Antimicrobial activity of green tea extract against isolates of methicillin-resistant Staphylococcus aureus and multi-drug resistant Pseudomonas aeruginosa

Objective:To evaluate antibacterial activity of the Indonesian water soluble green tea extract,Camellia sinensis,against clinical isolates of methicillin-resistantStaphylococcus aureus (S.aureus)(MRSA)and multi-drug resistant Pseudomonas aeruginosa(MDR-P.aeruginosa).Methods:Antimicrobial activity of green tea extract was determined by the disc diffusion method and the minimum inhibitory concentration(MIC)was determined by the twofold serial broth dilutions method.The tested bacteria using in this study were the standard strains and multi-drug resistant clinical isolates of S.aureus and P.aeruginosa,obtained from Laboratory of Clinical Microbiology,Faculty of Medicine,University of Indonesia.Results:The results showed that the inhibition zone diameter of green tea extracts forS.aureus ATCC 25923 and MRSA were(18.970依0.287)mm,and(19.130依0.250)mm respectively.While the inhibition zone diameter forP.aeruginosa ATCC 27853 and MDR-P.aeruginosawere(17.550依0.393)mm and(17.670依0.398)mm respectively.The MIC of green tea extracts againstS.aureus ATCC 25923 and MRSA were 400μg/mL and 400μg/mL,respectively,whereas the MIC for P.aeruginosa ATCC 27853 and MDR-P.aeruginosawere 800μg/mL,and 800μg/mL,respectively.Conclusions:Camellia sinensisleaves extract could be useful in combating emerging drug-resistance caused by MRSA andP.aeruginosa.

A new angiotensin-converting enzyme inhibitor from Peperomia pellucida(L.) Kunth

Objective:To isolate,identify,and evaluate a new angiotensin-converting enzyme inhibitor from Peperomia pellucida(L.)Kunth herbs.Methods:A dried sample of Peperomia pellucida herb was successively macerated with n-hexane and ethyl acetate.The ethyl acetate extract solution was evaporated to obtain the crude extract.Vacuum liquid column chromatography and thin layer chromatography were performed to obtain two pure compounds.Then,both compounds were elucidated and identified using the spectroscopic method.Angiotensin-converting enzyme inhibitory activity studies of both compounds were determined using angiotensin-converting enzyme kit WST-1 with spectrophotometer microplate reader 96-well at 450 nm wavelength.Results:Two bioactive compounds were successfully isolated from Peperomia pellucida herb,including a new compound of 2,3,5-trimethoxy-9-(12,14,15-trimethoxybenzyl)-1 H-indene and pellucidin A.Both compounds demonstrated angiotensin-converting enzyme inhibitory activity,with IC50 values of 72 μM(27.95 μg/mL)and 1 1μM(4.4 μg/mL),respectively.Conclusions:In the present study,two active angiotensin-converting enzyme inhibitors were successfully isolated and purified from Peperomia pellucida which is used as an antihypertensive in traditional medicine,and support its use as an angiotensin-converting enzyme-inhibiting drug.