Jean-Claude Baccou

High levels of antioxidant enzymes correlate with delayed senescence in nonnetted muskmelon fruits

Abstract. We investigated the senescence process in two nonnetted muskmelon (Cucumis melo L.)␣varieties␣Clipper and Jerac differing in their storage life. Our results indicate that senescence in Jerac (the short-storage-life variety, less than 7 d) is the result of lipid peroxidation by free radicals, membrane phospholipid breakdown, and a drop in the level of antioxidants, resulting in increased membrane leakiness. By contrast, evidence is presented that the high levels of two enzymes implicated in antioxidative defence, superoxide dismutase (SOD) and catalase, combined with changes in the three different classes of SOD during the storage stage, are involved in delaying the senescence process in Clipper and this could explain, at least, to some extent, the long storage life of Clipper (longer than 14 d).

Implication of steroid saponins and sapogenins in the hypocholesterolemic effect of fenugreek

The transformation of fenugreek subfractions, rich in steroid saponins, was studied upon their passage through the digestive tract to determine the contribution of saponins and/or diosgenin and other steroid sapogenins to the hypocholesterolemic effect of fenugreek seeds. Feces of alloxan diabetic dogs fed fenugreek subfractions were analyzed, and diosgenin, smilagenin and gitogenin were identified and measured using capillary gas chromatography/mass spectrometry. Our results show that saponins are, in part (about 57%), hydrolyzed into sapogenins in the digestive tract. It appears that saponins may be implicated, alone or together with diosgenin, in the observed hypocholesterolemic effect of fenugreek seeds in diabetic dogs.

Antidiabetic Effects of Subtractions from Fenugreek Seeds in Diabetic Dogs

Abstract We have previously shown that the antidiabetic property of fenugreek seeds (Trigonella foenum graecum L.) is associated with the defatted seed material which is rich in fibers, saponins, and proteins. In the present work this defatted preparation was divided into two subfractions: subfraction “a” which contains the testa and endosperm and is rich in fibers (79.6%); and subfraction “b” which contains the cotyledons and axes and is rich in saponins (7.2%) and proteins (52.8%). We investigated the effects of each subfraction on hyperglycemia and the levels of pancreatic hormones when chronically administered to alloxan-diabetic dogs. Each subfraction was studied separately and was given to the dogs per os (mixed with the two daily meals), in addition to the insulin treatment (which was kept the same throughout the experiment) for a period of 21 days. The addition of subfraction “a” to insulin treatment resulted in a clear decrease of hyperglycemia and glycosuria accompanied by a reduction of the high plasma glucagon and somatostatin levels in diabetic dogs. The treatment also decreased the hyperglycemic response to the oral glucose tolerance test. In contrast the chronic administration of subfraction “b” had no effect on hyperglycemia or on the levels of pancreatic hormones in diabetic dogs. Our results show that the antidiabetic properties of fenugreek seeds are contained in the testa and endosperm. Although this subfraction is rich in fibers (high viscosity; 115 cP), it is not possible to exclude the existence of one or more unknown active pharmacological compounds in this subfraction of the seed.

Hypocholesterolaemic effect of Fenugreek seeds in dogs

Fractions of fenugreek seed were added to the diet of normal or diabetic hypercholesterolaemic dogs for 8 days. The effects on levels of blood glucose, plasma glucagon and plasma cholesterol were investigated. The lipid extract had no effect. The defatted fraction which is rich in fibres (53.9%) and contains 4.8% of steroid saponins significantly lowered basal blood glucose (P less than 0.02), plasma glucagon (P less than 0.01) and plasma cholesterol (P less than 0.02) levels in normal dogs. The addition of this fraction to the food of diabetic hypercholesterolaemic dogs caused a decrease of cholesterolaemia (P less than 0.02) and reduced hyperglycaemia. In conclusion, the defatted portion of fenugreek seed induces a hypocholesterolaemic effect.

Effects of Fenugreek Seeds on Endocrine Pancreatic Secretions in Dogs

The components of fenugreek seeds were separated and analyzed to determine which fraction of the seed had hypoglycemic activity. These fractions were administered orally to normal or diabetic dogs for 8 days. The effect on blood glucose and pancreatic hormones was studied in normal dogs. The lipid extract had no effect; the defatted fraction (50.2% fibers: gum 17.7%, hemicellulose 22%, cellulose 8.3%, lignin 2.2%) lowered basal blood glucose level, plasma glucagon and somatostatin levels and reduced the orally induced hyperglycemia. The addition of this fraction to the insulin treatment resulted in a decrease of hyperglycemia and glycosuria in diabetic dogs. The results indicate that the defatted part is responsible for the antidiabetic action. However, the present study does not permit one to know whether the effects are caused by an unknown pharmacological compound or by the gastrointestinal action of fibers.

16-Hydroxylation of Iridal (Triterpenoid from Iris Species) Mediated by Cytochrome P-450

Abstract Incubation of a monocyclic iridal (a triterpenoid from Iris species) with rat liver microsomes in the presence of NADPH led to the degradation of this substrate and to the generation of 16-hydroxy-iridal (isoiridogermanal). This reaction which is inhibited by carbon monoxide seems to be mediated by cytochrome P-450. This observation strongly suggests that this monoxygenase, which is also present in intracellular Iris membranes, could be involved in plant iridal biosynthesis pathways.

Magnesium bioavailability from magnesium-fortified spirulina in cultured human intestinal Caco-2 cells

Abstract The role of magnesium (Mg) for health promotion and disease prevention is generally accepted world wide. The aim of this study was to examine magnesium availability from Mg-fortified spirulina. We have used an in vitro digestion/Caco-2 cell culture system to measure magnesium spirulina availability. Magnesium concentration measurements were performed by atomic absorption spectrometry in digests containing the same amount of magnesium and at the basal side of Caco-2 cells exposed to these digests. Comparison was made with crude spirulina, Banania, Kellogs all bran and Magnogene (magnesium chloride) as a reference. Our results show that Mg-fortification of spirulina does not improve Mg availability and that crude spirulina represents an adequate source of Mg as efficient as All bran and Banania.

Glutathione-related enzymic activities in rats receiving high cholesterol or standard diets supplemented with two forms of selenium

Selenium deficiency was produced in rats fed a high cholesterol diet for 57 days (Group 1). It was characterized by an increase in malondialdehyde (MDA) an end product of lipid peroxidation and by the dramatic collapse of selenium-dependent glutathione peroxidase activity (GSHPx) in plasma, erythrocytes and in homogenate supernatant fraction of liver, kidney and heart compared with rats fed a standard diet containing sodium selenite (Group 3). A compensatory rise in the activity of liver glutathione S-transferase (GST) activity and also in glutathione reductase (GSSGR) activity was accompanied by an increase in NADPH-generating enzymes glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. Adequate dietary selenium supplementation by Se-rich Spirulina corrected all the selenium deficiency effects (Group 2), then, GSHPx and NADPH-consuming enzymes activities were of the same magnitude as those exhibited by rats fed a standard diet containing adequate selenium in the form of sodium selenite. Based on this study, it is concluded that Se-enriched Spirulina behave as an excellent selenium carrier.

Selective laser photolysis of organic molecules in complex matrices

Abstract Laser photolysis was used to eliminate selectivity non- desirable (toxic, carcinogenic, photosensitive) molecules in complex solutions for applications in various fields, such as the farm-produce industry, cosmetics, perfumes or biology. The principle of this experiment is based on the tuning of the laser wavelength to an absorption band of the non-desirable molecules which are excited and then dissociated. Destruction of the molecules is monitored by spectral changes, and photoproducts can be characterized by gas chromatography and mass spectrometry. The advantages of this technique are its rapidity, in situ reaction and quantitative elimination. Examples including the destruction of thujone in extract of Salvia, bergapten in essential oil of Bergamot, safrole in essential oil of Sassafras and phycocyanin and phycoerythrin in Porphyridium cruentum are presented and discussed.

Composition of the Volatile Fraction of the Concrete of Jasminum azoricum L.

ABSTRACT Analytical investigation of a concrete of Jasminum azoricum L. by GC and GC/MS allowed us to identify about 40 constituents. The major components were (E,E)-farnesol (30.1%) and geranyl linalool (21.7%). The composition of the concrete is compared with a laboratory prepared concrete of Jasminum sambac (L.) Soland.