Design, synthesis, and antihypertensive activity of curcumin-inspired compounds via ACE inhibition and vasodilation, along with a bioavailability study for possible benefit in cardiovascular diseases.

This study describes the synthesis of a novel series of curcumin-inspired compounds via a facile synthetic route. The structures of these derivatives were ascertained using various spectroscopic and analytic techniques. The pharmacological effects of the target analogs were assessed by assaying their inhibition of angiotensin-converting enzyme (ACE). All of the synthesized derivatives exhibited considerable inhibition of ACE, with half-maximal inhibitory concentrations ranging from 1.23 to 120.32 µM. In a docking analysis with testicular ACE (tACE), the most promising inhibitor (4j) was efficiently accommodated in the deep cleft of the protein cavity, making close interatomic contacts with Glu162, His353, and Ala356, comparable with lisinopril. Compounds 4i, 4j, 4k, and 4l were further selected for determination of their vasodilator activity (cardiac output and stroke volume) on isolated rat hearts using the Langendorff technique. The bioavailability of compound 4j was determined in experimental mice.

Calcitriol prevents peripheral RSC96 Schwann neural cells from high glucose & methylglyoxal-induced injury through restoration of CBS/H2S expression.

A meta-analysis has suggested that vitamin D deficiency is involved in diabetic peripheral neuropathy (DPN) and the levels of hydrogen sulfide (H2S) are also decreased in type 2 diabetes. The injection of vitamin D induces cystathionine-ß-synthase (CBS) expression and H2S generation. However, it remains unclear whether the supplementation of vitamin D prevents DPN through improvement of CBS/H2S expression. In the present study, RSC96 cells, a rat Schwann cell line, were exposed to high glucose and methylglyoxal (HG&MG) to simulate diabetic peripheral nerve injury in vivo. Before the exposure to HG&MG, the cells were preconditioned with calcitriol (CCT), an active form of vitamin D, and then CCT-mediated neuroprotection was investigated in respect of cellular viability, superoxide anion (O2(-)) generation, inducible nitric oxide (NO) synthase (iNOS)/NO expression, mitochondrial membrane potential (MMP), as well as CBS expression and activity. It was found that both high glucose and MGO decreased cell viability and co-treatment with the two induced a more serious injury in RSC96 cells. Therefore, the exposure to HG&MG was used in the present study. The exposure to HG&MG markedly induced iNOS expression, NO and O2(-) generation, as well as MMP loss. In addition, the exposure to HG&MG depressed CBS expression and activity in RSC96 cells. However, the preconditioning with CCT significantly antagonized HG&MG-induced cell injury including the decreased viability, iNOS overexpression, NO and O2(-) accumulation, as well as MMP loss. CCT also partially restored the decreased CBS expression and activity triggered by HG&MG, while the inhibition of CBS with hydroxylamine attenuated CCT-mediated neuroprotection. Moreover, the exogenous donation of H2S produced similar cellular protective effects to CCT. The data indicate that the supplementation of vitamin D prevents HG&MG-induced peripheral nerve injury involving the restoration of endogenous H2S system, which may provide a basal support for the treatment of DPN with vitamin D clinically.

Exogenous hydrogen sulfide alleviates high glucose-induced cardiotoxicity via inhibition of leptin signaling in H9c2 cells.

Hydrogen sulfide (H2S) protects cardiomyoblasts against high glucose (HG)-induced injury by inhibiting the activation of p38 mitogen-activated protein kinase (MAPK). This study aims to determine whether the leptin-p38 MAPK pathway is involved in HG-induced injury and whether exogenous H2S prevents the HG-induced insult through inhibition of the leptin-p38 MAPK pathway in H9c2 cells. H9c2 cells were treated with 35 mM glucose (HG) for 24 h to establish a HG-induced cardiomyocyte injury model. Cell viability; mitochondrial membrane potential (ΔΨ m); apoptosis; reactive oxygen species (ROS) level; and leptin, leptin receptor, and p38 MAPK expression level were measured by the methods indicated. The results showed pretreatment of H9c2 cells with NaHS before exposure to HG led to an increase in cell viability, decrease in apoptotic cells, ROS generation, and a loss of ΔΨ m. Exposure of H9c2 cells to 35 mM glucose for 24 h significantly upregulated the expression levels of leptin and leptin receptors. The increased expression levels of leptin and leptin receptors were markedly attenuated by pretreatment with 400 µM NaHS. In addition, the HG-induced increase in phosphorylated (p) p38 MAPK expression was ameliorated by pretreatment with 50 ng/ml leptin antagonist. In conclusion, the present study has demonstrated for the first time that the leptin-p38 MAPK pathway contributes to the HG-induced injury in H9c2 cells and that exogenous H2S protects H9c2 cells against HG-induced injury at least in part by inhibiting the activation of leptin-p38 MAPK pathway.

Inhibition of ROS-activated ERK1/2 pathway contributes to the protection of H2S against chemical hypoxia-induced injury in H9c2 cells.

Hydrogen sulfide (H(2)S) has been shown to exert cardioprotective effects. However, the roles of extracellular signal-regulated protein kinases 1/2 (ERK1/2) in H(2)S-induced cardioprotection have not been completely elucidated. In this study, cobalt chloride (CoCl(2)), a chemical hypoxia mimetic agent, was applied to treat H9c2 cells to establish a chemical hypoxia-induced cardiomyocyte injury model. The results showed that pretreatment with NaHS (a donor of H(2)S) before exposure to CoCl(2) attenuated the decreased cell viability, the increased apoptosis rate, the loss of mitochondrial membrane potential (ΔΨm), and the intracellular accumulation of reactive oxygen species (ROS) in H9c2 cells. Exposure of H9c2 cells to CoCl(2) or hydrogen peroxide (H(2)O(2)) upregulated expression of phosphorylated (p) ERK1/2, which was reduced by pretreatment with NaHS or N-acetyl-L-cysteine, a ROS scavenger. More importantly, U0126, a selective inhibitor of ERK1/2, mimicked the above cytoprotection of H(2)S against CoCl(2)-induced injury in H9c2 cells. In conclusion, these results indicate that H(2)S protects H9c2 cells against chemical hypoxia-induced injury partially by inhibiting ROS-mediated activation of ERK1/2.

[ERK1/2 mediates edaravone-triggered protection against myocardial damage induced by isoprenaline in H9c2 cells].

OBJECTIVE: To explore the effect of extracellular signal regulated kinase 1/2 (ERK1/2) on edaravone (EDA)-triggered protection against myocardial toxicity induced by isoprenaline (ISO) in H9c2 myocardial cells (H9c2 cells). METHODS: H9c2 cells were exposed to ISO at different concentrations to establish a cardiac toxicity model induced by persistent excitation of ß1 receptor. EDA was added before ISO as a pretreatment. PD-98059, an ERK1/2 inhibitor, was administered 1 h prior to EDA to inhibit the phosphorylation of ERK1/2. Cell viability was measured using cell counter kit (CCK-8). The expressions of p-ERK1/2 and t-ERK1/2 were tested by Western blotting. Mitochondrial membrane potential (MMP) was detected by Rhodamine123 (Rh123) staining and photofluorography. RESULTS: Exposure of H9c2 cells to 80 µmol/L ISO for 24 h down-regulated ERK1/2 phosphorylation and repressed MMP. Pretreatment with 10-40 µmol/L EDA for 1 h inhibited ISO-induced myocardial toxicity and pretreatment of 40 µmol/L EDA partially rescued ERK1/2 phosphorylation and MMP level. PD-98059 abolished cardiac protection of EDA, leading to myocardial toxicity and MMP loss. CONCLUSION: EDA can protect H9c2 cells against myocardial injury induced by ISO by suppressing ISO-triggered inhibition of ERK1/2 activation.