Bioactivity-Guided Isolation of Flavone Glycoside from Terminalia catappa: Evaluating Anti-MRSA and...

Antibiotic resistance is one of the major threats to public health in the twenty-first century. In this line of work, plants represent a priceless source of antimicrobial compounds since they house chemically different metabolites with a wide range of therapeutic applications. This study reports the bioactivity-guided fractionation, characterization, and evaluation of the efficacy of antimicrobial compounds from leaf acetone extracts of the traditional medicinal plant Terminalia catappa against bacterial clinical isolates and dermatophytes. The acetone extract of T. catappa was subjected to column chromatography for the separation and purification of the phytocompounds. The fractions were analyzed using a thin-layer chromatography-bioautography assay to detect the antimicrobial potency of the eluted compounds. The efficacy of the antimicrobial compounds was evaluated by the minimum inhibitory concentration, minimum bactericidal concentration, and minimum fungicidal concentration. Spectral characterization and structure elucidation of the compound were also achieved. The leaf acetone extract, when subjected to gradient elution by column chromatography, resulted in eight fractions. The fraction Fr-2 was subjected to thin-layer chromatographic elution, which resulted in the elution of phytocompound with Rf value of 0.50 and the phytocompound exhibited antimicrobial activity in the TLC-bioautography assay, and it was isolated in pure form and confirmed as Apigenin 7-O-ß-D-glucopyranoside. The compound exhibited significant inhibition of the clinical isolate Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus 1503 at 9.5 µg/mL. Dermatophytes, viz., Microsporum gypseum and Microsporum canis, were inhibited at 312 µg/mL. The present study successfully achieved the bioactivity-guided isolation and characterization of the flavone compound Apigenin 7-O-ß-D-glucopyranoside from T. catappa. Furthermore, the plant T. catappa represents a promising candidate for the exploration of antimicrobial compounds that could serve as potential plant-derived lead molecules for antimicrobial agents.