Isolation, Structural Characterization, and Potent Leishmanicidal, Anti-Cancer, and Anti-Microbial Activities of a New Diosgenin Glycoside from Malvastrum coromandelianum

The ever-evolving microbes have posed serious threats to human health for the past couple of decades, which has left the synthetic antibiotics useless against certain microbes. This has led to a paradigm shift towards discovery of benign bioactive materials from natural sources, especially plants. Phytochemical studies were therefore carried out on Malvastrum coromandelianum, resulting in the isolation of a new diosgenin glycoside, salmanoside (1), along with two known metabolites, identified as digitonin (2) and 7-hydroxycoumarin (3). Compound 1 was found to be a significant inhibitor of Leishmania tropica promastigotes (IC₅₀ = 43.33 µM), validated by in silico studies. The compound also inhibited the “super bug”, Staphylococcus aureus (Zone of inhibition = 48.0 mm) and Proteus mirabilis (45.5 mm), much stronger than the standards, azithromycin and ciprofloxacin, along with inhibition of other bacterial strains. Moreover, the compound was also found to be a potent PC3 (IC₅₀ = 7.55 ± 0.92 µM), HeLa (IC₅₀ = 29.05 ± 0.25 µM), and 3T3 (IC₅₀ = 32.68 ± 1.35 µM) cancer cell lines inhibitor. Salmanoside (1) exhibited moderate antioxidant and enzyme inhibitory potential. In addition, compound 2 (IC₅₀ = 14.5 µM) and 3 (IC₅₀ = 12.73 µM) also exhibited strong Leishmanicidal activities. These results highlight the significant pharmacological potential of M. coromandelianum for further in-depth studies, in the quest for new and safer drugs.