Isolation and Bioactivity of a Xanthone Glycoside from Peperomia pellucida

Patuloside A (3-β-D-glucopyranosyloxy-1,5,6-trihydroxy-9H-xanthene-9-one) is a xanthone glycoside isolated from Peperomia pellucida using chromatographic techniques (TLC, PTLC, GC) and the structure was confirmed on the basis of spectral data (liquid chromatography/electrospray-mass spectroscopy, 1H and 13C NMR including JMOD, COSY, NOESY, HMBC, HSQC). In vitro antibacterial, antifungal and cytotoxic activities of the compound were studied. Disc diffusion technique was used to determine in vitro antibacterial and antifungal activities. Cytotoxicity was determined against brine shrimp nauplii. In addition, minimal inhibitory concentration (MIC) was determined using serial dilution technique to find out antibacterial potency. The compound showed significant antibacterial activity against four Gram-positive bacteria (Bacillus subtilis, Bacillus megaterium, Staphylococcus aureus, Streptococcus β-haemolyticus) and six Gram-negative bacteria (Escheichia coli, Shigella dysenteriae, Shigella sonnei, Shigella flexneri, Pseudomonus aeruginosa, Salmonella typhi). The MIC values against these bacteria were ranged from 8 to 64 μg/mL. The compound showed weak antifungal activities against Aspergillus flavus and Candida albicans. In cytotoxicity determination, LC50 of the compound against brine shrimp nauplii was 18.24 μg/mL.