ABSTRACT
Objective: To evaluate the antimalarial activity of the ethylacetate and butanol fractions of Combretum nigricans (C. nigricans) leaf extract in mice. Methods: C. nigricans solvent (butanol and ethylacetate) fractions were screened for their phytochemical constituents using standard procedures illustrated by Harborne and Evans. The Peters' 4-day suppressive test against early malaria infection, Rane's curative test against established malaria and prophylactic test for residual activity were employed for evaluating the antimalarial potential in mice. Results: The phytochemical screening revealed the presence of alkaloids, terpenoids, saponins, and flavonoids in both fractions at different intensity. Both fractions exhibited significant antimalarial activity in all test models (P<0.05). The ethylacetate fraction of C. nigricans had better chemosuppressive and curative effects compared to the butanol fraction, which however, elicited a better chemoprophylactic effect. The chemosuppressive effect of C. nigricans ethylacetate fraction (200-800 mg/kg) was 77.6%, 69.1% and 86.1%; curative effect was 62.3%, 71.3% and 72.4%; while the chemoprophylactic activity was 32.1%, 48.6% and 61.2% respectively. C. nigricans butanol fraction (200-800 mg/kg) had 40.3%, 54.1% and 69.1% chemosuppression; 26.2%, 36.9% and 34.5% curative effect; and 48.4%, 70.0% and 87.4% chemoprophylaxis. Conclusions: Both solvent fractions of C. nigricans possess antimalarial activity, and may be useful at different stages of malaria therapy.
ABSTRACT
Aims: To investigate the variation in the activities of some soil enzymes and microbial respiration during phytoremediation of crude oil polluted agricultural soil. Study Design: Indigenous plants of a crude oil polluted agricultural farmland were harvested and identified. Two species (Schwenkia americana L. and Spermacoce ocymoides Burm. f.) were selected for this study. Nursery was set up using sterile soil and mature and viable seeds of selected species, and germinated seedlings were transplanted into an 8 kg potted homogenised polluted soil for remediation. Place and Duration of Study: Polluted agricultural soil from Ogoniland Nigeria, University of Port Harcourt ecological garden, between May 2017 and February 2018. Methodology: Protease activity was determined based on the amino acids released after incubation of soil with sodium caseinate. Phosphatase activities determination was based on determining the degradation extent of ρ-nitrophenol phosphate (PNPP) by the samples. Dehydrogenase activity was determined based on estimation of 2,3,5- triphenyltetrazolium chloride (TTC) reduction to triphenyl formazan (TPF) in soils after incubation. The substrate induced method was adapted to estimate the respiratory activity. Organic matter was determined by weight loss on ignition method. Results: Dehydrogenase activities in remediated groups increased after 4 weeks but decreased at the end of the remediation period. Protease and phosphatase activities, and soil organic matter of remediated groups reduced over time while the soil microbial respiratory activity reduced at the end of 12 weeks remediation. There was a restoration of the polluted soils by the treatments towards normalcy with regards to activities of proteases, acid and alkaline phosphatases, and dehydrogenases. Conclusion: Soil microbial activities can reflect soil quality, and soil enzyme activities can directly reflect the metabolic need and nutrient availability of soil microorganisms. The extracellular enzymes (protease, dehydrogenase, acid and alkaline phosphatase) were shown to vary with crude oil pollution relative to time thus indicating ameliorative effects.