Objective: In the present study, five new source compounds isolated from aerial parts of Gymnosporia royleana (G royleana) were screened for antibacterial and antifungal activities.
Methods: Extraction from plant material was carried out using cold maceration technique. Isolation of pure compounds was accomplished through repeated column chromatography of different fractions obtained from crude extract and using silica gel as stationary phase. Their structures were established via advanced spectroscopic techniques along with the spectral data previously reported for these compounds. Dilution method was used for the evaluation of antimicrobial potential of the compounds against various microbial strains.
Results: Among the tested compounds, Gymnosporin B displayed moderate antimicrobial activity against Escherichia Coli (E coli), Staphylococcus aureus (S aureus), Candida albicans (C albicans) and Aspergillus flavus (A flavus) [minimum inhibitory concentration (MIC) range; 32‒64 μg/mL]. Similarly, Gymnosporin C also showed moderate activity against E coli and S aureus (MIC; 32 μg/mL each) as well as weak activity against C albicans and A flavus (MIC; 64 μg/mL each). However, Royaflavone showed moderate antibacterial activity against S aureus only (MIC; 32 μg/mL). Antimicrobial activity of the rest of the compounds was weak and negligible.
Conclusion: The present study has provided fascinating results of antimicrobial activities of the isolated compounds. However, the broad antimicrobial spectrum of Gymnosporin B and Gymnosporin C demands for further exploration of these triterpenes, both on the basis of mechanism and quantitative structure-activity relationship.