Chemical composition and antioxidant activity of Borago officinalis L. leaf extract growing in Algeria

The aqueous and hydroalcoholic extracts of borage (Borago officinalis) leaves from Annaba region (Algeria) were preliminary analyzed for their phenolic profile (total phenolics, total flavonoids, total flavonols, total tannins and total anthocyanins). These extracts were evaluated for their antioxidant properties by different methods such as DPPH radical scavenging, test NBT and total antioxidant activity. The two extracts have exhibited a high antiradical capacity. Indeed, the ethanolic extract showed the lower IC50 values and the highest amount of phenolics (94.09 ± 1.72 mg gallic acid/g dry extract). Using LC-MS/MS analysis, it was possible to identify phenolic acids, flavonoids, sterol and for the first time oleuropein was identified in the aqueous extract of the plant. The obtained results have demonstrated that phenolic compounds are the major contributor to the antioxidant activity of plants.     

Preparation of Catechin Nanoemulsion from Oolong Tea Leaf Waste and Its Inhibition of Prostate Cancer Cells DU-145 and Tumors in Mice

Anti-cancer activity of catechin nanoemulsions prepared from Oolong tea leaf waste was studied on prostate cancer cells DU-145 and DU-145-induced tumors in mice. Catechin nanoemulsions composed of lecithin, Tween-80 and water in an appropriate proportion was prepared with high stability, particle size of 11.3 nm, zeta potential of −67.2 mV and encapsulation efficiency of 83.4%. Catechin nanoemulsions were more effective than extracts in inhibiting DU-145 cell growth, with the IC₅₀ being 13.52 and 214.6 μg/mL, respectively, after 48 h incubation. Furthermore, both catechin nanoemulsions and extracts could raise caspase-8, caspase-9 and caspase-3 activities for DU-145 cell apoptosis, arresting the cell cycle at S and G2/M phases. Compared to control, catechin nanoemulsion at 20 μg/mL and paclitaxel at 10 μg/mL were the most effective in reducing tumor volume by 41.3% and 52.5% and tumor weight by 77.5% and 90.6% in mice, respectively, through a decrease in EGF and VEGF levels in serum.     

Beneficial Effects of Green Tea Catechins on Female Reproductive Disorders: A Review

Tea is one of the most widely consumed beverages worldwide after water, and green tea accounts for 20% of the total tea consumption. The health benefits of green tea are attributed to its natural antioxidants, namely, catechins, which are phenolic compounds with diverse beneficial effects on human health. The beneficial effects of green tea and its major bioactive component, (−)-epigallocatechin-3-gallate (EGCG), on health include high antioxidative, osteoprotective, neuroprotective, anti-cancer, anti-hyperlipidemia and anti-diabetic effects. However, the review of green tea’s benefits on female reproductive disorders, including polycystic ovary syndrome (PCOS), endometriosis and dysmenorrhea, remains scarce. Thus, this review summarises current knowledge on the beneficial effects of green tea catechins on selected female reproductive disorders. Green tea or its derivative, EGCG, improves endometriosis mainly through anti-angiogenic, anti-fibrotic, anti-proliferative and proapoptotic mechanisms. Moreover, green tea enhances ovulation and reduces cyst formation in PCOS while improving generalised hyperalgesia, and reduces plasma corticosterone levels and uterine contractility in dysmenorrhea. However, information on clinical trials is inadequate for translating excellent findings on green tea benefits in animal endometriosis models. Thus, future clinical intervention studies are needed to provide clear evidence of the green tea benefits with regard to these diseases.     

Versatile chromatographic method for catechin determination in development of topical formulations containing natural extracts

Catechin is found in several natural sources, as Eugenia dysenterica and Syzygium cumini extracts. Its antioxidant and UV‐protective properties suggest a potential use in cosmetic and dermatological formulations. A simple analytical method capable of giving support to experiments performed along the development of topical formulations containing this natural substance (i.e. drug assay, skin permeation and stability studies), however, is still needed. Thus, this work aimed to develop and validate a selective HPLC method for catechin determination during the development of topical formulations. Separation was achieved using an RP‐C₁₈ column (300 × 3.9 mm; 10 μm), with a mobile phase of methanol–phosphoric acid 0.01 m (15: 85, v/v), a flow rate of 0.8 mL/min, temperature set at 40°C and UV detection at 230 nm. The method was linear in a range from 0.5 to 10.0 μg/mL (r = 0.9998), precise with an overall variation coefficient of 5.5% and accurate with catechin recovery from the skin layers >85%. Additionally, the method was sensitive (limit of detection, 0.109 μg/mL; limit of quantification, 0.342 μg/mL) and selective against plant extracts, skin matrices and formulation interferents, as well as catechin degradation products. It was also robust regarding both methodology parameters and analytical stability.     

Three new compounds from Sarcandra glabra

One new sesquiterpene lactone,1 α,8 α,9 α-trihydroxyeudesman-3(4),7(11)-dien-8 β,12-olide(1) and two new phenylpropanoidsubstituted catechin glycosides,glabraoside C(2) and glabraoside D(3) were isolated from the whole plant of Sarcandra glabra. Their structures were established by the analyses of spectral and chemical evidences.     

儿茶素-胞嘧啶分子间相互作用的密度泛函研究

采用密度泛函理论的B3LYP方法,在6-31+G*基组水平上研究了儿茶素-胞嘧啶分子间相互作用机制,得到稳定的儿茶素-胞嘧啶复合物11个.计算结果表明氢键对于复合物的稳定性起着重要的作用,并且当复合物形成2个或更多的氢键时,氢键的类型及强度共同决定着复合物的稳定性.我们还应用了分子中的原子(AIM)理论和自然键轨道(NBO)理论对这11种复合物中氢键的性质和特征进行了分析.通过研究发现,所有的氢键复合物进行基组重叠误差(BSSE)校正后的相互作用能为-17.35～-43.27kJ/mol,相互作用能主要由氢键所贡献.振动分析显示,氢键的形成使相对应键的对称伸缩振动频率减小,说明这些复合物中形成的氢键都是正常的红移型氢键,与实验结果相一致.     

Substituent and solvent effects on the structural bioactivity and anticancer characteristic of catechin as a bioactive constituent of green tea

In this study, quantum chemical calculations using density functional theory and 6‐311G (d) basis set have been applied to analyze the substituent effect on the electronic structural properties including thermochemical parameters as well as anticancer characteristics of catechin as a bioactive constituent of green tea. It has been found out that different substituents with two kinds of electron donating and electron withdrawing groups including ? NO₂, ? NH₂, ? Cl, ? OCH₃, and ? CH₃ leaded to different structural stabilities. The catechin with chloro substituents has been referred to the most stable catechin derivatives based on the minimum energy of investigated compounds. In this study, the calculated values have been compared in gas phase and different solvent media with a wide range of solvent dielectrics using the self‐consistent reaction field method with polarizable continuum model. Relative interaction energies between solute and solvent as well as dipole moment values have been analyzed. The results of solvent effect study revealed that the formation of hydrogen bonds accounts for the stabilization of catechin. These calculated data were found to be a logical way in predicting the relative stability of catechin derivatives and can be useful for drug design of anticancer drugs and would open a new door for the researchers who are interested in natural products. The results presented in this article will be helpful to improve existing model and will open up a whole new arena of study to understand the anticancer characteristic of these antioxidant drugs derived from natural products against the photosensitizing DNA damage induce by catechin extracts and enable a much clearer understanding of how anticancer drugs mediate their effects on the specific spot. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

对叔丁基杯[8]芳烃酯类衍生物的合成方法改进及其对酯型儿茶素的萃取性能

以酰氯为酰基化试剂,用三乙胺作缚酸剂和催化剂,制备了一系列对叔丁基杯[8]芳烃酯类衍生物(2a～2e),其结构经1H NMR, IR和元素分析表征.以2为萃取剂,考察了酯型儿茶素单体在二氯甲烷-水两相体系中的萃取分配行为.结果表明:2e的萃取效果最佳.     

Substitution pattern elucidation of hydroxypropyl Pinus pinaster (Ait.) bark polyflavonoid derivatives by ESI(−)‐MS/MS

The structure of condensed tannins (CTs) from Pinus pinaster bark extract and their hydroxypropylated derivatives with four degrees of substitution (DS 1, 2, 3 and 4) has been characterized for the first time using negative‐ion mode electrospray ionization tandem mass spectrometry (ESI(?)‐MS/MS). The results showed that P. pinaster bark CTs possess structural homogeneity in terms of monomeric units (C₁₅, catechin). The oligomer sizes were detected to be dimers to heptamers. The derivatives showed typical phenyl‐propyl ether mass fragmentation by substituent elimination (58 amu) and inherent C₁₅ flavonoid fissions. The relative abundance of the product ions revealed a preferential triple, tetra‐/penta‐ and octa‐ hydroxypropylation substitution pattern in the monomer, dimer and trimer derivatives, respectively. A defined order of –OH reactivity towards propylene oxide was established by means of multistage experiments (A‐ring ≥ B‐ring > C‐ring). A high structural heterogeneity of the modified oligomers was detected. Copyright © 2014 John Wiley & Sons, Ltd.     

高速逆流色谱分离同分异构体

应用高速逆流色谱法对同分异构体的分离纯化进行研究。实验结果表明,以正己烷-乙酸乙酯-水(体积比为1∶10∶10)为两相溶剂系统,上相为固定相,下相为流动相,进行二次高速逆流色谱分离,可从茶多酚中分离出g级的儿茶素同分异构体——(-)-表没食子儿茶素没食子酸酯(EGCG)和(-)-没食子儿茶素没食子酸酯(GCG),其高效液相色谱纯度均在98%以上。选择四氯化碳-氯仿-甲醇-水(体积比为7∶3∶7∶3)为溶剂系统,下相为固定相,上相为流动相,经一次高速逆流色谱即可将药物中间体溴代苯胺同分异构体进行有效的分离。