Rong-Liang Zheng

Scavenging effects of phenylpropanoid glycosides from Pedicularis on superoxide anion and hydroxyl radical by the spin trapping method(95)02255-4.

The scavenging activities of six phenylpropanoid glycosides, i.e. leucosceptoside A and martynoside, isolated from Pedicularis alashanica Maxim, verbascoside, and pediculariosides A, M and N isolated from Pedicularis striata Pall ssp. arachnoidea Franch Tsoong, on superoxide anion and hydroxyl radicals have been studied by the spin trapping method. The results demonstrated that the number of phenolic hydroxyl groups in the structures of the phenylpropanoid glycosides is related to their scavenging activities. The scavenging effects of the phenylpropanoid glycosides possessing two o-dihydroxyl groups were stronger than the effects of the compounds possessing two o-hydroxy-methoxy groups.

Inhibitions of the autoxidation of linoleic acid by flavonoids in micelles

The activities of five flavonoids as chain-breaking antioxidants have been studied for the autoxidation of linoleic acid in cetyl trimethylammonium bromide (CTAB) micelles at 37 degrees C. Flavonols such as quercetin, rutin and morin exhibited antioxidant activities, while two flavanones, naringin and hesperidin, did not suppress the oxidation appreciably. The ratio of rate constants for inhibition and propagation kinh/kp and stoichiometric factor n were determined.

Inhibition of the autoxidation of linoleic acid by phenylpropanoid glycosides from Pedicularis in micelles

The activities of six phenylpropanoid glycosides as chain-breaking antioxidants have been studied for the autoxidation of linoleic acid in cetyl trimethylammonium bromide (CTAB) micelles at 37 degrees C. Verbascoside, isoverbascoside, echinacoside and pedicularioside A, which possess four phenolic hydroxyl groups, exhibited antioxidant activities, while cistanoside D possessing only two phenolic hydroxyl groups and permethyl verbascoside without phenolic hydroxyl group did not suppress the oxidation appreciably. The ratio of rate constants for inhibition and propagation kinh/kp and stoichiometric factor n were determined.

Retardation of skeletal muscle fatigue by the two phenylpropanoid glycosides: Verbascoside and Martynoside from Pedicularis plicata Maxim

The effects of the phenylpropanoid glycosides verbascoside and martynoside from Pedicularis plicata were investigated on muscle contractility in Bufo gastrocnemius muscle electrically stimulated in vitro. The maximum amplitude and maintained time of contraction were mechanically recorded and used as indices of muscle contractility. After 30u2005min pretreatment of the muscle, verbascoside at 20.0u2005µM resisted muscle fatigue significantly while martynoside at 80.0u2005µM improved muscle contractility only slightly. These two glycosides resisted muscle fatigue depending on their antioxidative activities, which is in agreement with the role of reactive oxygen species (ROS) in promoting fatigue in skeletal muscle. Copyright

Difference in antioxidation for schisandrins and schisantherin between bio- and chemo- systems

The difference in antioxidation and the mechanism of action of schisandrins and schisantherin in biological and chemical systems was investigated. The antioxidative activities of schisandrin A (SA), schisandrin B (SB) and schisantherin D (SD) isolated from Schisandra chinensis Baill were studied on haemolysis of mouse erythrocytes and on autooxidation of linoleic acid induced by a water‐soluble free radical initiator, 2,2′‐azobis(2‐amidino‐propane)dihydrochloride. It was found that SA, SB and SD inhibited haemolysis of erythrocytes but did not inhibit peroxidation of linoleic acid in micelles. Chlorhexidine, an inhibitor of demethylase, significantly inhibited the antioxidative activities of SA, SB and SD on haemolysis. The results indicated that the methoxy groups in SA, SB and SD may be demethylated by demethylase contained in erythrocytes and metabolized to produce phenolic hydroxyl groups which inhibit the peroxidation of erythrocyte membranes.

Reaction of hydroxyl radical with phenylpropanoid glycoside and its derivatives by pulse radiolysis

The reaction of hydroxyl radical with 1 phenylpropanoid glycoside (PPG), cistanoside C, and its 3 derivatives: 1-0-β-D-2-(p-hydroxyphenyl)-ethanyl-glucose, 6-O-(E)-femloyl-glucose and 6-O-(E)-p-hydroxy-cinnarnoylglucose isolated from folk medicinal herbs was investigated by pulse radiolysis technique respectively. The reaction rate constants were determined by analysis of built-up trace of absorption at λmax of specific transient absorption spectra of PPG and its derivatives upon attacking · OH. All four compounds react with · OH at close to diffusion controlled rate (1. 03 × 109-19.139 × 109 L · mol−1 · s−1), suggesting that they are effective · OH scavengers. The results demonstrated that the numbers of phenolic hydroxyl groups of PPG and its derivatives are directly related to their scavenging activities. By comparing the reaction rates of · OH with 1-O-β-D-2-(p-hydroxyphenyl)-ethanyl-glucose, 6-O-(E)-feruloyl-glucose or 6-O-(E)-p-hydroxy-cinnomoyl-glucose, it is evident that the phenylethyl group is more impofiant than phenylacryloyl group for scavenging · OH.

Fast repair of DNA radicals in the earliest stage of carcinogenesis suppresses hallmarks of cancer

Genomic instability is a characteristic of most cancers and could be directly caused by DNA damage. DNA repair maintains genomic integrity, reducing the onset of cancer. A distinct DNA fast repair process, synonymous fast repair, is initiated and finished in a microsecond time scale, enormously faster by approximately 9 orders than enzymatic repair, and thus eradicates the headstream of DNA damage, DNA radicals exclusively, in the earliest stage of carcinogenesis. The known enzymatic repair cannot repair DNA radicals and mutation, but fast repair can. Therefore, the fast repair mechanism is a defence in the front line in fighting carcinogenesis. If there was no fast repair, certainly much more DNA steady damage would accumulate and would lead to mutation and cancer with high risk. Almost all the tested phytophenols with fast repair activity, except one, are able to suppress the hallmarks of cancer, such as morphological normalization, redifferentiation, decrease of cancer growth and transplanting rate, inhibition of telomerase, metastasis and angiogenesisin vitro and in vivo, reducing cancer incidence and mortality rate in animals.