Effect of extracts of Parquetina nigrescens (Afzel.) bullock on rat gastrointestinal microflora

Plants with antibacterial activity have gained increasing importance due to the development of antimicrobial drug resistance organisms and the occurrence of undesirable side effects of some antibiotics. This study is aimed at the evaluation of the in-vivo and in-vitro activities of water and ethanol extracts of Parquetina nigrescens (PN) on gastrointestinal microflora of small mammals. Twenty-one Wistar rats were grouped into 7 of 3 rats each. Group A serves as the control, the other groups were separately administered extract in the following ratio: Group B-50 mg/kg, Group C-100 mg/kg, Group D-200 mg/kg of aqueous extract respectively and Group E-50 mg/kg, Group F-100 mg/kg, Group G-200 mg/kg of ethanol extract respectively. The experiment was conducted for 21days. Caecum samples were collected and serially diluted in peptone water for microbial analysis. The mean total bacteria counts, Enterobacteriaceae and Lactobacilli counts showed a significant (p≤0.05) decrease in Group C (51.67 x 106 CFU/g, 41.67 x 106 CFU/g and 40.67 x 106 CFU/g), Group D (37.3 x 106 CFU/g, 34.3 x 106 CFU/g and 35.0 x 106 CFU/g), Group F (38 x 106 CFU/g, 34 x 106 CFU/g and 37.33 x 106 CFU/g) and Group G (37.0 .x 106 CFU/g, 25.33 x 106 CFU/g and 19.33 x 106 CFU/g) respectively when compared with the control (98.33 x 106 CFU/g, 57.33 x 106 CFU/g and 71.33 x 106 CFU/g). The in vitro analysis showed ethanol extracts exhibiting the highest inhibitory potentials (90%) on the isolated microorganisms, while the least effective (30%) was 50 mg/ml of the water extract. The phytochemical screening of Parquetina nigrescens showed the presence of anthraquinones, saponins, phlobatannis, ascorbic acid, alkaloids, flavanoids and terpenoids