Preliminary Phytochemical Screening, GC-MS analysis and Comparative In- Vitro Antibacterial Evaluation of Three Terminalia Species (T. alata, T. arjuna, and T. bellirica) from the Eastern Ghats, India

Abstract The genus Terminalia (Combretaceae) includes ecologically and ethnomedicinally significant deciduous trees, long used in Indian traditional medicine for cardiovascular, hepatic, and antimicrobial purposes. This study evaluated three sympatric species, i.e., Terminalia alata Heyne ex Roth, Terminalia arjuna (Roxb. ex DC.) Wight & Arn., and Terminalia bellirica (Gaertn.) Roxb were collected from the Paderu forest region, Alluri Sitharama Raju District, Andhra Pradesh, India. Shade-dried bark powder was sequentially Soxhlet-extracted using five solvents of increasing polarity: methanol, acetone, ethyl acetate, petroleum ether, and water. Qualitative phytochemical screening confirmed terpenoids, phenols, and flavonoids in polar extracts of all species, with T. arjuna showing the broadest metabolite profile (eight classes, including alkaloids, cardiac glycosides, and saponins). Antibacterial activity was assessed by cup-plate agar diffusion against two Gram-positive (Bacillus subtilis, Streptococcus mutans) and two Gram-negative (Escherichia coli, Pseudomonas fluorescens) bacteria at 10, 5, and 2.5 mg doses, revealing clear dose-dependence. Methanol and ethyl acetate extracts were most active: the T. alata methanol extract inhibited B. subtilis by 22 mm, and the T. bellirica ethyl acetate extract inhibited S. mutans by 22 mm (both at 10 mg), compared with 32–43 mm for streptomycin (positive control). Benzene and aqueous extracts showed zones ≤10 mm or no inhibition. GC-MS profiling of the three most active extracts tentatively identified species-specific compounds, including a Maillard-derived pyranone (DDMP) and 5-hydroxymethylfurfural in T. bellirica, in free arabinose and an aliphatic diol in T. arjuna, and an imide/malonate-ester pair in T. alata.