用自旋捕捉技术检测争光霉素A6产生的活泼自由基

本文用自旋捕捉技术与ESR相结合的方法,研究了争光霉素A₆-Fe²⁺复合物产生的活泼自由基。结果发现用NOS自旋捕捉剂可检测到该体系所产生的超氧阴离子自由基。在水溶剂中用PBN自旋捕捉到了羟基自由基。根据PBN-OH自旋加合物在水溶剂和甲醇溶剂中的超精细分裂常数,进一步确证了羟基自由基的生成。     

用流式细胞光度术(FCM)研究争光霉素对肿瘤及正常细胞周期的影响

用流式细胞光度术发现七种争光霉素组分(A₂+B₂混合品,A₂,A₂,A₅,A₆,A₅₀₃₃和B₂)都使中国仓鼠卵巢细胞(CHO)阻断在G₂期,而对G₁→S→G₂的进行无影响。这种G₂期阻断呈剂量依赖性。不同组分的G₂阻断效应不同,在40 μg/ml时,以A₄和A₅最强,其次为A₆,A₂,A₂+B₂混合物和B₂,而A₅₀₃₃无影响。用等毒性剂量,所有组分都使小鼠艾氏腹水癌产生多倍化细胞。由于争光霉素的G₂期阻断效应与抑瘤存在着平行关系,我们认为争光霉素的抑瘤作用与癌细胞被阻断在G₂期有关。     

争光霉素A5和争光霉素A2的抗肿瘤作用与毒性研究

争光霉素是由浙江平阳分离的链霉菌产生的抗肿瘤物质,是由十多种组分组成的复合物。理化性质研究表明,争光霉素A₂、A₅、B₂等组分与日本报道的博莱霉素(Bleomycin)相应的组分A₂、A₅、B₂等相同。目前国外临床使用的博莱霉素是以A₂为主要组分的复合物。我们对A₅与A₂组分进行了比较研究,结果表明,两者的生物活性有明显差别,主要表现为:(1)对小鼠食管癌(SGA-73)的抑制作用,A₆比A₂强;(2)在小鼠食管癌组织中的浓度(微生物测定法),A₅比A₂高;(3)对小鼠肺的损害作用,A₅比A₂轻;(4)对小鼠的急性毒性,A₅比A₂低。上述研究结果提示,争光霉素A₅是具有一定特点的新抗癌药。最近,单一组分的争光霉素A₅定名为平阳霉素。     

维拉帕米增强博莱霉素A5抗癌活性的机制

本文利用流式细胞术(FCM)和动物整体水平的同位素标记药物示踪方法探讨了维拉帕米(VP)增强博莱霉素A₅(BLM)抗癌活性的机制。实验发现VP显著增强BLM对S-180和HEP-2细胞的G₂期阻断效应。VP改变了⁵⁷Co-BLM在荷瘤小鼠部分器官中的分布,增加厂该药在肿瘤中的积聚。VP增強BLM抗癌活性可能是通过增加药物在肿瘤中的积聚,增强药物的G₂期阻断效应以及其它作用实现的。     

人参总皂甙对14C-花生四烯酸在兔血小板中代谢的影响

本文报道人参总皂甙对花生四烯酸在免血小板中代谢的影响。方法采用放射薄层扫描、放射自显影及放射活性测定等同位素技术。结果表明,人参总皂甙抑制兔血小板血栓素A₂的生物合成,并呈量效关系。同时对前列腺素A₂也有抑制作用。这种抑制怍用的机理,可能是人参总皂甙抑制了血小板环氧酶和血栓素A₂合成酶的活性。     

博来霉素A6抗人体肝癌的实验研究

用克隆形成测定法检查博来霉素A₆对人肝癌、鼻咽癌和胃癌等细胞系的杀伤作用,发现对肝癌BEL-7402细胞有高度活性,半数杀伤浓度(IC₅₀)为6×10^-11mol/L。用流式细胞光度术研究表明,博来霉素A₆对肝癌BEL-7402细胞有G₂期阻断作用。在裸鼠可以耐受的剂量下,博来霉素A₆对移植性人肝癌的肿瘤生长有显著抑制作用,抑制率为75%。研究结果提示博来霉素A₆有可能用于肝癌化疗。     

不同组分的57Co(钴57)——争光霉素在肿瘤动物中的分布特性及其与抑瘤和毒性关系的探讨

⁵⁷Co标记的七种争光霉素组分(A₂+B₂混合品、A₂、A₄、A₅、A₆、A₅₀₃₃和B₂)在实体型艾氏腹水癌小鼠的分布实验中,发现七种组分都亲瘤和抑瘤。争光霉素A₅和A₆的亲瘤性最高。用等毒性剂量,A₅、A₄和A₂具有最高的抑瘤性。小鼠肝、肾和肿瘤对各种标记的争光霉素组分的摄取以A₅₀₃₃为最低,A₆为最高,因此目前看来,以A₆进行临床试用的前景似比其他的组分为差。A₅₀₃₃在肺中集聚少,排出较快,急性毒性又最低,按相等的LD₅₀剂量给药其抑瘤率也较高,从减少肺纤维化这点考虑,它可能是值得进一步研究的。A₅亲瘤抑瘤较高,肾和肝摄取较高,但较A₆为低,排出较慢,在体内保留时间较长,也是一种有发展前途的单一争光霉素组分。     

平阳霉素的分离和鉴别

轮枝链霉菌平阳新变种(Str.Verticillus Vat.Pingyangensis n.Var.)所产生的抗肿瘤抗菌素是由十余种组分组成的复合物,其中两个主要组分分别与博莱霉素A₂和B₂完全相同。在生产过程中通过菌种选育和发酵工艺的改进,产品的组成发生了变化,主要组分变成了博莱霉素A₅,已正式命名为平阳霉素。它在复合物中所占比例一般约为60%。本文报告平阳霉素的分离、理化性质和鉴别。     

可变误差多面体法用于多种维生素的同时测定

本文基于对多元校正分析模型的简要讨论,探索了应用可变误差多面体法同时测定维生索B₁,B₂,B₆和烟酰胺的可行性。其结果准确度和精密度均较满意。维生素B₁,B₂,B₆及烟酰胺的回收率分别是99.8±0.9%(CV),100.1±0.8%(CV),100.2±2.1%,100.1±0.7%(CV)。结果表明,通过公式K_S=A_SC_S^T(C_SC_S^T)^-1计算校正系数矩阵K_S,并结合可变误差多面体法这一直接求解方法,能有效地提高分析结果的准确度,克服组分间的交互作用及病态,是多元校正分析的较佳策略之一。     

国产制霉菌素中两个主成分的结构鉴别

国产制霉菌素中的两个主成分C₁和C₂,经紫外光谱,质子核磁共振和快原子轰击质谱的分析测定,鉴别为制霉菌素A₃和Polyfungin B。     

博来霉素A2和B2的HPLC测定

建立了HPLC法测定博来霉素A_2和B_2。采用C_(18)柱,以硫酸钾缓冲液和乙腈为流动相,梯度洗脱,检测波长为254nm。博来霉素A_2和B_2均在0.05～2mg/ml浓度范围内线性关系良好,平均回收率为99.1%和107.2%,RSD为0.96%和1.58%。     

The effect of bleomycin on prolyl hydroxylase and DNA chain breakage: structure-activity relationship.

The activity of purified prolyl hydroxylase (proline, 2-oxoglutarate dioxygenase, EC 1.14.11.2) was enhanced about 3-fold by addition of bleomycin in the assay mixture. Various members of the bleomycin family, their derivatives and degradation products were investigated for activities against prolyl hydroxylase together with their activities of DNA chain breakage to determine relationships between the structure of bleomycin and its various actions. All the bleomycins with various terminal amine parts and desamide bleomycin stimulated the enzymatic activity but did not exhibit an effect on DNA chain breakage. The stimulatory activity of bleomycin was not decreased by hydrolysis with 0.3 N H2SO4 at 80 degrees C for 6 hours, conditions which liberates the sugar moiety, but was eliminated by hydrolysis with 6 N HCl at 105 degrees C for 24 hours. In contrast both treatments decreased the DNA chain breakage activity of bleomycin. Optical spectral studies revealed that all the bleomycins and their hydrolysates which stimulated the prolyl hydroxylase activity made complexes with ferrous ion, one of the cofactors of this enyzme.     

Role of terminal substituents in the pulmonary toxicity of bleomycins

When administered to mice by the intratracheal route, bleomycin analogs produce pulmonary toxicity of varying severity. Analogs differ from each other by chemical groups (terminal substituents) linked to the bithiazole rings. Amines with structures identical to the terminal substituents of bleomycins A2′-a, A2′-b, A2′-c, A5, A6, and B2 were administered to mice endotracheally (10–500 nmol). Discrete end groups produced the same spectrum of pathological changes in the lung as did intact bleomycins, namely, pulmonary fibrosis and metaplasia. Relative to Blenoxane, bleomycin A5 is as toxic while the toxicity of bleomycin B2 is comparatively mild. The severity of pulmonary fibrosis and metaplasia of these bleomycins can be attributed to the terminal substituents, spermidine and agmatine. Spermidine produced severe fibrosis and metaplasia, comparable to that produced by bleomycin A5. Agmatine, the end group of bleomycin B2 was the least toxic of the terminal substituents, suggesting that the diminished pulmonary toxicity of bleomycin B2 can be accounted for by the terminal agmatine moiety. These studies indicate an important role for the terminal substituent in bleomycin-induced lung injury.     

Fibrogenic structure-activity study of the bleomycin molecule

In the present study the fibrogenic potential of intact bleomycins as well as their acetyldipeptide and terminal polyamine constituents have been assessed. Administration of Blenoxane, bleomycin A2, or bleomycin B2 to rats produced histopathologic evidence of pulmonary fibrosis when tissues were examined 28 days following a single intratracheal dose. These compounds also produced a readily detectable increase in pulmonary collagen synthesis as evidenced by an approximate twofold increase over control values in the formation of [3H]hydroxyproline in an in vitro lung mince system. Lung collagen synthetic activity remained significantly elevated over control values for up to 2 weeks. However, neither the acetyldipeptides nor the polyamine constituents of bleomycin A2 and B2 produced detectable increases in lung collagen synthesis or in histopathologic evidence of pulmonary injury. Spermine and spermidine, the terminal amine components associated with bleomycin-A6 and with tallysomycin A, tallysomycin B, and bleomycin-A5, respectively, did produce significant pulmonary fibrotic injury in rats following intratracheal administration. Out of an extensive series of polyamines, bleomycin acetyldipeptides and intact bleomycin and tallysomycin analogs, only spermine and spermidine were found to produce hydrogen peroxide and acrolein upon incubation in vitro with amine oxidase, a common pulmonary enzyme. Conclusions regarding the relative toxicity of different bleomycin analogs based solely on the toxicity produced by administration of their terminal amine constituent must therefore be made with caution.     

3-氨基苯甲酰胺增强平阳霉素的抗瘤作用

3 AB是聚(ADP-R)合成酶抑制剂,能在体外和体内协同地增加平阳霉素对S_(180)的抑制作用,而本身不具有抗瘤与细胞毒作用。这种加强作用与3 AB的剂量有关,剂量加强因子为4。在体内实验中加用3 AB后,平阳霉素对小鼠S_(180)的抑制率由原来的32.3%,41.4%,37.4%和66.0%分别增至60.1%,72.4%,68.3%和77.8%,我们还在体内探讨了量效关系及给药方式的影响。     

提高麦迪霉素有效组分的研究

本文对提高麦迪霉素有效组分A_1作了研究。根据麦迪霉素有效组分A_1与其主要杂质柱晶白霉素A_6结构上的区别,在发酵培养基中流加了能转化为丙酰CoA的前体物质,得到了较为满意的结果。实验证明,流加蛋氨酸,适当调整培养基中的葡萄糖、玉米粉含量,在不影响效价的情况下,可使有效组分A_1的含量提高8.7％。使用正交设计法,得到最佳条件的组合,使有效分组A_1的含量提高9.7％。流加异亮氨酸、缬氨酸可使有效组分A_1的含量提高13％和10.2％。     

Solid-phase synthesis of deglycobleomycin and bleomycin

The bleomycins are a group of structurally related glycopeptide antibiotics originally isolated from Streptomyces verticillus in the 1960s. They are used for the treatment of cancers including Hodgkin's lymphomas, carcinomas of the skin, head and neck, and testicular tumors. Whereas analogs of bleomycin have been synthesized to facilitate an understanding of its biochemical properties, the complexity of the molecule has severely limited the total number of analogs synthesized. The solid-phase synthesis of fully functional and active deglycobleomycin and bleomycin analogs is described. This approach has resulted in the synthesis of over 160 unique deglycobleomycin and bleomycin analogs in the past two years, an accomplishment that would not have been possible without the solid-phase methodology.