The pathological manifestation of various diseases can be suppressed by the activation of nuclear factor erythroid 2 p45-related factor 2 (Nrf2), a transcriptional regulator of the cellular redox balance. Haberlea rhodopensis Friv. is a resurrection plant species endemic for Bulgaria, containing biologically active phenylethanoid glycosides that might possess antioxidant or redox activity. This study aimed to analyze the metabolic profile of in vitro cultured H. rhodopensis and to identify molecules that increase Nrf2 expression in bone marrow neutrophils. Fractions B, D, and E containing myconoside, or myconoside and calceolarioside E in ratios 1:0.6 and 0.25:1 were found to be the most active ones. Fraction B (200 µg/mL) improved neutrophil survival and strongly increased the Nrf2 intracellular level, while D and E, as well as, myconoside and calceolarioside E at the same ratios had a superior effect. Calceolarioside E (32 µg/mL) had stronger activity than myconoside, the effect of which was very similar to that of 2-cyano-3,12-dioxo-oleana-1,9(11)-dien-28-oic acid methyl ester (CDDO-Me), used as a positive control. These data indicate that both molecules, used alone or in combination have stimulatory activity on the endogenous Nrf2 level, indicating their therapeutic potential to regulate the cellular redox homeostasis oxidative stress-associated pathologies.

Natural deep eutectic solvents (NADES) have been developed in order to replace traditional volatile and toxic organic solvents for the extraction of biologically active substances from natural sources. Recent research has shown that NADES are able to retain and even improve the antioxidant properties of the molecules dissolved in them. The aim of the present study was to evaluate the antioxidant activity of the extracts of two medicinal plants, Plantago major and Sideritis scardica, and of propolis with 10 different NADES. The results obtained confirm that NADES extracts of medicinal plants and propolis have a good antioxidant potential, allowing obtaining natural antioxidants without the application of organic solvents. Because of the biocompatibility and low toxicity of the NADES, the opportunity to apply these extracts directly in formulations, such as cosmetics, food supplements, etc., seems promising.

Scrophularia aestivalis Griseb. is a Balkan endemic species whose phytochemical composition and medicinal properties have not been previously investigated. The therapeutic potential of Scrophularia species has attracted considerable attention, resulting in extensive studies on their chemical and pharmacological properties, with over 200 secondary metabolites identified to date. The present study aimed to explore the phytochemical composition of Bulgarian-origin S. aestivalis, including isolation and characterization of individual secondary metabolites. From methanol extract of the plant’s aerial parts, aucubin, harpagide, 8-O-acetylharpagide, cis- and trans-harpagoside, 6-O-methyl catalpol, acylated derivatives of catalpol, and linarin were isolated and identified. The anti-obesity activity of the extract and primary fractions was evaluated in a Caenorhabditis elegans model of obesity. Significant lipid-reducing activity was demonstrated in four fractions, indicating promising anti-obesogenic properties. Following chemical profiling and quantitative analysis, the main components of the most active fractions were identified, namely the cis- and trans-harpagoside isomers. Subsequent experiments demonstrated that treatment with harpagoside reduced lipid accumulation and improved mitochondrial function in glucose-supplemented worms, with the data suggesting potential involvement of the SKN-1 signaling pathway.