Evaluation of dietary plants for superoxide generation (or its inhibition), or scavening activities, and their active constituents

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Super oxide anion radical (SO), the initial active oxygene species, is known to be very important in the primary metabolisms and also physiological functions in biological systems. The excess generation of SO is, however, closely related to ageing and carcinogenesis. In addition to the enzymatic (SOD) heterolytic reaction, the control of SO by food constituents may be important in our daily life. We have already established assay methods for SO generation or scavenging using an enzyme, xanthine oxidase, or HL-60 cells. By these methods, some significant dietary plants from tropical south-east Asia and also from Japan have been found. 1'-Acetoxychavicol acetate (ACA) from Languas galanga, a highly potent anti-tumor promoter, has been estimated to be a strong inhibitor of xanthine oxidase. It also inhibited TPA-stimulated SO generation in HL-60 cells differentiated with DMSO.The SO generation inhibition was observed by a flow cytemetory to also occur inside the cells. SO generation had been known to be related to anti-tumor promotion. Then, inhibition of SO generation was proposed to be one of the mechanisms of ACA for anti-tumor promotion. (R) -Rosmarinic acid was isolated from green perilla as an SO scavenging agent. Interestingly, it did not inhibit Epstein-Barrvirus activation induced by a tumor promoter, which has been known to well correlated to anti-tumor promotion. Further studies on these activities must present us more important information about the relationship between SO and carcinogenesis.