Ya-Ling Chang

Pyranoquinoline alkaloids from Zanthoxylum simulans

Three new pyranoquinoline alkaloids, simulenoline, peroxysimulenoline and benzosimuline, together with 22 known compounds, were isolated from the stem bark of Formosan Zanthoxylum simulans. Structures including zanthodioline, a known alkaloid without published data, were elucidated by spectral evidences. Among the isolates, 14 compounds showed strong anti-platelet aggregation activity in vitro.

Chemical and anti-platelet constituents from Formosan Zanthoxylum simulans

A pyrrole alkaloid, pyrrolezanthine [5-hydroxymethyl-1-[2-(4-hydroxyphenyl)-ethyl]-1H-pyrrole-2-carbaldehyde]; a lignan, (-)-simulanol [4- [3-hydroxymethyl-5-((E)-3-hydroxypropenyl)-7-methoxy-2,3-dihydrobenzofuran-2-yl]-2,6-dimethoxy-phenol] and a monocyclic gamma-pyrone, zanthopyranone [3,5-dimethoxy-2-methyl-pyran-4-one], together with 28 known compounds were isolated from the stem wood of Formosan Zanthoxylum simulans. Their structures were determined through spectral analyses. Among the isolates, 11 compounds showed anti-platelet aggregation activity in vitro.

Antiplatelet effects of some aporphine and phenanthrene alkaloids in rabbits and man

Two aporphines (boldine and laurolitsine) and five phenanthrene alkaloids (litebamine, secoboldine, N‐cyanosecoboldine, N‐methylsecoglaucine and N‐methylsecopredicentrine) were evaluated in‐vitro for their ability to inhibit platelet aggregation.

YC-1 induces apoptosis of human renal carcinoma A498 cells in vitro and in vivo through activation of the JNK pathway.

The aim of this study was to elucidate the mechanism of YC‐1{3‐(5′‐hydroxy methyl‐2′‐furyl)‐1‐benzylindazole}‐induced human renal carcinoma cells apoptosis and to evaluate the potency of YC‐1 in models of tumour growth in mice.

The synergic effect of vincristine and vorinostat in leukemia in vitro and in vivo

BackgroundCombination therapy is a key strategy for minimizing drug resistance, a common problem in cancer therapy. The microtubule-depolymerizing agent vincristine is widely used in the treatment of acute leukemia. In order to decrease toxicity and chemoresistance of vincristine, this study will investigate the effects of combination vincristine and vorinostat (suberoylanilide hydroxamic acid (SAHA)), a pan-histone deacetylase inhibitor, on human acute T cell lymphoblastic leukemia cells.MethodsCell viability experiments were determined by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, and cell cycle distributions as well as mitochondria membrane potential were analyzed by flow cytometry. In vitro tubulin polymerization assay was used to test tubulin assembly, and immunofluorescence analysis was performed to detect microtubule distribution and morphology. In vivo effect of the combination was evaluated by a MOLT-4 xenograft model. Statistical analysis was assessed by Bonferroni’s t test.ResultsCell viability showed that the combination of vincristine and SAHA exhibited greater cytotoxicity with an IC50 value of 0.88 nM, compared to each drug alone, 3.3 and 840 nM. This combination synergically induced G2/M arrest, followed by an increase in cell number at the sub-G1 phase and caspase activation. Moreover, the results of vincristine combined with an HDAC6 inhibitor (tubastatin A), which acetylated α-tubulin, were consistent with the effects of vincristine/SAHA co-treatment, thus suggesting that SAHA may alter microtubule dynamics through HDAC6 inhibition.ConclusionThese findings indicate that the combination of vincristine and SAHA on T cell leukemic cells resulted in a change in microtubule dynamics contributing to M phase arrest followed by induction of the apoptotic pathway. These data suggest that the combination effect of vincristine/SAHA could have an important preclinical basis for future clinical trial testing.

(±)‐Govadine and (±)‐THP, Two Tetrahydroprotoberberine Alkaloids, as Selective α1‐Adrenoceptor Antagonists in Vascular Smooth Muscle Cells

(±)‐Govadine and (±)‐THP ((±)‐2,3,10,11‐tetrahydroxytetrahydroprotoberberine HBr) have been shown to inhibit noradrenaline‐induced contraction of rat thoracic aortae. The pharmacological activity of the compounds was determined in thoracic aortae and cardiac tissue isolated from the rat and in trachea isolated from the guinea‐pig to determine the selectivity of the compounds towards different types of receptor.

CIS-19, a novel platelet activating factor receptor antagonist: in vitro and in vivo studies.

The effects of CIS-19 (cis-2-(3,4-dimethoxyphenyl)-6-isopropoxy-7-methoxyl-1-(N-methylforma mido)-1,2, 3,4-tetrahydronaphthalene) was determined in vitro in rabbit platelets and in vivo in rats and guinea-pigs. CIS-19 inhibited in a selective and concentration-dependent manner the aggregation and ATP release reaction of rabbit platelets induced by PAF (4 nM). The IC50 values of CIS-19 on PAF-induced aggregation of washed platelets and platelet-rich plasma were 11.3 +/- 2.7 and 16.8 +/- 3.0 microM respectively. BN52021 also inhibited PAF-induced aggregation of washed platelets with an IC50 value of 11.7 +/- 2.8 microM. CIS-19 inhibited [3H]PAF (4 nM) binding to washed rabbit platelets with an IC50 value of 1.5 +/- 0.2 microM. The concentration-response curve of PAF-induced aggregation of washed platelets was shifted rightwards by CIS-19 with pA2 and pA10 values of 7.1 (6.8-7.3 for 95% confidence limit) and 6.1 (5.8-6.2) respectively. The thromboxane B2 formation of washed platelets caused by AA, collagen or thrombin was not affected by CIS-19 of concentrations below 400 microM. CIS-19 (25 microM) completely blocked PAF-induced, but not collagen- or thrombin-induced [3H]inositol monophosphate formation of washed platelets. When CIS-19 (2.5 and 5 mg/kg) was injected i.v. into the femoral vein, it did not affect the blood pressure of rats, but antagonized PAF (2.5 micrograms/kg, i.v.)-induced hypotensive shock either preventively or curatively. CIS-19 (2.5 and 5 mg/kg) also blocked PAF (50 ng/kg)-induced, but not AA (50 micrograms/kg)-induced, bronchoconstriction in guinea-pigs. It is concluded that CIS-19 is an effective PAF receptor antagonist not only in vitro, but also in vivo.

Effect of a potent cyclooxygenase inhibitor, 5-ethyl-4-methoxy-2-phenylquinoline (KTC-5), on human platelets

Because the metabolites of arachidonic acid participate in many physiopathological responses, including inflammation and platelet aggregation, cyclooxygenase inhibitors are important in the treatment of associated diseases. A biologically active compound, 5‐ethyl‐4‐methoxy‐2‐phenyl‐quinoline (KTC‐5), selectively and concentration dependently inhibited aggregation of platelets from man and ATP release caused by arachidonic acid (200 μM) and collagen (10 μ g mL−1) without affecting the aggregation caused by thrombin (0.1 U mL−1) and U46619 (2 μM). The IC50 value (drug concentration inhibiting maximum response by 50%) of KTC‐5 for aggregation induced by arachidonic acid and collagen was 0.11 ± 0.04 μM and 0.20 ± 0.03 μM, respectively. This inhibitory effect of KTC‐5 was reversible and time dependent. KTC‐5 specifically inhibited intracellular calcium mobilization initiated by arachidonic acid or collagen without affecting that caused by thrombin or U46619 in human platelets. Furthermore, KTC‐5 inhibited thromboxane B2 and prostaglandin D2 formation provoked by arachidonic acid. The IC50 value of KTC‐5 for arachidonic‐acid‐induced thromboxane B2 formation was 0.07 ± 0.02 μM. Based on these observations, the data indicated that KTC‐5 potently inhibited human platelet aggregation and ATP release mainly via the inhibition of the cyclooxygenase‐1 activity. Moreover, KTC‐5 inhibited lipopolysaccharide‐induced prostaglandin E2 formation in RAW264.7 cells in the presence of external arachidonic acid with an IC50 value of 0.17 ± 0.06 μM. Immunoblot analysis showed that KTC‐5 did not affect the cyclooxygenase‐2 expression in the presence of lipopolysaccharide on RAW264.7 cells. This result indicated that KTC‐5 affects the activity of cyclooxygenase‐2. According to these data, we concluded that KTC‐5 is a cyclooxygenase inhibitor for both subtypes.

Synthesis, antiplatelet and vasorelaxing effects of monooxygenated flavones and flavonoxypropanolamines

A series of flavones and flavonoxypropanolamines were synthesized and tested in‐vitro for their ability to inhibit aggregation of washed rabbit platelets and human platelet‐rich plasma (PRP), and for vasoconstriction of rat thoracic aorta. The various substituted positions of the hydroxyl group in flavone ring B and the various oxypropanolamine side chains substituted at position C‐2′ of flavone modified the antiplatelet effects. All the compounds tested in human PRP showed significant inhibition of secondary aggregation induced by adrenaline (epinephrine), suggesting that the antiplatelet effect of these compounds is mainly due to an inhibitory effect on thromboxane formation. Compounds 11 and 12 also had potent vasorelaxant effects in rat thoracic aorta. Phenylephrine‐ and high‐K+‐induced 45Ca2+ influx in aorta were both inhibited by the selected compound 11. This result indicates that the inhibitory effect of 11 on the contractile response caused by high‐K+ medium and noradrenaline (norepinephrine) in rat thoracic aorta is mainly due to inhibition of Ca2+ influx through both voltage‐dependent and receptor‐operated Ca2+ channels.

Comparison of Phorbol Ester-induced Responses in Rabbit and Human Platelets and Difference in Shape Change.

Phorbol 12,13-dibutyrate (PDBu) induced aggregation and ATP release of washed human and rabbit platelets in a concentration-dependent manner. The EC(50) for PDBu-induced aggregation of washed human and rabbit platelets were 67.6 ± 3.3 and 32.7 ± 5.9 nM, respectively. PDBu and l-oleoyl-2-acetylglycerol (OAG) also caused a shape change in rabbit platelets detected by microscopic and turbidimetric techniques. Both 20K and 47K proteins of rabbit platelets were phosphorylated by PDBu treatment. All the PDBu-induced responses of human and rabbit platelets were blocked by a protein kinase C inhibitor, staurosporine, in a concentration-dependent manner. In both human and rabbit platelets, PDBu induced no phosphoinositide breakdown, caused no increase of [Ca(2+)](f) and induced no formation of TxB(2). Indomethacin, BN52021, nitroprusside and cytochalasin B did not inhibit, whereas verapamil, prostaglandin E, and EGTA inhibited PDBu-induced aggregation of washed human and rabbit platelets. Apyrase and creatine phosphate/creatine phosphokinase inhibited PDBu-induced aggregation, but did not affect the shape change or 20K myosin light chain phosphorylation of rabbit platelets. In Ca(2+)-free Tyrodes solution containing 1 mM EGTA, PDBu induced a shape change in rabbit platelets and this effect was inhibited by staurosporine and cytochalasin B. It is concluded that PDBu and OAG induce a shape change in rabbit platelets probably through phosphorylation of 20K myosin light chain.