多酸化合物药物化学的研究进展

系统论述了当前国内外对多酸化合物药物特性的研究工作新进展 ,特别对多金属氧酸盐的抗艾滋病、抗肿瘤、抗病毒、抗风湿等化学理论进行了论述 ,同时对多金属氧酸盐的药物特点。

低分子量肝素治疗的临床实验监测

目的 进一步探讨活化的部分凝血活酶时间 (APTT)对低分子量肝素 (LMWH)治疗的实验监测价值。方法 对LMWH治疗前及治疗后的 2 6 2份血浆标本进行了APTT和抗 Ⅹa的测定 ,观察不同抗 Ⅹa活性水平的LMWH对APTT的影响。结果 当LMWH的抗 Ⅹa活性在 0 .8～ 1.2U/ml时 ,APTT中度延长 ,当LMWH的抗 Ⅹa活性大于 1.2U/ml时 ,APTT明显延长。结论 当使用治疗剂量的LMWH ,特别是剂量≥ 1mg/kg体重时 ,须常规监测APTT作为安全用药的实验检测指标。

Sulfated polysaccharides with antioxidant and anticoagulant activity from the sea cucumber Holothuria fuscogliva

Sea cucumber is a traditional nutritional food and medicinal resource with many bioactive components in China. Holothuriafuscogliva is a big sea cucumber with a rich of bioactive polysaccharides. To investigate the bioactivities of the polysaccharides from sea cucumber H. fuscogliva, we prepared the sulfated polysaccharides （HfP） from sea cucumber H. fuscogliva using a protease hydrolysis method. Antioxidant activities of HfP were investigated, including hydroxyl radical scavenging activity and superoxide radical scavenging activity. And, the anticoagulant activities of HfP were studied, including the activated partial thromboplastin time （APTT）, prothrombin time （PT） and thrombin time （TT）. The average molecular weight was 1 867.1 Da, with a sulfate content of 20.7%. In addition, the molar ratio of monosaccharide composition of HfP was Man： Rha： Glc A： Glc： Gal： Xyl： Fuc=0.083 6： 0.437： 0.134： 0： 1.182： 0.748： 1. It had a strong antioxidant activity, the hydroxyl and superoxide radical scavenging activity ECs0 of HfP was 3.74 and 0.037 mg/mL, respectively. It also showed a good anticoagulant activity in our study. The APTT of HfP was much higher than that of heparin sodium, and the PT and TT of HfP was close to that ofheparin sodium at a low concentration. Therefore, HfP shows a good antioxidant and anticoagulant activity and it may become a potential candidate of the natural antioxidant and anticoagulant and will have a good application future in health product or medicine industry.

PEGylation of Hirudin and Analysis of Its Antithrombin Activity in vitro

Hirudin is the most anticoagulant drug found in nature, but its short serum half-life significantly inhibits its clinical anpplication. The PEGvlation of hirudin, the most promising anticoagulant drug, was performed in this paper. The optimal reaction conditions for PEG ylated hirudin were investigated, wh.en the PEGylation react, on.wasconducted under 4℃ after 10h, in the borate buffer at pH 8.5 .with the molar ratio 230 ： 1 of PEG to hirudin, a higher modification extent was achieved. Finally, the bioactivity of PEGylated hirudin was measured in vitro.Compared with unmodified hirudin, 26% of anti-thrombin activity was retained.

Design, Preparation and in vitro Bioactivity of Mono-PEGylated Recombinant Hirudin

Hirudin, the most potent inhibitor of thrombin found in nature, has a short half-life in serum, which sig-nificantly limits its clinical application as an anticoagulant. Recently, PEGylation has been commonly used as an effective method to prolong its half-life in serum. In contrast to the nonspecific pEGylation under basic conditions that targets lysine residues randomly, PEGylation sites under mildly acidic conditions preferably targets histidine residues, and there is only one histidine residue at 51 in r-hirudin; therefore, succinimidyl carbonyl methoxy poly-ethylene glycol （SC-mPEG, 20000） was attached to r-hirudin at mildly acidic pH to favor the formation of mono-PEGylated r-hirudin. The reaction mixture with high mono-PEGylated ratio was easily separated by a one-step ion-exchange chromatographic （IEC） procedure. Approximately 79.71% of the mono-PEGylated r-hirudin was PEGylated at His51, which showed that the acidic PEGylation operation prevented the PEGylation of active center （Lys47） of r-hirudin in pdnciple. Mono-PEGylated.product with purity higher than. 95% was obtained as the pre-dominant product, and 34% of the anticoagulant activity was retained in vitro. The staining method for sodium dodecyl sulfate polyacrylamide gel electrophoresis （SDS-PAGE） was improved to obtain perfect electrophoretic pattern in less than 5min. More accurate molecular weight was deduced due to the use of PEGs as molecular weight standards.

Study on Antithrombotic and Antiplatelet Activities of Low Molecular Weight Fucoidan from Laminaria japonica

The antithrombotic and antiplatelet effects of two fucoidan fractions with low molecular weight and different sulfate content from Laminaria japonica were compared in order to examine the influence of chemical character on their antithrombotic activity and the possible mechanism. Both LMW fucoidan fractions exhibited favorable antithrombotic activity in an Fecl3-induced arterial thrombosis. The antithrombotic activity of LMW fucoidan was related with decrease of TXB2 and whole blood viscosity and hematocrit. LMW fucoidan showed a correlation between anticoagulant, antiaggregant and antithrombotic effects in vivo. For LMW fucoidan, antithrombotic activity required high dose of 5-10 nmol kg-1, concomitantly with increase in anticoagulant activity and inhibition of platelet aggregation. Administration of LMW fucoidan significantly promoted the 6-keto-PGF1α content and decreased the TXB2 content, indicating its inhibition of tissue factor pathway and regulation of metabolism of arachidonic acid. By comparison, highly sulfated fucoidan LF2 with Mw 3900 seemed to be a more suitable choice for antithrombotic drug for its antithrombotic activity accompanied with specific inhibitory activity on platelet aggregation, low anticoagulant activity and low hemorrhagic risk in vivo.

In-vitro anticoagulant activity of fucoidan derivatives from brown seaweed Laminaria japonica

Fucoidan, a group of sulfated heteropolysaccharides, was extracted from Laminaria japonica, an important economic alga species in China. The anticoagulant activity of fucoidan and its derivatives (including sulfated, phosphorylated, and aminated fucoidan) was examined using in-vitro anticoagulant systems. The correlation between chemical variations within the fucoidan group and anticoagulant activity was determined. The in-vitro anticoagulant properties of fucoidan and its derivatives were determined by measuring activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). The results indicate anticoagulant activity in all samples using APTT and TT assays; however, only the fucoidan derivatives affected the PT assay. Thus, the fucoidan derivatives were able to inhibit both intrinsic and extrinsic blood coagulants. Fucoidan (FPS) and its derivatives presented better anticoagulant activity than low molecular weight fucoidan (DFPS) and its derivatives, suggesting that molecular weight and proper conformation are contributing factors for anticoagulant activity of polysaccharides. Amino groups have a positive charge and can thus change the charge density of fucoidan. Accordingly, among the tested samples, aminated fucoidan (NF) was the most active reflecting the importance of charge density for anticoagulant activity. Available data obtained using in-vitro models suggest that the sulfate content, sulfate/total-sugar ratio, molecular weight, and the substituted group of fucoidan are important factors for anticoagulant activity but that the influence of sulfate, phosphate and amino groups on anticoagulant activity was different.

Anticoagulation early after mechanical heart valve replacement

Objective： To explore the changes of coagulation activity and the characters of anticoagulation early after mechanical heart valve replacement. Methods： All patients only took warfarin orally for anticoagulation. The predicted international normalized ratio （INR） was 1.5 to 2.0. Several coagulation markers were monitored early after valve replacement. Complications associated with anticoagulation were recorded and analyzed. The patients were divided into three groups based on the number and position of mechanical valve prothesis, including group M （mitral valve replacement）, group A （aortic valve replacement） and group D （mitral and aortic valve replacement）.Comparison was made between the three groups. Results： Three events of mild cerebral embolism and five events of mild bleeding occurred during the early postoperative period. One patient suffered from mild cerebral embolism on the 4th day after operation, accompanied by large volume of pericardial drainage. Two patients with bleeding had lower INRs than predicted range. However, INR in one patient with mild cerebral embolism was in the predicted range. There was no significant difference in thrombo time （TT）, activated partial thromboplastin time （APTT） and 1NR on the 3rd day after operation compared to those before operation; meanwhile, plasma fibrinogen （FIB） concentration was higher than that before operation （P〈0.05）. 1NR had no significant changes on the 2nd day after the beginning of anticoagulation compared to that before operation; however, 1NR was significantly elevated on the 4th day （P〈0.05）. Warfarin doses and INRs were similar among the three groups, but FIB concentrations in plasma were higher in groups M and D than in group A （P〈0.01）. Conclusion： Hypercoagulabale state exists early after mechanical heart valve replacement. When anticoagulation begins is determined by the change of coagulation markers, not by the volume of chest or pericardial drainage. INR can not accurately reflect the coagulation state sometimes, especially during the first 3 days after anticoagulation. The number and position of mechanical valve prothesis could affect coagulation state. Therefore, anticoagulation therapy should be regulated accordingly.

Chemical Characteristics and Anticoagulant Activities of Two Sulfated Polysaccharides from Enteromorpha linza (Chlorophyta)

Two sulfated polysaccharides, designated MP and SP, were extracted from the marine green alga Enteromorpha linza using hot water and then purified using ion-exchange and size-exclusion chromatography. The anticoagulant activities of MP and SP were examined by determination of their activated partial thromboplastin time （APTT）, thrombin time （TT） and prothrombin time （PT） using human plasma. Results showed that MP and SP were composed of abundant rhamnose with small amounts of xylose and glucuronic acid, whereas SP also contained a small amount of galactose. Approximate molecular weights of MP and SP were 535 and 502 kDa, respectively. As compared with SP, MP had higher contents of sulfate ester （19.0%） and uronic acid （14.9%）. The MP mainly consisted of （1→4）-linked rhamnose residues with partially sulfated groups at the C-3 position, and small amounts of （1→3, 4）-linked rhamnose, （1→2,4）-linked rhamnose, （1→4）-linked glucuronic acid and （1→4）-linked xylose residues. The SP contained abundant （1→4）-linked rhamnose with minor amounts of （1→3）-linked rhanmose, （1→3, 4）-linked rhamnose, （1→2, 4）-linked rhanmose, （1→4）4inked glucuronic acid, （1→4）-linked xylose, and （1→3）-linked galactose residues. The sulfate groups were mainly located at C-3 of （1→4）-linked rhamnose residues. Both MP and SP, in particular the former, effectively prolonged APTT and TT. This work demonstrates that MP and SP have unique structural characteristics distinct from those of other sulfated polysaccharides from Enteromorpha. The MP is a potential source of anticoagulant, and the difference in anticoagulant activities of the two sulfated polysaccharides is directly linked to the discrepancy of their chemical features.

Screening of solanum surrattense for antibacterial,antifungal,phytotoxic and haemagglutination

OBJECTIVE： Plants produce a variety of useful bio- active materials that have been used to cure differ- ent ailments of human beings. With the same idea in mind, the crude methanolic extract and various fractions of Solanum surrattense were screened for antibacterial, antifungal, phytotoxic and heamag- glutination activities. METHODS： Standardized assays were followed for the determination of antibacterial, antifungal phy- totoxic and heamagglutination activity. RESULTS： The results of the antibacterial showed that crude methanolic extract was significantly ac- tive against Staphylococcus aureus （86%） The n- hexane fraction showed good activity against Pseu- domonas aerogenosa （66.6%） and Bacillus subtilus （66.6%）. The crude methanolic extract and various fractions were inactive against all test fungi. The crude methanolic extract, n-hexane, CHCI3 and aqueous fractions showed moderate phytotoxic ac- tivities of 46.67%, 40.00%, 33.34% and 33.34% re- spectively at 1000 pg/mL. The crude methanolic ex- tract and various fractions S. surrattense were un- able to aqqlutinate RBCs of the human blood indi-cating that this species lack phytolectins. CONCLUSION： The test sample showed significant antibacterial activity, no antifungal and heamagglu- tination activity while moderate phytotoxic was ob- served against Lemna minor L.

Deciphering structural and functional roles of disulfide bonds in decorsin

Decorsin, an antagonist of integrin glycoprotein IIb/IIIa, contains Arg-Gly-Asp （RGD） sequence and three disulfide bridges. The function of RGD sequence has already been well defined, but the roles of conserved disulfide bonds in antihemostatic proteins still remain unclear. Herein we use the fusion expression and characterization of mutant decorsin to study the func- tions of disulfide bonds in protein structure, stability and biological activity. The purified protein shows an apparent inhibition of activity to platelet aggregation induced by ADP with IC50 of 500 nM. The removal of cys7-cysl5 （from cysteine to serine） at the N-terminal causes a thirty-fold decrease of the inhibition activity with IC50 of 15 ~tM, whereas the mutation of cys22-cys38 at the C-terminal completely impairs the biological activity of decorsin. The overall secondary and tertiary struc- tures of decorsin are disrupted inevitably without disulfide bonds. Using a domain insertion mutation, the retaining of RGD loop and the adjacent disulfide bond produces a week antihemostatic activity of decorsin. This reveals that the overall structure of decorsin stabilized by the three conserved disulfide bridges is cooperative for antihemostatic function. Our study on the ef- fect of disulfide bonds together with RGD-sequence on the protein function is helpful for structure-based drug design of an- tithrombotic research.

Antifungal, phytotoxic and hemagglutination activity of methanolic extracts of Ocimum basilicum

OBJECTIVE: To report some of the pharmacological features of the medicinal plant Ocimum basilicum.METHODS: In the current studies, Antifungal activity of crude methanolic fraction of Ocimum basilicum was determined against eight pathogenic fungal strains using tube dilution assay. The methanolic fraction was also investigated for phytotoxic and hemagglutination activity.RESULTS: Of the eight strains investigated only Candida albicans and Curvilaria lunata were found to be least affected by plant extract while the rest were significantly inhibited. Moderate phytotoxic activity was observed against lemna minor. Hemagglutination activity showed absence of phytolectins and hence no agglutination of erythrocytes.CONCLUSION: The crude extract of Ocimum basilicum has significant properties against fungi and phytotoxic substances.