Structure of an antioxidant from fermented soybeans (tempeh)

Abstract

In an exhaustive investigation of the antioxidative properties of tempeh constituents, the substance at R f 0.58 (cyclohexane/ethyl ether, 9:1) was isolated and purified. Until now, only the ultraviolet and fluorescence data of the substance were known, and the presence of an OH group was indicated. In the present paper, the structure of the substance at R f 0.58 was elucidated by the application of spectroscopic methods and found to be 5-(δ-tocopheroxy)-δ-tocopherol. That previous researchers did not confirm antioxidant activity in tempeh oil has been related to the way the tempeh oil was prepared. Previous suggestions regarding the substance at R f 0.58 as being one of the main tempeh antioxidants could not be proved. The antioxidative effect of tempeh oil seems to be the result of a synergistic effect of tocopherols (present in the soybeans) and amino acids (liberated during the fermentation process with Rhizopus oligosporus). JAOCS 74, 477-479 (1997).Tempeh is an indigenous food in southeast Asia, especially Indonesia. Owing to its nutritive qualities and sensory acceptability, it is gradually becoming popular in the West. Tempeh has several beneficial characteristics, antioxidative activity being the most important of them. For more than 10 yr, we have been working on the isolation and structural elucidation of tempeh constituents and investigating their physiological activities. The antioxidative property of tempeh is caused by the synergistic effect of some of the tempeh constituents on the tocopherols present. One of the antioxidants present in tempeh is the substance R f 0.58 (cyclohexane/ethyl ether, 9:1), which was isolated by Fukuyama et al.(1). This paper describes the isolation, purification, and elucidation of the structure of this substance and suggests reasons for deviation in the results of Stahl and Sims (2) and of Murata (3) concerning the antioxidative property of tempeh. MATERIALS AND METHODSAll organic solvents used were of analytical or higher grade and were obtained from Merck (Darmstadt, Germany). Silica Gel 60 (mesh 15-40 nm) and florisil (mesh 150-250 nm) for column chromatography, and thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) plates Si 60 were from Merck. The freeze-dryer was from Edwards (Crawley, England). Ultraviolet (UV) spectra were measured with a UV-visible recording spectrophotometer (model UV-160; Shimadzu, Kyoto, Japan). Samples were measured in n-hexane. Infrared (IR) spectra were measured with a Perkin Elmer 157 G grating IR spectrophotometer (Beaconsfield, England). Fluorescence spectra were recorded on a Perkin Elmer MPF 4 fluorescence spectrophotometer.1 H and 13 C nuclear magnetic resonance (NMR) spectra were measured on a Bruker AMX 500 (Karlsruhe, Germany). Mass spectra were measured on a VG Analytical ZAB HF mass spectrometer (Manchester, England) with inverse geometry, in which a fast atom bombardment (FAB) gun is implanted.Thin-layer chromatography (TLC). Analytical TLC was performed in a Desaga horizontal TLC chamber 5...

Changes in the Radical Scavenging Activity of Bacterial-Type Douchi, a Traditional Fermented Soybean Product, during the Primary Fermentation Process

“…[3][4][5] To examine the role of isoflavones in the antioxidant activities of the douchi, isoflavone isomers in the samples during fermentation were determined (Table 1). Neither -glucosides, daidzin, genistin, and glycitin, nor the corresponding aglycone isoflavones, genistein, daidzein, and glycitein changed significantly (p > 0:05) during the 36 h of fermentation, indicating that the Bacillus subtilis used in the present study did not convert glucoside isoflavones to aglycone isoflavones during fermentation.…”

“…[3][4][5]18) Statistical analysis showed that there was no significant correlation between the changes in aglycone isoflavones and the radical scavenging activity of the douchi during bacterial fermentation (p > 0:05), suggesting that isoflavone contributes little to the changes in the antioxidant activity of douchi.…”

“…Similar results were found in Mucor-type soybean production. 5) Most proteins and starchs also convert into simpler components through enzymatic reactions catalyzed by proteinase, peptidase, and amylase during fermentation. The production of douchi generally consists of soaking, boiling, fermentation, and seasoning of soybeans.…”

Effect of γ-Aminobutyric Acid-enriched Tempeh-like Fermented Soybean (GABA-Tempeh) on the Blood Pressure of Spontaneously Hypertensive Rats

“…11) Free amino acids and oligopeptides in foods have been reported not only to improve the umami taste, but also to have such nutritional advantages as rapid absorption, 12,13) muscle protein maintenance, 13) and antioxygenic activity. 14) These physiological eŠects can also be expected for GABAtempeh, but they do need to be assessed by feeding experiments.…”

Chemical composition, antimicrobial and antioxidant properties of seed oil plants of North-East India: A review

“…The flax plant Linum usitatissimum possesses various tocopherols and carotenoids and some sterols, thus making its oil high in antioxidants. Rapeseed oil and soyabean oil contain high percentage of tocopherols Glycine max L. Amarowicz et al, 1996;Hoppe et al, 1997;Wang, 2002 Coumarins Radical scavenging effect…”