PHYTOCHEMICALS AND ANTIMICROBIAL POTENCY OF LEAVES EXTRACTS OF UZIZA LEAF (Piper guineense) AND LEMON GRASS (Cymbopogen citratus) AGAINST CLINICAL ISOLATES

Medicinal plants have long been recognized for their therapeutic properties and remain an essential source of bioactive compounds with potential antimicrobial activity. The growing problem of antibiotic resistance has heightened global interest in exploring natural plant extracts as alternative or complementary agents against infectious diseases. This study evaluated the phytochemical composition and antimicrobial potential of lemongrass (Cymbopogon citratus) and uziza leaf (Piper guineense) extracts against selected bacterial and fungal pathogens. Fresh leaves of both plants were collected from local markets in Benin City, Edo State, Nigeria, authenticated, air-dried, pulverized, and extracted using ethanol and water. Phytochemical screening revealed the presence of alkaloids, flavonoids, tannins, terpenoids, and saponins in varying concentrations. Lemongrass contained high levels of alkaloid, flavonoids and tannins, while uziza exhibited moderate presence of these compounds. Saponin was present in lemongrass but absent in uziza. Antimicrobial testing showed that ethanolic extracts demonstrated superior activity compared to aqueous extracts. The ethanolic extract of lemongrass exhibited the highest inhibition zone of 20 mm against S. aureus and 15 mm against E. coli at 100% concentration, while the uziza ethanolic extract produced inhibition zones of 18 mm and 15 mm, respectively, against the same organisms. Pseudomonas sp. showed moderate sensitivity with inhibition zones of 12 mm, whereas fungal isolates Aspergillus sp., Penicillium sp. and Fusarium sp. recorded inhibition zones ranging from 10 to 15 mm. The minimum inhibitory concentration (MIC) for ethanolic extracts ranged from 50 mg/mL for S. aureus, E. coli and Pseudomonas sp. to 100 mg/mL (for fungal isolates), while minimum bactericidal concentrations (MBCs) were observed at 100 mg/mL. Aqueous extracts displayed weaker activity, requiring higher concentrations (100 mg/mL) for inhibition and showing little or no effect on fungal isolates. Overall, these findings highlight the significant antimicrobial potential of lemongrass and uziza leaf extracts, particularly their ethanolic forms, which exhibited notable inhibitory effects against common bacterial pathogens. The results support their traditional medicinal use and underscore their potential as natural sources of plant-based antimicrobial agents.