Phytochemical, Antioxidant and Antimicrobial Activity of Ethanol and Aqueous Stem Extracts of Pseudocedrela kotschyi

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Pharmaceutical Journal of Kenya


Introduction: Secondary plant metabolites found in medicinal plants have been known to have antimicrobial activity against a wide range of microorganisms including orodental, respiratory and urinary pathogens. Aim: The aim of this research was to evaluate the phytochemical, antioxidant and antimicrobial activity of aqueous and ethanol stem extracts of Pseudocedrela kotschyi (Pk), a plant of use in folklore medicine, against dental and other community acquired infections caused by pathogens, so as to validate some of its therapeutic claims. Methodology: The plant metabolites were extracted (cold maceration method) using distilled water and 70 % ethanol for aqueous and ethanol extract respectively. Preliminary phytochemical screening was carried out on the extracts to determine various secondary metabolites. Total flavonoid and phenolic contents were determined using Folin-Ciocalteu’s reagent and colorimetric aluminium chloride method respectively. The antimicrobial activity was investigated using agar well diffusion method. The antioxidant activity was assayed using 2,2-diphenyl-1-picryl hydrazyl (DPPH), 2,20-azinobis-(3-ethylbenzothiazoline- 6-sulphonate) (ABTS+) and ferric reducing antioxidant power (FRAP). Results: Both the aqueous and ethanol extract were found to contain alkaloids, flavonoids, saponin, cardiac glycosides, steroids, terpenoids, carbohydrates, phenols and tannins. The flavonoid and phenolic contents in both aqueous and ethanol stem extracts of Pk was found to be 0.099 ± 0.01 and 0.399±0.0 mg/mL quercetin equivalent and 0.48±0.00 and 1.38±0.01mg/g gallic acid equivalent respectively. The zones of inhibition were found to be from 3-20mm and 4-18mm for the ethanol and aqueous extracts respectively. The standards cultures were highly susceptible to the two extracts while the clinical isolates were mostly resistant. The DPPH and percentage ABTS•+ scavenging activity was found to be highest at 0.0312 and 0.0625 mg/mL, 0.5 and 0.25 mg/ mL for the aqueous and ethanol extract respectively. The percentage FRAP activity was highest at 0.50 mg/mL for both extracts. Conclusion: This research confirms the presence of phytochemicals responsible for antioxidant and antimicrobial activity against orodental, respiratory and urinary pathogens. It was found that ethanol extract of Pk inhibited 80% of the pure isolates of bacterial strains under investigation while the aqueous extract inhibited less than 70% of the same organisms.



Pseudocedrela kotschyi, antimicrobial, antioxidant, chewing stick, ethanol and aqueous extract