Design, synthesis and in vitro and in vivo antitumor activities of novel beta-carboline derivatives

To further our SAR study on the chemistry and antitumor activity/neurotoxicity of beta-carboline alkaloids, several series of beta-carboline derivatives with various substituents were designed and synthesized from the starting material l-tryptophan on the basis of harmine chemical structure. Cytotoxic activities of these compounds were investigated in vitro. The results showed that some beta-carboline derivatives had significant cytotoxic activities against human tumor cell lines. Among all the synthesized beta-carboline derivatives, the compounds 27, 28 and 32, having a benzyl substituent at both position-2 and 9, respectively, were found to be the most potent compounds with IC50 value lower than 50 microM against all human tumor cell lines examined. Acute toxicities and antitumor activities of the selected beta-carboline derivatives in mice were also evaluated. The results demonstrated that a benzyl substituent at position-2 increased the antitumor activity as well as acute toxicity significantly. However an (ethoxycarbonyl)amino substituent at position-3 reduced the acute toxicity as well as antitumor activity remarkedly. These data suggested that (1) the antitumor potencies of beta-carboline derivatives were enhanced by the introduction of benzyl substituent into the position-2; (2) the acute toxicity of beta-carboline derivatives reduced dramatically by the introduction of an appropriate substituent into the position-3 and 9; (3) the beta-carboline structure might be an important basis for the design and synthesis of new antitumor drugs with significant antitumor activity and low toxicity.     

Diarrhea reduces the rates of cardiac protein synthesis in myofibrillar protein fractions in rats in vivo

Although chronic diarrhea affects heart function and morphology, the pathogenic mechanisms are unknown. It was our hypothesis that diarrhea imposes metabolic stress to inhibit the synthesis of new contractile proteins. To test this hypothesis, we investigated the effects of lactose-induced diarrhea in rats. The groups were: 1) freely fed controls, 2) rats with lactose-induced diarrhea or 3) pair-fed rats. After 1 wk, hearts from the rats were subjected to subcellular fractionation techniques to isolate the major protein fractions, including myofibrillar proteins. The rates of protein synthesis were measured with concomitant assay of cardiac composition and plasma analytes. In comparison with the control group, diarrhea induced the following changes (P < 0.05): a decrease in heart weight, reduced RNA and mixed protein contents and a reduction in the fractional rate of mixed protein synthesis. There was a reduction in the content of all protein fractions. The fractional synthesis rate was reduced only for the myofibrillar fraction. Plasma insulin-like growth factor-I, but not corticosterone, was reduced. Plasma cholesterol and triglyceride concentrations were also reduced. In comparison with the pair-fed group, diarrhea induced the following changes (P < 0.05): a reduction in heart weight and fractional rate of mixed protein synthesis, reduced myofibrillar absolute synthesis rate and increased sarcoplasmic/myofibrillar fractional synthesis rate ratio. Plasma bicarbonate, triglyceride and urea concentrations were reduced, with an increase in albumin. Diarrhea impaired cardiac biochemistry, including a reduction in protein content and synthesis. A substantial proportion of these changes is due to anorexia, but the selective reduction in the synthesis of contractile proteins is a feature exclusive to the diarrhea group and may be due to reductions in plasma insulin-like growth factor-I.     

A new nitrosyl ruthenium complex: synthesis, chemical characterization, in vitro and in vivo antitumor activities and probable mechanism of action

This study describes the synthesis of a new ruthenium nitrosyl complex with the formula [RuCl₂NO(BPA)] [BPA = (2-hydroxybenzyl)(2-methylpyridyl)amine ion], which was synthesized and characterized by spectroscopy, cyclic voltammetry, X-ray crystallography, and theoretical calculation data. The biological studies of this complex included in vitro cytotoxic assays, which revealed its activity against two different tumor cell lines (HeLa and Tm5), with efficacy comparable to that of cisplatin, a metal-based drug that is administered in clinical treatment. The in vivo studies showed that [RuCl₂NO(BPA)]is effective in reducing tumor mass. Also, our results suggest that the mechanism of action of [RuCl₂NO(BPA)] includes binding to DNA, causing fragmentation of this biological molecule, which leads to apoptosis.     

氟对体内和体外酶活性的影响

目的 探讨氟对抗氧化活性的影响。方法 随机选择氟暴露工人20名、健康的非氟暴露工人15名,测量尿氟含量,外周血AKP、SOD、GSH－Px活性及Cu、Zn、Ca、Mg离子含量。另随机选择健康非氟暴露者10名,抽取静脉血,分离血清,均加入氟化钠,使反应体系中氟浓度分别达到0、2．63、10．52和21．04mmol/L;室温下反应30min后,测定AKP、SOD和GSH－Px活性。结果 氟暴露工人尿氟、血清AKP、全血GSH－Px活性高于非氟暴露者,而血精SOD活性和Cu、Zn、Ca、Mg含量低于非氟 暴露者。体外加氟实验显示,氟浓度21．04mmol/L组AKP活性高于对照组,而SOD和GSH－Px活性低于对照组。结论 氟可致抗氧化酶活性改变。     

Vitamin B-6 deficiency in rats reduces hepatic serine hydroxymethyltransferase and cystathionine beta-synthase activities and rates of in vivo protein turnover, homocysteine remethylation and transsulfuration

Vitamin B-6 deficiency causes mild elevation in plasma homocysteine, but the mechanism has not been clearly established. Serine is a substrate in one-carbon metabolism and in the transsulfuration pathway of homocysteine catabolism, and pyridoxal phosphate (PLP) plays a key role as coenzyme for serine hydroxymethyltransferase (SHMT) and enzymes of transsulfuration. In this study we used [(2)H(3)]serine as a primary tracer to examine the remethylation pathway in adequately nourished and vitamin B-6-deficient rats [7 and 0.1 mg pyridoxine (PN)/kg diet]. [(2)H(3)]Leucine and [1-(13)C]methionine were also used to examine turnover of protein and methionine pools, respectively. All tracers were injected intraperitoneally as a bolus dose, and then rats were killed (n = 4/time point) after 30, 60 and 120 min. Rats fed the low-PN diet had significantly lower growth and plasma and liver PLP concentrations, reduced liver SHMT activity, greater plasma and liver total homocysteine concentration, and reduced liver S-adenosylmethionine concentration. Hepatic and whole body protein turnover were reduced in vitamin B-6-deficient rats as evidenced by greater isotopic enrichment of [(2)H(3)]leucine. Hepatic [(2)H(2)]methionine production from [(2)H(3)]serine via cytosolic SHMT and the remethylation pathway was reduced by 80.6% in vitamin B-6 deficiency. The deficiency did not significantly reduce hepatic cystathionine-beta-synthase activity, and in vivo hepatic transsulfuration flux shown by production of [(2)H(3)]cysteine from the [(2)H(3)]serine increased over twofold. In contrast, plasma appearance of [(2)H(3)]cysteine was decreased by 89% in vitamin B-6 deficiency. The rate of hepatic homocysteine production shown by the ratio of [1-(13)C]homocysteine/[1-(13)C]methionine areas under enrichment vs. time curves was not affected by vitamin B-6 deficiency. Overall, these results indicate that vitamin B-6 deficiency substantially affects one-carbon metabolism by impairing both methyl group production for homocysteine remethylation and flux through whole-body transsulfuration.     

Comparison of dihydrofolate reductase activities for folic acid in pigs and rats using in vivo and in vitro evaluation techniques

The activity of dihydrofolate reductase (DHFR) for folic acid (PteGlu) was evaluated in pigs by in vivo and in vitro experiments. The results were compared with those of rats. Since bile secretion of reduced folates reflects the activity of DHFR for PteGlu in the body, the bile secretion rates of reduced folates including tetrahydrofolate (H4PteGlu), 5-methyltetrahydrofolate, 5,10-methylenetetrahydrofolate, and 10-formyltetrahydrofolate were determined by using high-performance liquid chromatography with electrochemical detection, after the intravenous injection of PteGlu at 1 mg/kg body weight to pigs and rats. Although the PteGlu injection raised the total secretion rate of reduced folates. the total increased amount of reduced folates secreted into bile from 0 h to 2.5 h after PteGlu injection in pigs was about one-tenth of that in rats. The enzyme kinetics of DHFR for PteGlu was examined at the physiological condition (pH 7.4 and 3 7 degrees C). Affinity chromatography was applied to liver homogenates of pigs and rats to obtain DHFR. The final product of the enzyme reaction, H4PteGlu, was measured. The Km for pig enzyme was similar to that for rat enzyme, whereas the Vmax for the pig enzyme was less than 1/5 of that for the rat's. The comparison of the ratio of Vmax to Km between pig and rat enzymes suggests that PteGlu is a much less efficient substrate for pig liver DHFR. In short, these results from in vivo and in vitro experiments suggest that the role of DHFR for PteGlu in pigs is physiologically much less important than that in rats.     

Preparation and antitubercular activities in vitro and in vivo of novel Schiff bases of isoniazid

Structural modification of the frontline antitubercular isonicotinic acid hydrazide (INH) provides lipophilic adaptations (3–46) of the drug in which the hydrazine moiety of the parent compound has been chemically blocked from the deactivating process of N²-acetylation by N-arylaminoacetyl transferases. As a class, these compounds show high levels of activity against Mycobacterium tuberculosis in vitro and in tuberculosis-infected macrophages. They provide strong protection in tuberculosis-infected mice and have low toxicity. With some representatives of this class achieving early peak plasma concentrations approximately three orders of magnitude above minimum inhibitory concentration, they may serve as tools for improving our understanding of INH-based treatment modalities, particularly for those patients chronically underdosed in conventional INH therapy.     

Antispermatogenic effect of embelin, a plant benzoquinone, on male albino rats in vivo and in vitro

Embelin, the active principle of the seeds of Embelia ribes Burm, has been isolated and the purity established. Daily subcutaneous administration of the compound at a dose of 20 mg/kg body weight to male albino rats for 15 or 30 days revealed an inhibition of: a) epididymal motile sperm count, b) fertility parameters such as pregnancy attainment and litter size, and c) the activities of the enzymes of glycolysis and energy metabolism. These changes were reversible, as seen after 15 and 30 days of recovery. Addition of embelin to epididymal sperm suspensions caused a dose- and duration-dependent inhibition of spermatozoal motility and the activities of the enzymes of carbohydrate metabolism. Light and scanning electron microscopy showed that both in vivo and in vitro treatment with the drug causes profound morphological changes in spermatozoa such as: a) decapitation of the spermatozoal head, b) discontinuity of the outer membranous sheath in the mid-piece and the tail region, and c) alteration in the shape of the cytoplasmic droplet in the tail.     

Serum alpha-tocopherol, lipids, potassium, and creatine phosphokinase in normal and malabsorption patients.

Serum alpha-tocopherol, lipids, potassium, and creatine phosphokinase levels were measured in 20 adult male control patients and eight malabsorption patients. The malabsorption group had significantly lower serum alpha-tocopherol levels than the control group. This change was independent of serum total lipid levels that were not significantly different among the two groups. Serum potassium and creatine phosphokinase levels that are normally used to assess muscle pathology in man did not correlate with serum alpha-tocopherol levels in either the control of the malabsorption groups. Body mass indices that are directly related to adiposity of the individuals were calculated. Among the control patients, there was a significant increase in serum alpha-tocopherol and serum total lipids with increase in body mass index. Similar correlations did not exist in the malabsorption group. In the latter group serum alpha-tocopherol levels may have reached low enough levels to be independent of factors such as adiposity and serum total lipids.     

Fatty acyl amide derivatives of doxorubicin: synthesis and in vitro anticancer activities

Doxorubicin is extensively used in anticancer therapy. Doxorubicin is highly hydrophilic, has short half-life, and its use is associated with severe side effects at high doses. Fatty acyl amide derivatives of doxorubicin were synthesized with the expectation to improve the lipophilicity and anticancer activity of the drug. The lipophilicity was enhanced with the increase in chain length of fatty acyl moiety. Conjugation of 4′-amino group with fatty acids through an amide bond reduced the anticancer activity in leukemia, breast, ovarian, and colon cancer cell lines, suggesting that the presence of free amino group is required for anticancer activity of doxorubicin. Dodecanoyl-doxorubicin derivative was consistently the most effective among the synthesized derivatives and inhibited the proliferation of colon (HT-29) and ovarian (SK-OV-3) cancer cells by 64% and 58%, respectively, at a concentration of 1 μM after 96 h incubation.     

Dietary genistein affects brain protein synthesis rates in ovariectomized female rats

The purpose of this study was to determine whether genistein affects the rate of brain protein synthesis in ovariectomized female rats. Experiments were conducted on three groups of 12-wk-old female rats: those in group 1 were ovariectomized to reduce the level of plasma sex hormone; those in group 2 were ovariectomized and fed diets containing 0.01% genistein; and those in group 3 were sham-operated controls. The fractional rates of protein synthesis in the brain of ovariectomized rats fed genistein were significantly greater than those in ovariectomized rats without genistein treatment. In the cerebral cortex and cerebellum, the RNA activity [g protein synthesized/(g RNA.d)] significantly correlated (r > 0.86, P < 0.001) with the fractional rate of protein synthesis. The RNA concentration (mg RNA/g protein) was not related to the fractional rate of protein synthesis in any organ. The results suggest that the addition of genistein to the diet of ovariectomized female rats is likely to increase the rate of protein synthesis in the brain, and that RNA activity is at least partly related to the fractional rate of brain protein synthesis.