RESUMO
AIMS: The aim of this study was to investigate the antimicrobial activities of Etlingera pubescens, and to isolate and identify the antimicrobial compound. METHODS AND RESULTS: The crude extracts of E. pubescens were obtained through methanol extraction, and evaluated for antimicrobial activities. From this extract, 1,7-bis(3,4-dihydroxyphenyl)heptan-3-yl acetate (etlingerin) was isolated. When compared to curcumin (a compound with a similar chemical structure), etlingerin showed twofold lower minimum inhibitory concentration values while also being bactericidal. Through time kill assay, etlingerin showed rapid killing effects (as fast as 60 min) against the Gram-positive bacteria (Staphylococcus aureus ATCC 43300 and Bacillus subtilis ATCC 8188). Further assessment revealed that etlingerin caused leakage of intracellular materials, therefore suggesting alteration in membrane permeability as its antimicrobial mechanism. Cytotoxicity study demonstrated that etlingerin exhibited approximately 5- to 12-fold higher IC50 values against several cell lines, as compared to curcumin. CONCLUSIONS: Etlingerin isolated from E. pubescens showed better antibacterial and cytotoxic activities when compared to curcumin. Etlingerin could be safe for human use, though further cytotoxicity study using animal models is needed. SIGNIFICANCE AND IMPACT OF THE STUDY: Etlingerin has a potential to be used in treating bacterial infections due to its good antimicrobial activity, while having potentially low cytotoxicity.
Assuntos
Antibacterianos/farmacologia , Antibacterianos/toxicidade , Diarileptanoides/farmacologia , Diarileptanoides/toxicidade , Bactérias Gram-Positivas/efeitos dos fármacos , Zingiber officinale/química , Animais , Antibacterianos/efeitos adversos , Antibacterianos/isolamento & purificação , Bornéu , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Células Cultivadas , Curcumina/farmacologia , Diarileptanoides/efeitos adversos , Diarileptanoides/isolamento & purificação , Humanos , Testes de Sensibilidade Microbiana , Permeabilidade/efeitos dos fármacos , Extratos Vegetais/química , Extratos Vegetais/farmacologiaRESUMO
PURPOSE: Chlorella vulgaris (CV), a fresh water alga has been reported to have hypoglycemic effects. However, antioxidant and anti-inflammatory effects of CV in diabetic animals have not been investigated to date. The aim of the present study was to investigate the role of CV in inflammation and oxidative damage in STZ-induced diabetic rats. MATERIALS AND METHODS: Male Sprague-Dawley rats (300 - 400g) were divided into 4 groups: control, CV, STZ-induced diabetic rats, and STZ rats treated with CV (150mg/kg body wt). Blood samples were drawn from orbital sinus at 1 and 4 weeks for determination of oxidative cellular damage (DNA damage and lipid peroxidation [malondialdehyde, MDA]), inflammation (tumour necrosis factor alpha, TNF-α) and antioxidant status (catalase, CAT, and superoxide dismutase, SOD). RESULTS: CV did not have any effects on glucose levels in diabetic rats, over the 4 weeks of treatment. However, it reduced significantly DNA damage and blood MDA levels in STZ-induced diabetic rats compared to the control group. Plasma levels of TNF-α however did not show any significant changes in STZ-induced diabetic rats fed with CV. Antioxidant enzyme SOD showed no significant changes in all groups but CAT activity was reduced in STZ-induced diabetic rats compared to the control. CONCLUSIONS: CV did not have hypoglycaemic effect but it has a protective role in STZ-induced diabetic rats by reducing oxidative DNA damage, and lipid peroxidation.