Antioxidant and antiglycation properties of different solvent extracts from Chinese olive (Canarium album L.) fruit.

OBJECTIVE: To evaluate the antioxidant activity, antiglycation property, and bioactive components content of different solvent extracts from Chinese olive (Canarium album L.) fruit. METHODS: The dry powder of Chinese olive fruit was extracted with different solvents, i.e., water, water/ethanol (1/1, v/v), ethanol, methanol, acetone and ethyl acetate. The total phenolic, total flavonoids and total triterpenoids contents of various extracts were determined by spectrophotometric methods. Phenolic compounds were identified by high performance liquid chromatography. The assayed antioxidant activity was determined in vitro models such as antioxidant capacity by radical scavenging activity using 2,2'-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), 1,1-diphenyl-2-picryl- hydrazyl (DPPH) and nitrite oxide methods, chelating activity on metal ions, lipid and protein peroxidation methods. In vitro glucose-bovine serum albumin assay was used to evaluate the antiglycation of various extracts. RESULTS: The water/ethanol extracts of Chinese olive fruit exerted significant scavenging effects on free radicals and strong inhibitory effects on advanced glycation end products formation. The Chinese olive fruit extracts were rich in phenolic compounds and triterpenoids. Gallic acid, ferulic acid and rutin were identified from the water/ethanol extracts. Correlation analysis indicated that there was a linear relationship between the antioxidant potency, free radical scavenging ability and phenolic compounds content of the Chinese olive fruit extracts. CONCLUSIONS: Chinese olive fruit could be a natural candidate for studies of dietary complement to diabetes treatment since it combines antioxidant and antiglycation activities.

Effects of hospital generic drug substitution on diabetes therapy.

OBJECTIVES: To evaluate the effects on physicians' prescribing behavior and on the therapeutic outcome of non-insulin-dependent diabetes patients of substituting different generic brands of metformin. METHODS: We adopt a retrospective cohort study involving 280 type-2 diabetes patients who regularly used the outpatient services of one medical center and who had changed metformin brands five times between 2003 and 2008. The aim was to examine the effects of switching brands. The generalized estimating equation was used to determine whether drug brand switching affected patient glycated hemoglobin A1c (HbA1c) levels, their prescribed daily dose, or their adherence to medication with metformin. RESULTS: HbA1c levels increased from 7.91 to 8.34 throughout the study period, although it was found that brand switching did not adversely affect HbA1c levels after controlling for patient characteristics and the time course of the study. Furthermore, the prescribed daily dose of metformin was stable throughout the study period, and was approximately 0.8 of the defined daily dose. Finally, although adherence was significantly higher with the original metformin than with the four generic brands, patients still maintained high levels of adherence of >0.8. CONCLUSION: Although switching between different brands of metformin slightly affected the prescribing behavior of the physicians, there was no unfavorable effect on patient HbA1c levels. Thus, the policy of substituting between different generic brands of metformin is a good cost-effective approach that does not adversely affect the quality of diabetes patient care.

Optimization of a natural medium for cellulase by a marine Aspergillus niger using response surface methodology.

The components of a natural medium were optimized to produce cellulase from a marine Aspergillus niger under solid state fermentation conditions by response surface methodology. Eichhornia crassipes and natural seawater were used as a major substrate and a source of mineral salts, respectively. Mineral salts of natural seawater could increase cellulase production. Raw corn cob and raw rice straw showed a significant positive effect on cellulase production. The optimum natural medium consisted of 76.9 % E. crassipes (w/w), 8.9 % raw corn cob (w/w), 3.5 % raw rice straw (w/w), 10.7 % raw wheat bran (w/w), and natural seawater (2.33 times the weight of the dry substrates). Incubation for 96 h in the natural medium increased the biomass to the maximum. The cellulase production was 17.80 U/g the dry weight of substrates after incubation for 144 h. The natural medium avoided supplying chemicals and pretreating substrates. It is promising for future practical fermentation of environment-friendly producing cellulase.

Induction of apoptosis by the Lactuca indica L. in human leukemia cell line and its active components.

Lactuca indica L. (Compositae family) is used as a folk medicine in anti-inflammatory, antibacterial, antidiabetic, and other medications in Asia. The objectives of this study were to evaluate the antiproliferative effect of ethanol extracts of Lactuca indica L. (EEL) on human leukemic HL-60 cell lines and its active components. The results showed that EEL exhibited strong cytotoxic effects against HL-60 cells; the IC50 value was 313 microg/mL. Flow cytometric analysis of the externalization of phosphatidylserine (PS) using the annexin V/PI method on EEL-treated HL-60 cells showed a concentration-dependent increase of apoptosis. Moreover, EEL could induce typical DNA fragmentation in a concentration- and time-dependent manner as determined by electrophoresis and TUNEL assays. The treatment of HL-60 cells with EEL induced significant accumulation of cells in the G0/G1 phase, indicating that EEL is a cell-cycle-dependent anticancer agent. Our results also indicate that EEL-induced apoptosis in HL-60 cells is associated with the loss of mitochondrial membrane potential (delta psi m). EEL contains 5% phenolic compounds, such as quercetin, caffeic acid, rutin, and chlorogenic acid. Among the four active phenolic compounds, quercetin was found to be the most effective in inhibition against cell viability and in alteration of mitochondrial function. Our results suggest that the induction of apoptosis by EEL might offer a pivotal mechanism for its chemopreventive action.

Evaluation of antioxidant activity and inhibitory effect on nitric oxide production of some common vegetables.

The objectives of this study were to study the antioxidant activities and nitric oxide (NO) scavenging effects of vegetables in vitro systems and to study the inhibitory effects of vegetables on the NO production and NO-induced DNA damage in RAW 264.7 macrophage. The results indicated that water extracts from Indian lotus, Jew's ear, shiitake, eggplant, and winter mushroom showed stronger antioxidant activity and free-radical-scavenging ability than that of other vegetable extracts. The scavenging effects of vegetable extracts on NO derived from sodium nitroprusside (SNP) were in decreasing order of water spinach > Indian lotus > eggplant and garland chrysanthemum. In the macrophage model system, the water extracts from fresh daylily flower, sponge gourd, pea sprout, and eggplant exhibited over 80% inhibition on NO generation stimulated by lipopolysaccharide. The extract from fresh daylily flower that expressed the strongest inhibition on NO production was attributed to the ability to reduce the inducible nitric oxide synthase (iNOS) induction. However, the extracts from pea sprout and eggplant suppressed the NO production by scavenging on NO and inactivating toward iNOS enzyme. In addition, the water extracts from fresh daylily flower, sponge gourd, pea sprout, and eggplant also showed over 40% inhibitory effect on DNA damage induced by SNP in RAW 264.7 macrophage. The data also indicated that eggplant and pea sprout extracts contained higher total phenolic compounds, anthocyanins, and ascorbic acids and appeared to be responsible for their antioxidant activities and scavenging effects on NO derived from SNP.

Antioxidant activities of phenolic acids on ultraviolet radiation-induced erythrocyte and low density lipoprotein oxidation.

The exposure of mammalian cells to UV light induces various deleterious responses. Some of the major harmful effects are DNA damage, cell membrane peroxidation, systemic immune suppression, and aging acceleration. Reactive oxygen species and free radicals are believed to be largely responsible for some of the deleterious effects of UV upon cells. Typical administration of antioxidants has recently proved to represent a successful strategy for protecting the cells against UV-mediated oxidative damage. The objective of this study was to investigate the inhibitory effect of phenolic acids (caffeic acid, ferulic acid, gallic acid, and protocatechuic acid) on oxidative damage in human erythrocytes and low-density lipoprotein (LDL) induced by UVB radiation. The results revealed that the thiobarbituric acids reactive substances induced by UVB were decreased from 2.78 to 0.12-0.89 nmol MDA/mg protein in erythrocyte ghost and from 0.72 to 0.14-0.43 nmol MDA/mg protein in LDL by the addition of phenolic acids (100 muM). Caffeic acid, ferulic acid, and gallic acid exhibited over 85 and 60% inhibitory effect toward UVB-induced oxidation in erythrocytes and LDL, respectively. Phenolic acids, especially gallic acid, could maintain the normal glutathione levels and glutathione peroxidase activity in hemolysate from erythrocytes that were exposed to UVB radiation in comparison with untreated control. The results indicate that the antioxidant activities of caffeic acid and ferulic acid play a potential role in protection against UVB oxidative damage to human erythrocytes and LDL.

Comparison of Antimutagenic Effect of Various Tea Extracts (Green, Oolong, Pouchong, and Black Tea).

The antimutagenic effects of various tea extracts prepared from nonfermented tea (green tea), semifermented tea (oolong tea and pouchong tea), and fermented tea (black tea) were investigated by Salmonella/microsome assay. No mutagenicity or toxicity in Salmonella typhimurium TA98 and TA100 was observed with any tea extract. The tea extracts markedly inhibited the mutagenicity of 2-amino-3-methylimidazo(4,5-f)quinoline, 3-amino-1,4-dimethyl-5H-pyridol(4,3-b)indole,2-amino-6-methyldipyrido(l,2-a:3',2'-d)imidazole, benzo[a]pyrene, and aflatoxin B1 toward S. typhimurium TA98 and TA100 in the presence of S9 mixture, especially those of oolong and pouchong teas inhibited over 90% mutagenicity of these five mutagens at the dosage of 1 mg per plate. Among four tea extracts, black tea exhibited the weakest inhibitory effect on mutagenicity of these five mutagens. The mutagenicity of 4-nitroquinoline-N-oxide, a direct mutagen, was not inhibited by black and oolong tea extracts to S. typhimurium TA98 in the absence of S9 mixture but was increased by the tea extracts at the dose of 1 mg per plate to S. typhimurium TA100. As the antimutagenic effect of semifermented tea was stronger than nonfermented and fermented teas, some antimutagenic substances might be formed during manufacturing processes of tea.