Comparative Phytochemical, Antioxidant and Antimicrobial Profiling of the Aqueous and Ethanolic extracts of Piper guineense (African Pepper) Fruit and Seed
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The relentless rise of multidrug-resistant pathogens, coupled with the deleterious health impacts of oxidative stress, has intensified the global search for novel, safe, and effective bioactive compounds from natural sources. Piper guineense (Schumach. and Thonn), (Family- Piperaceae) commonly known as African black pepper, West African black pepper, Ashanti pepper, or uziza is renowned for its rich phytochemical profiles and antimicrobial activities. The aim of this study was to access the phytochemicals, antioxidants and antimicrobial profiling of the aqueous and ethanolic extracts of Piper guineense fruit and seed. Samples of commercial Piper guineense fruits and seeds were sourced from Local Markets in Benin City and identified by lecturers in the Plant Biology and Biotechnology laboratory, University of Benin while the microbial isolates used were obtained from stock cultures of clinical isolates stored from cases of Nosocomial infections from University of Benin teaching Hospital (UBTH). The phytochemical, antioxidants and antimicrobial properties were assayed using standard methods. Also antimicrobial activities of the plant extracts were investigated using agar well diffusion methods. Data obtained for the different parameters were subjected to statistical analysis using the analysis of variance. The results of the qualitative phytochemical composition of ethanolic and aqueous extracts of P. guinense revealed the presence of alkaloids, flavonoids, phenols, saponins, terpenoids, glycosides and steroids were present in ethanolic and aqueous extracts of P. guinense while anthraquinones was present in ethanolic extract and absent in aqueous extract. The quantitative phytochemical composition of ethanolic and aqueous extracts of P. guinense shows that Saponins (10.05±1.05 mg/g) had the highest composition, followed by phenolics (8.51±2.56 mg/g) in aqueous extract while flavonoids (12.10±2.17 mg/g) had the highest composition in ethanolic extract of P. guinense.. Also, aqueous extract (22.82%) had the highest percentage yield compared to ethanolic extract (17.87%). Zone of inhibition of the aqueous fruit and seed extract of Piper guineense on bacterial isolates ranged from 6.6±1.6 - 12.9±1.1mm while zone of on fungal isolates ranged from 4.5±1.5 - 11.3±1.5 mm respectively. Zone of inhibition of the ethanolic fruit and seed extract of Piper guineense on bacterial isolates ranged from 6.6±1.6 - 23.5±1.6 mm while zone of on fungal isolates ranged from 3.5±1.6 - 21.5±2.5 mm respectively. The Minimum Inhibitory Concentration ranged from 0.9 – 8 mg/ml for aqueous extract and 0.9 - 8 mg/ml for ethanolic extract. Minimum Bactericidal/Fungicidal concentrations (MBCs/MFCs) in aqueous ranged from 4 – 12 mg/ml and 0.9 – 8 mg/ml for ethanolic extracts. DPPH for aqueous extract ranged from 0.756±0.66 (10 µg/mL) to 0.306±0.21 (200 µg/mL), ethanolic extract range from 0.623±0.31 (10 µg/mL) to 0.226±0.05 (200 µg/mL) compared to control (Ascorbic acid) which range from 0.421±0.13 (10 µg/mL) to 0.110±0.04 (200 µg/mL). Percentage inhibition of aqueous extract ranged from 13.5±0.41 (10 µg/mL) to 56.12±0.66 (200 µg/mL), ethanolic extract ranged from 17.65±0.41 (10 µg/mL) to 78.62±0.66 (200 µg/mL) while control (ascorbic acid) range from 49.81±0.11 (10 µg/mL) to 98.01±0.35 (200 µg/mL). ethanolic extract (262.2 ± 7.3 µmol Fe²⁺/g) had the highest reducing power compare to ethanol extract (133.6 ± 11.3 µmol Fe²⁺/g) when compared to control (ascorbic acid) 615.5 ± 10.6 7.3 µmol Fe²⁺/g. The antimicrobial and antioxidant activities observed in Piper guinense fruit and seeds aqueous and ethanolic extracts is due to the presence of phytochemicals. The use of Piper guinense in folk medicine is therefore recommended
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