Antimicrobial Effect of 7-O-Butylnaringenin, a Novel Flavonoid, and Various Natural Flavonoids against Helicobacter pylori Strains

Abstract: The antimicrobial effect of a novel flavonoid (7-O-butylnaringenin) on Helicobacter pylori 26695, 51, and SS1 strains and its inhibitory effect on the urease activity of the strains were evaluated and compared with those of several natural flavonoids. First, various flavonoids were screened for antimicrobial activities using the paper disc diffusion method. Hesperetin and naringenin showed the strongest antimicrobial effects among the natural flavonoids tested, and thus hesperetin and naringenin were selected for comparison with 7-O-butylnaringenin. The antimicrobial effect of 7-O-butylnaringenin was greater than that of the hesperetin and naringenin. H. pylori 51 was more sensitive to 7-O-butylnaringenin (2 log reduction of colony forming units, p \u3c 0.05) than the other two strains at 200 μM. 7-O-Butylnaringenin also showed the highest inhibitory effect against urease activity of H. pylori. Morphological changes of H. pylori 26695 treated with these flavonoids indicated that both hesperetin and 7-O-butylnaringenin at 200 μM damaged the cell membranes

Myofilament Ca2+ desensitization mediates positive lusitropic effect of neuronal nitric oxide synthase in left ventricular myocytes from murine hypertensive heart

AbstractNeuronal nitric oxide synthase (NOS1 or nNOS) exerts negative inotropic and positive lusitropic effects through Ca2+ handling processes in cardiac myocytes from healthy hearts. However, underlying mechanisms of NOS1 in diseased hearts remain unclear. The present study aims to investigate this question in angiotensin II (Ang II)-induced hypertensive rat hearts (HP). Our results showed that the systolic function of left ventricle (LV) was reduced and diastolic function was unaltered (echocardiographic assessment) in HP compared to those in shams. In isolated LV myocytes, contraction was unchanged but peak [Ca2+]i transient was increased in HP. Concomitantly, relaxation and time constant of [Ca2+]i decay (tau) were faster and the phosphorylated fraction of phospholamban (PLN-Ser16/PLN) was greater. NOS1 protein expression and activity were increased in LV myocyte homogenates from HP. Surprisingly, inhibition of NOS1 did not affect contraction but reduced peak [Ca2+]i transient; prevented faster relaxation without affecting the tau of [Ca2+]i transient or PLN-Ser16/PLN in HP, suggesting myofilament Ca2+ desensitization by NOS1. Indeed, relaxation phase of the sarcomere length–[Ca2+]i relationship of LV myocytes shifted to the right and increased [Ca2+]i for 50% of sarcomere shortening (EC50) in HP. Phosphorylations of cardiac myosin binding protein-C (cMyBP-C282 and cMyBP-C273) were increased and cardiac troponin I (cTnI23/24) was reduced in HP. Importantly, NOS1 or PKG inhibition reduced cMyBP-C273 and cTnI23/24 and reversed myofilament Ca2+ sensitivity. These results reveal that NOS1 is up-regulated in LV myocytes from HP and exerts positive lusitropic effect by modulating myofilament Ca2+ sensitivity through phosphorylation of key regulators in sarcomere

Different Regulation of Atrial ANP Release through Neuropeptide Y2 and Y4 Receptors

Neuropeptide Y (NPY) receptors are present in cardiac membranes. However, its physiological roles in the heart are not clear. The aim of this study was to define the direct effects of pancreatic polypeptide (PP) on atrial dynamics and atrial natriuretic peptide (ANP) release in perfused beating atria. Pancreatic polypeptides, a NPY Y4 receptor agonist, decreased atrial contractility but was not dose-dependent. The ANP release was stimulated by PP in a dose-dependent manner. GR 23118, a NPY Y4 receptor agonist, also increased the ANP release and the potency was greater than PP. In contrast, peptide YY (3-36) (PYY), an NPY Y2 receptor agonist, suppressed the release of ANP with positive inotropy. NPY, an agonist for Y1, 2, 5 receptor, did not cause any significant changes. The pretreatment of NPY (18-36), an antagonist for NPY Y3 receptor, markedly attenuated the stimulation of ANP release by PP but did not affect the suppression of ANP release by PYY. BIIE0246, an antagonist for NPY Y2 receptor, attenuated the suppression of ANP release by PYY. The responsiveness of atrial contractility to PP or PYY was not affected by either of the antagonists. These results suggest that NPY Y4 and Y2 receptor differently regulate the release of atrial ANP

Expression of C-type Natriuretic Peptide and its Specific Guanylyl Cyclase-Coupled Receptor in Pig Ovarian Granulosa Cells

Background: C-type natriuretic peptide (CNP) was isolated from porcine brain and is a 22-amino acid peptide which belongs to the natriuretic peptide (NP) family. Even though this peptide shares structural similarity to other endogenous NPs including atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) its receptor selectivity is different from other NPs. The present study was undertaken to investigate the expression of C-type natriuretic peptide (CNP) and its specific guanylyl cyclase (GC)-coupled receptor in the granulosa cells of the pig ovarian follicle. Results: Specific 125I-[Tyr0]-CNP(1-22) binding sites were localized in the granulosa cell layer of the ovarian follicle with an apparent dissociation constant (Kd>) and a maximal binding capacity (Bmax) of 1.41±0.39 nM and 2.75±0.65 fmol/mm2 respectively. Binding of 125I-[Tyr0]-CNP(1-22) to these sites was also prevented by atrial natriuretic peptide (ANP(1-28)), brain natriuretic peptide (BNP(1-26)) and des[Gln18,Ser19,Gly20, Leu21,Gly22] ANP(4-23) (C-ANP). Production of 3’,5’-cyclic guanosine monophosphate (cGMP) by particulate GC in the granulosa cell membranes was stimulated by natriuretic peptides (NPs) with a rank order of potency of CNP(1-22)>>BNP(1-26)>ANP(1-28). HS-142-1, a selective antagonist of the two recognized GC-coupled NPRs, inhibited CNP(1-22)-stimulated cGMP production in granulosa cell membranes in a dose-dependent manner. Also mRNAs for all three recognized NPRs were detected in granulosa cells using reverse transcriptase-polymerase chain reaction (RT-PCR). Serial dilution curves of granulosa cell extracts were parallel to the standard curve of synthetic CNP. Conclusion: These results indicate that CNP and its specific receptor are expressed in the granulosa cells of the pig ovary, and suggest that CNP may be a local autocrine and/or paracrine regulator via activation of its specific GC-coupled receptor, NPR-B