Effects of Artificial Stomach Fluid and Digestive Enzymes on the Aglycone Isoflavone Contents of Soybean and Black Bean (Rhynchosia Molubilis: Yak-Kong.
- Author:
Soon Ah KANG
1
;
Ki Hyo JANG
;
Yunhi CHO
;
Kyunghee HONG
;
Ji Hae SUH
;
Ryowon CHOUE
Author Information
1. Department of Medical Nutrition, Craduate School of East-West Medical Science, Research Institute of Clinical Nutrition, Kyung Hee University, Seoul, Korea.
- Publication Type:In Vitro ; Original Article
- Keywords:
soybean;
black bean (yak-kong);
isoflavone;
aglycone;
in vitro conversion
- MeSH:
alpha-Glucosidases;
beta-Glucosidase;
Biological Availability;
Dietary Supplements;
Female;
Genistein;
Humans;
Hydrolysis;
Isoflavones;
Medicine, East Asian Traditional;
Methanol;
Osteoporosis, Postmenopausal;
Phytoestrogens;
Saliva;
Saliva, Artificial;
Soybeans*;
Stomach*
- From:The Korean Journal of Nutrition
2003;36(1):32-39
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
Phytoestrogens, especially soy-derived isoflavones, are receiving great scrutiny as a food supplement for preventing hormone dependent disease such as postmenopausal osteoporosis. Their beneficial effects are derived from aglycone form of isoflavones, such as daidzein, genistein or glycitein. In contrast to the common usage of soybean, black bean (Rhynchosia Molubilis : Yak-kong) has been used as a supplement for preventing postmenopausal osteoporosis in oriental medicine. To investigate the effects of the saliva, artificial stomach fluid, and digestive enzymes on the conversion of glycosidic isoflavone to aglycone form, soybean and black bean were extracted with 70% methanol and freeze-dried. The recovery yield of methanol extracts of black bean was 14.1% which was higher than that of soybean, 13.5%. In terms of total isoflavones, we routinely obtained larger amount of isoflavones from black bean than those from soybean. By incubating methanol extracts of soybean and black bean with IN HCI for 180 min, the proportions of aglycones relative to the total isoflavone were significantly increased (32.4% and 52.4%, respectively). In vitro conversion, digestive enzymes (beta-glucosidase and alpha-glucosidase) may hydrolyze glycosidic bond of isoflavone more effectively than saliva or artificial stomach fluid did. It seems to say that the activity of beta-glucosidase was higher than those of alpha-glucosidase. The rate of conversion of glucoside form to aglycone form in black bean and soybean was low in physiological condition (pH) tested, although the enzymatic hydrolysis of glucoside was active. These results demonstrated that the composition of aglycone in food may be the important factors in terms of the bioavailability of isoflavones.
