Determination of the variations in levels of phenolic compounds in soybean ( Glycine max Merr.) sprouts infected by anthracnose ( Colletotrichum gloeosporioides )

BACKGROUND: Soybean sprouts (Kongnamool) are one of the most popular and nutritive traditional vegetables in East Asia. Anthracnose caused by Colletotrichum gloeosporioides is one of the most serious diseases of soybean sprouts. In order to obtain basic information for breeding and/or selecting soybean genotypes with increased natural defense against anthracnose, phenolic compounds were profiled for healthy and infected soybean (Glycine max Merr.) sprouts by using high-performance liquid chromatography coupled with tandem mass spectrometry. RESULTS: Tryptophan and eight phenolic compounds (daidzin, genistin, malonyldaidzin, malonylgenistin, daidzein, glycitein, genistein and coumestrol) were determined from healthy and inoculated sprouts. Total identified phenolic content was 40.02 ± 0.03 mg kg⁻¹, 99.4% of which was isoflavones. CONCLUSION: The monitoring suggested that de novo induced glycitein appeared to act as a phytoalexin in the defence mechanism of the soybean sprouts against C. gloeosporioides, and constitutively formed seven phenolic components that functioned as phytoanticipins in the diseased soybean sprouts.