Soybean cake as a source of stable bioactive compounds (647.43)

Abstract

Soybean cake is a byproduct of soybean oil processing rich in bioactive compounds. In this study we evaluated the effect of soybean cake extracts on cell viability, cycle and apoptosis in human colon adenocarcinoma cell line (HT‐29) and their stability under different storage conditions. Soybean cake from soybean oil industry (SCI) and produced under laboratory conditions (SCL) were extracted with a ternary mixture (water:ethanol:ethyl acetate), lyophilized and incubated with HT‐29 cells at concentrations (10 to 400 mg/g) from 6 to 96 h. The dry extracts were stored in freezer or room temperature (light or dark) and the following analysis were conducted at regular intervals during 120 days: spectrophotometric assays for phenolic compounds, flavonoids and saponins; antioxidant capacity (AC) by FRAP and TEAC assays; isoflavones and soyasaponins by LC‐DAD‐MS. SCL and SCI extracts showed high levels of phenolic compounds (12.36 and 10.45 mg gallic acid/g), flavonoids (7.24 and 9.98 mg genistein/g), saponins (224.86 and 253.99 mg/g) and AC (FRAP: 71.35 and 91.57 µmol Fe+2/g; TEAC: 105.02 and 103.90 µmol Trolox/g). LC‐DAD‐MS analysis revealed that SCI extract presented higher levels of β‐glycosylated isoflavones (3.67 mg/g) than SCL (0.72 mg/g). Aglycone isoflavones were present in higher levels in SCL extract (3.16 mg/g) than in SCI (0.82 mg/g). Both extracts reduced in a time‐dose dependent fashion cell viability when compared to control at concentrations starting from 100 mg/g. These reductions ranged from 4% to 84% and from 24% to 85% when cells were incubated with SCL and SCI, respectively. After incubation with SCL a decrease in the percentage of cells at G0/G1 phase and an increase in G2/M phase was observed, as well as an increase in the apoptosis rate. After 120 days of storage, bioactive compounds’ levels did not change, with the exception of FRAP values. Extracts showed anticancer effects in vitro and soybean cake is a potential source of stable bioactive compounds for in vivo studies.Grant Funding Source: FAPERJ, CNPq, CAPES, UFRJ