Phenolic and flavonoid compounds and antioxidant activity in flowers of nine endemic Verbascum species from Iran

BACKGROUND In this study, flowers of nine mullein species (Verbascum erianthum, V. songaricum, V. speciosum, V. szovitsianum, V. stachydiforme, V. sinuatum, V. haussknechtianum, V. cheirantifolium, and V. saccatum) were collected from Iran. The total flavonoid content (TFC), antioxidant activity, total carotenoid (TCC), beta-carotene content and the amount of phenolic compounds were determined in all of the collected mullein species. Quantitative analysis of phenolic compounds was performed using high-performance liquid chromatography with diode-array detection (HPLC-DAD). RESULTS Verbascum saccatum and V. songaricum, in particular, were found to be rich in total flavonoids and exhibited the highest antioxidant capacity. The HPLC-DAD analysis revealed that V. erianthum possessed the highest amount of caffeic acid (0.022 g kg(-1) DW), chlorogenic acid (2.649 g kg(-1) DW), p-coumaric acid (0.253 g kg(-1) DW), and apigenin (0.066 g kg(-1) DW). The highest gallic acid (0.134 g kg(-1) DW), rutin (5.254 g kg(-1) DW), quercetin (1.303 g kg(-1) DW), and cinnamic acid (1.031 g kg(-1) DW) content were observed in V. saccatum. Our results demonstrate the considerable variations in the TFC, antioxidant activity, TCC, and beta-carotene content among the mullein species. CONCLUSIONS The findings of this study provide useful information for breeding strategies, and for choosing the best species with high phenolic compound content to produce natural antioxidants for medical and pharmaceutical use. (c) 2021 Society of Chemical Industry.

Automated summary

The study revealed significant variations in TFC, antioxidant activity, TCC, and beta-carotene content among different mullein species. Verbascum saccatum and V. songaricum were found to be particularly rich in total flavonoids and exhibited the highest antioxidant capacity. The results provide valuable information for breeding strategies and selecting the best species with high phenolic compound content for producing natural antioxidants for medical and pharmaceutical use.