A comparative study on flavour components and therapeutic properties of unfermented and fermented defatted soybean meal extract

Microbial fermentation of plant material alters the composition of volatile and non-volatile plant natural products. We investigated the antioxidant, anticancer, and antiviral properties of extracts of defatted soybean meal fermented with Aspergillus fumigatus F-993 or A. awamori FB-133 using in vitro methods. Gas chromatography–mass spectrometry analysis of soybean meal fermented with A. awamori FB-133 and A. fumigatus F-993 identified 26 compounds with 11,14-octadecadienoic acid and methyl ester (63.63%) and 31 compounds with butylated hydroxytoluene (66.83%) and δ-myrcene (11.43%) as main constituents, respectively. The antioxidant activities of DSM extract were 3.362 ± 0.05 and 2.11 ± 0.02 mmol TE/mL, FDSM treated with A. awamori FB-133 were 4.763 ± 0.05 and 3.795 ± 0.03 mmol TE/mL and FDSM treated with A. fumigatus F-993 were 4.331 ± 0.04 and 3.971 ± 0.02 mmol TE/mL as determined by ABTS and FRAP assays, respectively. Both fermented extracts had better antioxidant activity than the unfermented extract as shown by multiple antioxidant activity assays. The concentration of fermented extracts required for 50% inhibition of cell viability was significantly lower than that of the unfermented extract when tested against the human liver cancer cell line HepG2 as shown by cell viability assays, indicating strong anticancer activity. The IC(50) values for DSM, FDSM with A. fumigatusF-993 and FDSM with A. awamori FB-133 were27, 16.88 and 8.60 μg/mL, respectively. The extract of FDSM with A. awamori FB-133 showed the strongest anticancer activity, compared to DSM and FDSM with A. FumigatusF-993 extracts. Fermented extracts also reduced hepatitis A virus titres to a greater extent than unfermented extracts, thus showing strong antiviral property. Hepatitis A virus titres were reduced by 2.66 and 3 log(10)/0.1 mL by FDSM with A. fumigatusF-993 and FDSM by A.awamori FB-133, respectively, compared to DSM (5.50 log(10)/0.1 mL). Thus, the fermentation of soybean meal with A. fumigatusF-993 or A. awamori FB-133 improves the therapeutic effect of soybean extracts, which can be used in traditional medicine.