Phytochemical Profiling, Spectroscopic Characterization, and Antimicrobial Assessment of Piper guineense Seeds

Piper guineense is a perennial West African spice plant commonly known as Uziza, traditionally used for its medicinal and nutritional properties. This study investigates the phytochemical composition, spectroscopic characterization, and antimicrobial activity of Piper guineense seed extracts against selected clinical pathogens. Soxhlet extraction was performed using n -hexane, followed by phytochemical screening and compound quantification via Gas Chromatography–Flame Ionization Detection (GC-FID). Proximate analysis revealed a high carbohydrate content (54.92%), along with protein (10.5%), ash (14.65%), fiber (8.59%), fat (4.99%), and moisture (6.34%). Phytochemical profiling identified 19 secondary metabolites, with tannins (44.17 µg/mL) being the most abundant. The extract showed significant antimicrobial activity against Staphylococcus aureus , Salmonella enterica , Pseudomonas aeruginosa , Bacillus subtilis , Citrobacter murliniae , Bacillus licheniformis , and Micrococcus roseus , with mean inhibition zones ranging from 19.33 to 21.67 mm. Minimum inhibitory concentrations (MICs) ranged from 62.5 to 500 mg/mL. Spectroscopic structural elucidation using ¹H NMR, ¹³C NMR, Infrared (IR) spectroscopy, Mass Spectrometry (MS), and Elemental analysis confirmed the identity of the principal isolated compound as β-amyrin, a pentacyclic triterpenoid known for its broad pharmacological activities. These findings support the ethnomedicinal application of Piper guineense and highlight its potential as a source of lead compounds for developing novel antimicrobial agents.