Dietary plant protein is well known to reduce serum cholesterol levels. Rice bran is a by-product of rice milling and is a good source of protein. The present study examined whether feeding rats a high-cholesterol diet containing 10% rice bran protein (RBP) for 10 d affected cholesterol metabolism. Rats fed dietary RBP had lower serum total cholesterol levels and increased excretion of fecal steroids, such as cholesterol and bile acids, than those fed dietary casein. In vitro assays showed that RBP strongly bound to taurocholate, and inhibited the micellar solubility of cholesterol, compared with casein. Moreover, the bile acid-binding proteins of the RBP were eluted by a chromatographic column conjugated with cholic acid, and one of them was identified as hypothetical protein OsJ_13801 (NCBI accession No. EAZ29742) using MALDI-TOF mass spectrometry analysis. These results suggest that the hypocholesterolemic action of the RBP may be caused by the bile acid-binding proteins.

There has been no report about in vivo active cholesterol-lowering dipeptide in any protein origin, despite their potential health benefits. Cattle heart protein hydrolysate ultra-filtrate (HPHU, molecular weight < ca. 1,000 Da peptide mixture) exhibits cholesterol-lowering activity in hypercholesterolemic rats, but the active peptide in HPHU that lowers serum cholesterol levels and its molecular mechanism are unknown. In this study, we separated and purified HPHU to identify a novel cholesterol-lowering dipeptide (phenylalanine-proline, FP) and characterized the mechanism underlying its effects in vivo and in vitro. We identified FP as an active peptide from HPHU by MALDI-TOF mass spectrometry. FP significantly decreased serum total and non-HDL cholesterol and hepatic cholesterol levels in rats. FP significantly increased serum HDL cholesterol, accompanied by a significant decrease in the atherogenic index. FP also significantly increased fecal cholesterol and acidic steroid excretion. Moreover, FP significantly decreased ATP-binding cassette transporter A1 (ABCA1) expression in the rat jejunum and reduced cholesterol absorption in Caco-2 cells. We found a novel cholesterol-lowering dipeptide FP that could improve cholesterol metabolism via the down-regulation of intestinal ABCA1. The cholesterol-lowering action induced by FP was disappeared in PepT1KO mice. FP-induced cholesterol-lowering action is mediated via PepT1 in mice.

Naringenin (NN) is one of the most abundant flavonoids in citrus and grapefruits, and has been shown to have antioxidant properties in vitro. The purpose of the study is...

Tea polyphenols lower the levels of cholesterol in the blood by decreasing the cholesterol micellar solubility. To clarify this mechanism, the interactions between taurocholic acid and (−)-epigallocatechin gallate (EGCg) and its derivatives were investigated. 13C NMR studies revealed remarkable chemical-shift changes for the carbonyl carbon atom and the 1″- and 4″-positions in the galloyl moiety. Furthermore, 1H NMR studies using (−)-EGCg derivatives showed that the number of hydroxyl groups on the B ring did not affect these interactions, whereas the carbonyl carbon atom and the aromatic ring of the galloyl moiety had remarkable effects. The configuration at the 2- and 3-positions of the catechin also influenced these interactions, with the trans-configuration resulting in stronger inhibition activity than the cis-configuration. Additionally, a 1:1 component ratio for the catechin–taurocholic acid complex was determined by electrospray ionization–mass spectrometry. These molecular mechanisms contribute to the development of cholesterol-absorption inhibitors.

Hawthorn (Crataegus pinnatifida) fruit has a long history of use as a traditional Chinese medicine and shown to have many health benefits including antioxidant and anti-aging. In this study, the...

Methylglyoxal (MGO), a cytotoxic byproduct of glycolysis, causes neuro oxidative damage and apoptosis, and plays key roles in diabetic encephalopathy (DE). The goal of this research was to evaluate the roles of lutein attenuated MGO‐induced damage in PC12 cells as well as the underlying mechanisms. The findings of this study showed that lutein has a significant impact on reducing the generation of reactive oxygen species (ROS) and oxidative stress in MGO‐induced PC12 cells, which may be attributed to the increased antioxidant enzymes activity and the decreased MDA levels. Moreover, treatment with lutein also alleviated cell apoptosis and mitochondrial damage. Real‐time PCR and western blot analysis showed that lutein enhanced the Bcl‐2:Bax ratio, inhibited the expression of caspase‐3 and caspase‐9, and increased the protein level of phosphorylated Akt. The network pharmacology and molecular docking prediction results suggested that the phosphoinositide 3‐kinase/protein kinase B (PI3K/Akt) signaling pathway was a potential mechanism of lutein in DE treatment. Furthermore, LY294002, a specific PI3K inhibitor, partially abolished the protective effect of lutein. These results presented that lutein attenuated oxidative damage and apoptosis triggered by MGO in PC12 cells via the PI3K/Akt signaling pathway. Practical applications Lutein is a common carotenoid dispersed in fruits and vegetables. This article confirmed a protective effect of lutein on oxidative damage and apoptosis in PC12 cells after MGO damage. These results indicated that lutein could potentially be developed as a nutraceutical or functional food in the prevention of diabetic‐related neurodegenerative diseases.

In our previous study, rice bran protein (RBP) inhibited cholesterol micellar solubility in vitro and decreased serum cholesterol level in rats. In the present study, RBP was separated and purified by size-exclusion chromatography and reversed-phase chromatography. The active protein of RBP related to cholesterol micellar solubility was identified as lectin and non-specific lipid-transfer protein 1 using MALDI-TOF mass spectrometry analysis.

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