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BACKGROUND AND PURPOSE Current methods used to treat critical limb ischaemia (CLI) are hampered by a lack of effective strategies, therefore, therapeutic vasculogenesis may open up a new field for the treatment of CLI. In this study we investigated the ability of the DPP-4 inhibitor, sitagliptin, originally used as a hypoglycaemic agent, to induce vasculogenesis in vivo. EXPERIMENTAL APPROACH Sitagliptin were administered daily to C57CL/B6 mice and eGFP transgenic mouse bone marrow-transplanted ICR mice that had undergone hindlimb ischaemic surgery. Laser Doppler imaging and flow cytometry were used to evaluate the degree of neovasculogenesis and circulating levels of endothelial progenitor cells (EPCs) respectively. Cell surface markers of EPCs and endothelial NOS (eNOS) in vessels were studied. KEY RESULTS Sitagliptin elevated plasma glucagon-like peptide-1 (GLP-1) levels in mice subjected to ischaemia, decreased plasma dipeptidyl peptidase-4 (DPP-4) concentration, and augmented ischaemia-induced increases in stromal cell-derived factor-1 (SDF-1) in a dose-dependent manner. Blood flow in the ischaemic limb was significantly improved in mice treated with sitagliptin. Circulating levels of EPCs were also increased after sitagliptin treatment. Sitagliptin also enhanced the expression of CD 34 and eNOS in ischaemic muscle. In addition, sitagliptin promoted EPC mobilization and homing to ischaemic tissue in eGFP transgenic mouse bone marrow-transplanted ICR mice. CONCLUSION AND IMPLICATIONS Circulating EPC levels and neovasculogenesis were augmented by the DPP-4 inhibitor, sitagliptin and this effect was dependent on an eNOS-related pathway in a mouse model of hindlimb ischaemia. The results indicate that oral administration of sitagliptin has therapeutic potential as an inducer of vasculogenesis.

Histone deacetylases (HDACs) are a family of enzymes that play a crucial role in biological process and diseases. In contrast to other isozymes, HDAC8 is uniquely incapable of histone acetylation. In order to delineate its physiological function, we developed HDAC8-selective inhibitors using knowledge-based design combined with structural modeling techniques. Enzyme inhibitory analysis demonstrated that some of the resulting compounds (22 b, 22 d, 22 f, and 22 g) exhibited anti-HDAC8 activity superior to PCI34051, a known HDAC8-specific inhibitor, with IC(50) values in the range of 5-50 nM. Among them, compound 22 d showed antiproliferative effects toward several human lung cancer cell lines (A549, H1299, and CL1-5); it exhibited cytotoxicity against human lung CL1-5 cells similar to that of SAHA yet without significant cytotoxicity for normal IMR-90 cells. Expression profiling of HDAC isoforms in three cancer cell lines indicated that the HDAC8 level in CL1-5 is higher than that in H1299 and CL1-1 cells, a result consistent with the differential cytotoxicity of compound 22 d. These results suggest the effectiveness of our design concept, which may lead to a tool compound for studying the specific role of HDAC8 in cellular biological processes.

BACKGROUND: It was reported in a previous paper that the yam tuber storage protein dioscorin exhibited antihypertensive effects on spontaneously hypertensive rats. The aim of the present study was to evaluate and compare the effects of packets of instant food (30 g) with (treated meal) and without (placebo) lyophilised yam powder on hypertensive subjects. RESULTS: A placebo-controlled feeding trial was conducted daily for 5 weeks (stage 1), followed by a 1 week washout and then a 5 week crossover (stage 2). Twenty-one subjects finished the trial. One packet of treated meal contained 140 ± 2.54 mg of dioscorin according to enzyme-linked immunosorbent assay. The blood pressure results of the treated meal and placebo groups at stage 1 end versus originals, but not at stage 2 end versus stage 2 beginning, were significantly different by the paired t test. Systolic (SBP) and diastolic (DBP) blood pressure readings after treated meal intervention, but not after placebo intervention, differed significantly from the original values based on one-way analysis of variance followed by the post hoc Tukey test; the reductions in SBP and DBP were 6.52 and 4.76 mmHg respectively. The feeding trial did not appear to affect serum lipid profiles or other biochemical measurements of cardiovascular risk. CONCLUSION: Intake of an instant food containing 140 mg of dioscorin over 5 weeks had a regulating effect on human blood pressure. Copyright © 2008 Society of Chemical Industry

Yam storage protein (YSP) was purified from tubers of Dioscorea alata L. Tainong No. 1 (TN1) to homogeneity by DE-52 ion-exchange chromatography. The short-term (24 h) and long-term (25 days) antihypertensive effects of YSP-TN1 and its peptic hydrolyzates (PH-TN1) were measured in spontaneously hypertensive rats (SHRs). For 24-h antihypertensive measurements, SHRs (age 10 weeks, body weight from 240 to 250 g) were administered orally once (YSP-TN1 and PH-TN1, 40 mg kg−1 SHR) to measure the mean blood pressure (MBP), systolic blood pressure (SBP) and diastolic blood pressure (DBP). For a long-term antihypertensive measurement, SHRs (age 12 weeks, body weight from 250 to 270 g) were administered orally once a day for 25 days (YSP-TN1, 40 mg kg−1 SHR) to measure SBP, DBP and MBP. Captopril (10 or 15 mg kg−1 SHR) was used as a positive control. It was found that short-term administration of 40 mg kg−1 SHR of YSP-TN1 and PH-TN1 effectively lowered SHRs' MBP, SBP and DBP (For YSP-TN1, the lowest blood pressure was reached in the fourth hour and for PH-TN1 in the eighth hour). The lasting effects of PH-TN1 on reduced SHRs' BP were better than those of YSP-TN1 for one oral administration. For oral administration of 40 mg YSP-TN1 kg−1 SHR, the reduced MBP was 21.5 mmHg, which was comparable to 25.2 mmHg (the fourth hour) of 10 mg captopril kg−1 SHR oral administration. For oral administration of 40 mg PH-TN1 kg−1 SHR, the reduced MBP was 33.7 mmHg, comparable to 38.4 mmHg (the fourth hour) of 15 mg captopril kg−1 SHR. For long-term 25-day oral administration of 40 mg YSP-TN1 kg−1 SHR once a day, it was found that a feeding trial of YSP-TN1 effectively lowered SHRs' SBP, DBP and MBP. The greatest reduction in SHRs' blood pressure was reached on the ninth day, for the reduced SBP, 27.7 mmHg; for the reduced DBP, 28.3 mmHg; and for the reduced MBP, 27.5 mmHg. Copyright © 2006 Society of Chemical Industry

The commercial polysaccharides of alginic acid (medium (3500 cps, 2% solution) and low (250 cps, 2% solution) viscosities) were esterified with acidic methanol (1 mmol L−1 HCl) at 4 °C with gentle stirring for 5 days to obtain methyl esters of medium-viscosity alginic acid (ME-MVA) and low-viscosity alginic acid (ME-LVA). These ME-MVA and ME-LVA were reacted with alkaline hydroxylamine to obtain medium-viscosity alginic acid hydroxamates (MVA-NHOH) and LVA-NHOH. The percentages of hydroxamic acid content in MVA-NHOH and LVA-NHOH were calculated as 25% and 20%, respectively. The hydroxamate derivatives of alginic acid were used to test the antioxidant and semicarbazide-sensitive amine oxidase (SSAO) inhibitory activities in comparison with original materials (MVA and LVA). The half-inhibition concentrations, IC50, of scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) were 24.5 and 29.8 µg mL−1 for MVA-NHOH and LVA-NHOH, respectively. However, few scavenging activities of the MVA and LVA were found at the same concentrations. The IC50 of the positive control of butylated hydroxytoluene was 5 µg mL−1. The scavenging activity of DPPH radical was pH-dependent, and the optimal pH for both of MVA-NHOH and LVA-NHOH was the Tris-HCl buffer (pH 7.9). Using electron spin resonance (ESR) to detect the activity of scavenging hydroxyl radicals, both alginic acid hydroxamates showed dose-dependent scavenging activities, and the IC50 was 90 and 92 µg mL−1, respectively, for MVA-NHOH and LVA-NHOH. Both alginic acid hydroxamates also exhibited protection against hydroxyl radical-mediated DNA damage. Both MVA-NHOH and LVA-NHOH showed dose-dependent inhibitory activities against bovine SSAO (2.53 units); the IC50 was 0.16 and 0.09 µg mL−1, respectively, for MVA-NHOH and LVA-NHOH, compared with 3.81 µg mL−1 of semicarbazide (positive controls). Amine oxidase activity staining also revealed that both MVA-NHOH and LVA-NHOH exhibited SSAO inhibitory activities. Both MVA-NHOH and LVA-NHOH showed mixed non-competitive inhibition against bovine SSAO. It was found that the V′max value was reduced and the K′m value was either increased (added MVA-NHOH, 0.05 µg mL−1) or reduced (added LVA-NHOH, 0.11 µg mL−1) in the presence of alginic acid hydroxamate. Copyright © 2006 Society of Chemical Industry

Gynura formosana Kiamnra (Compositae) is a herbal folk medicine that is a popular vegetable in Taiwan. The free-radical scavenging activities of a 70% aqueous acetone extract from the herb G formosana were evaluated. Bioassay-guided fractionation, column separation on Diaion, Toyopearl HW 40(C), Sephadex LH-20 and MCI CHP20P, and high-performance liquid chromatography (HPLC) were used to isolate for the first time in G formosana four potent phenolics [caffeic acid (I), quercetin 3-O-rutinoside (II), kaempferol 3-O-rutinoside (III) and kaempferol 3-O-robinobioside (IV)]. The IC50 values of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity for compounds I–IV were 6.7, 7.7, 300.3 and 286.7 µM, respectively, and, for superoxide radical scavenging activity, they were 187.3, 25.8, 55.3 and 87.4 µM, respectively. Using a spin trapping electron spin resonance (ESR) method, caffeic acid (I) and quercetin 3-O-rutinoside (II) exhibited good hydroxyl radical activity. The free radical scavenging activity of G formosana phenolics may improve the economic value of this herb and assist in its development as a health food. Copyright © 2004 Society of Chemical Industry

Biological functions of flavanones have been studied extensively, however, the structure-related activities of flavanones on 12-o-tetradecanoylphorbol 13-acetate (TPA)-induced promotive effects are still unclear. In this study, flavanone, 2'-OH flavanone, 4'-OH flavanone, 6-OH flavanone showed the most significant dose-dependent inhibition on TPA-induced proliferative effects among eight tested flavanones in NIH3T3 cells. TPA-induced mitogen activated protein kinases (MAPK) phosphorylation, ornithine decarboxylase (ODC), c-Jun, and cyclooxygenase 2 (COX-2) protein expressions in a time-dependent manner, and the maximal inductive time point is at 1 h for MAPK phosphorylation and 6 h for others. Flavanone, 2'-OH flavanone, 4'-OH flavanone, 6-OH flavanone showed the dose-dependent inhibition on TPA-stimulated MAPK phosphorylation, COX-2, ODC, c-Jun protein expressions. Induction of, prostaglandin E(2) (PGE(2)) production was detected in TPA-treated NIH3T3 cells, and flavanone, 2'-OH flavanone, 4'-OH flavanone, 6-OH flavanone inhibited significantly PGE(2) production induced by TPA. Addition of PGE(2) reverses the inhibitory activities of flavanone, 2'-OH flavanone, 4'-OH flavanone, 6-OH flavanone on TPA-induced proliferation. And, PD98059, a specific inhibitor of ERKs, inhibited TPA-induced MAPK phosphorylation, accompanied by decreasing COX-2, c-Jun, and ODC protein expression, and showed dose-dependent inhibition on TPA-induced proliferation in cells. These results demonstrated that PGE(2) is an important mediator in TPA-induced proliferation, and MAPK phosphorylation was located at the upstream of COX-2, c-Jun, and ODC gene expressions in TPA-induced responses. Furthermore, flavanone, 2'-OH flavanone, 4'-OH flavanone, 6-OH flavanone (100 microM) suppressed TPA-induced colony formation associated with blocking MAPK phosphorylation, ODC, c-Jun, and COX-2 proteins expression. And, 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay showed that flavanone, 2'-OH flavanone, 4'-OH flavanone, 6-OH flavanone did not perform potent anti-radical activities among these eight tested compounds. In conclusion, this study provided molecular evidences to demonstrate that flavanone, 2'-OH flavanone, 4'-OH flavanone, 6-OH flavanone were potent inhibitors on TPA-induced responses without notable cytotoxicity through suppression of PGE(2) production; and anti-radical activity of flavanones was not correlated with preventing the occurrence of tumor promotion. We proposed that blocking TPA-induced intracellular signaling responses might be involved in the anti-promotive mechanism of flavanones.

Plasma amine oxidase (plasma AO, EC 1.4.3.6) is a copper-containing AO which converts benzylamine (BZ) to benzaldehyde, generating hydrogen peroxide and ammonia. The peroxidase was used as an ancillary enzyme to couple hydrogen peroxide to 3-amino-9-ethylcarbazole (AEC) to achieve plasma AO activity after electrophoresis on native polyacrylamide gels. It was confirmed that plasma AO is inhibited by semicarbazide but neither by clorgyline nor by deprenyl. We also used plasma AO activity staining for the screening of natural inhibitors. This fast and sensitive method can be used in the process of plasma AO purification, characterization, and inhibitor screening.

A general method for detecting protease activities on acrylamide or agarose gels after sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS-PAGE) using specific aminoacyl p-nitroanilide (NA) or peptidyl NA as substrate is described. This method is extended from the spectrophotometric assay of p-nitroaniline, which is a chromogenic product liberated by protease action on aminoacyl NA or peptidyl NA. The acrylamide gel containing protein bands was dipped directly into a solution which contained specific synthetic aminoacyl NA or peptidyl NA as a substrate or had been overlaid with an agarose gel containing the same substrate. The p-nitroaniline released on the acrylamide or agarose gel by the specific protease was diazotized with sodium nitrite and then coupled to N-(1-naphthyl)-ethylenediamine to produce distinct activity band(s). The substrates used for protease activity staining on gels were identical to those used for spectrophotometric assays. Some applications are described.

Isocitrate was cleaved into succinate and glyoxylate by isocitrate lyase (ICL) in the glyoxylate cycle. We used lactate dehydrogenase as an ancillary enzyme to further metabolize the glyoxylate to glycolate in the presence of NADH. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and 2,6-dichlorophenol-indolphenol (DCPIP) were used in the coupling reactions for detecting ICL activity after electrophoresis on either native or sodium dodecyl sulfate (SDS) polyacrylamide gels. This fast and sensitive method can be used in the process of ICL enzyme purification and characterization.

Pectinesterase (PE), from commercial orange peels or ammonium sulfate fractionation (50-80% saturation) of pea pods, was detected on polyacrylamide gels after native acidic polyacrylamide gel electrophoresis (PAGE) or sodium dodecyl sulfate (SDS)-PAGE by using the synthetic substrate beta-naphthyl acetate (beta-NA). The release of beta-naphthol (at 322 nm) from beta-NA was proportional to PE activity. The PE activity bands on polyacrylamide gels after native acidic PAGE or SDS-PAGE were stained with a combination of tetrazotized o-dianisidine and beta-NA. This fast and sensitive method can be used for enzyme purification and characterization.

The failure of activity staining of trypsin inhibitors in crude leaf extracts of sweet potato varieties including Tainong 27, Tainong 34, and Tainong 57 on a 15% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gel was prevented by dipping the gels in solutions containing 10-40 mM hydrogen peroxide, 10 mM Tris buffer (pH 7.9) for 30 min before staining.