Screening of Thamnolia vermicularis var. subuliformis for antimicrobial, antioxidant and cytotoxic activities
Thamnolia vermicularis (Icmadophilaceae) has commonly been used as a tea with the local name of „snow tea“ in some part of China, where this species of lichens is also used as food  and for the treatment of psychic disorders, high blood pressure and inflammatory conditions of the respiratory tract . In this study, T. vermicularis var. subuliformis is collected in Serbia and chloroform, ethyl acetate and methanol extracts of this lichen were studied for the antioxidant, antimicrobial and cytotoxic activities. The antimicrobial activity of the extracts were tested against twelve human and plant pathogenic bacteria using a disc-diffusion method, and the minimum inhibitory concentration (MIC) values of each active extract were determined. The inhibition zones and minimal inhibitory concentration (MIC) values of bacterial strains were in the range of 10–42mm and 50–300µg/ml, respectively. Furthermore, the extracts scavenged 1,1-diphenyl-2-picrylhydrazyl radical (DPPH.), resulting in IC50 >50µg/ml. All the extracts showed moderate antioxidant activity comparable with BHT. Viability HeLa cells treated with the ethyl acetate and chloroform extracts of T. vermicularis var. subuliformis decreased with increasing concentrations of these extracts. IC50 value after 24 hours for the ethyl acetate extract was 162.50±5.80µg/ml, while for the chloroform extract this value was 159.32±5.16µg/ml. All the tested concentrations of the ethyl acetate and chloroform extracts after 72 hours of treatment of HeLa cells showed a cytotoxic effect. The methanolic extract containing the lowest content of baeomycesic and squamatic acid showed the lowest activity.
Acknowledgements: Ministry of Science and Environment of the Republic of Serbia (Grant No. 142025).
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