知母宁清除自由基作用的量子化学研究

目的：研究知母宁的山酮结构是否有利于提高其清除自由基活性并探讨矢线宁酚羟基活性的顺序，方法：用半经验量子化学方法ＡＭ１计算出知母宁不同状态的ΔＨＯＦ值和电子自旋密度分布，以ΔＨＯＦ值作为衡量知母宁清除自由基活性的理论指标，观察结果因素对ΔＨＯＦ值的影响。     

环丙沙星与牛血清白蛋白的相互作用

血清白蛋白是血浆中含量最丰富的重要载体蛋白 ,药物进入血浆后 ,首先与血清白蛋白结合 ,然后再被运送到身体的各部位。随着药代动力学及临床药理学迅猛发展 ,药物 蛋白质结合对药代动力学影响 ,又有了更深刻的认识。因此 ,研究药物与血清白蛋白的相互作用有重要意义[1] 。本文应用荧光光度法研究了生理ｐＨ值条件下 ,环丙沙星与牛血清白蛋白 (ＢＳＡ)的相互作用 ,利用环丙沙星对蛋白质荧光的猝灭求出环丙沙星与蛋白质的结合常数 ,考察了药物对蛋白质构象的影响 ,并根据热力学参数确定了它们之间的主要作用力类型。这对阐明药物在体内的输…     

Antioxidant and antiacetylcholinesterase activities of Sorbus torminalis (L.) Crantz (wild service tree) fruits

In this study, the antioxidant and antiacetylcholinesterase activities of Sorbus torminalis (L.) Crantz fruits were evaluated. Total phenolic and flavonoid compounds, 2,2′-azino-bis (3-ethylbenzothioazoline-6-sulfonic acid), 2,2′-diphenyl-1-picrylhydrazyl, and superoxide anion radicals scavenging activities and ferric-reducing antioxidant power of water, ethyl acetate, acetone, and methanol extracts were determined for the measurement of the antioxidant activity. Quercetin and α-tocopherol were used as standard antioxidants. The inhibitory effect of the water extract on acetylcholinesterase (AChE) was evaluated using the Ellman method and galantamine was used as a standard. Water extract had the highest total phenolic concentration and the strongest antioxidant activity followed by ethyl acetate and acetone extracts whereas methanol extract has the lowest phenolics and weakest antioxidant activity. Moreover, water extract showed moderate ability to inhibit AChE. It was concluded that fruits of S. torminalis have antioxidant and anti-AChE activities and that the plant might be a natural source of antioxidants and AChE inhibitors.     

In vitro antioxidant properties of morphine.

Morphine is implicated in diverse functions, from development to immune modulation in the central and peripheral nervous systems. It has also been used extensively in the clinical management of pain due to its potent analgesic effect. This study was designed to evaluate the in vitro antioxidant capacity of morphine using different antioxidant tests, including total antioxidant activity, reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging and metal chelating activities. Morphine exhibited strong total antioxidant activity. The concentrations of 25, 50 and 75 microgml(-1) of morphine showed 79.1, 84.3 and 92.3% inhibition on peroxidation of linoleic acid emulsion, respectively. On the other hand, at 75 microgml(-1) concentration of standard antioxidant, such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and alpha-tocopherol, exhibited 88.7, 94.5 and 70.4% inhibition on peroxidation of linoleic acid emulsion, respectively. In addition, morphine had effective reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging and metal chelating activities at the same concentrations (25, 50 and 75 microgml(-1)). These various antioxidant activities were compared to standard antioxidants such as BHA, BHT and alpha-tocopherol.     

A kinetic study of the role of band 3 anion transport protein in the transport of salicylic acid and other hydroxybenzoic acids across the human erythrocyte membrane.

The mechanism of transport of salicylic acid and five other hydroxybenzoic acids across the human erythrocyte membrane was investigated. The specific anion transport inhibitor, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, reduced but did not totally abolish transport of these acids. This observation suggests that these acids are transported by two parallel processes, one involving the band 3 anion transport protein channel and the other probably involving passive diffusion of the un-ionized molecule. The activation energies for membrane transport were large (99-127 kJ.mol-1), an observation that is consistent with the rate-limiting step for anion transport being the conformational change of the band 3 anion transport protein.     

Antioxidant activity of saponins isolated from ivy: alpha-hederin, hederasaponin-C, hederacolchiside-E and hederacolchiside-F

The antioxidant activities of alpha-hederin and hederasaponin-C from Hedera helix, and hederacolchisides-E and -F from Hedera colchica were investigated, in this study. The antioxidant properties of the saponins were evaluated using different antioxidant tests: 1,1-di-phenyl-2-picryl-hydrazyl (DPPH.) free radical scavenging, total antioxidant activity, reducing power, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities. Alpha-hederin, hederasaponin-C, as well as hederacolchisides-E and -F exhibited a strong total antioxidant activity. At the concentration of 75 pg/mL, these saponins showed 94, 86, 88 and 75% inhibition on lipid peroxidation of linoleic acid emulsion,respectively. These various antioxidant activities were compared with model antioxidants such as a-tocopherol, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT).     

Bioassay of ferulic acid derivatives as influenza neuraminidase inhibitors

Four series of ferulic acid derivatives were designed, synthesized, and evaluated for their neuraminidase (NA) inhibitory activities against influenza virus H1N1 in vitro. The pharmacological results showed that the majority of the target compounds exhibited moderate influenza NA inhibitory activity, which was also better than that of ferulic acid. The two most potent compounds were 1m and 4a with IC₅₀ values of 12.77 ± 0.47 and 12.96 ± 1.34 μg/ml, respectively. On the basis of the biological results, a preliminary structure–activity relationship (SAR) was derived and discussed. Besides, molecular docking was performed to study the possible interactions of compounds 1p , 2d , 3b , and 4a with the active site of NA. It was found that the 4-OH-3-OMe group and the amide group (CON) of ferulic acid amide derivatives were two key pharmacophores for NA inhibitory activity. It is meaningful to further modify the natural product ferulic acid to improve its influenza NA inhibitory activity.     

Antiradical efficacy of phytochemical extracts from defatted rice bran.

The phytochemical compounds oryzanols, tocopherols, tocotrienols and ferulic acid were identified in the crude methanolic extracts (CME) of defatted rice bran (DRB) by HPLC. Enrichment of antioxidants in CME was achieved by sequential extraction and fractionation resulting in three enriched fractions viz. acetone extract (AE), acetone extract-lipophilic fraction (AE-LP) and acetone extract-polar fraction (AE-PP). The scavenging effects of DRB extracts and their phytochemical constituents against DPPH and superoxide radicals were investigated. The EC(50) (g antioxidant/kg DPPH) values of CME, AE, AE-LP, AE-PP, oryzanols, ferulic acid, tocols (Tmix), tricin, beta-sitosterol, BHT and TBHQ were 1,977, 1,945, 7,985, 1,072, 972, 174, 164, 3,947, 21,416, 1,120 and 61, respectively. Tricin and beta-sitosterol isolated from CME were identified with the help of spectral data. The DRB extracts and their phytochemical constituents when assayed by cytochrome c and NBT methods showed positive superoxide radical scavenging effects. The order of efficacies of the extracts was AE-PP>AE>CME>AE-LP in both assays, but the activities were higher for the former method. The DPPH as well as superoxide scavenging activities of AE, AE-LP and AE-PP could largely be attributed to the levels of total phenols (TPC) and ferulic acid in it.