Evaluation of antioxidant potential of medicinal plants from Malaysian Rubiaceae (subfamily Rubioideae)

This paper evaluates the antioxidant potential of 22 species of medicinal plants from Malaysian Rubiaceae. The ferric thiocyanate (FTC), thiobarbituric acid (TBA), total phenolic content (TPC) and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays were employed. The tested extracts showed strong antioxidant potential when compared to butylated hydroxytoluene (BHT), quercetin and vitamin E with percent inhibition of 91 - 99% in the FTC, and 77 - 97% in the TBA assays. The TPC of extracts found varied from 8.55 to 120.63 mgGAE/gPE. Psychotria griffithii and Hydnophytum formicarum showed total phenolic content of more than 100 mgGAE/gPE and strong DPPH radical-scavenging activity with IC50 values of 14.0 and 22.4 μg/ml, respectively. The standard vitamin C and BHT showed IC50 values of 12.8, and 5.6 mg/ml, respectively. A good correlation was observed between total phenolic content and radical-scavenging activities. The medicinal plants in this study tested are expected to be good sources of natural antioxidants.Keywords: Antioxidant, Rubiaceae, ferric thiocyanate (FTC), thiobarbituric acid (TBA), 1,1-diphenyl-2-picrylhydrazyl (DPPH), total phenolic content (TPC

Metabolic alteration in obese diabetes rats upon treatment with Centella asiatica extract

Ethnopharmacological relevance ‘Pegaga’ is a traditional Malay remedy for a wide range of complaints. Among the 'pegaga’, Centella asiatica has been used as a remedy for diabetes mellitus. Thus, we decided to validate this claim by evaluating the in vivo antidiabetic property of C. asiatica (CA) on T2DM rat model using the holistic 1H NMR-based metabolomics approach. Method In this study, an obese diabetic (mimic of T2DM condition) animal model was developed using Sprague–Dawley rats fed with a high-fat diet and induced into diabetic condition by the treatment of a low dose of streptozotocin (STZ). The effect of C. asiatica extract on the experimental animals was followed based on the changes observed in the urinary and serum metabolites, measured by 1H NMR of urine and blood samples collected over the test period. Results A long-term treatment of obese diabetic rats with CA extract could reverse the glucose and lipid levels, as well as the tricarboxylic acid cycle and amino acid metabolic disorders, back towards normal states. Biochemical analysis also showed an increase of insulin production in diabetic rats upon treatment of CA extract. Conclusion This study has provided evidence that clearly supported the traditional use of CA as a remedy for diabetes. NMR-based metabolomics was successfully applied to show that CA produced both anti-hyperglycemic and anti-hyperlipidemic effects on a rat model. In addition to increasing the insulin secretion, the CA extract also ameliorates the metabolic pathways affected in the induced diabectic rats. This study further revealed the potential usage of CA extract in managing diabetes mellitus and the results of this work may contribute towards the further understanding of the underlying molecular mechanism of this herbal remed

Investigation of cell parameters, microstructures and electrochemical behaviour of LiMn2O4 normal and nano powders.

Nano materials are usually difficult to prepare. This work presents a simple way of preparing LiMn2O4 nano powders using the high-energy ball milling method. This method has the advantage of producing pure, single-phase and crystalline nano powders. The milling method is carefully controlled to avoid unwanted chemical reactions that may change the stoichiometry of the material. Nano powders of between 30 and 50 nm are obtained. Structural studies of the nano powders, as well as the more-conventional micron-sized LiMn2O4, are made using X-ray diffraction and neutron diffraction methods. Electrochemical evaluation of the materials is undertaken with a three-probe cyclic voltammetry technique and galvanostatic charge-discharge measurements. Structural studies reveal that not only are the crystallites of the nano powders much reduced in size from the normal powders, but their cell parameters are also smaller. The performance characteristics of the nano material show an improvement over that of the micron-sized material by about 17% in the 1st cycle and 70.6% in the 5th cycle, at which the capacity is 132 mAh g(-1). The normal material suffers from severe capacity fading but the nano material shows much improved capacity retention. © 2008, Elsevier Ltd