Determination of biological activities and phenolic contents of Dactylorhiza romana Subsp. georgica tubers spreaded in the natural flora of Gümüşhane

Kelkit District of Gümüşhane Province is considered to be one of the important plant areas due to the variety of plants present in the district. Different plant species belonging to the Orchidaceae family show intense distribution in this region. In particular, the tubers of Dactylorhiza romana subsp. georgica commonly used by the local population to alleviate many diseases by conventional methods. In this study, it is aimed to enlighten the biological activities and phenolic content of this plant used by local people and thus to evaluate its traditional use from a biotechnological point of view. For this purpose, total phenolic and flavonoid content, total antioxidant capacity, antioxidant activity of the tuber extracts prepared with solvents with different polarities (chloroform, ethyl acetate, methanol, ethanol and hexane) were determined by spectrophotometric methods and phenolic content by HPLC analysis. In addition, the antimicrobial activity of the extracts against 13 microorganisms including 3 Gram (+), 3 Gram (-) bacteria and 7 fungi (2 yeast, 5 mold) were determined by disk diffusion and microdilution methods. To the highest total phenolic content (29.15±0.24 mg GAE/g extract), total flavonoid content (6.97±0.25 mg QE/g extract), ABTS radical scavenging activity (89.49±0.83 mg AAE/g extract, 50.17±0.96 mg TE/g extracts), DPPH radical scavenging activity (9.02±0.01 mg AAE/g extract, 12.58±0.08 mg TE/g extract) were observed in the ethyl acetate extracts. There was a correlation between total phenolic and flavanoids of the tuber extracts and antioxidant capacity results. Nine of the twenty phenolic components scanned were detected in the ethyl acetate extract that has the highest phenolic content. The highest phenolic component amount was detected as benzoic acid (1455.3 µg/g extract), well known for its antimicrobial activity. In the antimicrobial activity assays, the extracts did not show any inhibition against the molds used in the study. In the disc diffusion method, it was determined that the extracts used in the study formed a zone of inhibition against some bacteria and yeasts, whereas the extracts showed more antimicrobial activity than yeast species rather than bacteria. The lowest MIC value was found to be 0.5125 mg/ml for C. albicans and C. tropicalis in the chloroform extract and 0.5125 mg/ml for C. albicans in ethyl acetate extract. According to the results of this study, the tuber extracts of Dactylorhiza romana subsp. georgica are thought to have the potential to be used as a natural and alternative source in the food and pharmaceutical industries in the field of biotechnology due to their high biological activities. Key words: Antimicrobial activity, Antioxidant activity, Dactylorhiza romana subsp. georgica, Total phenolic, Total flavonoid