Yoshiaki Shirataki

Inhibitory effects of chlorogenic acids on linoleic acid peroxidation and haemolysis

Abstract Antioxidant activities of chlorogenic acid and related catechols were investigated by both the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging system and the superoxide anion-mediated linoleic acid peroxidation system. At 10 μM, chlorogenic acid, 3,5-dicaffeoylquinic acid, caffeic acid and protocatechuic acid showed more scavenging activities on DPPH than dl -α-tocopherol or ascorbic acid. DPPH radical scavenging activities of these compounds increased dose-dependently at concentrations ranging from 1 to 50 μM; 1 mol of chlorogenic acid reacted with ca 4 mol of radical, and 1 mol of 3,5-dicaffeoylquinic acid with ca 6 mol of radical. Chlorogenic acid, 3,5-dicaffeoylquinic acid and caffeic acid inhibited the formation of conjugated diene from linoleic acid. The inhibitory activity of 3,5-dicaffeoylquinic acid was stronger than that of chlorogenic acid or caffeic acid; dl -α-tocopherol was the most inhibitory of the other catechols tested. Effects on the haemolysis and peroxidation of mouse erythrocytes induced by H 2 O 2 was also examined. Cafreic acid, chlorogenic acid, 3,5-dicaffeoylquinic acid and dl -α-tocopherol exhibited strong inhibitory activities, but cinnamic acid, p -coumaric acid, ferulic acid, protocatechuic acid and vanillic acid were ineffective. Caffeic acid (25 μM) inhibited the rupture and haemolysis of erythrocytes.

Cancer prevention and therapy with kiwifruit in Chinese folklore medicine: A study of kiwifruit extracts

Kiwi gold fruits were extracted successively with hexane, acetone, methanol and 70% methanol, and further fractionated by silica gel and ODS column chromatographies for the assays of various biological activities. Five fractions H1, H2 (hexane extract), Al, A2 (acetone extract) and M2 (methanol extract) showed selective cytotoxic activity against human oral tumor cell lines, which was more sensitive than human gingival fibroblasts. More hydrophilic fractions [70M3, 70M4, 70M5] of 70% methanol extract displayed higher anti-HIV activity, radical generation and O2- scavenging activity. The antibacterial activity of 70% methanol extracts [70M0, 70M1, 70M2, 70M3, 70M4] was generally lower than that of more lipophilic fractions (hexane, acetone, methanol extracts), although each fraction did not show any specific antimicrobial action. All fractions were inactive against Helicobacter pylori. These results demonstrate that gold kiwifruit extracts contain valuable, various bioactive materials, which can be separated with each other.

New resveratrol oligomers in the stem bark of Vatica pauciflora

Abstract Five new resveratrol oligomers; pauciflorols A–C ( 1–3 ), isovaticanols B ( 6 ) and C ( 8 ), and three new oligostilbene glucosides; pauciflorosides A ( 11 ), B ( 13 ), C ( 14 ), were isolated from the stem bark of Vatica pauciflora (Dipterocarpaceae) together with known 17 resveratrol oligomers ( 4, 5, 7, 9, 10, 12 and 15–25 ) and bergenin ( 26 ). The structures of isolates were established on the basis of detailed spectroscopic analysis. The typical and characteristic spectral properties of some resveratrol oligomers were also discussed.

Inhibitory effects of Astragali Radix, a crude drug in Oriental medicines, on lipid peroxidation and protein oxidative modification by copper.

Effects of Astragali Radix, the root of Astragalus membrauaceus Bunge, were investigated on oxidative stress such as lipid peroxidation and protein oxidative modification by copper. The results showed that these effects are similar to those of mannitol and superoxide dismutase as a free radical scavenger. It was demonstrated that Astragali Radix have inhibitory effects on oxidative stress induced by copper.

Differential interaction of Sophora isoflavonoids with lipid bilayers.

The mechanisms of some biological effects exerted by flavonoids (e.g. activity against lipid oxidation, multidrug resistance modulation) may involve their interactions with lipid bilayers. Due to variety of substituents attached to the flavonoid nucleus individual isoflavones significantly differ in their properties; in particular they may differently interact with membranes. For this reason we have investigated the interactions of different isoflavones with lipid bilayers. The influence of four plant isoflavones on the phase transitions of dipalmitoylphosphatidylcholine (DPPC) and on liposome aggregation was studied, using microcalorimetry and absorption measurements, respectively. We found that isoflavones substituted with one or two prenyl groups less effectively induce liposome aggregation than more polar ones, possessing no prenyl groups. For aggregation-promoting compounds, rather small differences in the influence on phosphatidylcholine, phosphatidylserine and phosphatidylinositol liposomes were recorded. On the other hand, the alteration of DPPC phase transitions by prenyl-substituted isoflavones was more pronounced than changes induced by non-prenyl ones. On the basis of observed effects we conclude that prenyl-substituted isoflavones penetrate deeper into the lipid bilayer while more polar ones act closer to the membrane surface. Comparing our results with biological tests it seems that interactions with the hydrophobic core of membranes are responsible for the activity of the studied isoflavones.

Antibacterial Activity of Artificial Phenothiazines and Isoflavones from Plants

Significant antimicrobial action was detected in vitro and in vivo in phenothiazines that are applied to humans as neuroleptics or antihistamines. Both Gram-positive and Gram-negative bacteria were equally sensitive, with the MIC varying between 25 and 100 μg/ml with most agents. Some phenothiazines were bactericidal, while others were bacteriostatic in action. Similar activity could be observed in isoflavonones obtained from the plants Sophora spp. Trifluoperazine and methdilazine exhibited antimycobacterial properties as well, and in experimental animals the latter showed definite healing properties. Chlorpromazine and thioridazine were able to eliminate R-plasmids in drug-resistant bacteria. Artificially synthesized Benzo[α]phenothiazines could effectively suppress adenovirus oncogene expression. Phenothiazines have now been shown to inhibit efflux pumps in multidrug-resistant bacteria.

Inhibitory effects of isoflavones in roots of Astragalus membranaceus BUNGE (Astragali Radix) on lipid peroxidation by reactive oxygen species

Possible inhibitory effects were investigated of isoflavones in the roots of Astragalus membranaceus BUNGE (Astragali Radix), afrormosin, calycosin, formononetin and odoratin on lipid peroxidation by reactive oxygen species. Calycosin inhibited lecithin peroxidation which was induced by hydroxy radical‐generation by interaction of haemoglobin and hydrogen peroxide. Calycosin and formononetin inhibited lecithin peroxidation which was induced by superoxide anion generation by xanthine‐xanthine oxidase. Other isoflavones had no inhibitory effects on lecithin peroxidations. These results demonstrated that the antioxidant properties of isoflavones, which have a methoxy group at the 4′ position, are derived from hydroxy groups at the 7 and 4′ position.

Two flavanones in Sophora leachiano and some related structures

Abstract A novel flavanone, leachianone A, with a lavandulyl residue was isolated from the roots of Sophora leachiano in addition to sophoraflavanone G. The structure was determined to be 5,7,4′-trihydroxy-8-lavandulyl-2′-methoxyflavanone by means of NMR ( 1 H- 1 H and 1 H- 13 C COSY) spectral analysis. The structural relationships of leachianone A with isokurarinone and vexibidin, and of sophoraflavanone G and kushenol F with nor -kurarinone and vexibinol are also discussed.

Inhibitory effects of Astragali Radix, crude drug in Oriental medicines on lipid peroxidation and protein oxidative modification of mouse brain homogenate by copper

Astragali Radix, the root of Astragalus membranaceus Bunge, is a crude drug used widely in Oriental medicines. It is a major component of Ougi‐Keishi‐gomotsu‐to, a traditional herbal medicine, used for neurop patients with abnormal sensations and neuropathic pain of the legs. It was shown to have inhibitory effects on lipid peroxidation and protein oxidative modification by copper. The effects were similar to and stronger than those of mannitol and superoxide dismutase as free radical scavengers. These results demonstrated that Astragali Radix has inhibitory effects on oxidative stress induced by metal.

Four isoflavanones from roots of Sophora tetraptera

Four new isoflavanones, tetrapterols F–I, were isolated from roots of Sophora tetraptera in addition to seven known flavonoids, lupinifolin, 8-O-methylretusin, 5,7,4′-trihydroxy-6,3′-di(γ,γ-dimethylallyl)isoflavone, (−)-maackiain, sophoracarpan A, medicagol and 2-(2,4-dihydroxyphenyl)-5,6-methylenedioxybenzofuran. The structure of the new isoflavanones was determined to be 3,5,7–trihydroxy-2′-methoxy-8-γ,γ-dimethylallyl-6‴,6‴-dimethylpyrano[2‴,3‴:4′,3′]isoflavanone(tetrapterol F), 5,7,2′,4′-tetrahydroxy-6,5′-di(γ,γ-dimethylallyl)isoflavanone(tetrapterol G), 5,7,2′–trihydroxy–4′–methoxy-8,5′-di(γ,γ-dimethylallyl) isoflavanone(tetrapterol H) and 7,4′-dihydroxy-6,3′-di(γ,γ-dimethylallyl)isoflavanone (tetrapterol I) by means of spectroscopic analysis.