Determination of total phenolic and flavonoid contents, antioxidant and antimicrobial activities of some important salep orchids

ABSTRACT I n this study we evaluated the secondary metabolites, total phenolic (TPC) and flavonoid contents (TFC), antioxidant and antimicrobial activities of salep orchids, Anacamptis morio , Anacamptis pyramidalis , Neotinea tridentata , Ophrys mammosa , Ophrys lutea , and Ophrys speculum . DPPH free radical scavenging assay was used to determine the antioxidant activities of n -hexane, chloroform, methanol and water extracts of the plants. The antimicrobial activities were also determined by the Broth micro-dilution method. The extracts were studied for antimicrobial activity by the Minimum Inhibitory Concentration (MIC) approach against seven clinical pathogenic bacteria and two fungi. Phytochemical screening revealed that the presences of coumarins, flavonoids, flavanones, cardiac glycosides, proteins and quinones. The extracts had variable TPC and TFC, with values of 4.46 ± 0.19–45.83 ± 1.86 mg gallic acid equivalent/g dry weight and 0.67 ± 0.04–8.64 ± 0.37 mg quercetin equivalent/g dry weight respectively. O. speculum had the highest (35.12%) antioxidant activity, followed by O. mammosa (33.17%). Chloroform extracts of all species showed significant antioxidant and antimicrobial activity. These bioactivities of the chloroform extracts were positively associated with the total phenolic and flavonoid contents. The MIC concentrations ranged from 0.156–20 mg/mL. The present investigation shows that the extracts of these species, especially chloroform extracts, could be used as potential antioxidant and antimicrobial sources.