Antioxidative Effect of Conjugated Linolenic Acid in Diabetic and Non-Diabetic Blood: an in vitro Study

Recent advances in the development of bitter gourd seed oil: from chemical composition to potential applications

Non-conventional seed oils are being considered novelty foods due to the unique properties of their chemical constituents. Numerous such seed oils serve as nutritional and functional supplements, making them a point of interest for scholars. Bitter gourd (Momordica charantia L.) seed oil (BGSO) has been widely used in folk medicine worldwide for the treatment of different pathologies, such as diabetes, cancer, and several inflammatory diseases. Therefore, its nutritional and medicinal value has been extensively studied. Considering the potential use of BGSO, it is imperative to have a comprehensive understanding of this product to develop and use its biologically active ingredients in innovative food and pharmaceutical products. An extensive understanding of BGSO would also help improve the economic feasibility of the bitter gourd seed processing industry and help prevent environmental pollution associated with the raw waste produced during the processing of bitter gourd seeds. This review addresses the potential uses of BGSO in terms of food and pharmaceuticals industry perspectives and comprehensively summarizes the oil extraction process, chemical composition, biological activity, and the application prospects of BGSO in clinical medicine.

Vernicia fordii (Hemsl.) Airy Shaw extract stimulates insulin secretion in pancreatic β-cells and improves insulin sensitivity in diabetic mice

ETHNOPHARMACOLOGICAL RELEVANCE

Vernicia fordii (Hemsl.) Airy Shaw (V. fordii) is also known as the tung tree and its leaves and fruit are used as an oriental treatment for dyspepsia, edema, and skin diseases, which are known as diabetic complications.

AIM OF THE STUDY

In this study, we aimed to investigate the methanolic extract (VF5) of the leaves of V. fordii as an insulin secretagogue and its probable mechanism and verify the effect in HFD-fed mice.

MATERIALS AND METHODS

The insulin secretagogue activity of different doses of VF5 (0.1, 0.3 and 1.0 μg/ml) was assessed using in vitro insulin secretion assay and confirmed the anti-diabetic effect in mice fed HFD for 4 weeks with different doses of VF5 (10, 20 and 50 mg/kg oral) for another 6 weeks. Glbenclamide (30 mg/kg, oral) was used as positive control drug. The possible mechanisms were evaluated by using Gö6983 (10 μM), U73122 (10 μM) and nifedipine (10 μM). The major constituents of VF5 were analyzed by UPLC-QToF-MS and ¹H and ¹³C NMR spectroscopy.

RESULTS

UPLC-QToF-MS and NMR spectroscopy analysis indicated that one of the main active components of VF5 was tigliane-diterpene esters. VF5 functioned as an insulin secretagogue and enhanced mitochondria respiration and insulin homeostasis. We confirmed that VF5 preserved the β-cell and reduced the β-cell expansion which caused by metabolic stress under HFD. The antidiabetic role of VF5 in HFD fed mice was assessed by glucose tolerance test (GTT) and insulin tolerance test (ITT), fasting plasma insulin level, fasting blood glucose level, AKT signal in peripheral tissue in the absence of toxic effects. Mechanistically, insulinotropic effect of VF5 was mediated by activation of PKCα via intracellular Ca²⁺ influx and enhanced mitochondria function.

CONCLUSION

VF5 exhibits potent insulin secretagogue function and improves insulin sensitivity and protection of pancreatic β-cells from metabolic stress without toxicity. Taken together, our study suggests that VF5 could be potentially used for treating diabetes and metabolic diseases through improving β-cell function.

Antioxidants profile of Momordica charantia fruit extract analyzed using LC-MS-QTOF-based metabolomics

Momordica charantia fruit is claimed to have healthy benefit. Despite this potential claim, the phytochemical study of this fruit is still lacking. Thus, this study aimed to evaluate the antioxidants profile of Momordica charantia (Cucurbitaceae) fruit. The antioxidant activity of the ethanolic extracts of various polarities was evaluated and the metabolites that are responsible for its activity were identified using metabolomics approach. Six different mixture of ethanol in water that are 0%, 20%, 40%, 60%, 80%, and 100% (v/v) was extracted using dveseeded fruit sample. Liquid chromatography-mass spectrometry-quadrupole time of flight and multivariate data analysis was used to identify the metabolites that were either antioxidants or pro-oxidants. The 80% ethanol extract exhibited the most antioxidant activity when tested in both 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) antioxidant assays. This extract showed the most intense LC-MS signals represented to ascorbic acid, margarolic acid, brevifolincarboxylic acid, quercetin 3-O-glycoside, kuguacin H, cucurbitacin E, 3-malonylmomordicin I, and goyaglycoside G correlating to the anti-oxidant activity. This study reports for the first time the existence of brevifolincarboxylic acid in this fruit, and the antioxidant activity of 3-malonylmomordicin I and goyaglycoside G. In addition, the loading plots revealed the unknown compounds possessing the antioxidant activity which are potential to be isolated in the future study.

Pomegranate seed oil and bitter melon extract supplemented in diet influence the lipid profile and intensity of peroxidation in livers of SPRD rats exposed to a chemical carcinogen

Despite promising health effects of pomegranate seed oil (PSO) and bitter melon extract (BM) used for centuries as food and traditional medicine, neither mechanism of action nor safety has been fully recognized. This study aimed to evaluate the influence of diet supplementation with PSO and BM on fatty acid, conjugated fatty acid and cholesterol content in rat' livers, since liver is crucial for lipid metabolism. Oxidation indicators (malondialdehyde, oxysterols and tocopherols) were also determined. Lipid profiles did not reveal the presence of punicic acid, while other conjugated dienes and trienes, including rumenic acid, were determined. Both supplementation and exposition to carcinogen significantly increased cholesterol and reduced selected oxysterols levels, simultaneously increasing malondialdehyde content in animals suffering from cancer. Impact of PSO and BM on oxidative status varied depending on carcinogen exposure and coexisting neoplastic process, which is important, due to the growing interest in their use in prevention and therapy of various diseases, including cancer.

A novel nanoformulation of α-eleostearic acid restores molecular pathogenesis of hypersensitivity

AIM

The present work provides first-time empirical and molecular interaction evidence to establish the higher biofunctionality of a therapeutic lipid, α-eleostearic acid (ESA), encapsulated in a novel and thoroughly characterized biocompatible nanoemulsion (NE) system (particle size <200 nm).

MATERIALS & METHODS

A novel methodology was employed to fabricate novel formulations of ESA. Molecular biological tools and assays were used to arrive at definite conclusions.

RESULTS

The proinflammatory profile was found to be significantly mitigated in the hypersensitized rats administered with the ESA-NE formulation more emphatically as compared with ESA-conventional emulsion in both in vivo and ex vivo models.

CONCLUSION

The novel ESA-NE formulation shows a lot of palpable promise for clinical applications.

Tung Tree (Vernicia fordii, Hemsl.) Genome and Transcriptome Sequencing Reveals Co-Ordinate Up-Regulation of Fatty Acid β-Oxidation and Triacylglycerol Biosynthesis Pathways During Eleostearic Acid Accumulation in Seeds

The tung tree (Vernicia fordii) is one of only a few plant species that produces high oil-yielding seeds rich in α-eleostearic acid (α-ESA, 18:3Δ9cis, 11trans, 13trans), a conjugated trienoic fatty acid with valuable industrial and medical properties. Previous attempts have been made to engineer tung oil biosynthesis in transgenic oilseed crops, but these efforts have met with limited success. Here we present a high-quality genome assembly and developing seed transcriptomic data set for this species. Whole-genome shotgun sequencing generated 176 Gb of genome sequence data used to create a final assembled sequence 1,176,320 kb in size, with a scaffold N50 size of >474 kb, and containing approximately 47,000 protein-coding genes. Genomic and transcriptomic data revealed full-length candidate genes for most of the known and suspected reactions that are necessary for fatty acid desaturation/conjugation, acyl editing and triacylglycerol biosynthesis. Seed transcriptomic analyses also revealed features unique to tung tree, including unusual transcriptional profiles of fatty acid biosynthetic genes, and co-ordinated (and seemingly paradoxical) simultaneous up-regulation of both fatty acid β-oxidation and triacylglycerol biosynthesis in mid-development seeds. The precise temporal control of the expression patterns for these two pathways may account for α-ESA enrichment in tung seeds, while controlling the levels of potentially toxic by-products. Deeper understanding of these processes may open doors to the design of engineered oilseeds containing high levels of α-ESA.

Studies on the antidiabetic activities of Momordica charantia fruit juice in streptozotocin-induced diabetic rats

CONTEXT

Momordica charantia Linn (Cucurbitaceae) (MC) is used in folk medicine to treat various diseases including diabetes mellitus.

OBJECTIVE

This study investigates the antidiabetic activities of Momordica charantia (bitter gourd) on streptozotocin-induced type 2 diabetes mellitus in rats.

MATERIALS AND METHODS

Male Wister rats were randomly assigned to 4 groups. Group I, Normal control; Group II, STZ diabetic; Group III and IV, Momordica charantia fruit juice was orally administered to diabetic rats (10 mL/kg/day either as prophylaxis for 14 days before induction of diabetes then 21 days treatment, or as treatment given for 21 days after induction of diabetes). The effects of MC juice were studied both in vivo and in vitro by studying the glucose uptake of isolated rat diaphragm muscles in the presence and absence of insulin. Histopathological examination of pancreas was also performed.

RESULTS

This study showed that MC caused a significant reduction of serum glucose (135.99 ± 6.27 and 149.79 ± 1.90 vs. 253.40* ± 8.18) for prophylaxis and treatment respectively, fructosamine (0.99 ± 0.01 and 1.01 ± 0.04 vs. 3.04 ± 0.07), total cholesterol, triglycerides levels, insulin resistance index (1.13 ± 0.08 and 1.19 ± 0.05 vs. 1.48 ± 1.47) and pancreatic malondialdehyde content (p < 0.05). While it induced a significant increase of serum insulin (3.41 ± 0.08 and 3.28 ± 0.08 vs. 2.39 ± 0.27), HDL-cholesterol, total antioxidant capacity levels, β cell function percent, and pancreatic reduced glutathione (GSH) content (p < 0.05) and improved histopathological changes of the pancreas. It also increased glucose uptake by diaphragms of normal (12.17 ± 0.60 vs. 9.07 ± 0.66) and diabetic rats (8.37 ± 0.28 vs. 4.29 ± 0.51) in the absence and presence of insulin (p < 0.05).

CONCLUSIONS

Momordica charantia presents excellent antidiabetic and antioxidant activities and thus has great potential as a new source for diabetes treatment whether it is used for prophylaxis or treatment.

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.

Bitter melon: a panacea for inflammation and cancer

Nature is a rich source of medicinal plants and their products that are useful for treatment of various diseases and disorders. Momordica charantia, commonly known as bitter melon or bitter gourd, is one of such plants known for its biological activities used in traditional system of medicines. This plant is cultivated in all over the world, including tropical areas of Asia, Amazon, east Africa, and the Caribbean and used as a vegetable as well as folk medicine. All parts of the plant, including the fruit, are commonly consumed and cooked with different vegetables, stir-fried, stuffed or used in small quantities in soups or beans to give a slightly bitter flavor and taste. The plant is reported to possess anti-oxidant, anti-inflammatory, anti-cancer, anti-diabetic, anti-bacterial, anti-obesity, and immunomodulatory activities. The plant extract inhibits cancer cell growth by inducing apoptosis, cell cycle arrest, autophagy and inhibiting cancer stem cells. The plant is rich in bioactive chemical constituents like cucurbitane type triterpenoids, triterpene glycosides, phenolic acids, flavonoids, essential oils, saponins, fatty acids, and proteins. Some of the isolated compounds (Kuguacin J, Karaviloside XI, Kuguaglycoside C, Momordicoside Q-U, Charantin, α-eleostearic acid) and proteins (α-Momorcharin, RNase MC2, MAP30) possess potent biological activity. In the present review, we are summarizing the anti-oxidant, anti-inflammatory, and anti-cancer activities of Momordica charantia along with a short account of important chemical constituents, providing a basis for establishing detail biological activities of the plant and developing novel drug molecules based on the active chemical constituents.

Characterization of a soluble phosphatidic acid phosphatase in bitter melon (Momordica charantia)

Momordica charantia is often called bitter melon, bitter gourd or bitter squash because its fruit has a bitter taste. The fruit has been widely used as vegetable and herbal medicine. Alpha-eleostearic acid is the major fatty acid in the seeds, but little is known about its biosynthesis. As an initial step towards understanding the biochemical mechanism of fatty acid accumulation in bitter melon seeds, this study focused on a soluble phosphatidic acid phosphatase (PAP, 3-sn-phosphatidate phosphohydrolase, EC 3.1.3.4) that hydrolyzes the phosphomonoester bond in phosphatidate yielding diacylglycerol and P_i. PAPs are typically categorized into two subfamilies: Mg²⁺-dependent soluble PAP and Mg²⁺-independent membrane-associated PAP. We report here the partial purification and characterization of an Mg²⁺-independent PAP activity from developing cotyledons of bitter melon. PAP protein was partially purified by successive centrifugation and UNOsphere Q and S columns from the soluble extract. PAP activity was optimized at pH 6.5 and 53–60°C and unaffected by up to 0.3 mM MgCl₂. The K_m and V_max values for dioleoyl-phosphatidic acid were 595.4 µM and 104.9 ηkat/mg of protein, respectively. PAP activity was inhibited by NaF, Na₃VO₄, Triton X-100, FeSO₄ and CuSO₄, but stimulated by MnSO₄, ZnSO₄ and Co(NO₃)₂. In-gel activity assay and mass spectrometry showed that PAP activity was copurified with a number of other proteins. This study suggests that PAP protein is probably associated with other proteins in bitter melon seeds and that a new class of PAP exists as a soluble and Mg²⁺-independent enzyme in plants.

Comparative prophylactic effects of α-eleostearic acid rich nano and conventional emulsions in induced diabetic rats

The present work entailed perspicacious fabrication of Bitter Gourd Seed Oil Nanoemulsion (BGO-NE) for increasing bioavailability of CLnA in oxidative stress induced in vivo system. The BGO-NE was characterized and evaluated for dimensional as well as rheological changes periodically during a 12 week storage period. BGO comprising ∼50 % α-eleostearic acid, was assessed in conventional and NE formulation at different doses, for its ability to stimulate antioxidative enzyme marker paradigm comprising SOD, GPx, CAT and GSH, inherent to the subjects under study. The formulated BGO-NE (d < 100 nm) was found to be stable for 12 weeks compared to BGO-CE as was determined by particle size characterization and associated parameters. Diet supplementation of 0.5 % (w/v) BGO-NE formulation exhibited maximum efficiency in countering oxidative stress as compared to 1 % BGO-NE formulation and equivalent doses of BGO-CE. Higher efficacy at very low dose of the nano-sized formulation was thus, also established. Histopathological data from liver, pancreas and kidney sections corroborated the above findings. The present study with formulated BGO-NE and BGO-CE evaluates and confirms the implications of a NE formulation of a bioactive lipid - conjugated linolenic acid (CLnA), targeting specific in vivo processes to counter the negative influence of excess ROS (Reactive Oxygen Species) in the system. It, thus presents itself as a potent nutraceutical against diabetes mellitus in an optimized delivery system.

Studies on comparative efficacy of α-linolenic acid and α-eleostearic acid on prevention of organic mercury-induced oxidative stress in kidney and liver of rat

The present study was undertaken to evaluate the effect of α-linolenic acid and α-eleostearic acid, two isomers of linolenic acid, against oxidative stress induced by organic mercury in kidney and liver cells of rat. Male albino rats were divided into six groups. Groups 1, 2 were normal control and methyl mercury chloride (MeHgCl) treated (5 mg/kg BW/day) control, respectively. Groups 3, 4, 5 and 6 were orally treated with different doses of two fatty acids (0.5% and 1.0% of total lipid given for each isomer) along with MeHgCl (5 mg/kg BW). Results showed that activity of antioxidant enzymes viz. catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), reduced glutathione (GSH) in liver and kidney decreased significantly due to oxidative stress generated by MeHg. Administration of the linolenic acid isomers almost restored all the altered parameters and also reduced lipid peroxidation and leakage of trans-aminase enzymes from liver to blood due to liver injury when administrated in higher doses. Histopathology of liver and kidney cells showed that administration of α-linolenic acid significantly reduced the damage generated by MeHg. Thus, α-linolenic acid and α-eleostearic acid could serve as cost-effective and natural phytochemical preparation to protect against the adverse effects caused by organic mercury in human.

Growth inhibition and apoptotic effect of alpha-eleostearic acid on human breast cancer cells

Alpha-eleostearic acid (α-ESA) is a natural and biologically active compound which possesses potent antioxidant and anti-tumor activity. The purpose of this study was to confirm the anticancer activity of α-ESA against human breast cancer cells and to further elucidate its mechanism of activity. Human breast cancer cells and normal liver cells were used for in-vitro tests of the anticancer activity of α-ESA, including cytotoxicity, colony formation inhibition, EdU incorporation, AO/EB staining of apoptotic cells, cell cycle distribution through flow cytometry, and PPARγ, p21, Bax, p53, and caspase-3 mRNA expressions through RT-PCR. After α-ESA treatment, the proliferation, colony formation, and EdU labeling indices of cancer cells decreased (p < 0.05), while the AO/EB-stained apoptotic cells increased (p < 0.05). By FCM analysis, the apoptotic indices increased (p < 0.01), and the cell population decreased in S phase (p < 0.01) and increased in G(2)/M phase (p < 0.05) in α-ESA treated cancer cells. RT-RCR showed that α-ESA significantly increased the expression levels of PPARγ, p21, Bax, p53, and caspase-3 mRNA. The findings in these studies suggested that α-ESA exhibited a potential cytotoxicity and apoptosis induction effect on human breast cancer cells, with little effect on normal cells at certain concentrations. The mechanism for such effects might be associated with the inhibition of DNA synthesis, induction of apoptosis, and cell cycle arrest of cancer cells through up-regulation of PPARγ, p21, Bax, p53, and caspase-3 expressions.

The health promoting properties of the conjugated isomers of α-linolenic acid

The bioactive properties of the conjugated linoleic acid (CLA) isomers have long been recognised and are the subject of a number of excellent reviews. However, despite this prominence the CLA isomers are not the only group of naturally occurring dietary conjugated fatty acids which have shown potent bioactivity. In a large number of in vitro and in vivo studies, conjugated α-linolenic acid (CLNA) isomers have displayed potent anti-inflammatory, immunomodulatory, anti-obese and anti-carcinogenic activity, along with the ability to improve biomarkers of cardio-vascular health. CLNA isomers are naturally present in high concentrations in a large variety of seed oils but can also be produced in vitro by strains of lactobacilli and bifidobactena through the activity of the enzyme linoleic acid isomerase on α-linolenic acid. In this review, we will address the possible therapeutic roles that CLNA may play in a number of conditions afflicting Western society and the mechanisms through which this activity is mediated.

Antidiabetic effects of bitter gourd extracts in insulin-resistant db/db mice

Bitter gourd (BG, Momordica charantia) exerts proven blood glucose- and body weight-lowering effects. To develop an effective and safe application, it is necessary to identify the bioactive compounds and biochemical mechanisms responsible for these effects in type 2 diabetes. A total of forty-five 4-week-old male db/db mice were assigned to five groups of nine each. The mice were given sterile tap water as a control, a whole fruit powder, the lipid fraction, the saponin fraction or the hydrophilic residue of BG at a daily oral dosage of 150 mg/kg body weight for 5 weeks, respectively. Weight gain was significantly decreased in all the BG-treated groups (P ≤ 0.05). Glycated Hb levels were the highest in the control mice compared with all the four BG-treated mice (P = 0.02). The lipid fraction had the strongest effect, and it tended (P = 0.075) to reduce glycated Hb levels from 9.3 % (control mice) to 8.0 % (lipid fraction-treated mice). The lipid and saponin fractions reduced lipid peroxidation of adipose tissue significantly (P ≤ 0.01). Additionally, the saponin fraction and the lipid fraction reduced protein tyrosine phosphatase 1B (PTP 1B) activity in skeletal muscle cytosol by 25 % (P = 0.05) and 23 % (P = 0.07), respectively. PTP 1B is the physiological antagonist of the insulin signalling pathway. Inhibition of PTP 1B increases insulin sensitivity. This is the first study to demonstrate that BG is involved in PTP 1B regulation, and thus explains one possible biochemical mechanism underlying the antidiabetic effects of BG in insulin resistance and type 2 diabetes.