Amphotericin B-gum arabic conjugates:: Synthesis, toxicity, bioavailability, and activities against Leishmania and fungi
Amphotericin B-gum arabic conjugates:: Synthesis, toxicity, bioavailability, and activities against Leishmania and fungi
复制标题
DOI：
10.1007/s11095-006-9222-z
复制
发表时间：
2007-05-01
影响因子：
3.7
通讯作者：
Jayakrishnan, A.
中科院分区：
文献类型：
--
作者：
Nishi, K. K.;Antony, M.;Jayakrishnan, A.
目的.阿拉伯树胶是一种支链多糖，由超过90%的阿拉伯半乳聚糖组成，分子量约为250，000 Da，是所有天然树胶中最古老和最知名的。本研究的目的是检测多烯抗生素阿氏菌素B（AmB）与高碘酸氧化阿拉伯树胶结合后是否仍保留其抗真菌和抗利什曼原虫活性，并评价其毒性和生物利用度。AmB共轭氧化多糖通过希夫的连接在未还原（亚胺）和还原（胺）的形式，其特征在于药物含量，溶血潜力，分子量，在体外释放，并进行了检查，对白色念珠菌和新型隐球菌的抗真菌活性和抗利什曼原虫对杜氏利什曼原虫前鞭毛体的培养物中的抗利什曼原虫活性。通过小鼠和家兔静脉注射，评价了偶联物的毒性和生物利用度。发现缀合物是非溶血性的，并且小鼠耐受20 mg（AmB）/kg体重的两种缀合物的剂量。对小鼠内脏器官的组织学检查显示，肾脏、大脑、心脏或肝脏均无病变。注射后7天内脏中残留药物的估计显示，脾脏仍保留8.4 +/- 0.53 μ g/g组织。发现AmB在体外从两种缀合物释放，尽管从亚胺缀合物的释放比从胺缀合物的释放快得多。亚胺偶联物对L. donovani LV 9和DD 8菌株的平均浓度分别为0.37 ± 0.04和1.44 ± 0.18 μ M。胺缀合物的IC 50值高得多。最低抑菌浓度（MIC）为0.001;白色念珠菌和C.对于亚氨基和氨基缀合物，新生儿的浓度在0.5-0.9 μ g/mL的范围内。缀合物在兔中的生物利用度表明，亚胺缀合物在24小时内维持血浆浓度在20至5 μ g/mL的范围内，而胺缀合物在17至3 μ g/mL的范围内。该药物偶联物稳定、无溶血性、对动物内脏无毒性，并显示出良好的体外抗真菌和抗利什曼原虫活性。尽管多糖的大分子量，但来自缀合物的AmB在静脉注射后显示生物利用度。由于单次注射后在脾脏中发现最高浓度的AmB，因此这些缀合物可能具有抗利什曼原虫治疗的潜力。
Purpose. Gum arabic, a branched polysaccharide consisting of more than 90% arabinogalactan having a molecular weight around 250,000 Da is the oldest and best known of all natural gums. The objective of the present investigation was to examine whether amphotericin B (AmB), the polyene antibiotic when conjugated to periodate oxidized gum arabic still retained its anti-fungal and anti-leishmanial activity and to evaluate its toxicity and bioavailability.Methods. AmB conjugated to the oxidized polysaccharide through Schiff's linkages in the unreduced (imine) and reduced (amine) forms were characterized for the drug content, hemolytic potential, molecular mass, in vitro release and were examined for anti-fungal activity against Candida albicans and Cryptococcus neoformans and for anti-leishmanial activity against promastigotes of Leishmania donovani in culture. Toxicity and bioavailability were evaluated by intravenous (i.v) injections of the conjugates in mice and rabbits respectively.Results. The conjugates were found to be non-hemolytic and mice withstood a dosage of 20 mg (AmB)/kg body weight of both conjugates. Histological examination of the internal organs of mice showed no lesions in kidney, brain, heart or liver. Estimation of the residual drug in the internal organs 7 days post injection showed that the spleen still retained 8.4 +/- 0.53 mu g/g of tissue. AmB was found to be released from both conjugates in vitro although the release from the imine conjugate was much faster than from the amine conjugate. The concentrations inhibiting parasite growth by 50% (IC50) values for the imine conjugate against promastigotes of L. donovani LV9 and DD8 strains were 0.37 +/- 0.04 and 1.44 +/- 0.18 mu M respectively. The IC50 values for the amine conjugates were much higher. The minimum inhibitory concentration (MIC) against C. albicans and C. neoformans was in the range of 0.5-0.9 mu g/mL for both imino and amino conjugates. The bioavailability of the conjugate in rabbits showed that the imine conjugate maintained a plasma concentration in the range of 20 to 5 mu g/mL while for the amine conjugate it was in the range of 17 to 3 mu g/mL over 24 h.Conclusions. The drug conjugates were stable, non-hemolytic and non-toxic to the internal organs of the animal and showed good anti-fungal and anti-leishmanial activity in vitro. In spite of the large molecular weight of the polysaccharide, AmB from the conjugates showed bioavailability after i.v injection. Since the highest concentration of AmB was found in the spleen after a single injection, these conjugates may have potential in anti-leishmanial therapy.