Phytochemical Profiling and Broad-Spectrum Antimicrobial Potential of Meyna laxiflora Extracts against Bacterial and Fungal Pathogens

Abstract

Antimicrobial resistance poses a severe global public health threat, necessitating the discovery of novel bioactive agents from medicinal plants. Meyna laxiflora Robyns (Rubiaceae) is a wild edible ethnomedicinal plant traditionally utilized across India to manage infectious and inflammatory conditions. This study evaluated the qualitative phytochemical profile and broad-spectrum antimicrobial efficacy of fruit (MF), leaf (ML), and stem (MS) extracts of M. laxiflora prepared using solvents of varying polarity: methanol: water (9:1 v/v), ethanol: water (7:3 v/v), and dichloromethane:methanol (3:7 v/v). Qualitative screening identified flavonoids, tannins, phenolics, alkaloids, saponins, glycosides, terpenoids, and steroids across extracts. Antibacterial activity against Staphylococcus aureus (ATCC 5345) and Escherichia coli (ATCC 5346) and antifungal activity against Candida albicans were determined using the agar well diffusion method. Among the tested plant extracts, the methanol: water stem extract (MS1) demonstrated the highest antibacterial potency, generating mean inhibition zones of 17.56 ± 0.25 mm against E. coli and 17.48 ± 0.36 mm against S. aureus, compared to standard erythromycin (21.14 ± 0.31 mm and 22.36 ± 0.31 mm, respectively). For antifungal screening, extracts MS3, MF3, ML2, and ML3 exhibited marked inhibition against C. albicans (18.44 ± 0.31 to 18.86 ± 0.22 mm) compared to amphotericin B (22.12 ± 0.32 mm). One-way ANOVA and Tukey’s post-hoc tests revealed significant variations among extracts (p < 0.05), demonstrating that plant anatomical part and extraction solvent polarity critically govern antimicrobial potency. These findings validate the ethnomedicinal utility of M. laxiflora and underscore its potential as a sustainable natural source of therapeutic antimicrobial agents.