Determination of Anti-tuberculosis activity of Psychotria sarmentosa, Aponogeton crispus and two species of Pleurotus mushrooms

Tuberculosis (TB) is a chronic disease caused by Mycobacterium tuberculosis (Mtb) complex. The global TB epidemic has been aggravated by the emergence of disease outbreaks caused by multi-drug resistant and extensively drug-resistant strains. The aim of the present study was to evaluate the in-vitro, anti-TB activity of leaves of Psychotria sarmentosa, Aponogeton crispus and the mushrooms Pleurotus ostreatus and Pleurotus cystidiosus found in Sri Lanka. Leaves of Psychotria sarmentosa, Aponogeton crispus and the mushrooms; Pleurotus ostreatus and P. cystidiosus were dried until a constant weight and 120 g each were taken to prepare crude extracts with distilled water (1.9 L) by heating at a moderate temperature and the final volume was reduced to 240 ml. Freeze dried aqueous extracts were incorporated in Middle Brook 7H11 medium (1mg/ml) using pour plate method.Two ten-fold dilutions (10-2 and 10-4) of standard H37Rv Mtb suspensions were inoculated on Middle Brook 7H11 media with the crude extracts. The plates were incubated at 37 0C for 4 weeks until visible appearance of Mtb colonies. The inhibitory effect of each extract was calculated by the mean reduction of number of colonies on extract containing medium compared to extract-free control medium. Accordingly, the highest mean percentage inhibition was shown by P. sarmentosa (71.0 %). The mean percentage inhibition exerted by A. crispus, P. ostreatus and P. cystidiosus were 46.0 %, 43.4 % and 39.5 % respectively. Therefore, freeze-dried aqueous extract from leaves of P. sarmentosa has certain activity against the tested standard mycobacterial strain and has a potential to be used as an anti-TB drug component.