Bioactive compounds fractionated from endophyte Streptomyces SUK 08 with promising ex-vivo antimalarial activity

Objective: To determine ex vivo antimalarial activity and cytotoxicity of endophytic Streptomyces SUK 08 as well as the main core structure fractionated from its crude extract.Methods: The activities of SUK 08 crude extract were evaluated by using the Plasmodium lactate dehydrogenase assay and synchronization test against rodent malaria parasite Plasmodium berghei, instead of human malarial parasite Plasmodium falciparum. The cytotoxicity of the crude extract was determined by MTT assay. The crude extract was analyzed by thin-layer chromatography and gas chromatography–mass spectrophotometry.Results: The ethyl acetate crude extract showed very promising antimalarial activity with IC50 of 1.25 mg/m L. The synchronization tests showed that ethyl acetate extraction could inhibit all stages of the Plasmodium life cycle, but it was most effective at the Plasmodium ring stage. On the basis of a MTT assay on Chang Liver cells, ethyl acetate and ethanol demonstrated IC50 values of >1.0 mg/m L. The IC50 of parasitemia at 5% and30% for this extract was lower than chloroquine. Thin-layer chromatography, with 1: 9 ratio of ethyl acetate: hexane, was used to isolate several distinct compounds. Based on gas chromatography–mass spectrophotometry analysis, three core structures were identified as cyclohexane, butyl propyl ester, and 2,3-heptanedione. Structurally, these compounds were similar to currently available antimalarial drugs.Conclusions: The results suggest that compounds isolated from Streptomyces SUK 08 are viable antimalarial drug candidates that require further investigations.

Clonal distribution and possible micro evolution of methicillin-resistant Staphylococcus aureus strains in a teaching hospital in Malaysia

Objective:To genotypically characterize methicillin-resistant Staphylococcus aureus(MRSA)strains isolated from medical and surgical wards in Universiti Kebangsaan Malaysia Medical Centre(UKMMC)in 2009.Methods:MRSA strains were collected and molecularly typed by pulsed-field gel electrophoresis(PFGE).Results:PFGE typing on 180 MRSA isolated in UKMMC identified 5 pulsotypes(A-E)and 6 singletons,where pulsotypes B and C were suspected to he divergent clones originating from a single ancestor.This study also showed that most MRSA strains were isolated from swab(119 isolates),followed by blood(22 isolates),tracheal aspirate(11isolates)and sputum(10 isolates).On the other hand,urine and bone isolates were less,which were 4 and 1 isolates,respectively.The distribution of different pulsotypes of MRSA among wards suggested that MRSA was communicated in surgical and medical wards in UKMMC,with pulsotype B MRSA as the dominant strain.Besides,it was found that most deceased patients were infected by pulsotype B MRSA,however,no particular pulsotype could be associated with patient age,underlying disease,or ward of admittance.Conclusions:Five pulsotypes of MRSA and 6singletons were identified,with pulsotype B MRSA as the endemic strains circulating in these wards,which is useful in establishment of preventive measures against MRSA transmission.