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.
Keywords: Haberlea rhodopensis; NMR; Nrf2; calceolarioside E; myconoside; phenylethanoids.