Phytochemical Composition and Biological Activities of Philippine Premna serratifolia L. Crude and Solvent-Partitioned Leaf Extracts

Abstract

Premna serratifolia L. is a medicinal plant widely used in traditional medicine, known for its diverse pharmacological properties. This study evaluated the phytochemical composition, antioxidant, antibacterial, and antiurolithiatic activities of the crude methanolic extract and solvent-partitioned fractions—hexane (HXE), ethyl acetate (EAE), and aqueous (AQE)—of P. serratifolia leaves. Phytochemical screening and FTIR revealed the presence of flavonoids, terpenoids, naphthoquinones, and saponins in varying amounts across fractions. For antioxidant activity, the AQE exhibited the highest DPPH-radical scavenging activity (IC₅₀ = 297.6 ppm) and a total antioxidant activity of 1461.3 mg ascorbic acid equivalent (AAE)/g extract. Antibacterial activity evaluated using the Kirby–Bauer disk diffusion method showed all extracts inhibited Bacillus cereus and Staphylococcus aureus, with EAE producing the largest zones of inhibition (13-14 mm). EAE exhibited MIC values of 312.5 ± 0.0 µg/mL against Bacillus cereus and 625 ± 0.0 µg/mL against Staphylococcus aureus. TLC-agar-overlay bioautography localized the antibacterial activity of the EAE to relatively polar constituents. Antiurolithiatic activity was determined using an in vitro calcium oxalate nucleation assay. Among the extracts tested, only the HXE significantly inhibited calcium oxalate crystal formation, exhibiting more than 80% inhibition during the initial stages of crystallization and reducing crystal density and size under microscopic examination. The results highlight the potential of P. serratifolia L. as a source of bioactive compounds for the development of antioxidant, antibacterial, and antiurolithiatic agents.