Isolation and investigation of anti-tubercular ilicic acid from Sphaeranthus indicus against Mycobacterium tuberculosis H37Rv and MDR strains

The global burden of tuberculosis, particularly multidrug-resistant (MDR) strains of Mycobacterium tuberculosis, necessitates the urgent development of novel and effective therapeutic agents. Natural products derived from plants have long served as an essential resource for drug discovery, offering structurally diverse bioactive compounds. Sphaeranthus indicus, a plant traditionally valued for its medicinal properties, has shown promise as a source of antimicrobial agents. This study evaluated the antimycobacterial potential of S. indicus extracts and the isolated compound ilicic acid against M. tuberculosis H₃₇Rv and MDR isolates. Hexane, chloroform, and methanol extracts were screened using the microbroth dilution assay, with the hexane extract demonstrating superior activity (MIC: 125 μg/mL) against the H₃₇Rv strain. Purification of the hexane extract led to the isolation of ilicic acid, which exhibited significant antimycobacterial activity, inhibiting H₃₇Rv at 125 μg/mL. Against MDR isolates, ilicic acid displayed MIC values of 500 μg/mL for isolate 1, 125 μg/mL for isolate 2, and 250 μg/mL for isolate 3. These findings underscore the therapeutic potential of ilicic acid as a lead compound for developing anti-TB drugs, especially against drug-resistant strains. The study highlights S. indicus as a valuable source for discovering novel antimycobacterial agents, contributing to global efforts to combat TB resistance.