Peptides with antilipolytic and lipogenic activities from seeds of the bitter gourd Momordica charantia (family Cucurbitaceae)

Effect of Momordica charantia on lipid profile and oral glucose tolerance in diabetic rats

In this study, the methanol extract of Momordica charantia fruit extract was administered to diabetic rats to assess the long term effect of the extract on the lipid profile and the oral glucose tolerance test. Treatment for 30 days showed a significant decrease in triglyceride, low density lipoprotein and a significant increase in high density lipoprotein level. A significant effect on oral glucose tolerance was also noted. Chronic administration showed an improvement in the oral glucose tolerance curve. The effect was more pronounced when the test was done in rats fed the extract on the day of the test compared with tests done in rats which were not fed the extract on the same day.

Natural products with hypoglycemic, hypotensive, hypocholesterolemic, antiatherosclerotic and antithrombotic activities

This article reviews compounds of botanical origin which are capable of lowering plasma levels of glucose and cholesterol and blood pressure, as well as compounds inhibiting atherosclerosis and thrombosis. Hypoglycemic natural products comprise flavonoids, xanthones, triterpenoids, alkaloids, glycosides, alkyldisulfides, aminobutyric acid derivatives, guanidine, polysaccharides and peptides. Hypotensive compounds include flavonoids, diterpenes, alkaloids, glycosides, polysaccharides and proteins. Among natural products with hypocholesterolemic activity are beta-carotene, lycopene, cycloartenol, beta-sitosterol, sitostanol, saponin, soybean protein, indoles, dietary fiber, propionate, mevinolin (beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitor) and polysaccharides. Heparins, flavonoids, tocotrienols, beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitors (statins), garlic compounds and fungal proteases exert antithrombotic action. Statins and garlic compounds also possess antiatherosclerotic activity.

Momordica charantia (Bitter Gourd) peel, pulp, seed and whole fruit extract inhibits mouse skin papillomagenesis

The present study was designed to elucidate the inhibitory potential of Momordica charantia (Bitter Gourd) peel, pulp, seed and whole fruit extract on mouse skin papillomagensis with the modulatory influence of biotransformation system enzymes. Topical application of Momordica whole fruit extract (100 microl/animal per day) during the peri-initiation stage (1 week before and 2 weeks after initiation) by 7,12-dimethylbenz[a]anthracene (DMBA) and/or during the tumor promotion stage reduced the (i) tumor burden to 4.26, 3.72 and 3.11 (positive control value: 5.42); (ii) cumulative number of papillomas to 81, 67 and 53 (positive control value: 103); and (iii) percent incidence of mice bearing papillomas to 100, 94 and 94, respectively (positive control value: 100). In a comparison of the anticarcinogenic efficacy of Momordica peel, pulp, seed and whole fruit extract (100 microl/animal per day), after topical treatment during the peri-initiation and during the tumor promotion stage, revealed the modulation of the (i) tumor burden (tumors/mouse) to 3.06, 3.61, 3.17 and 3.11; (ii) cumulative number of papillomas to 49, 65, 54 and 53; and (iii) percent incidence of mice bearing papillomas to 84, 100, 94 and 94, respectively. Significant elevation in the sulfhydryl (-SH) level was observed in the liver and skin tissues by the topical treatment of Momordica peel, pulp, seed and whole fruit extract. Elevation in the hepatic levels of cytosolic glutathione S-transferase (GST) and microsomal cytochrome b, was also observed by the topical treatment of Momordica peel, seed and whole fruit extract. The results suggest the maximum chemopreventive potential is in the Momordica peel. Equivocal efficacy is in the Momordica seed and whole fruit extract. Biotransformation system enzymes may be the cause of this reduced papillomagenesis.

Postnatal efficacy of Momordica charantia peel, pulp, seed and whole fruit extract in the detoxication pathway of suckling neonates and lactating mice

The present study evaluates the postnatal efficacy of Momordica charantia peel, pulp, seed and whole fruit extract via assessing the modulation in the biotransformation system enzymes of suckling neonates and lactating mice. The peel, seed or whole fruit extract of Momordica (100 microl/animal/day) independently induced a significant increase in the hepatic levels of glutathione S-transferase (GST) and acid soluble sulfhydryl (-SH) after 14 or 21 days treatment in lactating dams (P < 0.01) and translactationally exposed neonates (P < 0.05). However, the elevation (P < 0.05) in hepatic cytochrome b5 (Cyt. b5) and cytochrome P-450 (Cyt. P-450) levels was observed only in the lactating dams treated with the respective extracts of peel, seed or whole fruit of Momordica. In lactating dams and suckling neonates the modulated levels of biotransformation system enzymes suggest the potential for the translactational passage of active principle(s) and/or metabolites of Momordica.

Anti-diabetic properties and phytochemistry of Momordica charantia L. (Cucurbitaceae)

Unripe fruit, seeds and aerial parts of Momordica charantia Linn. (Cucurbitaceae) have been used in various parts of the world to treat diabetes. Oral administration of the fruit juice or seed powder causes a reduction in fasting blood glucose and improves glucose tolerance in normal and diabetic animals and in humans. Animal and in vitro data support both insulin secretagogue and insulinomimetic activity of the fruit. However, enhanced insulin levels in vivo in response to its administration have not been observed. Although a wide range of compounds have been isolated from Momordica charantia, notably steroidal compounds and proteins, the orally active antidiabetic principle has not been adequately identified. A polypeptide, p-insulin, produces hypoglycaemic effects in humans and animals on subcutaneous injection, but oral activity is questionable. Other reported hypoglycaemic principles from Momordica charantia include the sterol glucoside mixture charantin (fruit) and the pyrimidine nucleoside vicine (seeds). However these are only effective at doses too high to account for all the activity of the plant extract. Principal toxicity of Momordica charantia in animals is to the liver and reproductive system. These effects have not been reported in humans despite widespread use of the fruit medicinally and as a vegetable.

Effect of trichosanthin and momorcharins on isolated rat hepatocytes

alpha-Momorcharin, beta-momorcharin and trichosanthin increased the secretion of glutamate-pyruvate transaminase, lactate dehydrogenase and isocitrate dehydrogenase by isolated rat hepatocytes into the culture medium. This hepatotoxic effect of the proteins appeared to be concentration-dependent. The plant proteins induced morphological changes in hepatocytes including increased formation of cytoplasmic blebs and a reduction of microvilli on plasma membrane.

Proteins with abortifacient, ribosome inactivating, immunomodulatory, antitumor and anti-AIDS activities from Cucurbitaceae plants

1. The biochemical characteristics and biological activities of eight Cucurbitaceae plant proteins designated trichosanthin (isolated from tubers of Trichosanthes kirilowii), beta-trichosanthin (isolated from tubers of Trichosanthes cucumeroides), alpha- and beta-momorcharins (isolated from seeds of Momordica charantia), momorchochin (isolated from tubers of Momordica cochinchinensis), luffaculin (isolated from seeds of Luffa acutangula) and luffin-a and luffin-b (isolated from seeds of Luffa cylindrica), were reviewed. 2. The isolation procedures for all eight proteins are based on aqueous extraction, acetone fractionation and ion exchange chromatography. Ammonium sulfate precipitation and gel filtration are steps which may be included to improve purification. 3. The proteins are basic in nature and possess a molecular weight of approx. 30,000. All except trichosanthin are glycoproteins. The content of Asx and Glx residues is high. The N-terminal amino acid residue is Asp. Their amino acid compositions and N-terminal amino acid sequences are similar. 4. Circular dichroism spectroscopic studies revealed that trichosanthin, alpha- and beta-momorcharins possess similar secondary but different tertiary structures. 5. Most of the proteins are immunologically distinct. 6. The proteins exhibit abortifacient, antitumor, ribosome inactivating and immunomodulatory activities. Trichosanthin manifests anti-human immunodeficiency virus activity.