 5.1 µM as well as B. subtilis and Curtobacterium flaccumfaciens pv. flaccumfaciens (MIC 21 µM for both). Compound 4 also strongly inhibited the growth of C. michiganensis (MIC 6.3 µM). Compounds 2, 4, and 5 displayed moderate to weak activity against B. subtilis and C. flaccumfaciens pv. flaccumfaciens with MIC values ranging from 100 to 402 µM. Rhodococcus fascians bacteria were moderately inhibited by compounds 3 (MIC 41 µM) and 4 (MIC 201 µM). Bactericidal activity was observed for compound 3 against C. michiganensis with a minimal bactericidal concentration (MBC) value of 83 µM. Compounds 2 and 3 demonstrated weak antifungal activity against Fusarium graminearum. Our findings underscore the value of bioassay-guided approaches in discovering previously undescribed bioactive compounds. Full article

Strategic scaffolds in molecules increase the possibility of obtaining derivatives with potential uses in scientific and industrial areas. The regio- and stereoselective reactions can be considered to gain these tactical motifs. Natural diterpenes are key molecules for reaching such aims. Among this class of compounds, neo-clerodanes are highlighted by the presence of a furan moiety in their chemical structure. This work describes a regio- and stereoselective strategy to gain beta-lactone and oxirane derivatives from kerlinic acid (1) when the β,γ-unsaturated carboxylic acid system is oxidized, preserving the furan moiety. Oxidation of 1 yielded salviaolide (2), suggesting regio- and stereoselective means. A reaction mechanism was proposed when oxidation of the acetate (1a), benzoate (1b), and methyl ester (1c) derivatives from 1 were gained. The obtention of the epoxide derivative 3, kernolide (4), and kernolide epoxide (5) also supported the reaction mechanism. X-ray diffraction analysis of 3, Karplus-type analyses, and DFT calculations from hypothetical intermediates revealed conformational preferences that guide the regioselectivity. The stereoselectivity was attributed to the natural origin of 1. All compounds were characterized by their physical and spectroscopical data. These results suggest the feasibility of promoting regioselective oxidation on neo-clerodane compounds, preserving the furan moiety. Full article

In this study, nine neo-clerodane-type diterpenoids (1–9) were isolated from the dichloromethane extract of Salvia guevarae Bedolla & Zamudio leaves. Compounds 1–6 were new natural products, and 7–9 were acetone artifacts. In addition, four neo-clerodanes diterpenoids (10–13) previously described from different sources and six triterpenoids—identified as 3β,20,25-trihydroxylupane, oleanolic acid, 3β-O-acetyl-oleanolic acid, ursolic acid, 3β-O-acetyl-betulinic acid, and 3β,28-O-diacetyl-betulin—were isolated. Additionally, five flavonoids were also isolated from the methanol extract: quercetin-3-O-β-xylopyranosyl-(1 → 2)-β-galactopyranoside, taxifolin-7-O-β-glucopyranoside, naringenin-7-O-β-glucopyranoside, a mixture of 2R and 2S eriodictyol-7-O-β-glucopyranoside, caffeic acid, the methyl ester of rosmarinic acid, and rosmarinic acid. The structure of the isolated compounds was established by spectroscopic means, mainly ¹H and ¹³C NMR, including 1D and 2D homo- and heteronuclear experiments. The absolute configuration of 1 and 10 was ascertained via an X-ray analysis, and that of the other compounds via ECD. The antiproliferative activity of some diterpenoids was determined using the sulforhodamine B method, where guevarain B (2) and 6α-hydroxy-patagonol acetonide (7) showed moderate activity against the K562 line, with IC₅₀ (μM) = 33.1 ± 1.3 and 39.8 ± 1.5, respectively. The NO inhibition in RAW 264.7 macrophage activity was also determined for some compounds, where 2-oxo-patagonal (6), 6α-hydroxy-patagonol acetonide (7), and 7α-acetoxy-ent-clerodan-3,13-dien-18,19:16,15-diolide (10) were proven to be active, with IC₅₀ (μM) of 26.4 ± 0.4, 17.3 ± 0.5, and 13.7 ± 2.0, respectively. The chemotaxonomy of Salvia guevarae is also discussed. Full article

Salvia semiatrata Zucc. (Lamiaceae) is endemic to Oaxaca, Mexico, and is known for its analgesic properties. Terpenoids and phenolic compounds with antinociceptive potential have been characterised from this species. The aim of this research was to determine the variation in terpenoids and flavonoids in ethyl acetate extracts of S. semiatrata collected from ten different localities, as well as to evaluate the antinociceptive effect between plants with higher and lower contents of these secondary metabolites. Quantification of S. semiatrata compounds was performed via HPLC-DAD, whereas in vivo evaluation of the antinociceptive effect was performed via formalin test. The results showed that the most abundant groups of metabolites are oleanolic acid (89.60–59.20 µg/mg), quercetin (34.81–16.28 µg/mg), catechin (11.30–9.30 µg/mg), and 7-keto-neoclerodan-3,13-dien-18,19:15,16-diolide (7-keto) (8.01–4.76 µg/mg). Principal component and canonical correspondence analysis showed that the most contrasting localities in terms of compound content and climatic variables are Miahuatlán and Santiago Huauclilla. The differences in metabolite content between the two locations did not affect the antinociceptive effects evaluated at a dose of 300 mg/kg, p.o. In conclusion, the results indicate that S. semiatrata is effective in relieving pain, regardless of the site of collection, reinforcing its traditional use as analgesic. Full article

The secondary metabolites of clerodane diterpenoids have been found in several plant species from various families and in other organisms. In this review, we included articles on clerodanes and neo-clerodanes with cytotoxic or anti-inflammatory activity from 2015 to February 2023. A search was conducted in the following databases: PubMed, Google Scholar and Science Direct, using the keywords clerodanes or neo-clerodanes with cytotoxicity or anti-inflammatory activity. In this work, we present studies on these diterpenes with anti-inflammatory effects from 18 species belonging to 7 families and those with cytotoxic activity from 25 species belonging to 9 families. These plants are mostly from the Lamiaceae, Salicaceae, Menispermaceae and Euphorbiaceae families. In summary, clerodane diterpenes have activity against different cell cancer lines. Specific antiproliferative mechanisms related to the wide range of clerodanes known today have been described, since many of these compounds have been identified, some of which we barely know their properties. It is very possible that there are even more compounds than those described today, in such a way that makes it an open field to discover. Furthermore, some diterpenes presented in this review have already-known therapeutic targets, and therefore, their potential adverse effects can be predicted in some way. Full article

The genus Ajuga (Lamiaceae) is rich in medicinally important species with biological activities ranging from anti-inflammatory, antitumor, neuroprotective, and antidiabetic to antibacterial, antiviral, cytotoxic, and insecticidal effects. Every species contains a unique and complex mixture of bioactive metabolites—phytoecdysteroids (PEs), iridoid glycosides, withanolides, neo-clerodane terpenoids, flavonoids, phenolics, and other chemicals with high therapeutic potential. Phytoecdysteroids, the main compounds of interest, are natural anabolic and adaptogenic agents that are widely used as components of dietary supplements. Wild plants remain the main source of Ajuga bioactive metabolites, particularly PEs, which leads to frequent overexploitation of their natural resources. Cell culture biotechnologies offer a sustainable approach to the production of vegetative biomass and individual phytochemicals specific for Ajuga genus. Cell cultures developed from eight Ajuga taxa were capable of producing PEs, a variety of phenolics and flavonoids, anthocyanins, volatile compounds, phenyletanoid glycosides, iridoids, and fatty acids, and demonstrated antioxidant, antimicrobial, and anti-inflammatory activities. The most abundant PEs in the cell cultures was 20-hydroxyecdysone, followed by turkesterone and cyasterone. The PE content in the cell cultures was comparable or higher than in wild or greenhouse plants, in vitro-grown shoots, and root cultures. Elicitation with methyl jasmonate (50–125 µM) or mevalonate and induced mutagenesis were the most effective strategies that stimulated cell culture biosynthetic capacity. This review summarizes the current progress in cell culture application for the production of pharmacologically important Ajuga metabolites, discusses various approaches to improve the compound yield, and highlights the potential directions for future interventions. Full article

Despite several studies on the Ajuga L. genus, the chemical composition of Ajuga pyramidalis, an alpine endemic species, is still largely unknown. The purpose of this study was to therefore deeper describe it, particularly from the phytochemistry and bioactivity perspectives. In that respect, A. pyramidalis was investigated and 95% of the extracted mass of the plant was characterized by chromatography and mass spectrometry. Apart from the already determined chemical compounds, namely, harpagide and 8-O-acetylharpagide, two iridoids, and neoajugapyrin A, a neo-clerodane diterpene, and three polyphenols (echinacoside, verbascoside and teupoloside) were identified for the first time in A. pyramidalis. Incidentally, the first RX structure of a harpagoside derivative is also described in this paper. The extracts and isolated compounds were then evaluated for various biochemical or biological activities; notably a targeted action on the renewal of the epidermis was highlighted with potential applications in the cosmetic field for anti-aging. Full article

Salvia amarissima Ortega is an endemic species of Mexico used in folk medicine to alleviate pain and as a nervous tranquilizer. The S. amarissima extract and one of its abundant metabolites, identified and isolated through chromatographic techniques, were investigated to obtain scientific evidence of its potential effects to relieve nociplastic pain such as fibromyalgia. Then, the extract and amarisolide A (3–300 mg/kg, i.p.) were pharmacologically evaluated in reserpine-induced fibromyalgia-type chronic pain and in depressive-like behavior (as a common comorbidity) by using the forced swimming test in rats. The 5-HT_1A serotonin receptor (selective antagonist WAY100635, 1 mg/kg, i.p.) was explored after the prediction of a chemical interaction using in silico analysis to look for a possible mechanism of action of amarisolide A. Both the extract and amarisolide A produced significant and dose-dependent antihyperalgesic and antiallodynic effects in rats, as well as significant antidepressive behavior without sedative effects when the antinociceptive dosages were used. The 5-HT_1A serotonin receptor participation was predicted by the in silico descriptors and was corroborated in the presence of WAY100635. In conclusion, S. amarissima possesses antihyperalgesic, antiallodynic, and anti-depressive activities, partially due to the presence of amarisolide A, which involves the 5-HT_1A serotonin receptor. This pharmacological evidence suggests that S. amarissima and amarisolide A are both potential alternatives to relieve pain-like fibromyalgia. Full article

Herbal medicines are still widely practiced in Kurdistan Region-Iraq, especially by people living in villages on mountainous regions. Among plants belonging to the genus Teucrium (family Lamiaceae), which are commonly employed in the Kurdish traditional medicine, we have analyzed, for the first time, the methanol and aqueous methanol extracts of T. parviflorum aerial parts. The plant is mainly used by Kurds to treat jaundice, liver disorders and stomachache. We aimed to determine the phytochemical profile of the extracts and the structures of the main components, so to provide a scientific rationale for the ancient use of the plant in the ethno-pharmacological field. TLC analysis of the two extracts on silica gel and reversed phase TLC plates, using different visualization systems, indicated similar contents and the presence of phenolics, flavonoids, terpenoids and sugars. The chlorophyll-free extracts exhibited weak/no antimicrobial activities against a panel of bacteria (MICs = 800–1600 µg/mL) and fungal strains (MICs ≥ 5 mg/mL). At the concentration of 600 µg/mL, the methanol extract showed moderate antiproliferative effects against A549 and MCF-7 cancer cell lines in the MTS assay. Moreover, both extracts exhibited a significant dose-dependent free radical scavenging action against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical (EC₅₀ = 62.11 and 44.25 μg/mL, respectively). In a phytochemical study, a high phenolic content (77.08 and 81.47 mg GAE/g dry extract, respectively) was found in both extracts by the Folin–Ciocalteu assay. Medium pressure liquid chromatographic (MPLC) separation of the methanol extract on a reversed phase cartridge eluted with a gradient of MeOH in H₂O, afforded two bioactive iridoid glucosides, harpagide (1) and 8-O-acetylharpagide (2). The structures of 1 and 2 were established by spectral data, chemical reactions, and comparison with the literature. Interestingly, significant amounts of hepatotoxic furano neo-clerodane diterpenoids, commonly occurring in Teucrium species, were not detected in the extract. The wide range of biological activities reported in the literature for compounds 1 and 2 and the significant antiradical effects of the extracts give scientific support to the traditional use in Iraqi Kurdistan of T. parviflorum aerial parts for the preparation of herbal remedies. Full article

Linearolactone (LL) is a neo-clerodane type diterpene that has been shown to exert giardicidal effects; however, its mechanism of action is unknown. This work analyzes the cytotoxic effect of LL on Giardia intestinalis trophozoites and identifies proteins that could be targeted by this active natural product. Increasing concentrations of LL and albendazole (ABZ) were used as test and reference drugs, respectively. Cell cycle progression, determination of reactive oxygen species (ROS) and apoptosis/necrosis events were evaluated by flow cytometry (FCM). Ultrastructural alterations were analyzed by transmission electron microscopy (TEM). Ligand–protein docking analyses were carried out using the LL structure raised from a drug library and the crystal structure of an aldose reductase homologue (GdAldRed) from G. intestinalis. LL induced partial arrest at the S phase of trophozoite cell cycle without evidence of ROS production. LL induced pronecrotic death in addition to inducing ultrastructural alterations as changes in vacuole abundances, appearance of perinuclear and periplasmic spaces, and deposition of glycogen granules. On the other hand, the in silico study predicted that GdAldRed is a likely target of LL because it showed a favored change in Gibbs free energy for this complex. Full article

Dietary supplements based on Teucrium chamaedrys L. subsp. chamaedrys aerial parts were banned, due to the hepatotoxicity of furan-containing neo-clerodane constituents. Indeed, the plant leaf content in phenolic compounds could be further exploited for their antioxidant capability. Accordingly, bio-guided fractionation strategies have been applied, obtaining seven partially purified extracts. These latter were chemically investigated through 1D and 2D NMR techniques and tested for their antiradical, reducing and cytotoxic capability. Data acquired highlighted that, through a simple phytochemical approach, a progressive neo-clerodane depletion occurred, while maximizing phenylethanoid glycosides in alcoholic fractions. Thus, although the plant cannot be used as a botanical remedy as such, it is suggested as a source of healthy compounds, pure or in mixture, to be handled in pharmaceutical, nutraceutical and/or cosmeceutical sectors. Full article

An infusion prepared from the aerial parts of Salvia amarissima Ortega inhibited the enzyme protein tyrosine phosphatase 1B (PTP-1B) (IC₅₀~88 and 33 μg/mL, respectively). Phytochemical analysis of the infusion yielded amarisolide (1), 5,6,4′-trihydroxy-7,3′-dimethoxyflavone (2), 6-hydroxyluteolin (3), rutin (4), rosmarinic acid (5), isoquercitrin (6), pedalitin (7) and a new neo-clerodane type diterpenoid glucoside, named amarisolide G (8a,b). Compound 8a,b is a new natural product, and 2–6 are reported for the first time for the species. All compounds were tested for their inhibitory activity against PTP-1B; their IC₅₀ values ranged from 62.0 to 514.2 μM. The activity was compared to that of ursolic acid (IC₅₀ = 29.14 μM). The most active compound was pedalitin (7). Docking analysis predicted that compound 7 has higher affinity for the allosteric site of the enzyme. Gas chromatography coupled to mass spectrometry analyses of the essential oils prepared from dried and fresh materials revealed that germacrene D (15) and β-selinene (16), followed by β-caryophyllene (13) and spathulenol (17) were their major components. An ultra-high performance liquid chromatography coupled to mass spectrometry method was developed and validated to quantify amarisolide (1) in the ethyl acetate soluble fraction of the infusion of S. amarissima. Full article

Genus Stachys, the largest genera of the family Lamiaceae, and its species are frequently used as herbal teas due to their essential oils. Tubers of some Stachys species are also consumed as important nutrients for humans and animals due to their carbohydrate contents. Three new neo-clerodane diterpene peroxides, named stachaegyptin F-H (1, 2, and 4), together with two known compounds, stachysperoxide (3) and stachaegyptin A (5), were isolated from Stachys aegyptiaca aerial parts. Their structures were determined using a combination of spectroscopic techniques, including HR-FAB-MS and extensive 1D and 2D NMR (¹H, ¹³C NMR, DEPT, ¹H-¹H COSY, HMQC, HMBC and NOESY) analyses. Additionally, a biosynthetic pathway for the isolated compounds (1–5) was discussed. The chemotaxonomic significance of the isolated diterpenoids of S. aegyptiaca in comparison to the previous reported ones from other Stachys species was also studied. Full article

In this study, we isolated from the aerial parts of Baccharis conferta Kunth (i) a new neoclerodane, denominated “bacchofertone”; (ii) four known terpenes: schensianol A, bacchofertin, kingidiol and oleanolic acid; and (iii) two flavonoids: cirsimaritin and hispidulin. All structures were identified by an exhaustive analysis of nuclear magnetic resonance (NMR) and mass spectroscopy (MS). Extracts from aerial parts were screened for anti-inflammatory activity in the mice ear edema model of 12-O-tetradecanoylforbol-13-acetate mice. Dichloromethane extract (BcD) exhibited 78.5 ± 0.72% inhibition of edema, followed by the BcD2 and BcD3 fractions of 71.4% and 82.9% respectively, at a dose of 1 mg/ear. Kingidiol and cirsimaritin were the most potent compounds identified, with a median effective dose of 0.12 and 0.16 mg/ear, respectively. A histological analysis showed that the topical application of TPA promoted intense cell infiltration, and this inflammatory parameter was reduced with the topical application of isolated compounds. Full article

Scutellaria barbata (Lamiaceae) is an important medicinal herb widely used in China, Korea, India, and other Asian countries. Neo-clerodane diterpenoids are the largest known group of Scutellaria diterpenoids and show promising cytotoxic activity against several cancer cell lines. Here, Illumina-based deep transcriptome analysis of flowers, the aerial parts (leaf and stem), and roots of S. barbata was used to explore terpenoid-related genes. In total, 121,958,564 clean RNA-sequence reads were assembled into 88,980 transcripts, with an average length of 1370 nt and N50 length of 2144 nt, indicating high assembly quality. We identified nearly all known terpenoid-related genes (33 genes) involved in biosynthesis of the terpenoid backbone and 14 terpene synthase genes which generate skeletons for different terpenoids. Three full length diterpene synthase genes were functionally identified using an in vitro assay. SbTPS8 and SbTPS9 were identified as normal-CPP and ent-CPP synthase, respectively. SbTPS12 reacts with SbTPS8 to produce miltiradiene. Furthermore, SbTPS12 was proven to be a less promiscuous class I diterpene synthase. These results give a comprehensive understanding of the terpenoid biosynthesis in S. barbata and provide useful information for enhancing the production of bioactive neo-clerodane diterpenoids through genetic engineering. Full article