Intrinsic activity of aqueous leaf extract of Cymbopogon citratus against plasmodium-mediated tropical disease
Objective: To investigate the intrinsic activity (efficacy) of aqueous leaf extract of Cymbopogon (C.) citratus against malaria, a plasmodium-mediated tropical disease. Materials and Methods: Plasmodium (P.) falciparum culture samples from 20 symptomatic adult outpatients were subjected to the antimalarial in vitro test. Parasite quantification by optical microscopy in the performance of in vitro antiplasmodial assays was employed. Roswell Park Memorial Institute (RPMI) 1640 was used as culture medium for cultivation of P. falciparum. Negative control was culture medium with the malarial parasites while treated drug was the leaf extract of C. citratus dissolved in dimethylsulphoxide (DMSO) and prepared into 7 levels concentration (3.125, 6.25, 12.5, 25, 50, 100 and 200 mg/mL.) After culture synchronized with sorbitol 5%, micromalarial culture were divided into control and treated groups then incubated in CO2 candle jar at 370C for 72 h. Each 8 h, the percentage of parasitemia were measured giving the activity of the extract on the growth stages of P. falciparum. Parasitemia was estimated by making the thin blood smear from the erythrocytes layer and stained with Giemsa (10%) for 30 mins. Using probit analysis, the antimlarial activity of the extract was calculated by counting the fifty percent of growth inhibition 50 (IC50). Results: The extract inhibited the growth of P. falciparum on mature schizont stage. The fifty percent inhibitory concentration (IC50) of the extract was 3.9 after 32 h incubation. Conclusion: The leaf extract of C. citratus has efficacious antimalarial effect against P. falciparum in vitro.
Optimization of fermentation conditions for the production of 2,3-butanediol by Klebsiella pneumonia ZH-1 using response surface methodology
[Background] It has been studied that the yield of 2,3-butanediol (2,3-BD) producing strains is low and does not meet the requirements of industrial production of 2,3-BD. [Objective] It was important to improve the production of 2,3-BD by Klebsiella pneumonia ZH-1 in shaking flask. [Methods] The effects of temperature, pH and rotating speed on the production of 2,3-BD were studied by single factor test and response surface method. [Results] The optimal cultivation conditions stimulating the maximal production of 2,3-BD were as follow: initial pH, 7, temperature, 37 oC and rotating speed, 140 r/min. Under this optimized conditions, the predicted maximal 2,3-BD yield was 21.54 g/L, whereas the yield of 2,3-BD can reach to 22.04 g/L after the application of response surface methodology. [Conclusion] Response surface methodology was a promising method for optimization of 2,3-BD production.
