A team of researchers has identified the active compounds that contribute to the health benefits of pre-germinated brown rice; the healthy components are a related set of sterol-like molecules known as acylated steryl-beta-glucosides (ASGs).
Pre-germinated rice (PR) is an emerging health food whereby brown rice is soaked in warm water prior to cooking; the warm bath induces germination, or sprouting, which stimulates rice enzymes to produce more nutrients. One such nutrient is the important brain chemical GABA (PR is thus often referred to as "GABA rice"), and animal studies have shown that a PR-rich diet can improve cognitive function. Other studies have found that PR can also act as an anti-diabetic.
The chemicals behind this effect were unknown, but now Robert Yu and colleagues used mass spectrometry and nuclear magnetic resonance approaches and identified the bioactive compounds as ASGs, a diverse family of molecules that consists of a glucose derivative, fatty acids, and sterols. The ASGs were concentrated in the rice bran (outer layer) and not the seed, so they would not be found in white rice.
The researchers then demonstrated that the ASGs had the ability to activate enzymes related to diabetes, and this activation required the acyl chemical group; regular steryl glucosides (SGs) had no effect. And, although ASGs are found in many plants, soybean derived ASGs had no effect on the diabetic enzymes, indicating the ASG complement specific to rice may be unique in its diabetic benefits.
The above story is based on materials provided by American Society for Biochemistry and Molecular Biology. Note: Materials may be edited for content and length.
- Seigo Usuki, Toshio Ariga, Somsankar Dasgupta, Takeshi Kasama, Keiko Morikawa, Shota Nonaka, Yasuhide Okuhara, Mitsuo Kise, and Robert K. Yu. Structural analysis of novel bioactive acylated steryl glucosdies (ASGs) in pre-germinated brown rice bran. Journal of Lipid Research, October, 2008
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