Reduced adiposity in bitter melon (Momordica charantia)-fed rats is associated with increased lipid oxidative enzyme activities and uncoupling protein expression

The effects of bitter melon (Momordica charantia) on anthropometric indices in adults: A systematic review and meta-analysis of randomized controlled trials

There is controversial data on the impacts of bitter melon (Momordica charantia) supplementations on anthropometric indices. Thus, we aimed to clarify this role of bitter melon through a systematic review, and meta-analysis of the trials. All clinical trials conducted on the impact of bitter melon on anthropometric indices were published until August 2023 in PubMed, Web of Sciences, Scopus, Embase, and Cochrane Library web databases included. Overall, 10 studies with 448 individuals were included in the meta-analysis. Meta-analysis of 10 trials with 448 participants revealed no significant reductions in body weight (BW) (WMD: 0.04 Kg; 95 %CI: -0.16-0.25; P =0.651), body mass index (BMI) (WMD: -0.18 kg/m2; 95 %CI: -0.43-0.07; P =0.171), waist circumference (WC) (WMD: -0.95 cm; 95 % CI: -3.05-1.16; p =0.372), and percentage of body fat (PBF) (WMD: -0.99; 95 % CI: -2.33-0.35; p =0.141) following bitter melon supplementation. There was no significant impact of bitter melon supplementation on BW, BMI, WC, and PBF. More large-scale and high-quality RCTs are necessary to confirm these results.

The promising roles of medicinal plants and bioactive compounds on hepatic lipid metabolism in the treatment of non-alcoholic fatty liver disease in animal models: molecular targets

Imbalance in hepatic lipid metabolism can lead to an abnormal triglycerides deposition in the hepatocytes which can cause non-alcoholic fatty liver disease (NAFLD). Four main mechanisms responsible for regulating hepatic lipid metabolism are fatty acid uptake, de novo lipogenesis, lipolysis and fatty acid oxidation. Controlling the expression of transcription factors at molecular level plays a crucial role in NAFLD management. This paper reviews various medicinal plants and their bioactive compounds emphasising mechanisms involved in hepatic lipid metabolism, other important NAFLD pathological features, and their promising roles in managing NAFLD through regulating key transcription factors. Although there are many medicinal plants popularly investigated for NAFLD treatment, there is still little information and scientific evidence available and there has been no research on clinical trials scrutinised on this matter. This review also aims to provide molecular information of medicinal plants in NALFD treatment that might have potentials for future scientifically controlled studies.

Effect of Momordica charantia Administration on Anthropometric Measures and Metabolic Profile in Patients with Obesity: A Pilot Clinical Trial

The aim of this study was to evaluate the effect of Momordica charantia (MC) administration on anthropometric measures in patients with obesity. A randomized, double-blind, placebo-controlled pilot clinical trial was carried out in 24 patients with obesity. Twelve patients randomly received MC (2000 mg/day) for 12 weeks, and 12 patients received placebo. Body weight (BW), body mass index (BMI), waist circumference (WC), body fat percentage, as well as clinical and laboratory determinations, were evaluated before and after the intervention. Results showed that while reductions in BW, BMI, WC, and body fat percentage were observed in the MC group, these differences did not reach statistical significance. Significant decreases in triglycerides (TG) (1.9 ± 0.6 mM vs. 1.7 ± 0.7 mM, P ≤ .05) and very low-density lipoprotein (VLDL) (0.4 ± 0.1 mM vs. 0.3 ± 0.1 mM, P ≤ .05) levels were found after the intervention with MC. In contrast, significant increases in BW (83.0 ± 10.7 kg vs. 84.6 ± 9.1 kg, P ≤ .05) and BMI (31.9 ± 1.5 kg/m² vs. 33.0 ± 1.3 kg/m², P ≤ .05) were observed in the placebo group. In conclusion, no significant reductions in BW, BMI, WC, and body fat percentage were observed after MC administration; however, MC significantly decreased TG and VLDL levels. The protocol was registered at ClinicalTrials.gov with the identifier NCT04916379.

Momordica Charantia: A Review of Its Effects on Metabolic Diseases and Mechanisms of Action

The global rise in the prevalence of metabolic diseases such as diabetes, obesity, and dyslipidemia is a serious public health issue. The search for safe and effective complementary and alternative therapies to treat metabolic disorders is a key field of research. Momordica charantia (MC) is a tropical and subtropical vine of the Cucurbitaceae family used as a medicinal plant since ancient times. Although MC has been widely studied for its hypoglycemic potential, hypolipidemic and antiobesity effects have also been reported in preclinical studies and clinical trials. This study aims to review the metabolic effects of MC reported in clinical trials as well as its mechanisms of action.

Promotion of Momordica Charantia polysaccharides on neural stem cell proliferation by increasing SIRT1 activity after cerebral ischemia/reperfusion in rats

The deacetylase SIRT1 has been reported to play a critical role in regulating neurogenesis, which may be an adaptive processes contributing to recovery after stroke. Our previous work showed that the antioxidant capacity of Momordica charantia polysaccharides (MCPs) could protect against cerebral ischemia/reperfusion (I/R) after stroke. However, whether the protective effect of MCPs on I/R injury is related to neural stem cell (NSC) proliferation remains unclear. In the present study, we designed invivo and invitro experiments to elucidate the underlying mechanisms by which MCPs promote endogenous NSC proliferation during cerebral I/R. Invivo results showed that MCPs rescued the memory and learning abilities of rats after I/R damage and enhanced NSC proliferation in the rat subventricular zone (SVZ) and subgrannular zone (SGZ) during I/R. Invitro experiments demonstrated that MCPs could stimulate the proliferation of C17.2 cells under oxygen-glucose deprivation (OGD) conditions. Further studies revealed that the proliferation-promoting mechanism of MCPs relied on increasing the activity of SIRT1, decreasing the level of acetylation of β-catenin in the cytoplasm, and then triggering the translocation of β-catenin into the nucleus. These data provide experimental evidence that the up-regulation of SIRT1 activity by MCPs led to an increased cytoplasmic deacetylation of β-catenin, which promoted translocation of β-catenin to the nucleus to participate in the signaling pathway involved in NSC proliferation. The present study reveals that MCPs function as a therapeutic drug to promote stroke recovery by increasing the activity of SIRT1, decreasing the level of acetylated β-catenin, promoting the nuclear translocation of β-catenin and thereby increasing endogenous NSC proliferation.

The Effect of Momordica charantia in the Treatment of Diabetes Mellitus: A Review

In recent years, many studies of Momordica charantia (MC) in the treatment of diabetes mellitus (DM) and its complications have been reported. This article reviewed the effect and mechanism of MC against diabetes, including the results from in vitro and in vivo experiments and clinical trials. The common side effects of MC were also summarized. We hope that it might open up new ideas for further mechanism exploration and clinical application as well as provide a scientific theoretical basis for the development of drugs or foods derived from MC.

Bitter Melon (Momordica charantia L.) Supplementation Has No Effect on Hypercholesterolemia and Atherosclerosis in Mice

Bitter melon (BM; Momordica charantia L.) has been reported to ameliorate diet-induced obesity and dyslipidemia. However, the effects of BM on atherosclerosis have not been determined. This study investigated the effects of BM diet-induced atherosclerosis in LDL receptor-deficient mice. A total of 30 female mice (aged 6-8 wk) were fed a saturated fat-enriched diet. In group 1 (n = 10), mice were fed this diet alone, whereas mice in groups 2 and 3 (n = 10/group) were fed the diet supplemented with BM either 0.1% or 1% by weight. After 12 wk, body weight, plasma cholesterol, and atherosclerotic plaque areas were analyzed. No significant differences in body weight and plasma cholesterol concentrations were observed among the groups. Also, BM supplementation did not affect atherosclerosis development. In conclusion, dietary BM has no effect on plasma cholesterol concentration and atherogenesis in hypercholesterolemic mice.

Possible molecular mechanisms of glucose-lowering activities of Momordica charantia (karela) in diabetes

Diabetes mellitus is a highly prevalent metabolic disorder which is characterized by impaired glucose tolerance, with a relative or absolute insulin deficiency and profound changes in the metabolism of macronutrients. Traditional and complementary medicine is therapeutic strategies that have both been applied to improving glycemic control. Momordica charantia is one of the plant-based, folk medicines that used for improving glycemic control. We aimed to review, the effects of M. charantia on blood glucose with a clarification of the molecular pathways involved. Of the compounds derived from the plants, the insulin-like peptide, charantin, and the alkaloid vicine, have been reported to have hypoglycemic effects. Different mechanisms contribute to the antidiabetic activities of M. charantia, these include increasing pancreatic insulin secretion, decreasing insulin resistance and increasing peripheral and skeletal muscle cell glucose utilization, inhibition of intestinal glucose absorption and suppressing of key enzymes in the gluconeogenic pathways.

Susceptibility of poultry associated bacterial pathogens to Momordica charantia fruits and evaluation of in vitro biological properties

The emerging incidence of antibiotic resistance trait among the bacteria populating poultry presents a devastating public health issue. On the other hand, at present, diabetes and obesity are the most serious public health issues and are increasing subsequently at alarming rate. In view of this, the present in vitro context was aimed to investigate the antibacterial activities of Momordica charantia (M. charantia) fruits extracts against poultry associated Bacillus spp. and to assess further its phytoconstituents, alpha-(α)-glucosidase activities, and anti-obesity properties. The anti-pathogenic attributes of M. charantia fruit extracts were carried out using disc diffusion assay and results showed the pronounced antibacterial trait of ethanolic extract with maximum zone of inhibition of 28.3 ± 1.2 mm against Bacillus licheniformis. The qualitative phytochemical analyses of fruit extracts illustrated the presence of diverse phytoconstituents. The α-glucosidase inhibition assay for the extracts was performed according to the α-glucosidase activity kit. The results depicted the lowest α-glucosidase activity (57.13 ± 2.3 to 18.14 ± 1.3 U/L) in the presence of ethanolic extract at varied concentrations. The anti-obesity potentialities of fruit extracts were demonstrated in terms of porcine pancreatic lipase (PPL type II) activity using p-nitro-phenyl butyrate (p-NPB) as a substrate. The ethanolic extract of M. charantia fruits was observed to exhibit maximum inhibition of pancreatic lipase ranging from 20.12 ± 2.3 to 68.34 ± 1.3% in a dose dependent manner with an IC₅₀ value of 607.6 ± 1.3 μg/mL. FTIR and GC-MS results indicated the presence of distinct compounds in the ethanol extract and major bioactive constituents were found to be Dimethyl sulfone (35.24%), 9-octadecanamide (20.52%), Pentadecanoic acid (6.64%), Lanost-9 (11)-en-18-oic acid, 23-(acetylxyl)-3-(4-bromobenzoyl) oxyl-20-hydroxyl-gamma-lactone (2.6%), and 2,2-sulfonyldiethanol (2.46%). In conclusion, M. charantia fruits could be of great concern in pharmaceutical industries due to its adequate biological properties and may also help in the management of poultry associated bacterial pathogens.

Momordica charantia (bitter melon) modulates adipose tissue inflammasome gene expression and adipose-gut inflammatory cross talk in high-fat diet (HFD)-fed mice

Systemic and tissue-specific inflammation has a profound influence on regulation of metabolism, and therefore, strategies to reduce inflammation are of special interest in prevention and treatment of obesity and type 2 diabetes (T2D). Antiobesity and antidiabetic properties of Momordica charantia (bitter melon, BM) have been linked to its protective effects on inflammation and gut microbial dysbiosis. We investigated the mechanisms by which freeze-dried BM juice reduces adipose inflammation in mice fed a 60% high-fat diet (HFD) for 16 weeks. Although earlier studies indicated that BM inhibited recruitment of macrophages (Mφ) infiltration in adipose tissue of rodents and reduced NF-kB and IL-1β secretions, the mechanisms remain unknown. We demonstrate that freeze-dried BM juice inhibits recruitment of Mφ into adipose tissue and its polarization to inflammatory phenotype possibly due to reduction of sphingokinase 1 (SPK1) mRNA in HFD-fed mice. Furthermore, reduction of IL-1β secretion by freeze-dried BM juice in the adipose tissue of HFD-fed mice is correlated to alleviation of NLRP3 inflammasome components and their downstream signaling targets. We confirm previous observations that BM inhibited inflammation of colon and gut microbial dysbiosis in HFD-fed mice, which in part may be associated with the observed anti-inflammatory effects in adipose tissue if HFD-fed mice. Overall, functional foods such as BM may offer potential dietary interventions that may impact sterile inflammatory diseases such as obesity and T2D.

Cucurbitane triterpenoids from the fruit of Momordica charantia L. and their anti-hepatic fibrosis and anti-hepatoma activities

Momordica charantia L. (Cucurbitaceae) is a popular vegetable and traditional folk medicine, that has been used for hundreds of years. In this study, three undescribed cucurbitane-type triterpene glycosides furpyronecucurbitane A, goyaglycoside I and charantagenin F along with nine known compounds were isolated from the immature fruit of Momordica charantia L. Their structures were identified on the basis of extensive 1D, 2D NMR and HRESIMS spectroscopy analysis. All isolated compounds were examined for their anti-hepatic fibrosis activity against murine hepatic stellate cells (t-HSC/Cl-6) and anti-hepatoma activity against two kinds of liver cancer cell lines (HepG2 and Hep3B). Among them, karaviloside III exhibited excellent inhibitory activity against activated t-HSC/Cl-6 cells and cytotoxic activity against Hep3B and HepG2 cell lines with IC₅₀ values of 3.74 ± 0.13, 16.68 ± 2.07 and 4.12 ± 0.36 μM, respectively, which may potential to be developed as a chemotherapy agent for treatment hepatic fibrosis or carcinoma and protection against both diseases.

Bitter gourd reduces elevated fasting plasma glucose levels in an intervention study among prediabetics in Tanzania

ETHNOPHARMACOLOGICAL RELEVANCE

Impaired glucose tolerance and diabetes mellitus have become major health issues even in non-industrialized countries. As access to clinical management is often poor, dietary interventions and alternative medicines are required. For bitter gourd, Momordica charantia L., antidiabetic properties have been claimed.

AIM OF THE STUDY

The main objective of the intervention study was to assess antidiabetic effects of daily bitter gourd consumption of 2.5g powder over the course of eight weeks among prediabetic individuals.

MATERIALS AND METHODS

In a randomized placebo-controlled single blinded clinical trial, 52 individuals with prediabetes were studied after consuming a bitter gourd or a cucumber juice. For reducing the impact of between subject differences in the study population, a crossover design was chosen with eight weeks for each study period and four weeks washout in between. Fasting plasma glucose was chosen as the primary outcome variable.

RESULTS

Comparing the different exposures, the CROS analysis (t=-2.23, p=0.031, r=0.326) revealed a significant difference in the change of FPG of 0.31mmol/L (5.6mg/dL) with a trend (R²=0,42387). The number of 44 finally complete data sets achieved a power of 0.82, with a medium-to-large effect size (Cohen's d 0.62). The effect was also proven by a general linear mixed model (estimate 0.31; SE: 0.12; p: 0.01; 95%CI: 0.08; 0.54). Not all participants responded, but the higher the initial blood glucose levels were, the more pronounced the effect was. No serious adverse effects were observed.

CONCLUSIONS

Bitter gourd supplementation appeared to have benefits in lowering elevated fasting plasma glucose in prediabetes. The findings should be replicated in other intervention studies to further investigate glucose lowering effects and the opportunity to use bitter gourd for dietary self-management, especially in places where access to professional medical care is not easily assured.

Recent Advances in Momordica charantia: Functional Components and Biological Activities

Momordica charantia L. (M. charantia), a member of the Cucurbitaceae family, is widely distributed in tropical and subtropical regions of the world. It has been used in folk medicine for the treatment of diabetes mellitus, and its fruit has been used as a vegetable for thousands of years. Phytochemicals including proteins, polysaccharides, flavonoids, triterpenes, saponins, ascorbic acid and steroids have been found in this plant. Various biological activities of M. charantia have been reported, such as antihyperglycemic, antibacterial, antiviral, antitumor, immunomodulation, antioxidant, antidiabetic, anthelmintic, antimutagenic, antiulcer, antilipolytic, antifertility, hepatoprotective, anticancer and anti-inflammatory activities. However, both in vitro and in vivo studies have also demonstrated that M. charantia may also exert toxic or adverse effects under different conditions. This review addresses the chemical constituents of M. charantia and discusses their pharmacological activities as well as their adverse effects, aimed at providing a comprehensive overview of the phytochemistry and biological activities of M. charantia.

Momordica charantia: a popular health-promoting vegetable with multifunctionality

Products derived from edible medicinal plants have been used for centuries to prevent, treat, and even cure multiple diseases. Momordica charantia L., widely cultivated around the world, is a typical one bred for vegetables and medicinal usage. All parts of M. charantia possess important medicinal properties, including antidiabetic, anticancer, hypotensive, anti-obesity, antimicrobial, antihyperlipidemic, antioxidant, anti-inflammatory, immuno-modulatory, anthelmintic, neuro-protective, as well as hepato-protective properties both in vitro and in vivo. This review summarizes the active components and medicinal properties of M. charantia, especially the activities and mechanisms of its anti-diabetic and anti-cancer properties. The anti-diabetic properties involve inhibiting intestinal α-glucosidase and glucose transport, protecting islet β-cells, enhancing insulin secretion, increasing hepatic glucose disposal, decreasing gluconeogenesis, and even ameliorating insulin resistance. Moreover, the expressions of PPARs could also be activated and up-regulated. Meanwhile, its anticancer properties are mostly due to apoptosis, cell cycle arrest, and expression of serum factors associated with immunity. In this review, we aim to provide an overview of M. charantia and its benefits for development as a functional food.

Protective effect of Momordica charantia water extract against liver injury in restraint-stressed mice and the underlying mechanism

Background: Momordica charantia is used in China for its jianghuo (heat-clearing and detoxifying) effects. The concept of shanghuo (the antonym of jianghuo, excessive internal heat) in traditional Chinese medicine is considered a type of stress response of the body. The stress process involves internal organs, especially the liver. Objective: We hypothesized that Momordica charantia water extract (MWE) has a hepatoprotective effect and can protect the body from stress. The aim of this study was to investigate the possible effects of MWE against liver injury in restraint-stressed mice. Design: The mice were intragastrically administered with MWE (250, 500 and 750 mg/kg bw) daily for 7 days. The Normal Control (NC) and Model groups were administered distilled water. A positive control group was intragastrically administered vitamin C 250 mg/kg bw. After the last administration, mice were restrained for 20 h. Results: MWE reduced the serum AST and ALT, reduced the NO content and the protein expression level of iNOSin the liver; significantly reduced the mitochondrial ROS content, increased the mitochondrial membrane potential and the activities of mitochondrial respiratory chain complexes I and II in restraint-stressed mice. Conclusions: The results indicate that MWE has a protective effect against liver injury in restraint-stressed mice. Abbreviations: MWE: Momordica charantia water extract; M. charantia: Momordica charantia L.; ROS: reactive oxygen species; NO: nitric oxide; iNOS: inducible nitric oxide synthase; IL-1β: interleukin-1 beta; TNF-α: tumor necrosis factor alpha; IL-6: interleukin 6; IFN-γ: interferon gamma; VC: vitamin C; ALT: alanine transaminase; AST: aspartate aminotransferase; GSH: glutathione; GSH-PX: glutathione peroxidase; MDA: malondialdehyde; BCA: bicinchoninic acid; TBARS: thiobarbituric acid reactive substances; Trolox: 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; JC-B: Janus Green B; DW: dry weight; FC: Folin-Ciocalteu; GAE: gallic acid equivalents; bw: body weight; NC: normal control group; Model: restraint stress model group; VC: positive control vitamin C group, 250 mg/kg bw; MWEL: Momordica charantia water extract low-dose group, 250 mg/kg bw; MWEM: Momordica charantia water extract middle-dose group, 500 mg/kg bw; MWEH: Momordica charantia water extract high-dose group, 750 mg/kg bw; HE: hematoxylin and eosin; ORAC: total oxygen radical absorbance capacity; ABAP: dihydrochloride; ATP: adenosine triphosphate.

Response of gut microbiota and inflammatory status to bitter melon (Momordica charantia L.) in high fat diet induced obese rats

ETHNOPHARMACOLOGICAL RELEVANCE

Bitter melon (Momordica charantia L.) is rich in a variety of biologically active ingredients, and has been widely used in traditional Chinese medicine (TCM) to treat various diseases, including type 2 diabetes and obesity.

AIM OF THE STUDY

We aimed to investigate how bitter melon powder (BMP) could affect obesity-associated inflammatory responses to ameliorate high-fat diet (HFD)-induced insulin resistance, and investigated whether its anti-inflammatory properties were effected by modulating the gut microbiota.

MATERIALS AND METHODS

Obese SD rats (Sprague-Dawley rats, rattus norregicus) were randomly divided into four groups: (a) normal control diet (NCD) and distilled water, (b) HFD and distilled water, (c) HFD and 300mg BMP/kg body weight (bw), (d) HFD and 10mg pioglitazone (PGT)/kg bw.

RESULTS

We observed remarkable decreases in the fasting glucose, fasting insulin, HOMA-IR index, serum lipid levels, and cell sizes of epididymal adipose tissues in the BMP and PGT groups after 8 weeks. BMP could significantly improve the proinflammatory cytokine tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), anti-inflammatory cytokine interleukin-10 (IL-10), and local endotoxin levels compared to the HFD group (p<0.05). BMP suppressed the activation of nuclear factor-κB (NF-κB) by inhibiting inhibitor of NF-κB alpha (IκBα) degradation and phosphorylation of c-Jun N-terminal kinase/ p38 mitogen-activated protein kinases (JNK/p38 MAPKs) in adipose tissue. Sequencing results illustrated that BMP treatment markedly decreased the proportion of the endotoxin-producing opportunistic pathogens and increased butyrate producers.

CONCLUSIONS

These results demonstrate that BMP ameliorates insulin sensitivity partly via relieving the inflammatory status in the system and in white adipose tissues of obese rats, and is associated with a proportional regulation of specific gut microbiota.

1H NMR-based metabolic study reveals the improvements of bitter melon (Momordica charantia) on energy metabolism in diet-induced obese mouse

CONTEXT

Obesity can be ameliorated by some natural products such as polyphenol, flavones and saponin. As a typical medicinal plant, Momordica charantia L. (Cucurbitaceae) (bitter melon, BM) contains these natural chemicals and reduces diet-induced obesity in mice.

OBJECTIVE

This study evaluates the metabolic effects of dietary BM supplement, investigates a global metabolic profile and determines associated perturbations in metabolic pathways.

MATERIALS AND METHODS

Male C57BL/6 mice were fed with low-fat diet (LFD), high-fat diet (HFD) and HFD supplemented with 5% BM based on 37.6 g/kg body weight in average for 12 weeks, respectively. Then energy metabolism was quantified using PhenoMaster/LabMaster. The spectroscopy of urine was acquired by nuclear magnetic resonance and latent biomarkers were identified. Pattern recognition analysis was used to discriminate associated metabolic profiles.

RESULTS

Dietary BM supplement reduced body weight gain (-0.15-fold, p < 0.01) and blood glucose levels (-0.19-fold, p < 0.01) in HFD-fed mice. Meanwhile, the levels of energy metabolism were enhanced (0.08-0.11-fold, p < 0.01). According to pattern recognition analysis, dietary BM supplement changed metabolic profiles in HFD-fed mice and the modified profiles were similar to those in LFD-fed mice. Finally, the mapping of metabolic pathways showed that dietary BM supplement primarily affected glucose metabolism-associated pathways.

DISCUSSION AND CONCLUSION

The results indicated that BM improves weight loss in diet-induced obesity and elevate energy expenditure in HFD-fed mice. The pattern recognition with metabolic study may be used as a noninvasive detection method to assess the effects of dietary BM supplement on mouse energy metabolism.

Beneficial role of bitter melon supplementation in obesity and related complications in metabolic syndrome

Diabetes, obesity, and metabolic syndrome are becoming epidemic both in developed and developing countries in recent years. Complementary and alternative medicines have been used since ancient era for the treatment of diabetes and cardiovascular diseases. Bitter melon is widely used as vegetables in daily food in Bangladesh and several other countries in Asia. The fruits extract of bitter melon showed strong antioxidant and hypoglycemic activities in experimental condition both in vivo and in vitro. Recent scientific evaluation of this plant extracts also showed potential therapeutic benefit in diabetes and obesity related metabolic dysfunction in experimental animals and clinical studies. These beneficial effects are mediated probably by inducing lipid and fat metabolizing gene expression and increasing the function of AMPK and PPARs, and so forth. This review will thus focus on the recent findings on beneficial effect of Momordica charantia extracts on metabolic syndrome and discuss its potential mechanism of actions.

Momordica charantia (Bitter Melon) reduces obesity-associated macrophage and mast cell infiltration as well as inflammatory cytokine expression in adipose tissues

Obesity is a world-wide epidemic disease that correlates closely with type 2 diabetes and cardiovascular diseases. Obesity-induced chronic adipose tissue inflammation is now considered as a critical contributor to the above complications. Momordica charantia (bitter melon, BM) is a traditional Chinese food and well known for its function of reducing body weight gain and insulin resistance. However, it is unclear whether BM could alleviate adipose tissue inflammation caused by obesity. In this study, C57BL/6 mice were fed high fat diet (HFD) with or without BM for 12 weeks. BM-contained diets ameliorated HFD-induced obesity and insulin resistance. Histological and real-time PCR analysis demonstrated BM not only reduced macrophage infiltration into epididymal adipose tissues (EAT) and brown adipose tissues (BAT). Flow cytometry show that BM could modify the M1/M2 phenotype ratio of macrophages in EAT. Further study showed that BM lowered mast cell recruitments in EAT, and depressed pro-inflammatory cytokine monocyte chemotactic protein-1 (MCP-1) expression in EAT and BAT as well as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) expression in EAT. Finally, ELISA analysis showed BM-contained diets also normalized serum levels of the cytokines. In summary, in concert with ameliorated insulin resistance and fat deposition, BM reduced adipose tissue inflammation in diet-induced obese (DIO) mice.

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.

cis-9, trans-11, trans-13-Conjugated linolenic acid induces apoptosis and sustained ERK phosphorylation in 3T3-L1 preadipocytes

OBJECTIVE

The aim of this study was to investigate the adipogenic effect of cis-9, trans-11, trans-13-conjugated linolenic acid (c9,t11,t13-CLN), a fatty acid naturally present in bitter melon.

METHODS

The 3T3-L1 murine preadipocyte cell line was used to test the effect of saponifiables from whole bitter melon and of commercially prepared pure c9,t11,t13-CLN on adipocyte differentiation. The effect of c9,t11,t13-CLN on 3T3-L1 cell viability was also tested at proliferation, mitotic clonal expansion, and terminal differentiation stages.

RESULTS

Compared to the free fatty acid control mixture, the proadipogenic effect on 3T3-L1 was less potent using saponifiables obtained from bitter melon. C9,t11,t13-CLN, unlike its non-conjugated counterpart linolenic acid (LN) or other common fatty acids such as oleic acid or linoleic acid, exerted no proadipogenic effect on 3T3-L1. In contrast to LN displaying no cytotoxic effect at a concentration ≤100 μM, c9,t11,t13-CLN caused a dose-dependent reduction in the viability of pre- and postconfluent preadipocytes associated with apoptosis. Sustained ERK/MAPK activation, accompanied by increased peroxisome proliferator-activated receptor γ phosphorylation, was seen in c9,t11,t13-CLN-treated cells at initiation of differentiation.

CONCLUSION

C9,t11,t13-CLN is less adipogenic for 3T3-L1 cells than LN and this is partly due to its apoptotic effect on proliferating preadipocytes and to the sustained ERK phosphorylation seen during mitotic clonal expansion.

Momordica charantia extract, a herbal remedy for type 2 diabetes, contains a specific 11β-hydroxysteroid dehydrogenase type 1 inhibitor

11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) catalyzes the intracellular regeneration of active cortisol from inert cortisone in key metabolic tissues, thus regulating ligand access to glucocorticoid receptors. There is strong evidence that increased adipose 11β-HSD1 activity may be an important aetiological factor in the current obesity and diabetes type 2 epidemics. Hence, inhibition of 11β-HSD1 has emerged as a promising anti-diabetic strategy, a concept that is largely supported by numerous studies in rodent models as well as limited clinical data with prototype inhibitors. Momordica charantia (also known as bitter melon, bitter gourd or karela) is traditionally used for treatment of diabetes in Asia, South America, the Caribbean, and East Africa. In the present study, we show that M. charantia extract capsules contain at least one ingredient with selective 11β-HSD1 inhibitory activity. The finding constitutes an interesting additional explanation for the well-documented anti-diabetic and hypoglycaemic effects of M. charantia.

Antidiabetic potentials of Momordica charantia: multiple mechanisms behind the effects

Momordica charantia fruits are used as a vegetable in many countries. From time immemorial, it has also been used for management of diabetes in the Ayurvedic and Chinese systems of medicine. Information regarding the standardization of this vegetable for its usage as an antidiabetic drug is scanty. There are many reports on its effects on glucose and lipid levels in diabetic animals and some in clinical trials. Reports regarding its mechanism of action are limited. So in the present review all the information is considered to produce some concrete findings on the mechanism behind its hypoglycemic and hypolipidemic effects. Studies have shown that M. charantia repairs damaged β-cells, increases insulin levels, and also enhance the sensitivity of insulin. It inhibits the absorption of glucose by inhibiting glucosidase and also suppresses the activity of disaccharidases in the intestine. It stimulates the synthesis and release of thyroid hormones and adiponectin and enhances the activity of AMP-activated protein kinase (AMPK). Effects of M. charantia like transport of glucose in the cells, transport of fatty acids in the mitochondria, modulation of insulin secretion, and elevation of levels of uncoupling proteins in adipose and skeletal muscles are similar to those of AMPK and thyroxine. Therefore it is proposed that effects of M. charantia on carbohydrate and fat metabolism are through thyroxine and AMPK.

Supplementation of bitter melon to rats fed a high-fructose diet during gestation and lactation ameliorates fructose-induced dyslipidemia and hepatic oxidative stress in male offspring

This study examined the impact of maternal high-fructose intake and if metabolic control in the offspring could benefit from supplementing bioactive food components such as bitter melon (BM) to the maternal diet. In Expt. 1, virgin female rats received control (C), high-fructose (F; 60%), or BM-supplemented fructose (FBM; 1%) diet before conception until d 21 of lactation. Weaned male offspring were fed the C diet for 11 wk, forming C/C, F/C, and FBM/C groups. The F/C group had elevated serum insulin, TG, and FFA concentrations and hepatic lipid alterations compared with the C/C and FBM/C groups (P < 0.05). The 2 latter groups did not differ. Expt. 2 had similar dam treatment groups, but offspring were weaned to the C or F diet, forming C/C, C/F, F/F, and FBM/F groups, and the dietary treatment was extended to 20 wk. The hepatic levels of stearyl-CoA desaturase and microsomal TG transfer protein mRNA were lower, but that of PPARγ coactivator 1-α and fibroblast growth factor 21 mRNA and fatty acid binding protein 1 protein were higher in the FBM/F group compared with the C/F and F/F groups (P < 0.05), indicating that maternal BM supplementation may reduce lipogenesis and promote lipid oxidation in offspring. The FBM/F group had significantly higher activities of liver glutathione peroxidase, superoxide dismutase, and catalase than the F/F group. The results indicate that supplementing BM to dams could offset the adverse effects of maternal high-fructose intake on lipid metabolism and antioxidant status in adult offspring.

Bioactives from bitter melon enhance insulin signaling and modulate acyl carnitine content in skeletal muscle in high-fat diet-fed mice

Bioactive components from bitter melon (BM) have been reported to improve glucose metabolism in vivo, but definitive studies on efficacy and mechanism of action are lacking. We sought to investigate the effects of BM bioactives on body weight, muscle lipid content and insulin signaling in mice fed a high-fat diet and on insulin signaling in L6 myotubes. Male C57BL/6J mice were randomly divided into low-fat diet control (LFD), high-fat diet (HFD) and HFD plus BM (BM) groups. Body weight, body composition, plasma glucose, leptin, insulin and muscle lipid profile were determined over 12 weeks. Insulin signaling was determined in the mouse muscle taken at end of study and in L6 myotubes exposed to the extract. Body weight, plasma glucose, insulin, leptin levels and HOMA-IR values were significantly lower in the BM-fed HFD group when compared to the HFD group. BM supplementation significantly increased IRS-2, IR β, PI 3K and GLUT4 protein abundance in skeletal muscle, as well as phosphorylation of IRS-1, Akt1 and Akt2 when compared with HFD (P<.05 and P<.01). BM also significantly reduced muscle lipid content in the HFD mice. BM extract greatly increased glucose uptake and enhanced insulin signaling in L6 myotubes. This study shows that BM bioactives reduced body weight, improved glucose metabolism and enhanced skeletal muscle insulin signaling. A contributing mechanism to the enhanced insulin signaling may be associated with the reduction in skeletal muscle lipid content. Nutritional supplementation with this extract, if validated for human studies, may offer an adjunctive therapy for diabetes.

Dietary bitter melon seed increases peroxisome proliferator-activated receptor-γ gene expression in adipose tissue, down-regulates the nuclear factor-κB expression, and alleviates the symptoms associated with metabolic syndrome

The objective of this study was to examine the extent to which bitter melon seed (BMS) alleviates the symptoms associated with metabolic syndrome and elucidate the mechanism by which BMS exerts beneficial effects. Three-month-old female Zucker rats were assigned to following groups: lean control (L-Ctrl), obese control (O-Ctrl), and obese + BMS (O-BMS). The control groups were fed AIN-93M purified rodent diet, and the O-BMS group was fed AIN-93M diet modified to contain 3.0% (wt/wt) ground BMS for 100 days. After 100 days of treatment, BMS supplementation in the obese rats lowered the total serum cholesterol by 38% and low-density lipoprotein-cholesterol levels by about 52% and increased the ratio of serum high-density lipoprotein-cholesterol to total cholesterol compared to the O-Ctrl group. The percentage of total liver lipids was about 32% lower and serum triglyceride levels were 71% higher in the O-BMS group compared to the O-Ctrl group. Serum glucose levels were significantly lowered partly because of the increase in the serum insulin levels in the BMS-based diet groups. BMS supplementation increased the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ) in the white adipose tissue of the obese rats significantly (P < .05) and down-regulated the expression of PPAR-γ, nuclear factor-κB (NF-κB), and interferon-γ mRNA in heart tissue of the obese rats. The findings of this study suggest that BMS improves the serum and liver lipid profiles and serum glucose levels by modulating PPAR-γ gene expression. To our knowledge, this study for the first time shows that BMS exerts cardioprotective effects by down-regulating the NF-κB inflammatory pathway.

Targeting metabolic syndrome: candidate natural agents

Following on from impressive economic development and urbanization, China is currently experiencing a high prevalence of metabolic syndrome. Patients with metabolic syndrome suffer from the "The Deadly Quartet" of hyperglycemia, hypertriglyceridemia, hypertension, and central (or upper body) obesity. Current treatment strategies directed towards metabolic syndrome tend to be limited to just one of these four conditions, so developing novel drugs to target multiple metabolic abnormalities could be preferable to current approaches. New insights suggest benefits of natural agents as treatments for metabolic syndrome. Herein, we review the evidence for using nine such agents developed on the basis of traditional medicine or herbal preparations.

Momordica charantia (bitter melon) inhibits primary human adipocyte differentiation by modulating adipogenic genes

BACKGROUND

Escalating trends of obesity and associated type 2 diabetes (T2D) has prompted an increase in the use of alternative and complementary functional foods. Momordica charantia or bitter melon (BM) that is traditionally used to treat diabetes and complications has been demonstrated to alleviate hyperglycemia as well as reduce adiposity in rodents. However, its effects on human adipocytes remain unknown. The objective of our study was to investigate the effects of BM juice (BMJ) on lipid accumulation and adipocyte differentiation transcription factors in primary human differentiating preadipocytes and adipocytes.

METHODS

Commercially available cryopreserved primary human preadipocytes were treated with and without BMJ during and after differentiation. Cytotoxicity, lipid accumulation, and adipogenic genes mRNA expression was measured by commercial enzymatic assay kits and semi-quantitative RT-PCR (RT-PCR).

RESULTS

Preadipocytes treated with varying concentrations of BMJ during differentiation demonstrated significant reduction in lipid content with a concomitant reduction in mRNA expression of adipocyte transcription factors such as, peroxisome proliferator-associated receptor gamma (PPARgamma) and sterol regulatory element-binding protein 1c (SREBP-1c) and adipocytokine, resistin. Similarly, adipocytes treated with BMJ for 48 h demonstrated reduced lipid content, perilipin mRNA expression, and increased lipolysis as measured by the release of glycerol.

CONCLUSION

Our data suggests that BMJ is a potent inhibitor of lipogenesis and stimulator of lipolysis activity in human adipocytes. BMJ may therefore prove to be an effective complementary or alternative therapy to reduce adipogenesis in humans.

Regulation of energy metabolism pathways by estrogens and estrogenic chemicals and potential implications in obesity associated with increased exposure to endocrine disruptors

The prevalence of obesity among children, adolescents and adults has been dramatically increasing worldwide during the last several decades. The obesity epidemic has been recognized as one of the major global health problems, because its health hazard is linked to a number of common diseases including breast and prostate cancers. Obesity is caused by combination of genetic and environmental factors. While genetic contribution to obesity has been known to be significant, the genetic factors remain relatively unchanged. Recent studies have highlighted the involvement of environmental "obesogens", i.e. the xenobiotic chemicals that can disrupt the normal development and homeostatic control over adipogenesis and energy balance. Several lines of evidence suggest that increasing exposure to chemicals with endocrine-disrupting activities (endocrine-disrupting chemicals, EDCs) contributes to the increased obesity. The cellular and molecular mechanisms underlying obesogen-associated obesity are just now being appreciated. In this paper, we comprehensively reviewed current knowledge about the role of estrogen receptors alpha and beta (ERalpha and ERbeta) in regulation of energy metabolism pathways, including glucose transport, glycolysis, tricarboxylic acid (TCA) cycle, mitochondrial respiratory chain (MRC), adenosine nucleotide translocator (ANT) and fatty acid beta-oxidation and synthesis, by estrogens; and then examined the disturbance of E(2)/ER-mediated energy metabolism pathways by environmental obesogens; and finally, we discussed the potential implications of disturbance of energy metabolism pathways by obesogens in obesity and pointed out several key aspects of this area that need to be further explored. A better understanding of the cellular and molecular mechanisms underlying obesogen-associated obesity will lead to new approaches for slow down and/or prevention of the increased trend of obesity associated with exposure to obesogens.

Dietary fat concentration influences the effects of trans-10, cis-12 conjugated linoleic acid on temporal patterns of energy intake and hypothalamic expression of appetite-controlling genes in mice

This study tested the hypothesis that the effect of trans-10, cis-12 conjugated linoleic acid (t10, c12 CLA) on energy intake (EI) and body weight (BW)/composition is confounded by dietary fat concentration and involves hypothalamic appetite-controlling mechanisms. ICR mice received low-fat (LF; 5 g/100 g) or high-fat (HF; 30 g/100 g) diets, with or without 0.5 g/100 g t10, c12 CLA (>98% pure) for 27 d. By d 13, BW and cumulative EI of the mice fed CLA supplemented LF diet (LF/CLA) were 6.6 and 23.6% lower, respectively, than the LF mice. In the subsequent 14 d, their EI rebounded and did not differ from the LF group. BW and EI did not differ between the HF and CLA supplemented HF (HF/CLA) groups. Hypothalamic pro-opiomelanocortin (POMC) mRNA expression was elevated (P = 0.031) on d 13 but suppressed (P < 0.001) on d 27 due to CLA treatment. CLA also suppressed AMP-activated protein kinase alpha2 expression. Mice in Expt. 2 received the LF diet, the LF/CLA, or were pair-fed the LF diet to the EI of the CLA group (LF/PF). LF/CLA and LF/PF mice did not differ in the hypothalamic POMC:neuropeptide Y expression ratio on d 13, but it was significantly lower in the LF/PF group on d 27. We conclude that the habitual dietary fat concentration influences the magnitude of weight loss induced by dietary t10, c12 CLA. The effect is in part independent of EI. Hypothalamic neuropeptides and nutrient sensing mechanisms may play a role.

Momordica charantia (bitter melon) reduces plasma apolipoprotein B-100 and increases hepatic insulin receptor substrate and phosphoinositide-3 kinase interactions

Aqueous extracts or juice from unripened fruit of Momordica charantia (bitter melon) has traditionally been used in the treatment of diabetes and its complications. Insulin resistance is characterized by significant down-regulation of hepatic insulin signalling as documented by attenuated phosphorylation of insulin receptor (IR), IR substrates 1 and 2, phosphoinositide-3 kinase, protein kinase B, and over-expression of phosphotyrosine phosphatase 1B. We recently demonstrated that bitter melon juice (BMJ) is a potent inhibitor of apoB secretion and TAG synthesis and secretion in human hepatoma cells, HepG2, that may be involved in plasma lipid- and VLDL-lowering effects observed in animal studies. The aim of this study was to evaluate the effects of BMJ on plasma apoB levels and hepatic insulin signalling cascade in mice fed high-fat diet (HFD). Female C57BL/6 mice (4–6 weeks old) were randomized into three groups receiving regular rodent chow, HFD and HFD+BMJ. The data indicate that BMJ not only improves glucose and insulin tolerance but also lowers plasma apoB-100 and apoB-48 in HFD-fed mice as well as modulates the phosphorylation status of IR and its downstream signalling molecules. Investigating the biochemical and molecular mechanisms involved in amelioration of diabetic dyslipidaemia by BMJ may lead to identification of new molecular targets for dietary/alternative therapies.

Bitter melon (Momordica charantia L.) inhibits adipocyte hypertrophy and down regulates lipogenic gene expression in adipose tissue of diet-induced obese rats

Bitter melon (Momordica charantia; BM) has been shown to ameliorate diet-induced obesity and insulin resistance. To examine the effect of BM supplementation on cell size and lipid metabolism in adipose tissues, three groups of rats were respectively fed a high-fat diet supplemented without (HF group) or with 5 % lyophilised BM powder (HFB group), or with 0·01 % thiazolidinedione (TZD) (HFT group). A group of rats fed a low-fat diet was also included as a normal control. Hyperinsulinaemia and glucose intolerance were observed in the HF group but not in HFT and HFB groups. Although the number of large adipocytes (>180 μm) of both the HFB and HFT groups was significantly lower than that of the HF group, the adipose tissue mass, TAG content and glycerol-3-phosphate dehydrogenase activity of the HFB group were significantly lower than those of the HFT group, implying that BM might reduce lipogenesis in adipose tissue. Experiment 2 was then conducted to examine the expression of lipogenic genes in adipose tissues of rats fed low-fat, HF or HFB diets. The HFB group showed significantly lower mRNA levels of fatty acid synthase, acetyl-CoA carboxylase-1, lipoprotein lipase and adipocyte fatty acid-binding protein than the HF group (P < 0·05). These results indicate BM can reduce insulin resistance as effective as the anti-diabetic drug TZD. Furthermore, BM can suppress the visceral fat accumulation and inhibit adipocyte hypertrophy, which may be associated with markedly down regulated expressions of lipogenic genes in the adipose.

Water extracts from Momordica charantia increase glucose uptake and adiponectin secretion in 3T3-L1 adipose cells

To examine the effects of Momordica charantia on glucose uptake and adiponectin secretion in adipose cells, 3T3-L1 adipocytes were treated with three concentrations (0.2, 0.3 and 0.4mg/ml) of water and ethanol extracts of Momordica charantia fruit and seeds alone and in combination with either 0.5nM or 50nM insulin. The treatment combination of 0.2mg/ml water extract and 0.5nM insulin was associated with significant (p<0.05) increases in glucose uptake (61%) and adiponectin secretion (75%) over control levels. The ethanol extract was not associated with an increase in glucose uptake; however, a dose-dependent decrease in basal glucose uptake and insulin-mediated glucose uptake was observed with the ethanol extract in combination with 50nM insulin. In the absence of insulin, no effects on glucose uptake were observed in adipocytes exposed to the water extracts whereas the highest concentration (0.4mg/ml) of the ethanol extract was associated with a significant (p<0.05) decrease in glucose uptake relative to controls. The present results indicate that water-soluble component(s) in Momordica charantia enhance the glucose uptake at sub-optimal concentrations of insulin in 3T3-L1 adipocytes, which is accompanied by and may be a result of increased adiponectin secretion from the 3T3-L1 adipocytes.

Lipid lowering effects of Momordica charantia (Bitter Melon) in HIV-1-protease inhibitor-treated human hepatoma cells, HepG2

1. Hyperlipidemic effects of HIV-1-protease inhibitors (PI) are associated with increased hepatic production of triglyceride (TG)-rich lipoproteins, rather than lipoprotein clearance. PI are known to increase apolipoprotein B (apoB) secretion, apoC-III mRNA expression and decrease apoA-1 secretion. Nutritional therapy remains an important strategy to manage PI-associated hyperlipidemia. 2. This study investigated the in vitro efficacy of Asian vegetable, Momordica charantia or bitter melon (BM) to ameliorate PI-associated apoB and lipid abnormalities in HepG2 cells. 3. Our study demonstrates that bitter melon juice (BMJ) significantly reduced apoB secretion and apoC-III mRNA expression and normalized apoA-I expression in PI-treated HepG2 cells. BMJ also significantly reduced cellular TG and microsomal TG transfer protein, suggesting that lipid bioavailability and lipidation of apoB assembly may play a role in decreased apoB secretion. 4. Identifying molecular targets of BM may offer alternative dietary strategies to decrease PI-associated hyperlipidemia and improve quality of life among HIV-1-infected patients.