Sesame seed (Sesamun indicum L.) has been recognized by Chinese medical professional as a pharmacopoeia Ban Chao Gang Mu claims that sesame seed will strengthen the body and prolong human¡¦s life.
Sesamin is one of the lignan compounds specifically occur in sesame seed. Sesamin has been attracted attention by many investigators for its diverse and meritorious physiological activities in experimental and humans. Evidence so far obtained supports that it is quite promising to use this compound as the functional material to formulate functional foods with health-benefit. A pioneer study by Shimizu of Kyoto University in Japan and his colleagues that reported the inhibigion of D5-desaturase activity in microorganisms opened a novel approach to health-benefit of sesamin. Using rats as experimental animal, sesamin has been found that shows various physiological functions as follows:
1. Lowering of serum cholesterol level, 2. Stimulation of alcohol metabolism and its detoxification, 3. Inhibition of the conversion of linoleic acid to arachidonic acid, and hence the production of eicosanoids, 4. Suppression of carcinogen-induced mammary tumorigenesis, 5. Improvemetn of immune function, 6. Anti-oxidative activity, and so on.
Other investigators also showed that dietary sesamin increases retention of tocopherols especially g-isoform in tissues and blood. Recent information indicated that sesamin is a potent inhibitor of cytochrome p450-mediated microsomal tocopherol degradation. Dietary sesamin also reportedly suppresses ageing in senescence-accelerated mouse model, and lowers blood pressure in rats. The combined effects of sesamin with tocopherol in reducing serum cholesterol level and in stimulating detoxification activity of the liver have been confirmed not only in experimental animals but also in humans.
Sesamin is not an anti-oxidant in vitro, and hence has attracted little attention by researches for many years despite that this compound is the most abundant lignan in sesame seed and oil. However, it is now revealed that, after being absorbed, it is converted to the compound(s) with radical scavenging propensity and exerts strong anti-oxidation activity in vivo. Accompanying the finding of its anti-oxidation property, various physiological activities not only of sesamin but also of other sesame lignans have been emerging from recent studies.
With regard to the mechanism behind the cholesterol-lowering activity of sesamin, it is result from reducing intestinal absorption of cholesterol in rats. Reduction in cholesterol absorption usually associates with an increase in hepatic cholesterogenesis. Interestingly, however, sesamin reduces hepatic activity of HMG-CoA reductase, a key enzyme in cholesterol synthesis. Therefore, sesamin exerts serum cholesterollowering activity through a quite unique mechanism. Sesamin can increase hepatic fatty acid oxidation, and it appears to be the most potent inducer of hepatic fatty acid oxidation among the various naturally occurring compounds insofar as reported. It was suggested that sesamin is a ligand and activator of peroxisome proliferators activated receptor(PPAR) and hence induces gene expression of hepatic fatty acid oxidation enzymes.
In summary, sesamin is considered as one of the most promising functional food component in taking account of its various physiological functions metitorious to human health and the availability in our food habits (and therefore its effectiveness at daily consumption). Consumption of sesamin appears highly safe and further expansion of the market for the sesamin as the health-benefits food component would highly be expected.
