The biochemistry and medical significance of the flavonoids.

https://aasldpubs.onlinelibrary.wiley.com/doi/epdf/10.1002/hep.510300437

Herbal products for liver diseases: a therapeutic challenge for the new millennium.

J. Neurochem. (2010) 112, 1500–1512.



Abstract

Recently more evidences support baicalein (Bai) is neuroprotective in models of ischemic stroke. This study was conducted to determine the molecular mechanisms involved in this effect. Either permanent or transient (2 h) middle cerebral artery occlusion (MCAO) was induced in rats in this study. Permanent MCAO led to larger infarct volumes in contrast to transient MCAO. Only in transient MCAO, Bai administration significantly reduced infarct size. Baicalein also markedly reduced apoptosis in the penumbra of transient MCAO rats. Additionally, oxygen and glucose deprivation (OGD) was used to mimic ischemic insult in primary cultured cortical neurons. A rapid increase in the intracellular reactive oxygen species level and nitrotyrosine formation induced by OGD was counteracted by Bai, which is parallel with attenuated cell injury. The reduction of phosphorylation Akt and glycogen synthase kinase-3β (GSK3β) induced by OGD was restored by Bai, which was associated with preserved levels of phosphorylation of PTEN, the phophatase that negatively regulates Akt. As a consequence, Bcl-2/Bcl-xL-associated death protein phosphorylation was increased and the protein level of Bcl-2 in motochondria was maintained, which subsequently antagonize cytochrome c released in cytosol. LY294002 blocked the increase in phospho-AKT evoked by Bai and abolished the associated protective effect. Together, these findings provide evidence that Bai protects neurons against ischemia injury and this neuroprotective effect involves PI3K/Akt and PTEN pathway.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1471-4159.2009.06561.x

Neuroprotection by baicalein in ischemic brain injury involves PTEN/AKT pathway.

Flavonoids within Scutellaria baicalensis may be potent antioxidants on the basis of our studies of S. baicalensis extract. To further this work, we studied the antioxidative effects of baicalein, ...

https://www.physiology.org/doi/pdf/10.1152/ajpheart.00163.2001

Baicalein attenuates oxidant stress in cardiomyocytes.

Flavonoids from shoots and roots of Trifolium repens (white clover) grown in presence or absence of the arbuscular mycorrhizal fungus Glomus intraradices.

145 flavonoids were studied for their inhibitory effects on the iron-induced lipid peroxidation in mitochondria obtained from rat livers. Of these compounds tested, 30, 57, 59, 67, 70, 72, 77, 102 and 110 (ED50 < or = 0.5 nmol/mg prot) showed distinctly more potent inhibitory activity than baicalein (ED50 < or = 5 nmol/mg prot) and 59 and 72 (ED50 < or = 0.05 nmol/mg prot) exhibited the most potent activity. In order to elucidate the relationships between substituents on the flavonoid skeleton and the biological activity, the quantitative structure-activity relationships (QSAR) were analyzed by the adaptive least-squares (ALS) method for 142 flavonoids. The analysis has shown that the presence of the 1,4- and 1,2-hydroquinone in A-ring and/or B-ring of flavonoids and hydrophobicity of the molecule are responsible for the in vitro inhibitory activity.

[Structure-activity relationship of flavonoids in suppressing rat liver lipid peroxidation].

In order to elucidate anti-inflammatory action of Sho-saiko-to, its components were analyzed and purified by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC), and their effects on lipid peroxidation were compared with those of Sho-saiko-to in guinea pig neutrophils, rat liver mitochondria and microsomes. The results obtained were as follows: 1) Sho-saiko-to gave no effect on arachidonate- and PMA (phorbol 13-myristate 12-acetate)-induced NADPH-O2- generation in neutrophils though it gave a weak LPS-like effect on the cells. No inhibition of reduced nicotinamido adenine dinucleotide phosphate (NADPH) oxidation was shown in liver microsomes. However, it markedly inhibited iron-induced lipid peroxidation in microsomes and mitochondria. 2) The active components to suppress lipid peroxidation could be concentrated in a lipid-soluble fraction from the Sho-saiko-to solution. The ED50 values to give 50% inhibition of the mitochondrial lipid peroxidation were 160 ng/mg prot, and 50 micrograms/mg prot, for the lipid-soluble fraction and Sho-saiko-to, respectively. 3) The components in the lipid-soluble fraction were further separated by TLC and HPLC, and their inhibitory effects on the lipid peroxidation were examined. The active components were baicalein, ginsenoside Rf and baicalin, of which ED50 values were 0.2, 0.2 and 1 nmol/mg prot, respectively. Glycyrrhizin and its derivatives, ginsenoside (except ginsenoside Rf), and saikosaponins gave no effect in the concentration examined. 4) From these results anti-inflammatory action of Sho-saiko-to was discussed.

Masanobu Miyahara

Papers

[Structure-activity relationship of flavonoids in suppressing rat liver lipid peroxidation].

[Suppression of lipid peroxidation by sho-saiko-to and its components in rat liver subcellular membranes].