Antiobesity effect of Tamarindus indica L. pulp aqueous extract in high-fat diet-induced obese rats.

Obesity and overweight are associated with atherosclerosis, fatty liver, hyperlipemia, diabetes mellitus, and various types of cancer. The global prevalence of overweight and obesity has reached epidemic proportions. Here, we investigated the effect of Tamarindus indica pulp aqueous extract (TIE) in diet-induced obese Sprague-Dawley rats. The animals were divided into five groups and labeled as follows: the normal control (NC) group received normal diet; the positive control (PC) group received high-fat diet; and the TIE 5, 25, and 50 groups, after the induction of obesity via a high-fat diet, received TIE at 5, 25, or 50 mg/kg orally for 10 weeks. It was observed that TIE decreased the levels of plasma total cholesterol, low-density lipoprotein (LDL), and triglyceride, and increased high-density lipoprotein (HDL), with the concomitant reduction of body weight. Moreover, TIE decreased plasma leptin and reduced fatty acid synthase (FAS) activity and enhanced the efficiency of the antioxidant defense system. TIE exhibits antiobesity effects, as indicated by a significant reduction in adipose tissue weights, as well as lowering the degree of hepatic steatosis in the obesity-induced rats. The extract possesses hepatoprotective activity, as it reversed the plasma liver enzymes level elevation prior to the high-fat diet. In conclusion, TIE improved obesity-related parameters in blood, liver, and adipose tissue in a rat model and suppressed obesity induced by a high-fat diet, possibly by regulating lipid metabolism and lowering plasma leptin and FAS levels. A dose-dependant effect of TIE is detected, where TIE at 50 mg/kg showed the most prominent effect, followed by TIE at 25 mg/kg and, subsequently, 5 mg/kg.

Systematic analysis of in vitro photo-cytotoxic activity in extracts from terrestrial plants in Peninsula Malaysia for photodynamic therapy.

One hundred and fifty-five extracts from 93 terrestrial species of plants in Peninsula Malaysia were screened for in vitro photo-cytotoxic activity by means of a cell viability test using a human leukaemia cell-line HL60. These plants which can be classified into 43 plant families are diverse in their type of vegetation and their natural habitat in the wild, and may therefore harbour equally diverse metabolites with potential pharmaceutical properties. Of these, 29 plants, namely three from each of the Clusiaceae, Leguminosae, Rutaceae and Verbenaceae families, two from the Piperaceae family and the remaining 15 are from Acanthaceae, Apocynaceae, Bignoniaceae, Celastraceae, Chrysobalanaceae, Irvingiaceae, Lauraceae, Lythraceae, Malvaceae, Meliaceae, Moraceae, Myristicaceae, Myrsinaceae, Olacaceae and Sapindaceae. Hibiscus cannabinus (Malvaceae), Ficus deltoidea (Moraceae), Maranthes corymbosa (Chrysobalanaceae), Micromelum sp., Micromelum minutum and Citrus hystrix (Rutaceae), Cryptocarya griffithiana (Lauraceae), Litchi chinensis (Sapindaceae), Scorodocarpus bornensis (Olacaceae), Kokoona reflexa (Celastraceae), Irvingia malayana (Irvingiaceae), Knema curtisii (Myristicaceae), Dysoxylum sericeum (Meliaceae), Garcinia atroviridis, Garcinia mangostana and Calophyllum inophyllum (Clusiaceae), Ervatamia hirta (Apocynaceae), Cassia alata, Entada phaseoloides and Leucaena leucocephala (Leguminosae), Oroxylum indicum (Bignoniaceae), Peronema canescens,Vitex pubescens and Premna odorata (Verbenaceae), Piper mucronatum and Piper sp. (Piperaceae), Ardisia crenata (Myrsinaceae), Lawsonia inermis (Lythraceae), Strobilanthes sp. (Acanthaceae) were able to reduce the in vitro cell viability by more than 50% when exposed to 9.6J/cm(2) of a broad spectrum light when tested at a concentration of 20 microg/mL. Six of these active extracts were further fractionated and bio-assayed to yield four photosensitisers, all of which are based on the pheophorbide-a and -b core structures. Our results suggest that the main photosensitisers from terrestrial plants are likely based on the cyclic tetrapyrrole structure and photosensitisers with other structures, if present, are present in minor amounts or are not as active as those with the cyclic tetrapyrrole structure.

Inhibitory effects of compounds from Zingiberaceae species on platelet activating factor receptor binding.

Ten compounds isolated from Alpinia mutica Roxb., Curcuma xanthorrhiza Roxb. and Kaempferia rotunda Linn. (Family: Zingiberaceae) were investigated for their platelet-activating factor (PAF) antagonistic activities on rabbit platelets using 3H-PAF as a ligand. Among them, four compounds showed significant inhibitory effects. Alpinetin and 5,6-dehydrokawain isolated from A. mutica exhibited IC50 values of 41.6 and 59.3 microM, respectively. The IC50 values of 3-deacetylcrotepoxide and 2-hydroxy-4,4',6'-trimethoxychalcone from K. rotunda were 45.6 and 57.4 microM, respectively. 1-Methoxy-2-methyl-5-(1',5'-dimethylhex-4'-enyl)-benzene, synthesized by methylation of xanthorrhizol which was obtained from C. xanthorrhiza, showed an IC50 value of 40.9 microM. The results indicated that these compounds were relatively strong PAF receptor binding inhibitors.

In vitro inhibitory effect of rubraxanthone isolated from Garcinia parvifolia on platelet-activating factor receptor binding.

Rubraxanthone and isocowanol isolated from Garcinia parvifolia Miq. were investigated for their inhibitory effects on platelet-activating factor (PAF) binding to rabbit platelets using 3H-PAF as a ligand. Rubraxanthone showed a strong inhibition with IC 50 value of 18.2 microM. The IC 50 values of macluraxanthone, 6-deoxyjacareubin, 2-(3-methylbut-2-enyl)-1,3,5-trihydroxyxanthone, 2-(3-methylbut-2-enyl)-1,3,5,6-tetrahydroxyxanthone and 1,3,5-trihydroxy-6,6'-dimethylpyrano(2',3':6,7)-4-(1,1-dimethylprop-2-enyl)-xanthone were also determined for comparison. In the course of our study on structure-activity relationship of xanthones, the results revealed that a geranyl group substituted at C-8 was beneficial to the binding while a hydroxylated prenyl group at C-4 resulted in a significant loss in binding to the PAF receptor.