梵净山翠峰茶叶多酚含量测定

通过使用紫外分光光度法测定了梵净山翠峰茶叶多酚的含量,结果显示茶叶多酚的含量是21．45mg／mL,为贵州铜仁茶叶的综合利用提供了科学依据。     

不同工艺对茶多酚提取效率和质量的影响研究

本文比较分析了目前从茶叶中提取茶多酚的四种工艺的主要特点和不足,并比较了工艺条件对茶多酚的提取效率和质量的影响.结果表明,提取率较好,茶多酚含量较高是金属离子盐沉淀和树脂吸附茶多酚提取工艺.     

Extraction of DNA suitable for PCR applications from mature leaves of Mangifera indica L.

Good quality deoxyribonucleic acid (DNA) is the pre-requisite for its downstream applications. The presence of high concentrations of polysaccharides, polyphenols, proteins, and other secondary me- tabolites in mango leaves poses problem in getting good quality DNA fit for polymerase chain reaction (PCR) applications. The problem is exacerbated when DNA is extracted from mature mango leaves. A reliable and modified protocol based on the cetyl- trimethylammonium bromide (CTAB) method for DNA extraction from mature mango leaves is described here. High concentrations of inert salt were used to remove polysaccharides; Polyvinylpyrrolidone (PVP) and β-mercaptoethanol were employed to manage phenolic compounds. Extended chloroform-isoamyl alcohol treatment followed by RNase treatment yielded 950?1050 μg of good quality DNA, free of protein and RNA. The problems of DNA degradation,contamination, and low yield due to irreversible binding of phenolic compounds and coprecipitation of polysaccharides with DNA were avoided by this method. The DNA isolated by the modified method showed good PCR amplification using simple se- quence repeat (SSR) primers. This modified protocol can also be used to extract DNA from other woody plants having similar problems.     

Phenolic profile of jujube fruit subjected to gut microbiota fermentation and its antioxidant potential against ethyl carbamate-induced oxidative damage

Objective: To evaluate the composition of bioactive substances and the antioxidant effects of jujube fruit under gut microbiota fermentation(GMF), and the inhibitory effect on cytotoxicity caused by ethyl carbamate(EC). Methods: Changes in the contents of flavonoids, polyphenols, total sugars, and reducing sugars of jujube fruit after GMF(0, 2, 6, 12, 24, and 48 h)were determined. The oxidation resistance of fermented jujube fruits(from 0 to 48 h fermentation) was evaluated using in vitro2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate)(ABTS) and ferric reducing antioxidant power(FRAP) assays. Inhibitory effects of 48 h-fermented jujube fruit at various concentrations(0.25, 0.50, 1.00, and 2.00 mg/m L) on EC-treated toxicity and DNA damage of Caco-2 cells were estimated using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2 H-tetrazolium bromide(MTT)and nuclear staining assays, respectively. Effects of different concentrations of jujube fruit on EC-treated Caco-2 cells' intracellular reactive oxygen species(ROS), glutathione(GSH) levels, and mitochondrial membrane potential(MMP) were also evaluated. Results: Jujube fruit has rich bioactive components after GMF and shows strong antioxidant capacity. Fermented jujube fruit can inhibit the cytotoxicity and DNA damage of Caco-2 cells caused by EC and reduce intracellular ROS generation, as well as restoring GSH and MMP. Conclusions: Fermented jujube fruit extracts produced by GMF still contain biologically active substances which retain biological activity and antioxidation capabilities.