In-vitro and in-vivo anti-inflammatory effect of oxyresveratrol from Morus alba L

Simultaneous determination of six major stilbenes and flavonoids in Smilax china by high performance liquid chromatography

A simple, sensitive and specific HPLC method was developed for simultaneous determination of the six major active constituents in Smilax china, namely taxifolin-3-O-glycoside (1), piceid (2), oxyresveratrol (3), engeletin (4), resveratrol (5) and scirpusin A (6), respectively. The samples were separated on an Aglient Zorbax XDB-C18 column with gradient elution of acetonitrile and 0.02% phosphoric acid (v/v) at a flow rate of 1.0 ml/min and detected at 300 nm. The six target compounds were completely separated within 35 min. All calibration curves showed good linearity (r2>0.999) within test ranges. The reproducibility was evaluated by intra- and inter-day assays and R.S.D. values were less than 3.7%. The recoveries were between 93.7 and 103.0%. The method was successfully applied to the analysis of six constituents in 15 commercial samples of S. china. The results indicated that the developed HPLC assay was readily utilized as a quality control method for S. china.

Chemical transformations of oxyresveratrol (trans-2,4,3',5'-tetrahydroxystilbene) into a potent tyrosinase inhibitor and a strong cytotoxic agent

From oxyresveratrol (trans-2,4,3',5'-tetrahydroxystilbene 1), seven derivatives were prepared, including trans-2-methoxy-4,3',5'-trihydroxystilbene (2), trans-2,3'-dimethoxy-4,5'-dihydroxystilbene (3), trans-4,3'-dimethoxy-2,5'-dihydroxystilbene (4), trans-2,4,3',5'-tetramethoxystilbene (5) and cis-2,4,3',5'-tetramethoxystilbene (6), 2,4,3',5'-tetrahydroxybibenzyl (7), and 2,4,3',5'-tetramethoxybibenzyl (8). The tetrahydroxybibenzyl 7, a hydrogenation product of 1, exhibited more potent tyrosinase inhibitory activity than the parent compound, without cytotoxicity. A kinetic study revealed that 7 was a reversible and non-competitive inhibitor of mushroom tyrosinase with l-dopa as the substrate. Analysis of the K(i) values indicated that 7 has a slightly higher affinity to the enzyme than 1. Compound 6, a tetra-O-methylated analogue of 1 with cis-configuration, was deprived of inhibitory effect on the enzyme tyrosinase, but showed very strong cytotoxicity against the human cancer cells KB, BC, and NCI-H187, with potency comparable to those of the anticancer agents ellipticine and doxorubicin. Data on the tyrosinase inhibitory activity and cytotoxicity of 1-8 indicated that O methylation on stilbene 1 destroyed anti-tyrosinase activity but generated cytotoxicity. Thus, facile preparations of a potent tyrosinase inhibitor (7) and a strong cytotoxic agent (6) from the natural product 1 were achieved through simple chemical reactions.

Oxyresveratrol (trans-2,3′,4,5′-tetrahydroxystilbene) is neuroprotective and inhibits the apoptotic cell death in transient cerebral ischemia

Oxidative stress is one of the major pathological factors in the cascade that leads to cell death in cerebral ischemia. Here, we investigated the neuroprotective effect of a naturally occurring antioxidant, oxyresveratrol, to reduce brain injury after cerebral stroke. We used the transient rat middle cerebral artery occlusion (MCAO) model of brain ischemia to induce a defined brain infarction. Oxyresveratrol was given twice intraperitoneally: immediately after occlusion and at the time of reperfusion. Oxyresveratrol (10 or 20 mg/kg) significantly reduced the brain infarct volume by approximately 54% and 63%, respectively, when compared to vehicle-treated MCAO rats. Also, the neurological deficits as assessed by different scoring methods improved in oxyresveratrol-treated MCAO rats. Histological analysis of apoptotic markers in the ischemic brain area revealed that oxyresveratrol treatment diminished cytochrome c release and decreased caspase-3 activation in MCAO rats. Also, staining for apoptotic DNA showed that the number of apoptotic nuclei in ischemic brain was reduced after oxyresveratrol treatment as compared to the vehicle-treated MCAO rats. This dose-dependent neuroprotective effect of oxyresveratrol in an in vivo stroke model demonstrates that this drug may prove to be beneficial for a therapeutic strategy to limit brain injury in acute brain ischemia.