Flavonoid glycosides fromMelandrium firmum

Linarin and schaftoside were isolated fromMelandrium firmum (Caryophyllaceae) and characterized by spectral data.     

Flavonoid impairment of neutrophil response

Flavonoids are a class of phenolic plant pigments which impair the oxidative burst of neutrophils to an extent dependent on their hydrophobicity. The distribution of quercetin and of morin in nitrogen-cavitated neutrophils paralleled their respective hydrophobic characteristics and respiratory burst inhibition. While both flavonoids were localized primarily in the specific granule membrane of neutrophils, the amount of quercetin was considerably greater than that of morin. We here demonstrate inhibition of the initial stimulation response, depolarization of the membrane potential as monitored by fluorescence of the membrane probe diS-C3-(5), and of the respiratory burst, monitored by following the destruction of diS-C3-(5), a reaction mediated by the H2O2 produced in the burst. The flavonoids kaempferol, morin, quercetin, or fisetin were preincubated with human neutrophils at a concentration of 100 microM per 2 X 10(6) cells/ml for 2-3 min and subsequently stimulated with 1 microgram/ml of the tumor promoter phorbol myristate acetate (PMA) or with 60 micrograms/ml of immune complex. The effect of each compound differed, i.e. depolarization was enhanced by some and inhibited by others, while H2O2 generation was inhibited by each, supporting our previous findings that membrane potential depolarization and the respiratory burst are dissociable events. Concentration-response experiments, performed at flavonoid concentrations between 12.5 and 500 microM to determine the IC50 values of these compounds for depolarization and burst activation, indicated that none of the flavonoids affected the resting potential, while all perturbed the stimulus-coupled response, the direction and extent of the perturbation depending upon the stimulus, and the function assessed. These data show that the effects of flavonoids on human neutrophils are complex and suggest several sites of action depending upon the flavonoid's subcellular distribution and pathway of stimulation.     

Flavonoid glycosides from Thalictrum przewalskii

A new flavonoid glycoside, 5,7-dihydroxy-4'-methoxyflavone-7-O-[6-O-(4-O-acetyl-alpha-L-rhamnosyl)-3-O-beta-D-glucosyl]-6-O-acetyl-beta-D-glucoside and three known flavonoid glycosides, 5,7-dihydroxy-4-methoxyflavone-7-0-[6-0-(4-0-acetyl-alpha-L-rhamnosyl)]-beta-D-glucoside, 3,5,7, 4'-tetrahydroxyflavonol-3-O-beta-D-glucoside and 5,7-dihydroxy-4'-methoxyflavone-7-O-(6-O-alphaL-rhamnosyl)-beta-D-glucoside were isolated from the whole plant of Thalictrum przewalskii. Their structures were determined on the basis of spectroscopic evidences.     

Coumarins as antioxidants

Coumarins, a well-known class of naturally occurring compounds, display a remarkable array of biochemical and pharmacological actions, some of which suggest that certain members of this group of compounds may significantly affect the function of various mammalian cellular systems. The development of coumarins as antioxidant agents has attracted much attention in recent years. Coumarins afford an opportunity for the discovery of new antioxidants with truly novel mechanisms of action. This review updates and expands the 2006 review by the same author. The review considers and incorporates the most recently published literature on coumarins as related to their antioxidant properties. A lot of coumarins have been identified from natural sources, especially green plants. These natural compounds have served as valuable leads for further design and synthesis of more active analogues. Beyond doubt, a deep understanding of the mechanisms of existing synthetic and natural coumarins will build the basis for the rational design.     

Flavonoid glycosides from Alchemilla speciosa

The new flavonol glycosides quercetin 3- O-beta-(2'- O-alpha- L-rhamnopyranosyl)-glucopyranoside uronic acid and kaempferol 3- O-beta-(2'- O-alpha- L-rhamnopyranosyl)-glucopyranoside uronic acid were isolated from the leaves of Alchemilla speciosa Buser together with 13 known flavonol and flavone glycosides and (+)-catechin. The structures were determined by spectroscopic methods.     

酸浆宿萼的黄酮苷类化学成分

目的研究茄科植物酸浆(Physalis alkekengiL.var.francheti(Mast.)Makino)宿萼的化学成分。方法用体积分数为80%的乙醇溶液加热回流提取,回收乙醇,浓缩后用水混悬,依次用环己烷、乙酸乙酯、正丁醇萃取;将正丁醇层通过聚酰胺柱色谱,Sephadex LH-20柱色谱、反相ODS开放柱色谱及反相制备HPLC等手段,共分离得到5个黄酮苷类化合物;利用其理化性质和波谱学分析数据,鉴定化合物结构。结果分离得到的5个黄酮苷类化合物,分别鉴定为木犀草素-7-O-β-D-葡萄糖苷(1),木犀草素-4′-O-β-D-葡葡萄糖苷(2),槲皮素-3-O-β-D-葡葡萄糖苷(3),槲皮素-7,3-二-O-β-D-葡葡萄糖苷(4),木犀草素7,3′-二-O-β-D-葡葡萄糖苷(5)。结论木犀草素-4′-O-β-D-葡萄糖苷(2),槲皮素-3,7-二-O-β-D-葡萄糖苷(4),木犀草素7,3′-二-O-β-D-葡萄糖苷(5)为首次从该属植物中分离得到,槲皮素-3-O-β-D-葡萄糖苷(3)为首次从该植物中分离得到。     

多茎委陵菜中的黄酮苷类成分

目的研究多茎委陵莱（Potentilla multicaulis Bunge）中的化学成分。方法多茎委陵菜的70％乙醇提取物经大孔吸附树脂、硅胶柱层析、ODS柱层析及凝胶柱层析,采用化学及光谱学方法进行结构鉴定。结果分离纯化得到5个黄酮苷类化合物和1个挥发油。分别为翻白叶苷A（Ⅰ）、槲皮素-3-Oα-L-鼠李糖苷（Ⅱ）、槲皮素-β-O-β-D-葡萄糖苷（Ⅲ）、山柰酚-3-β-D-葡萄糖苷（Ⅳ）、异鼠李素-3-O-β--D-吡喃葡萄糖-7-O-α-L-吡喃鼠李糖苷（Ⅴ）、邻苯二甲酸二（2-乙基己基）酯（Ⅵ）。结论化合物Ⅰ-Ⅳ,Ⅵ均为首次在该植物中分离得到,化合物Ⅴ为首次从委陵菜属植物中分离得到。     

Topical delivery of antioxidants

Reactive oxygen species (ROS) and free radicals have been implicated in a number of diseases and disorders, and the skin, for its localization, is exposed to a large number of environmental threats. Free radical scavengers and antioxidants have thus been proposed as protective or therapeutic agents against ROS-mediated injuries. Oral treatment with several antioxidants has been reported to provide skin protection against deleterious effects of ultraviolet radiation. Topical delivery of antioxidants has increasingly gained interest and development, especially by offering better targeting to the upper skin layer. However, the topical delivery of antioxidants for dermal action is a challenging research field since the molecules are, in general, susceptible to degradation. The search for a new delivery system that, simultaneously, preserves the antioxidant stability and enhances its deposition on the skin, opened a new chapter in drug delivery design. Nanocarriers have been successful in enhancing the clinical efficiency of several drugs. More recent approaches in modulating through the skin delivery led to the development of specialized nanoparticulated systems. The first part of this article presents a review of the potential of antioxidants as pharmacological agents in ROS related diseases, with a special focus on oxidative stress implicated skin pathologies: ROS formation and natural protection against ROS toxicity, ROS-mediated skin damage and skin protection by antioxidants. In the second part of this work, we present reported formulation strategies for dermal delivery of antioxidants focusing on the nanoparticulated systems developed in recent years.     

Micronutrient antioxidants and smoking

Cigarette smoking is a major risk factor in such human diseases as cardiovascular disease (especially atherosclerosis), lung cancer (the leading world-wide cancer killer), and chronic obstructive pulmonary disease (COPD). An avalanche of studies has suggested that a diet rich in fruit and vegetables is associated with decreased risk for atherosclerosis and cancer. However, the dietary intake of fruits and vegetables, as well as antioxidant micronutrients, is decreased in smokers. This, along with evidence of increased utilization of ascorbic acid and alpha-tocopherol, possibly on the basis of increased oxidative stress, contributes to the low plasma antioxidant concentrations seen in many smokers. This review addresses selected mechanistic considerations of this relationship.     

Anti-atherogenicity of nutritional antioxidants

Epidemiological studies have indicated that fruit- and vegetable-rich diets play a protective role against cardiovascular disease. An explanation for this protection lies in the presence of antioxidant vitamins in fruits and vegetables. A large number of studies have provided data suggesting that consumption of dietary antioxidants is associated with reduced risk for cardiovascular disease. Plausible mechanisms by which these antioxidants may reduce the development of atherosclerosis include inhibition of low-density lipoprotein (LDL) oxidation, cellular lipid peroxidation and cell-mediated oxidation of LDL, and reduction in blood cholesterol levels. This review reports on the recent data of the anti-atherosclerotic effects and mechanistical aspects of three major groups of dietary antioxidants: vitamin E, carotenoids and flavonoids.     

Endothelial dysfunction and antioxidants

The vascular endothelium plays a crucial role in the physiology of blood vessels and the pathological processes of atherosclerotic disease and acute coronary syndromes. Endothelial dysfunction is the core problem; it is an impairment of endothelium-dependent vasorelaxation caused by a loss of nitric oxide activity in the vessel wall, which results in impairment in the regulation of vascular homeostasis. Further understanding of its mechanisms of action and possible therapeutic targets will be of great importance. The group of antioxidant vitamins, A, C and E, would seem uniquely situated to reduce cardiovascular events by improving endothelial function by reducing the concentration of reactive oxygen species in the vessel wall and by preventing oxidative modification of low-density lipoprotein. Unfortunately, despite extensive studies in both observational and randomized trials, the weight of evidence points to little or no benefit from antioxidant therapy.