OTHER BIOLOGICAL EFFECTS OF C. TORA

VI. OTHER BIOLOGICAL EFFECTS OF C. TORA

A. Hypotensive Effect Aqueous and methanol extracts from Cassia seeds elicit hypotensive effects on

anesthetized rats. Experimental results indicate that the hypotensive effect of the C. tora extract possibly involves a vagal reflex that reciprocally alters the vasomotor tone of the centrally emanating sympathetic nervous system. It is shown that the capacity of C. tora extracts to reduce blood pressure is signif- icantly reduced in vagotomized rats and that hypotensive effects are greatly antagonized in rats whose sympathetic nervous systems are interrupted by transection of the spinal cord. Phytochemical studies also show that the active hypotensive principles are derived from the kernel of the seed and consist of mainly glycosides (7,8).

B. Lipid-Lowering Effect Ha et al. (9)investigated the lipid-lowering effect of C. tora ethanol extacts in

rats fed a high-cholesterol diet. Rats were fed either normal diets or diets high in cholesterol (10 g/kg diet), supplemented with C. tora ethanolic extract (0,

0.25, or 0.5%)for 4 weeks. Liver triglyceride and cholesterol contents were raised in the high-cholesterol groups and were significantly reduced in the groups fed C. tora. Serum levels of HDL cholesterol were slightly increased by

Antioxidant Activity of Cassia tora 567

may exert a lipid-lowering effect in rats fed high-cholesterol diets. Further- more, Choi et al. (10)indicated that ethanol-treated rats fed with 200 or 400 mg/kg body wt./day Cassia ethanolic extract had a hypolipemic effect compared with rats treated with ethanol alone.

C. Antiplasmodial Effect Plant extract of C. tora had antiplasmodial activity in vitro against Plasmo-

dium falciparum 3D7 and Dd2, and had an IC 50 value less than 5 Ag/mL on both tested strains (12). The effect of Cassia extracts on lymphocyte prolif- eration showed low toxicity to the human cells. This plant has been subjected to long-term clinical trials in folk medicine and is a promising plant.

D. Antifungal Activity An antifungal principle of defatted seed powder of C. tora was isolated by

extraction of the powder with benzene. Besides chrysophanol and other hydroanthroquinone derivatives, the major antifungal compound was iden- tified as chrysophanic acid-9-anthrine. This compound was active against Trichophyton rubrum , T. mentagrophytes, Microsporum canis, M. gypseum, and Geotrichum candidum in broth in the presence of 100 Ag/mL L -ascorbic acid as antioxidant (13).

VII. ANTIBACTERIAL EFFECT Thirteen phenolic glycosides including six new compounds were isolated from

seeds of C. tora. The structures of the new compounds, rubrofusarin trigluco- side, nor-rubrofusarin gentiobioside, demethylflavasperone gentiobioside, torachrysone gentiobioside, torachrysone tetraglucoside, and torachrysone apioglucoside, were deduced on the basis of spectroscopic and chemical evidence. The effect of the phenolic glycosides, their aglycones, and several other compounds structurally related to the on Escherichia coli K12, Pseu- domonas aeruginosa PAO1, and some strains of Staphylococcus aureus were then examined. Among them, torachrysone, toralactone, aloe-emodin, rhein, and emodin showed noticeable antibacterial effects on four strains of meth- icillin-resistant Staph. aureus with a minimum inhibitory concentration of 2–64 Ag/mL. On the other hand, the phenolic compounds tested did not show strong antibacterial effects on E. coli and Ps. aeruginosa (14).

A. Antihepatotoxic Effect Two new naphtho-pyrone glycosides, 9-[(beta- D -glucopyranosyl-(1-6)-O-be-

ta- D -glucopyranosyl)oxy]-10-hydroxy-7-methoxy-3-methyl-1H-naph-

568 Yen and Wu

glucopyranosyl)oxyl-rubrofusarin, together with cassiaside and rubrofu- sarin-6-beta-gentiobioside, were isolated from the seeds of C. tora L. Their structures were deduced on the basis of chemical and spectral data. The naphtho-gamma-pyrone glycosides were found to have significant hepato- protective effects against galactosamine damage, which were higher than that of silybin from Silybum marianum (11).

VIII. CONCLUSIONS Herbs have been used as food and for medicinal purposes for centuries. The

Chinese herb C. tora has been reported to have hypotensive, hypolipemic, antibacterial, antiviral, antifungal, and antihepatotoxic activity. The com- mercial products of C. tora include both unroasted and roasted samples, and the biological effects were found to be higher with unroasted C. tora than with the roasted product. Roasted C. tora has a special flavor and color, and it is popularly used to make a health drink. C. tora contains a variety of bioactive phenolic substances, including chrysophanol, emodin, rhein, etc., which are mainly responsible for the pharmacological action ascribed to them.

The extracts of C. tora scavenge hydrogen peroxide, superoxide anion, and hydroxyl radicals, inhibit lipid peroxidation, and suppress DNA damage in human lymphocytes induced by hydrogen peroxide. The unroasted C. tora extract has greater antioxidant activity than roasted samples. Higher roasting temperature and longer roasting periods reduced the antioxidant activity of

C. tora . The extracts of C. tora reacted under the HepG2 cell cultivating model of nonexogenic enzyme have suppressive effects for the DNA damage induced by B[a]P. The inhibitory effects of C. tora on DNA damage are similar to the trend of its antioxidant properties, and decreased with increas- ing roasting temperature. The mechanism involved in antigenotoxicity includes suppressing EROD, NADPH CYP-450 reductase in cells and promoting GST activity. Overall, the biological activities of extracts from roasted C. tora decreased as compared with that of unroasted samples. This result might be caused by the reduction of phenolics and anthraquinones in C. tora as a result of roasting.

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