Green tea catechins, including (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin (EGC) and (-)-epigallocatechin gallate (EGCG), are oxidized and dimerized during the manufacture of black tea and oolong tea to form orange-red pigments, theaflavins (TF), a mixture of theaflavin (TF1), theaflavin-3-gallate (TF2A), theaflavin-3'-gallate (TF2B) and theaflavin-3,3'-digallate (TF3). The present study was designed to compare the antioxidant activities of individual TF with that of each catechin using human LDL oxidation as a model. All catechins and TF tested inhibited Cu(+2)-mediated LDL oxidation. Analysis of the thiobarbituric acid-reactive substances (TBARS) and conjugated dienes produced during LDL oxidation revealed that the antioxidant activity was in the order: TF3 > ECG > EGCG > or = TF2B > or = TF2A > TF1 > or = EC > EGC. Four TF derivatives also demonstrated a dose-dependent antioxidant activity in Cu(+2)-mediated LDL oxidation at concentrations of 5-40 micromol/L. These results demonstrate that the TF present in black tea possess at least the same antioxidant potency as catechins present in green tea, and that the conversion of catechins to TF during fermentation in making black tea does not alter significantly their free radical-scavenging activity.

Five new Diels-Alder type adducts, mongolicins A - E, and nine known compounds, mongolicin F, chalcomoracin, mulberrofuran T, mulberrofuran G, mulberrofuran F, albanol B, kuwanon O, mulberrofuran H and kuwanon H, were isolated from the stem and root bark of Morus mongolica. Their structures were determined by spectroscopic analysis and chiroptical methods. Among them, compounds and showed potent anti-inflammatory activities (inhibition of release of beta-glucuronidase from rat PMNs induced by PAF) with inhibitory ratios of 80.4% (P<0.05) and 77.0% (P<0.001) at a concentration of 10(-5) mol L-1. Compounds and were active as antioxidatives (inhibition of liver microsomal lipid peroxidation induced by Fe2+-Cys system) with inhibitory ratios of 83.6% (P<0.05), 86.0% (P<0.05), and 63.0% (P<0.05) at a concentration of 10(-5) mol L-1.

The mulberry tree (Morus alba) plays a key role in agriculture, and its different parts have been used as popular Traditional Chinese Medicines for thousands of years. There are 16 species belonging to the Morus genus. Among them, 11 species distribute in China, most of which have been used as the substitutes of M. alba in local provinces. This review summarizes the structural characters of polyphenols, the main components in Morus, including Diels-Alder-type adducts, flavonoids, 2-arylbenzofurans, and stilbenes, and also their related bioactivities in the last 10 years.

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Five new compounds, named guangsangons A (1), B (5), C (6), D (7), and E (8), along with four known compounds, albafuran C (2), kuwanon X (3), kuwanon P (4), and kuwanon Y (9) were isolated from Morus macroura Miq.. Their structures were determined by means of spectroscopic analyses and chemical methods. These compounds were regarded biogenetically as Diels-Al-der type adducts, and 1H-NMR variable temperature experience suggested that they all existed as an equilibrium mixture of conformational isomers in solution. Compounds 1-3 and 5-9 showed good anti-oxidation activity, with the inhibitory rate of malondialdehyde being from 90.1% to 102.7% at a concentration of 10(-4) mol/L and from 70.9% to 88.1% at a concentration of 10(-5) mol/L. Compounds 1, 5, and 7 showed anti-inflammation activity, with the inhibitory rates of release of lysosome enzyme from polymorphonuclear leukocytes of rats being 19.0% (P > 0.05), 57.3% (P < 0.001) and 24.3% (P < 0.05) at concentrations of 10(-5) mol/L, respectively.