Selected Soybean Varieties Regulate Hepatic LDL-Cholesterol Homeostasis Depending on Their Glycinin:β-Conglycinin Ratio

Abstract

Clinical studies indicate that the consumption of soybean protein might reduce cholesterol and LDL levels preventing the development of atherosclerotic cardiovascular diseases. However, soybean variety can influence soybean protein profile and therefore affect soybean protein health-promoting properties. This study investigated the composition and effects of nineteen soybean varieties digested under simulated gastrointestinal conditions on hepatic cholesterol metabolism and LDL oxidation in vitro. Soybean varieties exhibited a differential protein hydrolysis during gastrointestinal digestion. Soybean varieties could be classified according to their composition (high/low glycinin:β-conglycinin ratio) and capacity to inhibit HMGCR (IC50 from 59 to 229 µg protein mL−1). According to multivariate analyses, five soybean varieties were selected. These soybean varieties produced different peptide profiles and differently reduced cholesterol concentration (43–55%) by inhibiting HMGCR in fatty-acid-stimulated HepG2 hepatocytes. Selected digested soybean varieties inhibited cholesterol esterification, triglyceride production, VLDL secretion, and LDL recycling by reducing ANGPTL3 and PCSK9 and synchronously increasing LDLR expression. In addition, selected soybean varieties hindered LDL oxidation, reducing the formation of lipid peroxidation early (conjugated dienes) and end products (malondialdehyde and 4-hydroxynonenal). The changes in HMGCR expression, cholesterol esterification, triglyceride accumulation, ANGPTL3 release, and malondialdehyde formation during LDL oxidation were significantly (p < 0.05) correlated with the glycinin:β-conglycinin ratio. Soybean varieties with lower glycinin:β-conglycinin exhibited a better potential in regulating cholesterol and LDL homeostasis in vitro. Consumption of soybean flour with a greater proportion of β-conglycinin may, consequently, improve the potential of the food ingredient to maintain healthy liver cholesterol homeostasis and cardiovascular function.

Soybean (Glycine max) INFOGEST Colonic Digests Attenuated Inflammatory Responses Based on Protein Profiles of Different Varieties

“…Additionally, higher lunasin concentration in dietary supplements was associated with higher antioxidant capacity [21]. Glycinin and β-conglycinin make up most of the protein content of soybean, and β-conglycinin in particular had been shown to be able to reduce obesity and LDL cholesterol, as well as inhibiting lipid accumulation and lowering inflammation [4,[22][23][24]. Peptides from soybean were also found to be able to reduce intestinal inflammation through maintenance of intestinal mucosal integrity and suppression pro-inflammatory biomarkers [25][26][27].…”

“…The main storage proteins of soybean are glycinin and β-conglycinin, making up 70% of the total seed protein [3]. The proportion of glycinin and β-conglycinin in different soybean varieties influences peptide release and antioxidant capacity under simulated gastrointestinal digestion conditions [4].…”

Radical Scavenging and Cellular Antioxidant Activity of the Cocoa Shell Phenolic Compounds after Simulated Digestion

“…To complete the gastric phase, the resulting oral phase was merged with the simulated gastric fluid and pepsin (2000 U mL −1 ) and incubated under continuous stirring (2 h, 37 • C). To model the intestinal phase, the gastric phase was combined with the simulated intestinal fluid that included pancreatin (100 U trypsin mL −1 ) and incubated for 2 h at 37 • C. The colonic phase was performed as previously described [22]. The intestinal phase was mixed with 5 mL of Pronase E (1 mg mL −1 ), the pH was adjusted to 8.0, and the digested CS was stirred at 37 • C for 1 h. After that, the pH in the digestion media was adjusted to 4.…”

Benefits of Soybean in the Era of Precision Medicine: A Review of Clinical Evidence

“…Soybean reportedly comprises 35–40% protein, 20% fat, 9% dietary fiber, and 8.5% moisture [ 28 ], but their compositions vary with their variety, planting location, and climate [ 29 ]. Major soy components with biological activities include peptides [ 30 - 36 ] and isoflavones [ 37 - 39 ].…”