Antioxidative-, Antimicrobial-, Enzyme Inhibition-, and Cytotoxicity-Based Fractionation and Isolation of Active Components from Monotheca buxifolia (Falc.) A. DC. Stem Extracts

The current study elaborates the pharmacological potential of the methanolic extract and its fractions of the stems of Monotheca buxifolia based on thin-layer chromatography and column chromatography analyses, exploiting biological and phytochemical assays. The results suggest that bioassay-guided isolation and fractionation led to the accumulation of biologically active components in the most active fractions that resulted in the isolation of different compounds. Structural elucidation of the purified compounds was accomplished using spectroscopic one-dimensional (¹H, ¹³C) and two-dimensional NMR (heteronuclear multiple quantum coherence, heteronuclear multiple bond coherence, and correlation spectroscopy) and spectrometric (electron ionization mass spectrometry and high-resolution electron ionization mass spectrometry) techniques. The n-hexane, CHCl₃, and EtAOc fractions led to the isolation of lupeol from different fractions. 1-Triacontanol was also isolated from the n-hexane fraction, while benzoic acid, methyl benzoate, ursolic acid, and 3-hydroxybenzoic acid were obtained from the EtOAc fraction. The compounds depicted good-to-moderate total antioxidative potential and total reducing power activity and significant free-radical scavenging activity. All the compounds showed significant urease and lipase inhibitory activity with poor-to-moderate amylase inhibition. Significant zone of inhibition was observed against different bacterial strains by the isolated compounds. This work therefore states that bioassay-guided isolation plays a vital role in the isolation of biologically active constituents that can be exploited for drug development.