Catechins attenuate myocardial cell infiltration and fibrosis but do not prolong graft survival in murine cardiac allografts

Although tea catechins have many biological functions, their effects on cardiac allograft rejection have not been well studied. We used a total allomismatch heart transplant model to test the effects of catechins in cardiac rejection. We have shown that cell infiltration and fibrosis were suppressed in catechin-treated allografts compared with nontreated transplants. However, catechins did not statistically prolong graft survival. We conclude that catechins have a potential to suppress inflammation in cardiac allografts.

Inactivation of human type A and B influenza viruses by tea-seed saponins

The effects of a mixture of tea-seed saponins obtained from the seeds of Camellia sinensis var. sinesis on human influenza viruses types A and B were investigated. At the concentrations of 60, 80, and 100 micrograms/ml, respectively, the mixture inactivated viruses A/Memphis/1/71 (H3N2), B/Lee/40, and A/PR/8/34 (H1N1) almost completely. The mixture also inactivated type A virus A/PR/8/34 after inoculation at concentrations of 1-30 micrograms/ml dose-dependently.

Anti-allergic effect of tea-leaf saponin (TLS) from tea leaves (Camellia sinensis var. sinensis)

We investigated the anti-allergic effect of tea-leaf saponin (TLS), which was a mixture of saponins separated from the leaves of Camellia sinensis var. sinensis, in guinea pigs and rats. TLS (20-100 mg/kg) dose-dependently inhibited experimentally-induced asthma, and ID50 was 61.7 mg/kg. TLS (20-100 mg/kg) dose-dependently inhibited a 48 h homologous PCA (passive cutaneous anaphylaxis) reaction, and the inhibitory effect was similar to that of tranilast. TLS (1-100 microg/ml) also inhibited the release of antigen-induced leukotriene (LT) C4 from sensitized guinea pig lung samples in a dose-dependent fashion, but did not prevent histamine release. TLS (0.01-0.5 microg/ml) inhibited histamine release from rat peritoneal mast cells induced by compound 48/80. At higher concentrations, TLS elicited histamine release. These findings suggest that TLS may be a useful protective agent against clinical allergy, and that the inhibitory effects of TLS on mediator release are in some way related to its inhibitory effect on experimentally-induced asthma and PCA reaction.

[Antimicrobial and anti-inflammatory actions of tea-leaf saponin]

Antimicrobial and anti-inflammatory actions of tea-leaf saponin, which was a mixture of saponin separated from leaves of Camellia sinensis var. sinensis, were investigated. Tea-leaf saponin showed relatively high antimicrobial activity against pathogenic dermal fungi and its MIC value for Microsporum audouinii was 10 microgam/ml. On the other hand, tea-leaf saponin inhibited rat paw edema induced by carrageenin in a dose dependent manner. Activation of hyaluronidase, one of the enzymes involved in inflammatory reactions, was inhibited by tea-leaf saponin. It was also found that tea-leaf saponin antagonized the action of leukotrien D4, one of the chemical mediators of inflammatory reactions. Any symptom of toxic reaction was not observed when tea-leaf saponin was administered orally to mice at a dose of 2000 mg/kg.

[Activation of retinoic acid (RA)-differentiated HL-60 cells by saponins]

The effect of saponins on the one of major functions of neutrophil, namely the generation of superoxide anion (O2-), was investigated using retinoic acid (RA)-differentiated HL-60 cells (promyelocytic leukemia cells). The generation of O2- from the cells induced by saponins was monitored by the reduction of cytochrome c. All five species of crude saponins studied here, i.e. tea-leaf saponins, tea-seed saponins, ginsenosides, soyasaponins and saikosaponins, stimulated the generation of O2- from RA-differentiated HL-60 cells. Tea-leaf saponins showed the highest stimulating activity, followed by soyasaponins and ginsenosides. The cytotoxic activity of saponins was determined by the dye exclusion method after the incubation of RA-differentiated HL-60 cells with various concentrations of saponins. Saikosaponins and tea-seed saponins exhibited considerable cytotoxic activity and hemolytic activity. To examine the involvement of protein kinase C (PKC) in the neutrophil activation by saponins, the effect of H-7, an antagonist of PKC, on the generation of O2- induced by saponins was investigated. H-7 was found to inhibit the generation of O2- in a dose-dependent manner, suggesting the participation of PKC in the neutrophil stimulating process by saponins. Tea-leaf saponins, ginsenosides and soyasaponins, which had high neutrophil stimulating activity and low cytotoxic activity, seemed to be useful as a biological response modifier (BRM) for the activation of neutrophil.

Reduction effect of theanine on blood pressure and brain 5-hydroxyindoles in spontaneously hypertensive rats

The effect of theanine, one of the components of green tea, on the blood pressure and brain 5-hydroxyindoles in spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) was investigated by intraperitoneally administering theanine. The effect of glutamine, which is structurally similar to theanine, was also examined. When SHR were injected with various amounts of theanine (0, 500, 1000, 1500, and 2000 mg/kg), the change was dose-dependent, and a significant decrease in blood pressure was observed with the high doses (1500 and 2000 mg/kg). A dose of 2000 mg/kg of theanine did not alter the blood pressure of WKY, while the same dose to SHR decreased it significantly. On the other hand, glutamine administration to SHR did not change either the blood pressure or the heart rate. The brain 5-hydroxyindole level was significantly decreased by theanine administration to both WKY and SHR, the decrease being dose-dependent.

A new glucuronide saponin from tea leaves (Camellia sinensis var. sinensis

A new glucuronide saponin (1) was isolated as its methyl ester (2) from the leaves of Camellia sinensis var. sinensis. On the basis of its spectral data and the results of chemical degradation, the structure was elucidated to be 3-O-[beta-D-galactopyranosyl(1-->2)-[beta-D- xylopyranosyl(1-->2)-alpha-L-arabinopyranosyl(1-->3)]- beta-D-glucuronopyranosyl]-21-O-cinnamoyl-16,22-di-O-acetylbarr ingtogenol C.