The pharmacological actions of murexine (urocanylcholine)

Murexine or urocanylcholine is a naturally occurring choline ester of urocanic acid which was found in very large amounts in the hypobranchial body of Murex trunculus and other prosobranchiate molluscs. In vertebrates and invertebrates, it was found to possess marked neuromuscular blocking and nicotinic actions, but was almost devoid of muscarinic effects. The blocking action of murexine was considered, on the basis of experimental and clinical evidence, to be of the “depolarizing” type. It was weaker than, but qualitatively very similar to, that produced by suxamethonium. The nicotinic action of murexine was stronger than that of suxamethonium in both experimental animals and human beings.     

The inhibition of rat and guinea pig cholinesterases by anionic hydrolysis products of methylphosphonic difluoride (difluoro)

Methylphosphonic difluoride (difluoro) and its hydrolysis products, methylphosphonofluoridate (MF) and fluoride, were examined for cholinesterase-inhibiting ability in rats and guinea pigs by both inhalation and intraperitoneal exposure routes. In vivo inhibition was compared to in vitro inhibition. In the whole animal, MF was the active chemical, but in vitro under special conditions, difluoro was more potent than MF and fluoride. Rat and guinea pig blood cholinesterase were equally sensitive to inhibition by MF, but only the guinea pig displayed cholinergic signs leading to death from MF toxicity. Data imply that MF is responsible for the cholinesterase inhibition resulting from exposure to DF vapor. MF may be the first example of a moderately strong acid shown to inhibit cholinesterase and cause death from cholinergic effects.     

Some pharmacological properties of murexine (urocanoylcholine)

Murexine (urocanoylcholine, [2-β-imidazol-4(5)-ylacryloyloxyethyl] trimethylammonium bromide) has been shown to possess ganglion stimulating and neuromuscular blocking actions in cat, dog and rat. The blockade has been shown to be of the depolarizing type both on the basis of the resemblance of the pharmacological properties of the substance to that of known depolarizing blocking agents, and also directly by recording the depolarization produced in the endplate region of the gracilis muscle of the rat.     

Toxicological evaluation of neoagarooligosaccharides prepared by enzymatic hydrolysis of agar

Agar, a heterogeneous polymer of galactose, is the main component of the cell wall of marine red algae. It is well established as a safe, non-digestible carbohydrate in Oriental countries. Although neoagarooligosaccharides (NAOs) prepared by the hydrolysis of agar by β-agarase have been reported to exert various biological activities, the safety of these compounds has not been reported to date. For safety evaluation, NAOs containing mainly neoagarotetraose and neoagarohexaose were prepared from agar by enzymatic hydrolysis using β-agarase DagA from Streptomyces coelicolor. Genotoxicity tests such as the bacterial reverse mutation assay, eukaryotic chromosome aberration assay, and in vivo micronucleus assay all indicated that NAOs did not exert any mutational effects. The toxicity of NAOs in rat and beagle dog models was investigated by acute, 14-day, and 91-day repeated oral dose toxicity tests. The results showed that NAO intake of up to 5,000 mg/kg body weight resulted in no significant changes in body weight, food intake, water consumption, hematologic and blood biochemistry parameters, organ weight, or clinical symptoms. Collectively, a no-observed-adverse-effect level of 5,000 mg/kg body weight/day for both male and female rats was established for NAO. These findings support the safety of NAO for possible use in food supplements and pharmaceutical and cosmetic products.     

Development of quantitative extraction method of amygdalin without enzymatic hydrolysis from tonin(Persicae Semen) by high performance liquid chromatography

Tonin(Persicae Semen) is the herb medicine that contains amygdalin as a major ingredient. Amygdalin in water is decomposed into benzaldehyde, HCN, and glucose by emulsin, a hydrolysis enzyme in tonin. A useful and practical method for the optimum extraction condition of amygdalin without enzymatic hydrolysis is required. The extraction yield of amygdalin of natural formula tonin was 0.1% from crude powders, 1.4% from small pieces, 3.5% from half pieces and 2.4% from whole pieces. The extraction yield of amygdalin of outer shell-eliminated tonin was 0.3% from crude powders, 1.4% from small pieces, and 3.5% from half pieces and whole pieces respectively. The extraction yield of amygdalin was most high when using the size larger than half.     

酶解法与LC-MS-MS相结合研究灯盏乙素在健康人体内的药代动力学

目的建立β-葡萄糖醛酸苷酶解法与LC-MS-MS法相结合测定人体血浆中灯盏乙素的苷元,研究健康男性单剂量口服灯盏花素分散片的药代动力学。方法血浆样品经β-葡萄糖醛酸苷酶水解,甲醇蛋白沉淀,色谱柱为Agilent ZORBAX SB C18(2.1 mm×150 mm,5μm),运用乙腈-甲醇-水洗脱,多反应监测(MRM)灯盏乙素苷元([M-H]-,m/z285.0/136.8)和内标槲皮素([M-H]-,m/z 301.1/120.8)。12名健康男性单剂量口服灯盏花素分散片120 mg后,采用该方法测定血浆中灯盏乙素苷元,使用DAS 1.0软件处理数据,计算药代动力学参数。结果灯盏乙素苷元在4.01~513.38μg·L-1范围内线性良好,日内日间精密度小于7.22%,提取回收率大于84.23%。12名健康男性单剂量口服灯盏花素分散片120 mg后,以灯盏乙素苷元为检测对象的主要药动学参数为:Cmax(μg·L-1):159.97±58.14;AUC(0-19)(μg·L-1·h):1151.37±279.80;AUC(0-∞)(μg·L-1·h):1194.13±264.51;Tmax(h):6.33±1.67;T1/2(h):2.83±0.60。结论建立的酶解与LC-MS-MS相结合分析方法准确灵敏,适用于灯盏乙素人体内的药代动力学研究。     

Kinetics and mechanism of enzymatic hydrolysis of pivampicillin monolayers

A study of the enzymatic hydrolysis of pivampicillin (an insoluble penicillin) extended as a monolayer on the aqueous interface at a constant surface pressure has been performed. Penicillinase promotes intensive hydrolysis of the pivampicillin monolayers, inducing their solubility. However, no action was observed with dog liver esterase. The hydrolytic process, which was dependent on the film surface pressure and on the quantity of the injected enzyme, is of the Michaelis-Menten type in two dimensions.     

响应面法优化硫酸软骨素提取的酶解工艺

目的以猪喉软骨为原料,提取硫酸软骨素,优化酶解工艺条件。方法采用碱提-酶解-醇沉的方法提取硫酸软骨素,在单因素试验的基础上,通过响应面分析优化酶解工艺。结果酶解最佳工艺组合为:胰酶浓度1.0%、pH值8.6、酶解温度46℃、酶解时间2.8 h。结论采用上述组合,以氨基葡萄糖含量为指标,氨基葡萄糖含量达25.94%。研究结果具有工业应用价值。     

Monitoring of enzymatic hydrolysis of penicillin G by pyrolysis-negative ion mass spectrometry

A pyrolysis-negative ion mass spectrometry (Pyr-NIMS) is used for the monitoring of enzymatic hydrolysis of penicillin G (Pen G) to 6-aminopenicillanic acid (6-APA) and phenyl acetic acid (PAA). The high sensitivity and rapid response time of Pyr-NIMS allow its application to the simultaneously determination of these compounds. The mass to charge (m/z) values of 262, 156 and 135 of Pen G, 6-APA and PAA respectively, are used for the quantitative measurements by selected ion monitoring (SIM). The limit of detection (LOD), linearity and relative standard deviation (n=5) are 10 ng ml(-1), 100 ng ml(-1)-1000 mg ml(-1) and 1.5%, respectively The results are compared with high performance liquid chromatography (HPLC). An important advantage of the presented analytical system is the high linearity of signals without preliminary separation and recalibration. The main and interactive effects of pH, temperature and concentration of Pen G for enzymatic hydrolysis of Pen G are studied. Optimize conditions of pH (8), temperature (28 degrees C) and concentration of Pen G (12% w/v) in real samples are obtained.     

Kinetics of the acidic and enzymatic hydrolysis of benazepril HCl studied by LC.

A reversed-phase high-performance liquid chromatographic (HPLC) method was developed and validated for the kinetic investigation of the chemical and enzymatic hydrolysis of benazepril hydrochloride. Kinetic studies on the acidic hydrolysis of benazepril hydrochloride were carried out in 0.1 M hydrochloric acid solution at 50, 53, 58 and 63 degrees C. Benazepril hydrochloride appeared stable in a pH 7.4 phosphate buffered solution at 37 degrees C and showed susceptibility to undergoing in vitro enzymatic hydrolysis with porcine liver esterase (PLE) in a pH 7.4 buffered solution at 37 degrees C. Benazeprilat appeared to be the major degradation product in both (chemical and enzymatic) studies of hydrolysis. Statistical evaluation of the proposed HPLC methods revealed their good linearity and reproducibility. Relative standard deviation (R.S.D.) was less than 4.76, while detection limits for benazepril hydrochloride and benazeprilat were 13.0 x 10(-7) and 9.0 x 10(-7) M, respectively. Treatment of the kinetic data of the acidic hydrolysis was carried out by non-linear regression analysis and k values were determined. The kinetic parameters of the enzymatic hydrolysis were determined by non-linear regression analysis of the data using the equation of Michaelis-Menten.     

牡蛎酶解工艺的研究

目的 获得最佳牡蛎蛋白的酶解工艺及以期提高酶解液水解度和蛋白回收率.方法 综合考虑蛋白回收率、水解度和腥、苦味及澄清度,进行最佳酶的筛选;正交试验确定酶的最佳水解条件;以水解度和蛋白回收丰为指标,研究热处理、超声处理和微波处理对酶解的影响.结果 与结论菠萝蛋白酶比较适合牡蛎蛋白质的水解,其最佳条件为:pH6,温度55℃,料水比为1:3,加酶量为800U/g,酶解时间4h,在此条件下酶解产物水解度为29.86%,蛋白回收率为67.55%;热处理、超声处理和微波处理不利于牡蛎蛋白的水解.