**1. Introduction**

Elder or black elder *(Sambucus nigra* L.) is a perennial, deciduous shrub or small tree with shallow roots, propagated by seed. The tree reaches up to 8–10 m in height and 20–30 cm in diameter. It blooms from May to June, depending on the altitude, with white-cream colored or greenish-yellow individual flowers gathered in flat, complex, umbrella-like umbels, approximately 10–20 cm in diameter, containing 3–5 small seeds. The blossoms are characterized by a fresh, intense, fruity-sweet aroma.

Black elderflower tea may help in a variety of cases, such as hoarse voice (dysphonia) and upper respiratory tract inflammation [1], hemorrhoids, ascites, high blood pressure, impotence, urinary tract inflammation, kidney and bladder inflammation, prostatitis, hematuria, shortness of breath (dyspnea), and obesity [2–4]. It has been found that elderflowers promote secretion from sweat glands, while elderberries stimulate renal activity. Up to this day, the blossoms of *Sambucus nigra* L. are used to treat diseases, such as fever, cold

**Citation:** Gentscheva, G.; Milkova-Tomova, I.; Nikolova, K.; Buhalova, D.; Andonova, V.; Gugleva, V.; Petkova, N.; Yotkovska, I.; Ivanova, N. Antioxidant Activity and Chemical Characteristics of *Sambucus nigra* L. Blossom from Different Regions in Bulgaria. *Horticulturae* **2022**, *8*, 309. https://doi.org/ 10.3390/horticulturae8040309

Academic Editor: Charalampos Proestos

Received: 7 March 2022 Accepted: 4 April 2022 Published: 6 April 2022

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and influenza infections [5]. In the composition of blossoms, a large number of bioactive ingredients can be found, including terpenes, sterols, polyphenols, proteins, vitamins and minerals [6–9].

The health benefits of different parts of the plant *Sambucus nigra* L. have been investigated by different authors [10,11] and the data are summarized in Table 1.

**Table 1.** Healing properties of *Sambucus nigra* L.


Polyphenolic compounds are chemical compounds with a positive effect on human health and various pharmacological effects: antiviral, antibacterial and anti-cancer functions [9]. Some publications have shown that elderflower extract contains bioactive compounds that are able to metabolize glucose and lipids, which leads to a reduction in fat accumulation [12,13]. Other studies have reported strong antimicrobial effects of elderflower on various nosocomial pathogens, especially on methicillin-resistant *Staphylococcus aureus* MRSA /clinically significant pathogen/ [14].

The healthy effects of *Sambucus nigra* L. on the human body based on the high antioxidants, bioactive flavonoids and phenolic acid content, mineral salts, and fibers, as well the aim to enrich a healthy diet with phytocomponents, motivates the research for the possibilities for inclusion of *Sambucus nigra* L. blossom in foods and beverages, as well its use in food supplements [15,16].

There are many studies on the bioactive compounds present in medical herbs; however, regarding the *Sambucus nigra* L. blossoms, the information is relatively insufficient. While the chemical composition of elderberries has been comprehensively studied and a lot of applications in pharmacy, in beverage production are known and food, there is still not enough information on leaves and blossoms from the Bulgarian region with respect to the bioactive compounds content. Given the above, our study focuses on the blossom of *Sambucus nigra* L. from four different regions in Bulgaria /Rhodopes, Plovdiv, Strandzha, and Dobrich/ and creating a profile of the chemical composition using spectrophotometric and HPLC methods to determine antioxidant activity, the content of carbohydrates, amino acids, total phenols and flavonoids.

### **2. Materials and Methods**

## *2.1. Plant Material*

Fresh blossoms of *Sambucus nigra* L. from different regions of Bulgaria (Strandzha, Plovdiv, the Rhodope Mountain and Dobrich region) were selected for this study. The blossom clusters of *Sambucus nigra* L. with attached leaves are harvested by cutting when the tree is in full bloom [17]. The intensive flowering period is in May–July, depending on the altitude of the region. The identification of plant material was performed in the Department of Plant and Fungal Diversity and Resources, Institute of Biodiversity and Ecosystem Research at the Bulgarian Academy of Sciences (IBER-BAS) in Sofia. The department's herbarium is the most representative source of information on the biological diversity of the flora of the Balkans and Bulgaria. It is registered in the Index Herbariorum as an internationally recognized Herbarium with the acronym SOM (Herbarium of Vascular Plants).
