The anti-adiposity effect of bitter melon seed oil is solely attributed to its fatty acid components.

BACKGROUND: Obesity is the leading chronic disease affecting people of all ages. The objective of this study was to optimize composition of a bitter melon seed oil (BMSO) product to maximize its anti-adiposity effect. METHODS: Bleaching oil, saponifiables and non-saponifiables were prepared from BMSO, with α-eleostearic acid (α-ESA) content in BMSO maintained in bleaching oil and saponifiables. C57BL/6 J mice were allocated into five groups (n = 10/group) to receive diet C [30% soybean oil (SBO)], BM [25% SBO + 5% BMSO], BMS, BMNS or BMD. For the three latter diets, saponifiables (hydrolyzed fatty acids from BMSO), non-saponifiables (excluding fatty acids from BMSO) or bleaching oil (excluding pigments from BMSO), respectively, were added in amount equivalent to their content in 5% BMSO and SBO was added to bring total fat to 30%. After 14 wk., indices associated with adiposity and safety, as well as lipid metabolic signaling in white adipose tissue (WAT), were measured. RESULTS: The body fat percentage of mice in group BM, BMS, BMNS, and BMD were 90 ± 26, 76 ± 21, 115 ± 30 and 95 ± 17% of that in group C. Based on body fat percentage and plasma leptin concentrations, an anti-adiposity effect was evident in groups BM, BMS and BMD (greatest effect in BMS). Histologically, inguinal fat had smaller adipocytes in groups BM, BMS and BMD (P < 0.05), but not in group BMNS, relative to group C. There were no differences among groups in blood pressure or heart rate. Moreover, Sirt1 mRNA levels in inguinal fat were significantly greater in groups BM, BMS and BMD than group C. CONCLUSION: We concluded that the anti-adiposity function of BMSO was solely attributed to the fatty acid fraction, with the free fatty acid form having the greatest effect.

A conjugated fatty acid present at high levels in bitter melon seed favorably affects lipid metabolism in hepatocytes by increasing NAD(+)/NADH ratio and activating PPARα, AMPK and SIRT1 signaling pathway.

α-Eleostearic acid (α-ESA), or the cis-9, trans-11, trans-13 isomer of conjugated linolenic acid, is a special fatty acid present at high levels in bitter melon seed oil. The aim of this study was to examine the effect of α-ESA on hepatic lipid metabolism. Using H4IIEC3 hepatoma cell line, we showed that α-ESA significantly lowered intracellular triglyceride accumulation compared to α-linolenic acid (LN), used as a fatty acid control, in a dose- and time-dependent manner. The effects of α-ESA on enzyme activities and mRNA profiles in H4IIEC3 cells suggested that enhanced fatty acid oxidation and lowered lipogenesis were involved in α-ESA-mediated triglyceride lowering effects. In addition, α-ESA triggered AMP-activated protein kinase (AMPK) activation without altering sirtuin 1 (SIRT1) protein levels. When cells were treated with vehicle control (VC), LN alone (LN; 100µmol/L) or in combination with α-ESA (LN+α-ESA; 75+25µmol/L) for 24h, acetylation of forkhead box protein O1 was decreased, while the NAD(+)/NADH ratio, mRNA levels of NAMPT and PTGR1 and enzyme activity of nicotinamide phosphoribosyltransferase were increased by LN+α-ESA treatment compared to treatment with LN alone, suggesting that α-ESA activates SIRT1 by increasing NAD(+) synthesis and NAD(P)H consumption. The antisteatosis effect of α-ESA was confirmed in mice treated with a high-sucrose diet supplemented with 1% α-ESA for 5weeks. We conclude that α-ESA favorably affects hepatic lipid metabolism by increasing cellular NAD(+)/NADH ratio and activating PPARα, AMPK and SIRT1 signaling pathways.

Altered white adipose tissue protein profile in C57BL/6J mice displaying delipidative, inflammatory, and browning characteristics after bitter melon seed oil treatment.

OBJECTIVE: We have previously shown that bitter melon seed oil (BMSO), which is rich in cis-9, trans-11, trans-13 conjugated linolenic acid, is more potent than soybean oil in attenuating body fat deposition in high-fat diet-induced obese C57BL/6J mice. The aim of this study was to obtain a comprehensive insight into how white adipose tissue (WAT) is affected by BMSO administration and to explore the underlying mechanisms of the anti-adiposity effect of BMSO. METHODS AND RESULTS: A proteomic approach was used to identify proteins differentially expressed in the WAT of mice fed diets with or without BMSO for 11 wks. The WAT was also analyzed histologically for morphological changes. Two-dimensional gel electrophoresis (pH 4-7) revealed 32 spots showing a statistically significant difference (P<0.05) in intensity in BMSO-treated mice and 30 of these were shown to code for 23 proteins (15 increased and 8 decreased expression; >2-fold change). Combined with histological evidence of macrophage infiltration and brown adipocyte recruitment, the proteomic and immunoblotting data showed that the WAT in mice subjected to long-term high dose BMSO administration was characterized by reduced caveolae formation, increased ROS insult, tissue remodeling/repair, mitochondria uncoupling, and stabilization of the actin cytoskeleton, this last change being putatively related to an increased inflammatory response. CONCLUSION: The anti-adiposity effect of BMSO is associated with WAT delipidation, inflammation, and browning. Some novel proteins participating in these processes were identified. In addition, the BMSO-mediated WAT browning may account for the increased inflammation without causing adverse metabolic effects.

Bitter melon seed oil-attenuated body fat accumulation in diet-induced obese mice is associated with cAMP-dependent protein kinase activation and cell death in white adipose tissue.

The aim of this study was to investigate the antiadiposity effect of bitter melon seed oil (BMSO), which is rich in the cis-9, trans-11, trans-13 isomer of conjugated linolenic acid. In Expt. 1, C57BL/6J mice were fed a butter-based, high-fat diet [HB; 29% butter + 1% soybean oil (SBO)] for 10 wk to induce obesity. They then continued to receive that diet or were switched to an SBO-based, high-fat diet alone (HS; 30% SBO) or containing bitter melon seed oil (BMSO) (HBM; 15% SBO + 15% BMSO) for 5 wk. The body fat percentage was significantly lower in mice fed the HBM diet (21%), but not the HS diet, compared with mice fed the HB diet. In Expt. 2, mice were fed an SBO-based, high-fat diet containing 0 (HS), 5 (LBM), 10 (MBM), or 15% (HBM) BMSO for 10 wk. In the LBM, MBM, and HBM groups, the body fat percentage was significantly lower by 32, 35, and 65%, respectively, compared with the HS control. The reduction in the HBM group was significantly greater than that in the LBM or MBM group. BMSO administration increased phosphorylation of acetyl-CoA carboxylase, cAMP-activated protein kinase (PKA), and signal transducer and activator of transcription 3 in the white adipose tissue (WAT), suggesting that PKA and leptin signaling might be involved in the BMSO-mediated reduction in lipogenesis and increase in thermogenesis and lipolysis. However, compared with the HS control, the HBM group had a significantly higher TNFα concentration in the WAT accompanied by TUNEL-positive nuclei. We conclude that BMSO is effective in attenuating body fat accumulation through mechanisms associated with PKA activation and programmed cell death in the WAT, but safety concerns need to be carefully addressed.

Two unhealthy dietary habits featuring a high fat content and a sucrose-containing beverage intake, alone or in combination, on inducing metabolic syndrome in Wistar rats and C57BL/6J mice.

To establish animal models with diet-induced metabolic disorders similar to human metabolic syndrome, 2 unhealthy dietary habits featuring a high fat content and a sucrose-containing beverage intake, alone or in combination, were tested on Wistar rats and C57BL/6J mice. The 2 dietary habits were, respectively, simulated by feeding a high-fat diet (regimen A) or additionally providing 30% sucrose (wt/vol) in the drinking water (regimen B). Using a 2 x 2 factorial design, 4 groups of animals were fed chow diet plus plain water (group C), high-fat diet (30% [wt/wt] fat) plus plain water (group A), chow diet plus sucrose in drinking water (group B), and high-fat diet plus sucrose in drinking water (group AB) for 26 weeks. In Wistar rats, regimen B caused a significant increase in visceral fat; serum levels of lipids, glucose, insulin, and uric acid; insulin resistance; and blood pressure, whereas regimen A only caused a significant increase in visceral fat and serum insulin levels (P < .05). In contrast, regimen A induced a full array of metabolic syndrome in C57BL/6J mice; but regimen B only caused slight obesity and hyperlipidemia. In both Wistar rats and C57BL/6J mice, there were no additive effects of the 2 regimens, indicated by significant interactions between regimens A and B on the metabolic indexes measured. These results show that, in terms of inducing metabolic syndrome, Wistar rats are more responsive to sucrose water regimen, whereas C57BL/6J mice are more responsive to the high-fat diet regimen.

Upregulation of lipogenesis and protein tyrosine phosphatase-1B expression in the liver of Wistar rats with metabolic syndrome chronically induced by drinking sucrose water.

BACKGROUND: Establishing animal models with metabolic disorders similar to human metabolic syndrome (MS) is important. In terms of eliciting a full array of MS, we have previously shown that Wistar rats are more responsive to sucrose water drinking than are C57BL/6J mice. This study was aimed at investigating the underlying molecular mechanism of sucrose water-induced MS in Wistar rats. METHODS: Male Wistar rats were divided into 2 groups (n = 8 for each group) which were given plain water (C group) or 30% sucrose water (SW group) to drink ad libitum. After 20 weeks, the transcriptional levels and protein translocation of hepatic sterol regulatory element-binding protein-1c (SREBP-1c) and carbohydrate response element-binding protein (ChREBP) as well as the protein levels of protein tyrosine phosphatase-1B (PTP-1B) in insulin-responsive tissues (liver, muscle, and adipose tissue) were measured. RESULTS: The sucrose water regimen successfully elicited visceral obesity, hypertriglyceridemia, insulin resistance, and high blood pressure. The upregulation of de novo lipogenesis in the liver of the sucrose water-treated rats was demonstrated by an increased activity of enzymes, mRNA levels of lipogenic proteins, and nuclear levels of SREBP-1c and ChREBP. Moreover, in the sucrose water-treated rats, protein levels of PTP-1B were significantly increased in liver and skeletal muscle but decreased in adipose tissue. CONCLUSION: The susceptibility of Wistar rats to sucrose water-induced MS is associated with the transactivation of SREBP-1c and ChREBP in the liver, and PTP-1B is involved in the upregulation of de novo lipogenesis in the liver and the pathology of systemic insulin resistance in rats with MS chronically induced by drinking sucrose water.

The functional assessment of Alpinia pricei on metabolic syndrome induced by sucrose-containing drinking water in mice.

This study was designed to test whether Alpinia pricei (AP), a member of the ginger family indigenous to Taiwan, reduced metabolic syndrome induced by sucrose-containing drinking water in C57BL/6J mice. Mice given a chow diet were divided into a control group (C) or a test group given 30% sucrose water (SW) to drink ad libitum. After 22 weeks, mice in the SW group were subdivided into SW and SW + AP groups, the latter receiving a chow diet with an ethanol extract of AP (1500 mg/kg dosage). Four weeks later, bio-indexes associated with metabolic syndrome were measured. Compared with the C group, the SW group had significantly higher body weight, visceral fat weights, serum and tissue lipid, serum insulin level and the area under the curve for blood glucose of the insulin tolerance test (p < 0.05). These indicators in the SW + AP group were lower than in the SW group except for serum lipid, although slightly higher than the C group. The SW + AP group also showed significantly lower serum levels of leptin and tumor necrosis factor-alpha and a significantly higher level of adiponectin than the SW group. These results indicated that visceral adiposity and insulin resistance induced by sucrose water drinking might be alleviated by AP supplementation.