Mineo Shimizu

Inhibition of lens aldose reductase by flavonoids

Abstract The inhibitory activities of 73 flavonoids against rat aldose reductase were systematically investigated and cosmosiin, luteolin-7-glucuronide, lonicerin, 6-hydroxyluteolin, kaempferol-3-rhamnoside and avicularin were newly found to be highly active. The degree of inhibition appears to depend on the solvent system used. In general flavones are more active than flavonols and flavanones, glycosides are more active than aglycones, and the number of sugars present affects the activity.

Antioxidative activity of flavones and flavonols in vitro

Forty‐one flavonoids of the flavone and flavonol types were investigated for their antioxidative activity using a lipid peroxidation generation system mediated by the addition of H2O2/Fe2+ to rat liver homogenate. The results showed that both types specifically and markedly reduced the production of peroxidants induced by H2O2, Fe2+ or a Fenton‐type reaction. The scavenging ability of these compounds was found to be associated closely with their chemical structure, especially the number of hydroxyl groups linked to the basic skeleton. However, there were some exceptions, implying that not only hydroxyl groups but also their configuration determines the activity.

Paeoniflorin attenuates learning impairment of aged rats in operant brightness discrimination task

The effects of paeoniflorin isolated from peony were examined on an aging-induced learning deficit in an operant brightness discrimination task in Fischer 344 rats. Learning in aged (25 months) rats was significantly impaired compared with young (5 months) rats. Daily administration of paeoniflorin (0.01 mg/kg, PO) significantly attenuated the learning impairment in aged rats, whereas it did not affect the learning in young rats. Although tacrine (0.3 and 1 mg/kg, IP), a cholinesterase inhibitor, also did not affect the learning in young rats, it slightly augmented the aging-induced learning deficit in the present task. These data indicate the therapeutic potential of paeoniflorin in the treatment of senile dementia and aging-induced cognitive dysfunction.

Scopadulcic acid-A and -B, new diterpenoids with a novel skeleton, from a Paraguayan crude drug “typychá kuratũ” (scoparia dulcis L.)

Abstract Scopadulcic acid-A and -B, diterpenoids with a novel skeleton, have been isolated from the whole plants of Scopari dulcis L., and their structures, including the absolute configuration, were determined based on the 2-D NMR and CD spectral data.

Paeonilactone-A, -B, and -C, new monoterpenoids from paeony root

Three new monoterpenoids named paeonilactone-A, -B, and -C were isolated from Paeony root (roots of Paeonia albiflora PALLAS var. trichocarpa BUNGE) and their structures were determined to be 2, 3, and 4, respectively, by means of chemical and spectroscopic studies.

Protective effects of some flavonoids on the renal cellular membrane.

By assaying lactate dehydrogenase and malondialdehyde leakage from LLC-PK1 cells in culture, a study was conducted to clarify whether flavonoid compounds ameliorate renal cellular injury. The cells were cultured with various concentrations of samples under routine conditions. The results demonstrated that baicalin, cirsimaritin, 6-hydroxyluteolin, luteolin, plantaginin, rhoifolin, sorbarin, afzelin, hyperin, isoquercitrin, isorhamnetin, kaempferitrin, kaempferol-7-glucoside, oxyayanin A, quercetin, quercitrin, rhamnetin and rutin exerted marked protective effects on the cells, whereas acacetin, apigenin, apiin, cirsilineol, genkwanin, pectolinarin and tetramethylquercitin had virtually no effect. In the light of these findings, we propose that the general capability of these compounds is largely decided by the number and position of phenolic hydroxyl groups linked to the structural backbone.

Two new flavone glycosides from Cirsium lineare

Abstract An examination of four species of Cirsium disclosed the presence of two new flavonoids in C. lineare . The structure of one was 5,4′-dihydroxy-6,7,3′-trimethoxyflavone (cirsilineol) 4′-monoglucoside and the other 5,3′,4′-trihydroxy-6,7-dimethoxyflavone (cirsiliol) 4′-monoglucoside. Luteolin 7-glucoside was found in C. suffultum , and pectolinarin and linarin in C. kamtschaticum and C. pectinellum .

Two new xanthone glycosides from Tripterospermum lanceolatum

Abstract Oleanolic acid, mangiferin, and two new xanthone glucosides, named lanceoside (1,8-dihydroxy-3,7- dimethoxyxanthone- 4-O-β- d -glucoside) and lancerin (C-4-β- d -glucosyl-1,3,7-trihydroxyxanthone), respectively, were isolated from the aerial parts of Tripterospermum lanceolatum.

A xanthone glycoside from Tripterospermum taiwanense and rutin from Gentiana flavo-maculata☆

Abstract Oleanolic acid, norathyriol, and a new xanthone glycoside, tripteroside, which was characterized as norathyriol 6- O -β- d -glucoside, were isolated from the fresh herb Tripterospermum taiwanense , and quercetin and rutin were isolated from the fresh herb Gentiana flavo-maculata .

Paeoniflorigenone, a new monoterpene from paeony roots

Abstract Paeoniflorigenone (1), a new monoterpene which produces a neuromuscular-blocking effect in mice, was isolated from paeony roots and its structure was elucidated.