Antimicrobial studies of rhizome of Swertia petiolata

Swertia petiolata is used as folkore medicine in the treatment of skin diseases and mental disorders, ulcers, liver disorder and as bitter tonic, febrifuge, anthelmintic, antimalarial and antidiarrheal. Extracts of Swertia petiolata were prepared by soxhlet method. Dilutions were made in DMSO and subjected to antimicrobial activity by using agar well diffusion method, plate count agar (PCA) plates were inoculated with 100μl of each pathogenic microorganism adjusted to standardized inoculum (1.5 × 108 CFU/ml) in triplicates and spread with sterile swabs. After incubation for 24 hrs at 37 °C, the plates were observed. The zone of inhibition was measured and expressed in millimeters. Whereas the standard antibiotics; cefutaxim and amoxicillin showed antimicrobial activity with zones of inhibition ranging from > 15 mm to 10-15 mm. The hydro methanol extract showed excellent activity against Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis = 10-15mm), Gram-negative bacteria (Escherichia coli = 10-15 mm). However chloroform and petroleum ether extracts did not show significant antibacterial activity reflected by >4mm (gram +ve) and 5-10 mm (Gram-ve) and >4 mm (Petroleum ether extract). Phytochemical analysis of the extract showed the presence of steroids, tannins, phenolics, saponins, alkaloids, flavonoids and glycosides. From the study, it can be concluded that Swertia petiolata possesses significant antimicrobial activity which might be due to the presence of any/all these active constituents.