Luteolin binds Src, promotes STAT3 protein ubiquitination and exerts anti-melanoma effects in cell and mouse models.

Signal transducer and activator of transcription 3 (STAT3) has been proposed as a target for melanoma prevention. Luteolin, a bioactive flavonoid abundant inmedicinal herbs, has been reported to have anti-melanoma activity in vitro. However, its in vivo anti-melanoma effects and underlying mechanisms have not been fully elucidated. In this study, ten cell lines and two mouse models (B16F10 allograft and A375 xenograft models) were used for assessing the in vitro and in vivo anti-melanoma effects of luteolin. A STAT3 over-activated stable A375 cell line was used to determine the contribution of STAT3 signaling in luteolin's anti-melanoma effects. Results showed that luteolin dose-dependently reduced viability of melanoma cells. Luteolin also induced apoptosis in, and suppressed migration and invasion of, A375 and B16F10 melanoma cells. Mechanistically, luteolin inhibited phosphorylation of STAT3 and Src (an upstream kinase of STAT3), accelerated ubiquitin-proteasome pathway-mediated STAT3 degradation, and downregulated the expression of STAT3-targeted genes involved in cell survival and invasion in melanoma cells. Molecular modelling and surface plasmon resonance imaging showed that luteolin stably bound to the protein kinase domain of Src. Animal studies demonstrated that prophylactic administration of luteolin restrained melanoma growth and Src/STAT3 signaling in both A375 and B16F10 melanoma-bearing mice. Moreover, luteolin's anti-melanoma effects were diminished by STAT3 over-activation in A375 cells. Our findings indicate that luteolin inhibits STAT3 signaling by suppressing STAT3 activation and promoting STAT3 protein degradation in melanoma cells, thereby exhibiting anti-melanoma effects. This study provides further pharmacological groundwork for developing luteolin as a chemopreventive agent against melanoma.

Evaluation of clinical safety and beneficial effects of stachyose-enriched α-galacto-oligosaccharides on gut microbiota and bowel function in humans.

Deshipu stachyose granules (DSG) is a mixture of α-galacto-oligosaccharides derived from the dietary roots of Lycopus lucidus Turcz. Our previous study showed that DSG could improve the faecal microbial composition, and facilitate intestinal peristalsis and fecal excretion in mice. This study was designed to investigate the effect of DSG on gut microbiota and bowel function in humans. Two human intervention studies were conducted. In the first study, 100 healthy adults were treated without or with 5 g per day of DSG for 14 days. The microbiota composition in fecal samples was quantitatively analyzed before and after DSG supplementation. We found that DSG consumption significantly elevated the fecal bifidobacteria and lactobacilli levels, and also decreased the fecal Clostridium perfringens concentration. In the second study, 103 constipated patients were treated with 5 g per day of placebo or DSG for 30 days, and subsequently subjected to bowel function evaluation. As a result, dietary intake of DSG effectively improved the bowel function of constipated patients, as evidenced by the increased defecation frequency, softer stools and easier defecation. Moreover, clinical safety assessment showed that DSG at 5 g per day did not cause significant adverse effects in both healthy and constipated volunteers. In conclusion, DSG at 5 g d-1 beneficially modulated the gut microbiota in healthy adults and potently improved the bowel function of constipated patients without consequent adverse events. This study suggests that DSG holds promising potential for safe treatment of functional constipation.

Effects of spinach nitrate on insulin resistance, endothelial dysfunction markers and inflammation in mice with high-fat and high-fructose consumption.

BACKGROUND: Insulin resistance, which is associated with an increased risk of cardiovascular morbidity and mortality, has become a leading nutrition problem. Inorganic nitrate enriched in spinach has been demonstrated to reverse the pathological features of insulin resistance and endothelial dysfunction. However, the effects of a direct intake of nitrate-enriched spinach on insulin resistance and endothelial dysfunction have not been studied. OBJECTIVE: To investigate the effects of spinach nitrate on insulin resistance, lipid metabolism, endothelial function, and inflammation in mice fed with a high-fat and high-fructose diet. DESIGN: A diet intervention of spinach with or without nitrate was performed in mice. A high-fat and high-fructose diet was used to cause insulin resistance, endothelial dysfunction, and inflammation in mice. The impacts of spinach nitrate on lipid profile, insulin resistance, markers of endothelial function, and inflammation were determined in mice. RESULTS: Spinach nitrate improved the vascular endothelial function of the mice with high-fat and high-fructose consumption, as evidenced by the elevated plasma nitrite level, increased serum nitric oxide (NO) level and decreased serum ET-1 level after spinach nitrate intervention. Spinach nitrate also reduced serum triglycerides, total cholesterol, and low-density lipoprotein-cholesterol levels and elevated serum high-density lipoprotein-cholesterol levels in the mice fed with a high-fat and high-fructose diet. Mice receiving spinach with 60 mg/kg of nitrate (1.02±0.34) showed a significantly low homeostasis model assessment-insulin resistance index as compared with the model mice (2.05±0.58), which is indicating that spinach nitrate could effectively improve the insulin resistance. In addition, spinach nitrate remarkably decreased the elevated serum C-reactive protein, tumor necrosis factor α, and interleukin-6 levels induced by a high-fat and high-fructose diet. CONCLUSIONS: The intake of spinach nitrate can augment NO status, improve lipid homeostasis, relieve inflammation, and enhance endothelial function, suggesting that spinach is promising dietary supplements for insulin resistance prevention.

Differential protective effects of polyphenol extracts from apple peels and fleshes against acute CCl4-induced liver damage in mice.

The present study reports the phenolic profiles and antioxidant and hepatoprotective properties of Red Fuji apple peel polyphenolic extract (APP) and its flesh polyphenolic extract (AFP) against CCl4-induced acute hepatic damage in mice. It was found that the polyphenol and flavonoid contents of APP were significantly higher than those of AFP. APP was shown to exhibit stronger in vitro antioxidant activities than AFP in a dose-dependent manner. Administration of APP at 250 and 500 mg per kg bw to mice ahead of CCl4 injection was further shown to exhibit stronger in vivo protective effects than those of AFP and could observably antagonize the CCl4-induced increase in serum alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase activities and hepatic malondialdehyde levels, and prevent the CCl4-caused decrease in antioxidant superoxide dismutase and glutathione peroxidase activities, compared to CCl4-treated mice (p < 0.05). This finding demonstrates that the polyphenolic extract from apple, particularly its peel, can be explored as a chemopreventive or chemotherapeutic agent against oxidative-stress-related liver disorders.

Chemical composition of Pleurotus eryngii polysaccharides and their inhibitory effects on high-fructose diet-induced insulin resistance and oxidative stress in mice.

High intake of dietary fructose exerts a number of adverse metabolic effects. The present study investigates the preventive effects of Pleurotus eryngii polysaccharides (PEP), which showed powerful antioxidant activity in vitro, on insulin resistance and oxidative stress in mice fed a high-fructose diet. PEP was identified by HPLC as the heteropolysaccharides with d-glucose (62.8%, mol%), d-galactose (24.4%) and d-mannose (9.8%) being the main component monosaccharides. Mice fed 20% fructose in drinking water for 6 weeks significantly displayed hyperglycemia, hyperinsulinemia, dyslipidemia and liver oxidative stress with impaired insulin sensitivity (p < 0.05). The administration of PEP at 400 and 800 mg kg(-1) bw significantly reduced the fasting serum glucose and insulin concentrations and lipid deposition in HF-fed mice, and caused the reduction of liver lipid peroxidation and the elevation of the hepatic antioxidant system. The histopathology of the liver by conventional H&E and oil red O staining confirmed the liver steatosis induced by a HF diet and the hepatoprotective effect of PEP. These results suggest that Pleurotus eryngii is a potential source of polysaccharides, and might be regarded as a novel preventive and therapeutic product for the mitigation of insulin resistance, oxidative stress and liver dysfunction.

Protective effects of polyphenols-enriched extract from Huangshan Maofeng green tea against CCl4-induced liver injury in mice.

The study was to characterize the polyphenolic composition, antioxidant properties, and hepatoprotective effects of a polyphenols-enriched extract (HMTP) from Huangshan Maofeng green tea. HPLC analysis showed that three predominantly polyphenolic compounds present in HMTP were epigallocatechin (271.2 µg/mg extract), rutin (239.3 µg/mg) and epicatechin (89.3 µg/mg). HMTP was shown to exhibit strong scavenging activities against DPPH, O2(-), and OH, and ferric-reducing antioxidant power in vitro. Administration of HMTP at 200, 400 and 800 mg/kg bw in mice prior to CCl4 injury significantly decreased the CCl4-induced elevation of serum ALT, AST and ALP activities, and prevented an increase in hepatic MDA levels (p<0.05). Mice with HMTP pretreatment displayed a better profile of hepatosomatic index and the improved GSH-Px and SOD activities in the liver, relative to CCl4-intoxicated mice. Liver pathological observation also confirmed the protection on CCl4-caused histological alteration, suggesting that HMTP has potential to be explored as valuable hepatoprotective function food.

Stachyose-enriched α-galacto-oligosaccharides regulate gut microbiota and relieve constipation in mice.

This study probed the effects of Deshipu stachyose granules (DSG), a novel oligosaccharide preparation (55.3% stachyose, 25.8% raffinose, and 9.7% verbascose), on gut microbiota and constipation in mice. Mice were administered intragastrically without or with DSG (0.42, 0.83, and 2.49 g/kg bw), and feces were collected after 14 days of treatment and subjected to classical microbiological assays. Selective index (SI) and prebiotic index (PI) were incorporated to evaluate the prebiotic effect. DSG at 0.83 g/kg bw scored the highest SI and PI scores, thus supporting a strong prebiotic role. In addition, the impact of DSG (0.42, 0.83, and 1.68 g/kg bw) on defecation function of constipated mice was determined. Ink propulsion rate in the small intestine was significantly improved by DSG treatment. DSG supplementation also distinctly increased the weight and number of black feces within 5 h and evidently shortened the defecating time of first black feces, as compared with the constipation control mice. All of these findings indicate that DSG may promote the growth of beneficial intestinal bacteria and inhibit pathogenic bacteria and also facilitate intestinal peristalsis and fecal excretion, thereby enhancing intestinal health and relieving constipation.

Characterisation of polysaccharides from green tea of Huangshan Maofeng with antioxidant and hepatoprotective effects.

This study was to examine the hepatoprotective effects of polysaccharides from green tea of Huangshan Maofeng (HMTP) against CCl4-induced oxidative damage in mice. HMTP is an acidic heteropolysaccharide with galactose (35.0%, mol.%), arabinose (28.9%) and galacturonic acid (11.3%) being the main monosaccharide components. HMTP (400 and 800 mg/kg·bw) administered orally daily for 14 days before CCl4 administration significantly reduced the impact of CCl4 toxicity on the serum markers of liver damage, alanine aminotransferase, aspartate aminotransferase, total-cholesterol and triglycerides. This method of HMTP administration also markedly restrained hepatic lipid peroxidation formation of malondialdehyde and 15-F2t isoprostanes, and elevated the antioxidant levels of hepatic glutathione and superoxide dismutase. These results together with liver histopathology indicated that HMTP exhibited hepatoprotection against CCl4-induced injury, which was found to be comparable to that of biphenyldicarboxylate. The hepatoprotective effects of HMTP may be due to both the inhibition of lipid peroxidation and the increase of antioxidant activity.

Isolation, characterization, and hepatoprotective effects of the raffinose family oligosaccharides from Rehmannia glutinosa Libosch.

This study was aimed to isolate and characterize the raffinose family oligosaccharides (RGOs) from a novel plant source of Rehmannia glutinosa Libosch, and further evaluate whether RGOs can attenuate CCl4-induced oxidative stress and hepatopathy in mice. HPLC analysis showed that RGOs were mainly composed of stachyose (61.7%, w/w), followed by 23.7% raffinose and 7.1% sucrose. Administration of RGOs orally daily in mice for 21 days significantly reduced the impact of CCl4 toxicity on the serum markers of liver damage, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total-cholesterol (TC), and triglycerides (TG). RGOs also increased antioxidant levels of hepatic glutathione (GSH), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC), and ameliorated the elevated hepatic formation of malonaldehyde (MDA) induced by CCl4 in mice, which coincided with the histological alteration. These findings exhibited the potential prospect of RGOs as functional ingredients to prevent ROS-related liver damage.

Protective effects of Keemun black tea polysaccharides on acute carbon tetrachloride-caused oxidative hepatotoxicity in mice.

This study was designed to investigate chemical characterization of the water-soluble polysaccharides extracted from Keemun black tea (KBTP), and their antioxidant and hepatoprotective effects against CCl4-induced oxidative damage in mice. HPLC analysis revealed that KBTP is the typical acidic heteropolysaccharides and consisted of nine monosaccharides. Furthermore, KBTP showed highly ferric-reducing antioxidant power and scavenging effects against DPPH, OH and O2(-) in vitro. Administration of KBTP (200, 400 and 800 mg/kg bw) in mice ahead of CCl4 injection could observably antagonize the CCl4-induced increases in serum ALT, AST, TG and TC, and the hepatic MDA and 8-iso-PGF2a levels, respectively. Mice with KBTP pretreatment displayed a better profile of hepatosomatic index and the improved GSH and SOD activities in comparison with CCl4-intoxicated mice. These biochemical results were further supported with liver histopathological assessment, revealing that KBTP has an observable prevention of liver damage induced by CCl4 in mice.