Reduction of lauric acid content in virgin coconut oil improved plasma lipid profile in high-fat diet-induced hypercholesterolemic mice.

Virgin coconut oil (VCO) is claimed to have various health benefits, but favorable effects of its major component (∼50%), lauric acid, are controversial. Therefore, we aimed to reduce lauric acid content (∼30%) in VCO and evaluate its effect compared to VCO and medium-chain triglycerides (MCT), on food intake, bodyweight (BW), lipid profiles, and hepatic histology. Female C57BL/6 mice were treated with different diets for 3 months: control (normal diet), high-fat diet (HF), HF + VCO, HF + MCT, HF + low lauric acid VCO (LLA), and normal diet + LLA (C + LLA). LLA was prepared by enzymatic interesterification of VCO with methyl octanoate (methyl caprylate) and methyl decanoate (methyl caprate). Plasma and liver lipids, including total cholesterol (TC), high-density lipoprotein (HDL), and triglyceride, were measured by colorimetric assay, and hepatic fat accumulation was examined by oil-red-O staining. HF mice exhibited high plasma and liver TC and low-density lipoprotein (LDL). VCO or MCT treatment lowered liver TC and LDL, whereas LLA increased plasma HDL and markedly improved TC:HDL ratio. The HF-induced hepatic fat accumulation was attenuated by all treatments, of which VCO was the most effective. Control mice administered with LLA demonstrated lower liver TC and LDL, but higher plasma TC and HDL compared to controls. Lowest BW gain and food intake were found in mice treated with LLA. In conclusion, VCO, MCT, and LLA ameliorated hepatic histopathology caused by HF. VCO and MCT improved liver lipid profiles, whereas LLA has more beneficial effect on plasma lipids via a better TC:HDL ratio and showed promise for BW control.

The new quinazoline derivative (N2-methyl-N4-[(thiophen-2-yl)methyl]quinazoline-2,4-diamine) vasodilates isolated mesenteric arteries through endothelium-independent mechanisms and has acute hypotensive effects in Wistar rats.

During the screening of new N2,N4-disubstituted quinazoline 2,4-diamines as phosphodiesterase-5 inhibitors and pulmonary artery vasodilators, one N2-methyl-N4-[(thiophen-2-yl)methyl]quinazoline-2,4-diamine (compound 8) presented a greater selectivity for systemic than pulmonary vasculature. The present study aimed to characterize its vasorelaxant and hypotensive effects in Wistar rats. Vasorelaxant effects of compound 8 and underlying mechanisms were evaluated on isolated mesenteric arteries. Acute hypotensive effect was evaluated in anesthetized rats. Additionally, cell viability and cytochrome P450 (CYP) activities were studied in rat isolated hepatocytes. Nifedipine was used as a comparator. Compound 8 induced a strong vasorelaxant effect, similar to nifedipine. This was unaffected by endothelium removal but was decreased by inhibitors of guanylate cyclase (ODQ) and KCa channel (iberiotoxin). Compound 8 enhanced sodium nitroprusside-induced relaxation, but inhibited vasoconstriction evoked by α1-adrenergic receptor activation and extracellular Ca2+ influx via receptor-operated Ca2+ channels. Acute intravenous infusion of compound 8 (0.05 and 0.1 mg/kg) produced hypotension. It showed similar potency to nifedipine for lowering diastolic and mean arterial blood pressure, but less so for the effect on systolic blood pressure. Compound 8 had no effect on hepatocyte viability and CYP activities except at high concentration (10 µM) at which a weak inhibitory effect on CYP1A and 3A was observed. In conclusion, this study identified a N2-methyl-N4-[(thiophen-2-yl)methyl]quinazoline-2,4-diamine with a potent vasodilator effect on resistance vessels, leading to an acute hypotensive effect and a low risk of liver toxicity or drug-drug interactions. These vascular effects were mediated mainly through sGC/cGMP pathway, opening of KCa channels, and inhibition of calcium entry.

Quinazoline-based human phosphodiesterase 5 inhibitors exhibited a selective vasorelaxant effect on rat isolated pulmonary arteries involving NO-sGC-cGMP pathway and calcium inhibitory effects.

Phosphodiesterase 5 (PDE5) inhibitors are an attractive option among the currently available therapies in the management of pulmonary arterial hypertension (PAH). Good selectivity for PDE5 is associated with reduced side effects and greater vasorelaxant effect on pulmonary arteries (PA). This study investigated the vasorelaxant effects of a series of quinazoline-based PDE5 inhibitors and their precise mechanisms action using rat isolated PA and aorta, as compared to sildenafil. Their effects on rat hepatocytes (viability and CYP activities) were also evaluated. Compounds 5 and 11 displayed lower human PDE5 IC50 of the analogs studied here and induced a greater relaxant effect on PA (EC50 0.94 ± 0.30 and 1.03 ± 0.23 µM, respectively). As compared to sildenafil (EC50 = 0.05 ± 0.02 µM on PA), the relaxant effect of 5 and 11 on PA was lower but their selectivity for PA compared to aorta was higher. The effects of 5 and 11 were reduced by NG-nitro-L-arginine methyl ester, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one, but not by indomethacin or potassium channels blockers. They also enhanced the relaxant effect of sodium nitroprusside, and inhibited extracellular Ca2+ influx and intracellular Ca2+release. Compounds 5 and 11 did not reduce hepatocyte viability except at concentration > 10 µM, inhibited CYP3A at 10 µM, like sildenafil, but did not induce CYP1A. In conclusion, this study identified 2 quinazoline analogues with good PDE5 inhibitory activity and good selectivity for the pulmonary vasculature. Their relaxant effect involves both the potentiation of nitric oxide-sGC-cGMP pathway and calcium inhibition. These compounds are potential leads for developing new drugs for PAH.

Isolation of Intrapulmonary Artery and Smooth Muscle Cells to Investigate Vascular Responses.

The intrapulmonary artery (IPA) and vascular smooth muscle cells (VSMCs) isolated from rat lungs can be used to study the underlying mechanisms of vasoconstriction and vasorelaxation. After isolating the IPA and VSMCs, the characteristics of vascular responses in physiological and pathological conditions can be assessed in the absence of extrinsic factors such as nerve signals, hormones, cytokines, etc. Thus, the IPA and VSMCs serve as excellent models for studying vascular physiology/pathophysiology, along with various experimental investigations, such as modulation by pharmacological agents, patch-clamp electrophysiological analysis, calcium imaging, etc. Here, we have used a technique for isolating the IPA to investigate vascular responses in an organ bath setup. IPA segments were mounted on the organ bath chamber via intraluminal wires and stimulated by various pharmacological agents. The changes in IPA vascular tone (i.e., vasoconstriction and vasorelaxation), were recorded using an isometric force transducer and physiological data analysis software program. We implemented several experimental protocols, which can be adapted to investigate the mechanisms of vasorelaxation/vasoconstriction for studying the pharmacological activities of phytochemical or synthetic drugs. The protocols can also be used to evaluate drugs' roles in modulating various diseases, including pulmonary arterial hypertension. The IPA model allows us to investigate the concentration-response curve, which is crucial in assessing drugs' pharmacodynamic parameters.

Dried mulberry fruit ameliorates cardiovascular and liver histopathological changes in high-fat diet-induced hyperlipidemic mice.

BACKGROUND AND AIM: Metabolic disease encompasses most contemporary non-communicable diseases, especially cardiovascular and fatty liver disease. Mulberry fruits of Morus alba L. are a favoured food and a traditional medicine. While they are anti-atherosclerotic and reduce hyperlipidemic risk factors, studies need wider scope that include ameliorating cardiovascular and liver pathologies if they are to become clinically effective treatments. Therefore, the present study sought to show that freshly dried mulberry fruits (dMF) might counteract the metabolic/cardiovascular pathologies in mice made hyperlipidemic by high-fat diet (HF). EXPERIMENTAL PROCEDURE: C57BL/6J mice were fed for 3 months with either: i) control diet, ii) HF, iii) HF+100 mg/kg dMF, or iv) HF+300 mg/kg dMF. Body weight gain, food intake, visceral fat accumulation, fasting blood glucose, plasma lipids, and aortic, heart, and liver histopathologies were evaluated. Adipocyte lipid accumulation, autophagy, and bile acid binding were also investigated. RESULTS AND CONCLUSION: HF increased food intake, body weight, visceral fat, plasma total cholesterol (TC) and low-density lipoprotein (LDL), TC/HDL ratio, blood glucose, aortic collagen, arterial and cardiac wall thickness, and liver lipid. Both dMF doses prevented hyperphagia, body weight gain, and visceral fat accumulation, lowered blood glucose, plasma TG and unfavourable TC/HDL and elevated plasma HDL beyond baseline. Arterial and cardiac wall hypertrophy, aortic collagen fibre accumulation and liver lipid deposition ameliorated in dMF-fed mice. Clinical trials on dMF are worthwhile but outcomes should be holistic commensurate with the constellation of disease risks. Here, dMF should supplement the switch to nutrient-rich from current energy-dense diets that are progressively crippling national health systems.

Extract of Aquilaria crassna leaves and mangiferin are vasodilators while showing no cytotoxicity.

The leaves of Aquilaria spp. promote "physiological balance", and are "cardiotonic and provide blood nourishment". In Asia, these leaves are increasingly consumed as tea and claimed to provide benefits to cardiovascular function, albeit without any scientific proof. Therefore, this study sought to evaluate the action of Aquilaria crassna leaf aqueous extract (AE) on vascular function and vascular smooth muscle cytotoxicity. AE and a main constituent, mangiferin were investigated for their vasorelaxation of rat mesenteric arteries and aortae in vitro. Acute cytotoxicity of AE (0.1-1000 µg/ml) and mangiferin (0.1-100 µM) on rat enzymatically isolated vascular smooth muscle cells was assayed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide. AE dilated rat mesenteric arteries (EC50∼107 µg/ml, Emax∼95%) more than aorta (EC50∼265 µg/ml, Emax∼76%, p < 0.05). AE-induced vasodilation in mesenteric artery was reduced by endothelial removal (EC50∼202 µg/ml, p < 0.05), incubation with endothelial nitric oxide synthase (eNOS) (100 µM, L-NAME) (EC50∼309 µg/ml, p < 0.05), and partly reduced by L-type Ca2+ channel blockade at higher concentrations. Likewise, mangiferin (1-100 µM) dilated the mesenteric artery more potently than the aorta. However, its maximum relaxation was less than with AE (41% in the mesenteric artery and <10% in the aorta). Isolated vascular smooth muscle cells incubated in AE or mangiferin for 1 h showed no cytotoxicity. Thus, AE is a vasorelaxant while being free of acute cytotoxicity towards vascular smooth muscle, thus potentially ameliorating human vascular dysfunction.

Ginger Extract and [6]-Gingerol Inhibit Contraction of Rat Entire Small Intestine.

This study aims to investigate the effect of oral administration and the direct action of ginger extract or [6]-gingerol on small intestinal contractility. The direct effect of 10 minutes preincubation of ginger ethanolic extract (10, 100 and 300 µg/mL) or [6]-gingerol (1, 30, and 100 µM) on 0.01 to 30 µM ACh-induced contractions of all parts of the small intestine isolated from normal rats was investigated using the organ bath technique. For in vivo study, the rats were orally administered with extract (10, 20, and 100 mg/kg/d) or [6]-gingerol (2 mg/kg/d) for 7 days, followed by determining the contractile responses to ACh of rat isolated duodenum, jejunum, and ileum and their histology were assessed. Direct application of the extract or [6]-gingerol attenuated ACh-induced contractions in each small intestinal segment, Emax was reduced by 40% to 80%, while EC50 increased 3- to 8-fold from control. Similarly, in the in vivo study ACh-induced contractions were reduced in all parts of the small intestine isolated from rats orally treated with ginger extract (20 and 100 mg/kg/d) or [6]-gingerol (2 mg/kg/d). Emax decreased 15% to 30%, while EC50 increased 1- to 3-fold compared to control. No discernable changes in the histology of intestinal segments were detectable. Thus, the results support the clinical application of ginger for disorders of gastrointestinal motility.