Determination of antioxidant activities of different extracts of (Nepeta nuda subsp. lydiae) which grows in Turkey naturally and analysis of phenolic contents by using LC-MS/MS

The antioxidant activities of ethanol and water extracts of Nepeta nuda subsp. lydiae leaves were determined by different in vitro methods such as; DPPH, ABTS, FRAP and CUPRAC assays. The results were compared to BHA, BHT and ascorbic acid as standard antioxidant compounds. Both water and ethanol extracts presented moderate antioxidant potential on DPPH free radical scavenging assay and CUPRAC assay. Also, both extracts presented low level on ABTS and FRAP assays. Also, the antimicrobial activity of Nepeta nuda subsp. lydiae was determinated by the disc diffusion method. In this study, the extract of Nepata nuda subsp. lydiae was showed the highest antibacterial activity against the B. megaterium. At the same time the lowest antibacterial activity was showed against P. aeruginosa and K. pneumoniae. The extract of Nepata nuda subsp. lydiae showed the highest antifungal activity against C. albicans but it did not show any significant antifungal activity against Y. lipolytica and S. cereviciae. In another step of this study, phenolic compounds of Nepeta nuda subsp. lydiae leaves were identified by LC-MS/MS. Chlorogenic acid, rosmarinic acid, coumaric acid and quinic acid, were found to be the most abundant compounds in the methanol extract of N. nuda subsp. lydiae, among the twenty-seven compounds studied by LC–MS/MS. Also, smaller amounts of kaempferol, p-coumaric acid, tr-caffeic acid, apigenin, luteolin and rhamnetin were identified, quantitatively. In conclusion, leaves of N. nuda subsp. lydiae have high potential of phenolic contents that mainly attributed with biological activities. Key words: Antioxidant activity, Antimicrobial activity, Nepeta nuda, Phenolic compound, Radical scavenging.