ANTIMICROBIAL AND ANTIOXIDANT SYNERGY OF PSORALEA CORYLIFOLIA LINN. AND PLUMBAGO ZEYLANICA LINN.

Objectives: Psoralea corylifolia L.(seeds) and Plumbago zeylanica L. (bark) were combined in the ratio of 8: 2 and named as “Swithranasini” and used for the treatment of skin diseases in ayurvedic medicine. Scientific studies validating the therapeutic properties for this indigenous medicine are lacking. This study focused on determining antimicrobial efficacy of methanol and butter milk extracts along with antioxidant efficacies of these plant parts independently and in combination.

Materials and Methods: Antimicrobial activity was tested against seven pathogenic bacteria and six pathogenic fungiby measuring the zone of inhibition. In vitro antioxidant activities were assayed by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method and Ferric reducing antioxidant power (FRAP) method.

Results: Individual extracts of the two plants showed better zone of inhibition (12- 40 mm) when applied alone but the activity was more when applied in combination (18-50 mm) against the tested pathogens. DPPH activity of methanol extracts showed higher radical scavenging activity when compared with the positive control, ascorbic acid. The IC₅₀ values are 442.080, 457.825, 432.040 and 394.563 ug/ml for A, B, A+B and ascorbic acid respectively. The FRAP method also showed excellent antioxidant potential in combination (85.454 mg of Gallic acid equivalents/g) when compared with individual extracts A (78.571 mg GAE/g) and B (75.472 mg GAE/g).

Conclusion: The results validate the potent use of “Swithranasini” against skin infections and results are an evidence for the existence of synergism among the compounds.