Antimicrobial and Antioxidant Xanthone Derivative from Piliostigma thonningii leaf

Antimicrobial resistance and oxidative stress-related pathologies have guided the scientific community into the pursuit of natural product based research. The study aim to isolate and characterize antimicrobial and antioxidant compound(s) from the leaves of Piliostigma thonningii. Bioactivity-guided fractionation was carried out with the structure of the isolated compound elucidated using 1H and 13C NMR as well as liquid chromatography coupled mass spectrometry (LC-MS). The isolated compound was screened against standard bacteria strains of Staphylococcus aureus and Pseudomonas aeruginosa as well as fungal strains of Candida albicans and Aspergillus niger using agar well diffusion method. The inhibitory zone diameter (IZD) were determined and compared with reference antimicrobial ciprofloxacin and miconazole. The free radical scavenging activity in comparison with the ascorbic acid standard was performed using the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay. The compound (8-hydroxyl-2,4,5-trimethoxyxanthone)  displayed a lower antimicrobial and antioxidant activities in comparison to the positive standard employed. However, despite lower effect of the compound, this work opens the perspective to use this molecule as 'leads' for the design of novel and selective drug candidates of pharmaceutical relevance.