Potentiation of antifungal activity of amphotericin B by essential oil from Cinnamomum cassia.

The antifungal activity of the essential oil from Cinnamomum cassia, alone or combined with amphotericin B, a drug widely used for most indications despite side-effects was investigated. The composition of the oil was analysed by GC/MS and characterized by its very high content of cinnamaldehyde (92.2%). The minimal inhibitory concentration (MIC 80%), used to evaluate the antifungal activity against Candida albicans, was determined by a macrobroth dilution method followed by a modelling of fungal growth. The essential oil of Cinnamomum cassia exhibited strong antifungal effect (MIC 80% = 0.169 microL/mL and K(aff) = 18,544 microL/mL). A decrease of the MIC 80% of amphotericin B was obtained when the culture medium contained essential oil concentrations ranging from 0.08 to 0.1 microL/mL. The strongest decrease (70%) was obtained when the medium contained 0.1 microL/mL of essential oil. This potentiation of amphotericin B obtained in vitro may show promise for the development of less toxic and more effective therapies especially for the treatment of HIV infection.

Lack of toxicity of hydroethanolic extract from Mitragyna inermis (Willd.) O. Kuntze by gavage in the rat.

In traditional medicine in Mali, extracts derived from Mitragyna inermis (Willd.) O. Kuntze (Family: Rubiaceae) are commonly used to treat malaria. The antimalarial activity and the lack of genotoxicity in vitro and in vivo have been demonstrated in previous studies. Acute and chronic evaluation of the toxicity of the hydroethanolic extract of Mitragyna inermis leaves was performed in this study, according to the recommendations (cahier de l'Agence no. 3) of the French Drug Office. Two dosages (300 mg/kg and 3 g/kg) were given in one single administration by gavage to male and female rats. No animal died and no behavioral signs of acute toxicity were observed. Chronic toxicity studies over 28 days showed no changes in body weight and no macroscopic abnormality in the 14 organs examined after the animals were sacrificed. With the 3 g/kg/d drug dosage (100-fold higher than those proposed in man), only slight histological abnormalities were observed. Statistically significant differences, compared to control animals, in the weight of some organs and the values of some haematological or biochemical parameters were observed. However, these values always remained in the range given by the breeder for naive animals of the same strain. These investigations thus seemed to indicate the safety of repeated oral administration (up to 3 g/kg/d) of the hydroethanolic extract of Mitragyna inermis leaves, which can therefore be continuously used with safety by the African population in traditional treatment of malaria.

Antifungal effect of various essential oils against Candida albicans. Potentiation of antifungal action of amphotericin B by essential oil from Thymus vulgaris.

The antifungal effect of the essential oil from Satureja montana L., Lavandula angustifolia Mill., Lavandula hybrida Reverchon, Syzygium aromaticum (L.) Merril and Perry, Origanum vulgare L., Rosmarinus officinalis L. and six chemotypes of Thymus vulgaris L. on Candida albicans growth were studied. The most efficiency was obtained with the essential oil from Thymus vulgaris thymol chemotype (MIC 80% = 0.016 microL/mL and Kaff = 296 microL/mL). The presence in the culture medium of essential oil from Thymus vulgaris thymol chemotype (0.01, 0.1, 0.2, 0.3 microg/mL) and amphotericin B involved a decrease of the MIC 80% of amphotericin B. In contrast, the combination of amphotericin B and low concentrations (0.00031-0.0025 microg/mL) of essential oil was antagonistic. The strongest decrease (48%) of the MIC 80% was obtained with medium containing 0.2 microL/mL of essential oil. These results signify that the essential oil of Thymus vulgaris thymol chemotype potentiates the antifungal action of amphotericin B suggesting a possible utilization of this essential oil in addition to antifungal drugs for the treatment of mycoses.

Differential activation by daphnetoxin and mezerein of PKC-isotypes alpha, beta I, delta and zeta.

Daphnetoxin, a mezerein derivative, was isolated from the stem bark of Daphne gnidium. Mezerein is a PKC activator that exhibits antileukemic properties. However, daphnetoxin and its analogue 12-hydroxydaphnetoxin were described as being devoid of this effect. In the present study daphnetoxin and mezerein were compared as PKC activators on classical (alpha and beta I), novel (delta) and atypical (zeta) isoforms, using an alternative in vivo yeast phenotypic assay. The aim was to clarify if daphnetoxin is a PKC activator and if the differences between the antiproliferative effect of mezerein and of its analogue daphnetoxin may be ascribed to differences on their potency or selectivity as PKC activators. Yeast samples expressing each of the mammalian PKC isoforms tested were incubated with daphnetoxin or mezerein. Growth inhibition caused by these drugs was assumed to be due to PKC activation since it did not occur when expression was not induced. Mezerein inhibited the growth of yeast expressing PKC alpha (IC(50) = 1190 +/- 237 nM; n = 20), PKC beta I (IC(50) = 908 +/- 46 nM; n = 20), and PKC delta (IC(50) = 141 +/- 25 nM; n = 20) but not of yeast expressing PKC zeta. Daphnetoxin also inhibited the growth of yeast expressing isoforms alpha, beta I and delta, being more potent than mezerein on PKC alpha (IC(50) = 536 +/- 183 nM; n = 20; P < 0.05), as potent as mezerein on PKC beta I (IC(50) = 902 +/- 129 nM; n = 20) and less potent than mezerein upon PKC delta (IC(50) = 3370 +/- 492 nM; n = 20; P < 0.05). These results show that daphnetoxin is a potent PKC activator but with a selectivity different from that of mezerein. It is suggested that the lack of antileukemic and antiproliferative effects of daphnetoxin may be due to its lower potency to activate PKC delta.

Chronic oat bran intake alters postprandial lipemia and lipoproteins in healthy adults.

This study evaluates the possible interaction between chronic oat bran intake and the postmeal metabolic response. Six normolipidemic men consumed three different diets for 14 d, at the end of which they consumed a test meal. The diets were C (control), basal low-fiber diet (15.6 g fiber/d) and a low-fiber (2.8 g fiber) test meal; OB (oat bran), basal low-fiber diet and a 40-g oat bran-enriched test meal (12.8 g fiber); and OB-A (oat bran-adaptation), 14-d oat bran (40 g/d) supplemented diet (23.8 g fiber/d) and an oat bran test meal (12.8 g fiber). The diets were fed in a random order. Fasting and postmeal blood samples were obtained for 7 h and lipoproteins were isolated. Adding oat bran to the test meals markedly reduced the postmeal insulin rise (P < 0.05). Compared with the low-fiber control diet, the effects elicited postprandially by adding oat bran to a single meal were enhanced after 14 d of oat bran feeding, ie, increased plasma triglycerides, phospholipids, and free cholesterol; decreased plasma esterified cholesterol; increased chylomicron and small-sized triglyceride-rich lipoprotein triglycerides; increased LDL and HDL free cholesterol; and decreased HDL esterified cholesterol. Thus, chronic oat bran feeding alters the postmeal response in human subjects.

Effects of pea and soybean fibre on postprandial lipaemia and lipoproteins in healthy adults.

To evaluate some possible mechanisms whereby total dietary fibre (TDF) may affect lipid metabolism in humans, six normolipidaemic males ingested on separate days a low-fibre test meal (2.8 g TDF) containing 70 g fat and 756 mg cholesterol, enriched with 10 g TDF in the form of either pea fibre or soybean fibre. Fasting and post-meal blood samples were obtained for 7 h and chylomicrons (CM) were isolated. Lipoproteins (VLDL+CM remnants, LDL, HDL) were isolated from the baseline samples and the samples of the 2-3 h triglyceride peaks. As compared to the postprandial response given by the control low-fibre test meal, adding fibre induced no change in serum glucose, insulin or Apo A1 and Apo B variations. The serum triglyceride response was not altered by adding fibres but the 2-3 h chylomicron triglyceride rise was increased (P < or = 0.05) by soybean fibre. VLDL+CM remnants, LDL and HDL triglyceride variations were unchanged with fibres. Cholesterolaemia decreased postprandially for 6 h, and was further lowered in the presence of pea fibre. This resulted from a marked decrease in serum esterified cholesterol. The chylomicron cholesterol and phospholipid rise was lowered in the presence of either fibre. The postprandial changes in the free cholesterol concentrations of the various lipoprotein classes were not altered by fibre whereas changes from baseline in esterified cholesterol concentrations were reduced by soybean fibre in LDL and amplified by soybean and pea fibres in HDL. The results obtained show that dietary fibre present in legumes may alter postprandial lipaemia and lipoproteins in humans to a variable extent. These effects could be related to some long-term metabolic effects.

Effects of salmon oil and corn oil on plasma lipid level and hepato-biliary cholesterol metabolism in rats.

The aim of this work was to compare the effects of n-3 and n-6 fatty acids on plasma lipid level and hepato-biliary cholesterol metabolism by studying rats fed semi-synthetic diets enriched with either 10% salmon oil, 10% corn oil, or a blend of 6% corn oil and 4% salmon oil. After 4 weeks of feeding, a drop in plasma lipid level was noted in the salmon oil group in comparison to the control group, whereas no change was observed in the corn oil group. An increase in production of cholesterol ester by the liver was recorded in the salmon oil group with a marked enhancement in acyl-CoA:cholesterol acyltransferase (ACAT: EC 2.3.1.26) activity and hepatic cholesterol concentration. Corn oil did not affect either ACAT activity or hepatic cholesterol storage. All bile parameters (flow, bile salts, phospholipids, cholesterol) increased in the salmon oil group, but the molar ratio of cholesterol participation in the bile secretion decreased. These changes in bile composition, as well as in hepatic metabolism of cholesterol, may help to explain the hypolipidemia following the intake of fish oil.

Effect of increasing amounts of dietary fish oil on brain and liver fatty composition.

Increasing dietary fish oil in rat had the following effect on brain lipids: Arachidonic acid regularly decreased; eicosapentanenoic acid, normally nearly undetectable, was present; 22:5(n - 3), dramatically increased but remained below 1% of total fatty acids; cervonic acid was increased by 30% at high fish oil concentration. Saturated and monounsaturated fatty acids were not affected regardless of chain-length. In contrast, in the liver, nearly all fatty acids (saturated, monounsaturated and polyunsaturated) were affected by high dietary content of fish oil, but liver function was normal: serum vitamin A and E, glutathione peroxidase, alkaline phosphatase, transaminases were not affected. Serum total cholesterol, unesterified cholesterol and phosphatidylcholine were slightly affected. In contrast, triacylglycerols were dramatically reduced in proportion to the fish oil content of the diet.

Compared effect of n-3 and n-6 dietary fatty acids on rat intestinal acyl-CoA:cholesterol acyltransferase activity.

Polyunsaturated fatty acids are known to lower plasma cholesterol concentrations. We studied their effect on intestinal acyl-CoA:cholesterol acyltransferase (ACAT) activity in rats fed either salmon oil or corn oil (17% fat) with or without 1% cholesterol. After an 8-week feeding period we confirmed the hypolipidemic effect of salmon oil and we established its ability to stimulate ACAT activity in rats fed low-cholesterol diets. The most striking effect of 1% dietary cholesterol on ACAT activity was obtained in the control group (34% enhancement), whereas cholesterol supplementation had no effect on ACAT activity in the salmon oil group. The results enable us to suggest that n-3 fatty acids have an effect per se on ACAT activity; the regulation of enzyme activity by dietary cholesterol probably involves independent processes.

Effects of fish oil, corn oil and lard diets on lipid peroxidation status and glutathione peroxidase activities in rat heart.

In this study, we investigated the effect of various types of fats on heart lipid peroxidation status and on blood lipid parameters. Rats were fed either a low-fat diet (2.2% lard plus 2.2% corn oil), a corn oil diet (17%), a salmon oil diet (12.5%) supplemented with 4.5% corn oil, or a lard diet (15%) supplemented with 2% corn oil. All diets were supplemented with 1% cholesterol. Rats were fed for eight weeks. When compared with the low-fat diet, the salmon oil-diet intake resulted in a lower blood cholesterol, triglyceride and phospholipid concentrations (-50, -56 and -30%, respectively). Corn oil only tended to lower blood lipids; this decrease was significant for triglycerides only (-40%). The hypocholesterolemic effect of salmon oil diet is even more pronounced, if blood cholesterol values are compared with those of rats fed the lard diet. Heart lipid composition was not affected by dietary manipulations. Fatty acid composition of cardiac phosphatidylcholines and phosphatidylethanolamines, however, were altered by high-fat diets. In phosphatidylcholine, salmon oil induced a twelvefold decrease in the n-6/n-3 ratio and a 26% increase in the unsaturation index. For phosphatidylethanolamine, the n-6/n-3 ratio decreased 7.7-fold and the unsaturation index increased by 13%. A 50% decrease of the n-6/n-3 ratio was observed in animals fed the lard diet. Ultramicroscopic examination of ventricles revealed that those of the salmon oil group significantly accumulated lipofuscin-like or ceroid material, whereas this accumulation was barely detectable in hearts of the other groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary salmon oil feeding on rat heart lipid status.

For 2 mo rats were fed a salmon oil diet (12.5%, wt/wt) supplemented with 4.5% (wt/wt) corn oil, a corn oil diet (17%, wt/wt) or a low fat diet (4.4%, wt/wt). Cardiac lipids were analyzed and fatty acid composition of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) was determined. Ventricular biopsies were taken for ultramicroscopic examination. Serum cholesterol, triglyceride, phospholipid and vitamin E concentrations were significantly lower in rats fed salmon oil than in those fed the other two diets, whereas serum transaminases and vitamin A were not significantly affected. Cardiac protein, phospholipid, triglyceride and cholesterol concentrations were unaffected by diet. Cardiac phospholipid composition remained unchanged and no significant changes in lyso-PC or lyso-PE levels were observed. However, the salmon oil diet produced a markedly lower n-6/n-3 ratio in both PE and PC than in the other two diets. This was the result of replacement of n-6 polyunsaturated fatty acids (PUFA), primarily 20:4n-6 with n-3 PUFA, primarily 22:6n-3. The unsaturation index of PC and PE was higher with the salmon oil diet than with the other two diets. Ventricular biopsies of rats fed salmon oil showed mild lipid accumulation associated with some lipofuscin-like material. It is suggested that, in rat heart, fish oil led to a moderate accumulation of lipids, the composition of which may include long-chain monounsaturated fatty acids and a degradative form of peroxidized lipids.

Effect of pectin, wheat bran and cellulose on serum lipids and lipoproteins in rats fed on a low- or high-fat diet.

1. Four groups of adult male Sprague-Dawley rats were fed for 6 weeks on a diet with a low-fat content (50 g/kg) and another four groups were given a diet rich in fat (250 g/kg) and cholesterol (12 g/kg). In both cases, the basal diets were either fibre-depleted or supplemented with cellulose (60 g/kg), wheat bran (100 g/kg) or low-methoxyl pectin (100 g/kg). 2. Low-methoxyl pectin displayed the most hypocholesterolaemic effect and decreased the cholesterol content of the very-low-density lipoproteins (VLDL) and low-density lipoproteins (LDL), when the low-fat diet was given. When rats were fed on the high-fat diet, pectin no longer had a hypocholesterolaemic effect but still decreased the VLDL-cholesterol content. Pectin lowered serum triglyceride and VLDL-triglyceride levels only when the low-fat diet was given. 3. Wheat bran exerted no hypocholesterolaemic effect in rats fed on the low- and high-fat diets, but decreased the cholesterol content of VLDL and lowered serum triglycerides and VLDL-triglycerides when the high-fat diet was given. 4. Purified cellulose had no significant effect on plasma lipids. 5. As shown by multivariance analysis, low-methoxyl pectin and wheat bran both beneficially modified the serum triglyceride and cholesterol variables except VLDL-triglycerides. However, the magnitude of the effect of each individual type of fibre was dependent on the fat and cholesterol content of the diet, suggesting the existence of different mechanisms of action.

Effect of dietary lipids on the lipid composition and phospholipid deacylating enzyme activities of rat heart.

Rats were fed lard-enriched (17%) or corn oil-enriched (17%) diets and were compared with rats fed a low fat (4.5%) diet. Cardiac protein, DNA, phospholipid (PL) and fatty acid (FA) compositions were analyzed. Neutral phospholipase A, lysophospholipase and creatine kinase activities in the membrane and cytosolic compartments were also investigated. No significant modification of cardiac protein, DNA nor PL was observed among the three groups. Some alterations appeared in the FA composition. A lard-enriched diet induced a significant increase of 22:5n-3 and 22:6n-3 in heart phosphatidylcholine (PC) and phosphatidylethanolamine (PE), whereas a linoleic acid-rich diet induced a specific increase of 22:4n-6 and 22:5n-6 in these two major PL. Compared to rats fed the low fat diet, membrane-associated phospholipase A activity, measured by endogenous hydrolysis of membrane PC and PE, showed a significant increase (+45%) for both PL in rats fed corn oil. However, the activity of membrane-associated phospholipases, measured with exogenous [1-14C]dioleoyl PC, was not different among the three groups of rats. Cytoplasmic activity was decreased in rats fed corn oil, and lysophospholipase and creatine phosphate kinase activities were not significantly affected by diet. FA modification of the long chain n-6 FA induced by corn oil may be responsible for the observed increase in phospholipase activity. Physiological implications are suggested in terms of membrane degradation and prostaglandin production.

Effect of wheat bran, pectin and cellulose on the secretion of bile lipids in rats.

We assayed the lipid content of bile from rats that had been fed either a standard diet (5% fat) or a high fat diet (25% fat, 1.2% cholesterol) in the presence or in the absence of various dietary fibers (namely, wheat bran, pectin and cellulose). The cholesterol concentration in bile from rats fed the high fat diet plus wheat bran or pectin was lower than that of the rats fed the high fat, high cholesterol diet without fiber. Bile phospholipids did not vary significantly from one group to another. In comparison to the standard diet, the high fat, high cholesterol diet led to a greater ratio of primary to secondary bile salts and a higher level of glycoconjugates. The observed differences may be explained by a variation in the metabolism of bile salts brought about by the difference in diet.