世界規模でのグリーンパパイヤの研究、土壌細菌叢の研究

Nature’s Food Antioxidants in Health and Disease Prevention

Librado A. SANTIAGO^a,b, James Akira OSATO^b,c and Akitane MORI ^a

^aDepartment of Neuroscience, Okayama University Medical School, Okayama 700, Japan, ^bOsato Research Institute, Gifu 500, Japan and ^cThe United Graduate School of Agricultural Science, Gifu University, Gifu 500, Japan

A trend for all things natural is now seen in the growing public inclination to turn back to the basics and in the increasing applications of natural preventive medicines, generating much of the research interests on the antioxidant properties of such products and the benefits in health, nutrition, and disease prevention. By seeing disease as a disturbance within the patient’s body system, changes in the normal redox equilibrium, i.e., excess production of reactive oxygen species such as hydroxyl, superoxide, hydrogen peroxide and other radicals, can cause damage to DNA, proteins, lipids, among others and result to various illnesses and in extreme cases, death. The body is highly endowed with enzymatic and non-enzymatic antioxidant defenses, which however, are depleted when the tissue is continuously attacked and damaged by free radicals. Supplementation with food dietary antioxidants is thus regarded as an important yet conservative approach in natural remedies against free radical-induced diseases. Natural medicines and supplements derived from numerous plant materials and microorganisms abound but their antioxidant activity is not fully understood. Our work has focused on the electron spin resonance (ESR) spectroscopic detection of the free radical scavenging activity of some of these food antioxidants such as papaya, baker’s yeast, soybean paste (miso), rice bran, horseradish (wasabi), and Bio-normalizer.

Materials and Methods

All reagents and chemicals used were of the highest grade available from commercial suppliers. A 2~3 week old Philippine variety unripe papaya; a yellow variety miso from Kaneko-Miso Ltd., Tokushima; baker’s yeast Saccharomyces cerevisiae under the trademark Saf-Instant (S.I. Lesaffre, France); wasabi from S&B Co., Tokyo; rice bran from commercial supplier; and Bio-catalyzer a.r No.11 (Bio-normalizer) from Sun-O International Inc., Gifu were used. The cerebral cortex of male adult Sprague-Dawley rats (Clea Japan Inc., Tokyo) was dissected and homogenized (0.05% w/v) in 0.1 M Tris-HCl buffer, pH 7.4. Test food samples were homogenized then centrifuged at 1000 rpm for 5 min at 4ºC. By ESR spectrometry/spin trapping (JEOL, JES-FE1XG, Tokyo), the reactions of these water-soluble extracts with the different free radicals generated in organic, aqueous, and brain homogenate systems such as 1-1 diphenyl-2-picrylhydrazyl (DPPH), hydroxyl, superoxide, and carbon-centered were tested as stated in previous reports (1~4). The superoxide dismutate (SOD) activity, assayed using ESR (2,9) was based on the ability of 25 mg/ml samples to dismutase almost completely the superoxide radicals generated from the hypoxanthine-xanthine oxidase system.

Results and Discussion

Table 1 shows the IC₅₀ of the food antioxidants and their corresponding antioxidative constituents required to inhibit the DPPH, hydroxyl and superoxide radicals. These crude/unpurified food antioxidants are thousand-fold less potent than their pure specific components such as vitamins C and E, malic and citric acids, and glucose. Except for papaya and miso, all samples were analyzed on dry weight basis such that the differences in the moisture content may have partly contributed to differences on the antioxidant potency of these food antioxidants. 200 mg/ml baker’s yeast scavenged 100% of the hydrogen radicals (7.8 x 10¹⁴ spins/ml) and 94.8% of the carbon-centered radicals (3.4 x 10¹⁶ spins/ml). Similarly, it required 180 mg/ml miso to quench 90% and 82% of the hydrogen radicals (1.7 x 10¹³ spins/ml) and carbon-centered radicals (3.9 x 10¹³ spins/ml), respectively. 25 mg/ml rice bran inhibited 60.9% of carbon-centered radicals (6.6 x 10¹² spins/ml). Because the bran is insoluble higher concentrations could not be prepared and tested. The papaya meat, seed and pulp contains 32, 98 and 33 units/ml of SOD-like activity while miso, rice bran, and baker’s yeast have 58, 65, and 75 units/ml, respectively. With both their intrinsic nutrient values and antioxidative protection, these nature’s food antioxidants are envisaged as double-pronged approaches in nutrition, health and medicine.

Of these dietary food antioxidants, Bio-normalizer – a fermented health food from papaya, yeast and other traditional Japanese foodstuffs – was studied in detail using experimental animal subjected to oxidative stress as in the models of post traumatic epilepsy, intracerebral microdialysis, ischemia/reperfusion injury, and aging, As shown in Table 2, Bio-normalizer exerted antioxidant protection in all of these animal models, thereby supporting its purported preventive and therapeutic actions.

Table 1. ESR spectroscopic detection of the free radical scavenging action of the water-soluble extracts of some naturally occurring food antioxidants.

NR – no reaction; d – delayed quenching action observed after 6-9 min in lieu of the usual analytical time of 50s; * commercially available; GSH – glutathione; SOD – superoxide dismutase.

Table 2. Antioxidant effects of Bio-normalizer on different experimental amal models.

TBARS, thiobarbituric acid reactive substances; *Med. Sci. Res., 1992; 21: 139-141, **NeuroReport, 1993; 4: 1031-1034, ***Neurochem. Res., 1993, 18: 711-717.

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Key words: Free radical scavengers, food antioxidants, ESR spectroscopy