No abstract

The effects of spirulina and its chromophore phycocyanin, both without bound Se or selenium-enriched, were studied on plasma cholesterol, early atherosclerosis, cardiac production of superoxide anions, and NAD(P)H oxidase expression in hamsters. Forty hamsters were divided into 5 groups of 8 and fed an atherogenic diet for 12 weeks. They received by gavage either 7.14 mL/(kg day) phycocyanin (PC), Se-rich phycocyanin (SePC), spirulina (SP) or Se-rich spirulina (SeSP) in water, or water as control. SeSP and SePC supplied 0.4 microg of Se per 100 g body weight. Plasma cholesterol and non-HDL cholesterol concentrations were lower in group consuming SePC. HDL-cholesterol was never affected. SePC significantly increased plasma antioxidant capacity by 42% compared with controls. A sparing effect in liver glutathione peroxidase (87% on average) and superoxide dismutase (56% on average) activity was observed for all the groups compared to controls. Aortic fatty streak area was significantly reduced in the experimental groups, especially by PC (82%) and SePC (85%). Cardiac production of superoxide anion significantly decreased by approximately 46-76% in the four experimental groups and especially in SePC group (76%). The expression of p22phox subunit of NAD(P)H oxidase decreased by 34% after consumption of SePC. The results indicate that chronic consumption of Se-rich spirulina phycocyanin powerfully prevents the development of atherosclerosis. The underlying mechanism is related mainly to inhibiting pro-oxidant factors and at a lesser extent improving the serum lipid profile.

We investigated the senescence process in two nonnetted muskmelon (Cucumis melo L.) varieties Clipper and Jerac diering 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 dierent 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).Isolation of microsomal membranes. Muskmelon pulp was homogenized in 50 mM Mes-Tris (pH 7.8) containing 0.25 M saccharose, 3 mM EDTA, 0.2 mM phenylmethylsulfonyl¯uoride (PMSF) and Planta (1998) 204: 377±382

A specific method for the spectrophotometric determination of total steroidal sapogenin, based on colour reactions with anisaldehyde, sulphuric acid and ethyl acetate and applicable to microgram amounts, is described.I t has been shown that this determination can be carried out directly on a saponin solution and that there is virtually no interference from sugars, sterols, fatty acids and vegetable oil. The sapogenins have the same colorimetric properties whether they are in the free state, bound with sugars, esterified with acetic acid or mono-or polyhydroxylated. The method described is accurate (relative error 1.4%), rapid, easily automated and gives a chromophore with the same absorption spectrum with only one peak at 430 nm for all of the sapogenins tested : diosgenin, tigogenin, hecogenin, smilagenin, yonogenin, tokorogenin, etc. The molar absorption coefficient is approximately 49 000.Steroidal sapogenins are raw materials that are widely used in the partial synthesis of steroidal drugs, and their economic importance is one of the reasons why much research has been carried out, especially on analytical methods. When we started our research on the possibility of using some plants growing in France to provide steroidal drugs, the previously employed methods, vix. , gra~imetry,l-~ infrared s p e c t r o~c o p y ,~~~ gas -liquid chromatography,6-11 c~lorimetry,l*~~ densitometric thin-layer c h r~m a t o g r a p h y ,~~~~~ thin-layer chromatography followed by s p e c t r o p h~t o m e t r y~~~~~ and column chromatography followed by infrared spectrophotometry,28 were found to be unsuitable.It appeared that spectrophotometry was the technique which would be the most useful for our purpose. However, most of the reagents used, for example, antimony(II1) chloride in acidic solution or sulphuric acid and formaldehyde, were applicable only to szpogenins that have the structure in the B-ring and a hydroxyl group in the 3-position (Table I). These characteristics also occur in phytosterols, and many sapogenins, such as tigogenin, gitogenin, hecogenin, smilagenin, yonogenin and tokorogenin, therefore cannot be determined. On the other hand, other methods determine only saturated sapogenins (reagents based on orthophosphoric acid and anisaldehyde) so that an additional method is needed for the determination of total sapogenin. Even the technique recently developed by Hiai et aZ.,23 in which vanillin and sulphuric acid were used, is not specific for sapogenins because sterols, bile acids and triterpenoid sapogenins, which have a hydroxyl group in the 3-position, give chromophores. It is known that sapogenins treated with concentrated sulphuric acid produce characteristic chromophores, all of which, however, do not absorb at the same wavelength. In addition, the problem of interferences is particularly important in this instance. This deficiency led us to devise a method that is both more specific for sapogenins and allowed us to determine all sapogenins, whatever their structural particularities. Such properties are very...