H2S preconditioning of human adipose tissue-derived stem cells increases their efficacy in an in vitro model of cell therapy for simulated ischemia.

AIMS: A major limitation of cell-based therapies for ischemia-reperfusion injury is the excessive loss of administered cells. We investigated whether H2S can improve the survival and efficacy of therapeutic cells in an in vitro model of cell-based therapy for simulated ischemia. MAIN METHODS: H9c2 rat cardiomyoblasts were exposed to oxygen-glucose deprivation and NaHS (3-30 µM) pretreated human adipose tissue derived stem cells (hASCs) were added after reoxygenization. Viability of both cell lines was assessed with flow cytometry after 24h. The effects of H2S on antioxidant defense, proliferation, AKT and ERK1/2 phosphorylation and mitochondrial activity were analyzed in hASCs. Proliferation was evaluated using propargylglycine, an inhibitor of endogenous H2S synthesis. KEY FINDINGS: NaHS pretreatment decreased the ratio of necrotic therapeutic cells by 41.8% in case of 3 µM NaHS and by 34.3% with 30 µM NaHS. The ratio of necrotic postischemic cardiomyocytes decreased by 35%, but only with the use of 3 µM NaHS. Antioxidant defense mechanisms and ERK-phosphorylation were enhanced after 3 µM NaHS treatment while AKT-phosphorylation was suppressed. NaHS dose-dependently increased the proliferation of hASCs while pretreatment with propargylglycine decreased it. SIGNIFICANCE: NaHS pretreatment can increase the survival of therapeutically used human adipose tissue-derived stem cells via increased antioxidant defense and improves the postischemic cardiac derived cells' survival as well. Proliferation of human adipose tissue-derived stem cells is enhanced by H2S. The underlying mechanisms involve enhanced ERK-phosphorylation and decreased AKT-phosphorylation. Pretreatment with NaHS may represent a simple pharmacological step that may enhance the efficacy of cell-based therapies.

The cardioprotective potential of hydrogen sulfide in myocardial ischemia/reperfusion injury (review).

Myocardial infarction is responsible for the majority of cardiovascular mortality and the pathogenesis of myocardial damage during and after the infarction involves reactive oxygen species. Serious efforts are under way to modulate the developing ischemia/reperfusion injury and recently the use of hydrogen sulfide (H2S) emerged as a new possibility. H2S has been best known for decades as a pungent toxic gas in contaminated environmental atmosphere, but it has now been recognized as a novel gasotransmitter in the central nervous and cardiovascular systems, similarly to nitric oxide (NO) and carbon monoxide (CO). This finding prompted the investigation of the potential of H2S as a cardioprotective agent and various in vitro and in vivo results demonstrate that H2S may be of value in cytoprotection during the evolution of myocardial infarction. Although several questions remain to be elucidated about the properties of this new gasotransmitter, increased H2S levels may have therapeutic potential in clinical settings in which ischemia/reperfusion injury is encountered. This review article overviews the current understanding of the effects of this exciting molecule in the setting of myocardial ischemia/reperfusion.

A simple method of surface functionalisation for immuno-specific immobilisation of proteins.

We present a new and advanced methodology, developed for surface functionalisation of gold and to study immobilisation of an immuno-specific system of proteins. A combination of electrochemical quartz crystal microbalance and Raman spectroscopy techniques allowed a complete understanding of the system starting from surface functionalisation and progressing to the functional structure analysis of immobilised proteins. A simple electrochemical procedure was formulated to prepare sulphonyl chloride terminated gold surfaces that form a strong sulphonamide bond with the receptor protein staphylococcal protein A (SpA). On the SpA grafted surfaces, the immobilisation of a human IgG and consecutive binding of an immuno-specific anti-human IgG was observed. The surface functional groups form a strong interaction with SpA without disturbing its functional properties. The native functional structure of SpA and also the IgGs was found to be retained in their immobilised state.

In vitro inhibition of lipopolysaccharide and mycobacterium bovis bacillus Calmette Guérin-induced inflammatory cytokines and in vivo protection from D-galactosamine/LPS -mediated liver injury by the medicinal plant Sclerocarya birrea.

Sclerocarya birrea is a medicinal plant used for the treatment of inflammatory- and bacterial-related diseases. The present study investigated in vitro and in vivo the effects of the stem bark methanol extract of S. birrea. Nitrite, TNF, IL-1beta, IL-6 and IL-12p40 production by bone marrow-derived macrophages (BMDM) pre-incubated with or without S. birrea, and stimulated with Lipopolysaccharide (LPS) or infected with live Mycobacterium bovis Bacillus Calmette Guérin (BCG) was evaluated. S. birrea extract inhibited, in a concentration-dependent manner, nitrite, TNF, IL-1beta, IL-6 and IL-12p40 production by BMDM stimulated with LPS or infected with live BCG. The iNOS expression was reduced by S. birrea after stimulation of BMDM with LPS. In addition, S. birrea inhibited the nuclear factor kB (NF-kB) activation by both LPS and BCG. The effects of the plant extract were also evaluated in an in vivo model of liver injury induced by D-galactosamine/LPS (D-GalN/LPS) administration in mice. S. birrea limited D-GalN/LPS-liver injury as assessed by a reduction in transaminases and TNF, IL-1beta, IL-6 serum levels, and translocation of NF-kB to the nucleus. Taken together, our data indicate that stem bark methanol extract of S. birrea possesses anti-inflammatory properties by inhibiting NF-kB activation and cytokine release induced by inflammatory or infectious stimuli.

Vasorelaxant effects of Brillantaisia nitens Lindau (Acanthaceae) extracts on isolated rat vascular smooth muscle.

Brillantaisia nitens Lindau (Acanthaceae) is traditionally used in Cameroon for the treatment of many diseases including cardiovascular disorders. We have studied its vasorelaxant effects in rat vascular smooth muscle. In this study, aqueous, methylene chloride, methanol, and methylene chloride/methanol leaves extracts of Brillantaisia nitens were tested for their relaxing ability in vitro. Strips of rat aorta, with or without intact endothelium, were mounted in tissue baths, contracted with KCl (60mM) or norepinephrine (10(-4)M), and then exposed to the plant extracts. These extracts exhibited concentration-dependent vasorelaxations of norepinephrine-induced contractions of intact aortic strips. The EC(50) were 0.42+/-0.01mg/ml (aqueous extract), 0.63+/-0.02mg/ml (methylene chloride extract), 0.73+/-0.02mg/ml (methanol extract) and 0.36+/-0.02mg/ml (methylene chloride/methanol extract). The methylene chloride/methanol (CH(2)Cl(2)/CH(3)OH) extract was the most potent relaxing extract. It caused a concentration-dependent and endothelium-independent relaxation of the rat aortic strips contracted by KCl or norepinephrine. On the NE-induced contraction, its maximal relaxant activity (109%) due to the dose of 1.5mg/ml, was not significantly modified by the pretreatment of aortic strips with indomethacin (89%, P>0.05) or with l-NAME (103%, P>0.05). This suggests that the vasorelaxation elicited by CH(2)Cl(2)/CH(3)OH extract was not mediated via endothelium-derived prostacyclin or nitric oxide. In contrast, this relaxation was markedly reduced by tetraethylammonium, a blocker of non-selective K(+) channels and glibenclamide, a blocker of ATP-sensitive K(+) channels. The CH(2)Cl(2)/CH(3)OH extract significantly inhibited Ca(2+)-induced concentration-contraction and the Ca(2+) influx in aortic strips incubated with 60mM KCl. These results indicate that the vasorelaxant effect of the CH(2)Cl(2)/CH(3)OH extract of Brillantaisia nitens is due to an inhibition of Ca(2+) influx, possibly via the activation of ATP-sensitive K(+) channels.

Methanol extract of Terminalia superba induces endothelium-independent relaxation of rat thoracic aorta.

Terminalia superba is highly regarded in some parts of Cameroon in traditional medical practice. We have studied the vasorelaxant effects of the stem bark methanol extract of T. superba on rat vascular smooth muscle. The results demonstrated that T. superba extract provoked a time-dependent relaxation of aortic rings precontracted with norepinephrine (10(-6) M). The vasorelaxant effect of the plant extract was not affected by endothelium removal or by pretreatment with indomethacin or N(W)-nitro-Larginine methyl ester (L-NAME). T. superba extract did not significantly, affect the contraction induced by 30 mM or 60 mM KCl as compared to those induced by NE. Relaxations elicited by T. superba extract were markedly reduced by glibenclamide, a putative blocker for K(ATP) channels and by tetraethylammonium, the non-specific K+ channel inhibitor. T. superba caused a time- and concentration-dependent relaxation of the rat aortic rings that were inhibited by charybdotoxin and iberotoxin but not by apamin. These finding indicate that T. superba extract at least partially relaxes the rat aorta by activating K+ channels, mainly KATP channels and large-conductance Ca2+ -activated K+ channels in rat aorta.

Glucose lowering efficacy of the aqueous stem bark extract of Trema orientalis (Linn) Blume in normal and streptozotocin diabetic rats.

The glucose-lowering efficacy of the aqueous stem bark extract of Trema orientalis (Ulmaceae) was evaluated both in normal and streptozotocin-induced diabetic rats. In normoglycemic rats, the single oral administration of the aqueous extract of T. orientalis failed to reduce blood glucose levels while in STZ-diabetic rats, the plant extract (38-300 mg/kg) exhibited significant hypoglycaemic activity with a maximum effect of 29.67%, 5 hours after administration of the 75 mg/kg dose when compared with the diabetic untreated group. Glibenclamide was not able to lower blood glucose in STZ-diabetic rats, while it significantly lowered the blood sugar in normoglycemic rats. The hypoglycaemic property of T. orientalis was also assessed by an oral glucose tolerance test (OGTT) in STZ-diabetic rats. The aqueous extract of T. orientalis and the reference drug, glibenclamide, (10 mg/kg) produced significant blood glucose lowering effects in the diabetic rats when compared to the diabetic controls. One week after repeated administration of T. orientalis extract, blood glucose levels were significantly decreased (p < 0.05) and still remained low after 2 weeks (p < 0.01). The results indicated that T. orientalis stem bark extract significantly reduces blood glucose in STZ-induced diabetic rats by a mechanism different from that of sulfonylurea agents. The present investigation provides pharmacological evidence that the use of this plant extract in traditional medicine for cardiovascular disease can be of benefit particulary in diabetic patients.

Antidiabetic and hypolipidaemic effects of a methanol/methylene-chloride extract of Laportea ovalifolia (Urticaceae), measured in rats with alloxan-induced diabetes.

A decoction of the leaves of Laportea ovalifolia is widely used in Cameroon for the treatment of several illnesses, including diabetes mellitus. The antidiabetic and hypolipidaemic effects of a methanol/methylene-chloride extract of the aerial parts of L. ovalifolia have now been investigated, in normal rats and rats with diabetes induced by the intraperitoneal injection of alloxan (at 150 mg/kg bodyweight). In the diabetic rats, 2 weeks of daily, intragastric treatment with the L. ovalifolia extract not only produced a significant reduction in the fasting serum glucose concentrations but also lowered the serum concentrations of total cholesterol, triglycerides, and low-density-lipoprotein cholesterol, lowered the ratio of total cholesterol to high-density-lipoprotein (HDL) cholesterol, and increased the serum concentration of HDL cholesterol. At least in rats with alloxan-induced diabetes, the methanol/methylene-chloride extract of L. ovalifolia therefore appears to possess antidiabetic and hypolipidaemic properties.

Possible mechanisms of action of the neutral extract from Bidens pilosa L. leaves on the cardiovascular system of anaesthetized rats.

The aim of this study was to investigate the hypotensive and cardiac effects of the neutral extract from Bidens pilosa leaves. Intravenous administration of the extract resulted in a biphasic dose-related hypotensive activity. In normotensive rats (NTR), B. pilosa decreased systolic blood pressure by 18.26%, 42.5% and 30% at doses of 10, 20 and 30 mg/kg, respectively. In spontaneously hypertensive rats (SHR), the decrease in systolic blood pressure was 25.77%, 38.96% and 28.64% at the above doses, respectively. These doses induced hypotension by 27%, 34.13% and 18.73% respectively in salt-loaded hypertensive rats. In NTR, B. pilosa reduced heart rate by 23.68% and 61.18% at doses of 20 and 30 mg/kg, respectively. The force of contraction of the heart was only affected at 30 mg/kg. The initial phase of hypotensive response was partially inhibited by atropine while propranolol increased this effect. These results suggest that B. pilosa exhibited its fi rst hypotensive effects by acting on the cardiac pump efficiency and secondly through vasodilation.

In vitro vascular smooth muscle contractile activity of Aspilia africana extract on rat aortic preparations.

Aspilia africana is widely used in ethnomedical practice in Africa for its ability to stop bleeding, even from a severed artery, as well as promote rapid healing of wounds and sores, and for the management of problems related to cardiovascular diseases. In the present paper, the methylene chloride/methanol extract of A. africana leaves was tested for its contractile activity in vitro. Rings of rat aorta, with or without an intact endothelium, were mounted in tissue baths, contracted with norepinephrine, and then exposed to the plant extract. The effect of the extract was also assessed on the baseline tension of aortic rings in normal and calcium-free PSS. At the lower doses, A. africana slowly re-inforced contractions induced by norepinephrine and relaxed precontracted tension at the highest concentration. The relaxant activity of the extract was endothelium-independent and was not modified by pre-treatment with Nw-nitro-L-arginine methyl ester or indomethacin, suggesting that its effect was not mediated by either nitric oxide or prostacyclin. A. africana extract induced slow and progressive increase in the basal vascular tone which was partially endothelium-dependent. In calcium-free PSS, a high proportion of the contractile activity was inhibited (77%), suggesting that A. africana contractile activity in vascular tissue depends, in part, on extracellular calcium.

Diterpenoid and limonoids from the stem of Pterorhachis zenkeri.

One new diterpenoid, methyl 3alpha-hydroxy-7-oxo-dehydroabietate (1), two new limonoids, 3alpha-deacetyl-amoorastatin (2) and 9beta-amoorastatin (3), and the known limonoid amoorastatin (4) were isolated from the stem of Pterorhachis zenkeri.

Antihypertensive effects of Dorstenia psilurus extract in fructose-fed hyperinsulinemic, hypertensive rats.

We examined the effect of methanol/methylene chloride extract of Dorstenia psilurus given by gastric intubation on systolic blood pressure, plasma glucose, insulin, cholesterol, triglycerides and creatinine in rats with fructose-induced hypertension. Male Wistar rats in groups of 6 animals each were fed fructose-rich diets or standard chow for 3 weeks and treated with 100 mg/kg/day or 200 mg/kg/day of plant extract or vehicle for 3 subsequent weeks. Systolic blood pressure was measured every three days using the indirect tail cuff method. Systolic blood pressure was higher in fructose-fed rats (142+/-2 mm Hg, p < 0.01) compared with the controls (112+/-2 mm Hg), and was lower in Dorstenia psilurus-treated groups (127+/-2 and 119+/-1 mm Hg for the dose of 100 and 200 mg/kg, respectively) compared with the fructose-fed rats. Plasma insulin, cholesterol and triglycerides were higher on the fructose-rich diet compared with the controls. Plasma insulin and cholesterol were lower in the Dorstenia psilurus-treated groups. These results suggest that, Dorstenia psilurus treatment could prevent and reverse high blood pressure induced by a diet rich in fructose probably by improvement of plasma insulin levels. The plant extract might prove useful in the treatment and/or prevention of hypertension.

Effects of methanol, cyclohexane and methylene chloride extracts of Bidens pilosa on various gastric ulcer models in rats.

Ethnobotanical studies have revealed that Bidens pilosa is used in the traditional management of wounds and chronic gastro-duodenal ulcers. This led us to screen the methanol, cyclohexane and methylene chloride extracts of the plant for anti-ulcerogenic activity using the HCl/ethanol gastric necrotizing solution. The methylene chloride extract, which showed the highest activity (100% inhibition) at a dose of 750 mg/kg compared with the methanol and cyclohexane extracts (41 and 46% inhibition, respectively), was further tested using the indomethacin-HCl/ethanol-, absolute ethanol- and pylorus ligation-induced ulcer methods. Pre-treatment with indomethacin significantly reduced the protective effect of the extract against HCl/ethanol solution to 31%. The extract had very little gastric mucosal protection against absolute ethanol (9.8% inhibition at 750 mg/kg) compared with the controls and neither reduced gastric acid secretion in vivo nor the acidity of gastric juice following in vitro incubation.

Prenylated flavonoids from the aerial parts of Dorstenia mannii.

Four new prenylated flavanones, dorsmanins 1, J and epi-dorsmanins F, G, identified, respectively, as 6,7-(2,2-dimethylpyrano)-8-prenyl-5,3',4'-trihydroxyflavanone, 6,7-(2,2-dimethyldihydropyrano)-8-prenyl-5,3',4'-trihydroxflavanone, and 2''-epimers of dorsmanins F and G were isolated from the aerial parts of Dorstenia mannii together with 13 known flavonoids: 4-hydroxylonchocarpin, 4-methoxylonchocarpin, 6-prenylchrysoeriol, 6,8-diprenyleriodictyol, gancaonin P and dorsmanins A-H. The structures of these secondary metabolites were determined by spectroscopic means and by comparison with published data and with authentic specimens for some of the known compounds.

[Hypotensive effects of a methanol extract of Bidens pilosa Linn on hypertensive rats]. / Effets hypotensifs de l'extrait au méthanol de Bidens pilosa Linn chez les rats hypertendus.

Bidens pilosa Linn is highly regarded in some parts of Cameroon in traditional folk medical practices. The hypotensive effects of the leaf methanol extract from Bidens pilosa Linn (Asteraceae) were evaluated in spontaneously hypertensive rats (SHR), salt-loading hypertensive rats (SLHR) and normotensive Wistar rats (NTR) using the indirect (tail-cuff) method. Acute changes in urine volume and urinary excretion of Na+ and K+ were also studied. The hypotensive effect of the extract was more remarkable in hypertensive than in normotensive rats. Bidens pilosa did not provoke significant changes in the heart rate and urine volume. Urinary excretion of Na+ was decreased by 36% in spontaneously hypertensive rats and the excretion of K+ increased by 35% in normotensive rats but the effects were not statistically significant. These results suggest that the extract is a useful antihypertensive drug which has no effect on the heart frequency. The hypotensive effects of the extract may be induced by vasodilation.