antibiotic k 4

Antibiotic K 4 is an inhibitor of angiotensin I converting enzyme produced by Actinomadura spiculosospora.

IKD-8344 is a macrocyclic dilactone originally isolated from an actinomycete species and has diverse biological activities, including anticancer, antimicrobial, and anthelmintic properties.1,2,3 It is cytotoxic to L5178Y murine leukemia cells (IC50 = 0.54 ng ml).1 IKD-8344 inhibits growth of the mycelial form of C. albicans (MIC = 6.25 μg ml) and potentiates the activity of polymyxin B against the multidrug-resistant pathogenic bacterium B. cenocepacia.2,3 It is active against T. spiralis in vitro and in vivo.1 |1. Minami, Y., Yoshida, K., Azuma, R., et al. Structure of a novel macrodiolide antibiotic IKD-8344. Tetrahedron Lett. 33(48), 7373-7376 (1992).|2. Hwang, E.I., Yun, B.S., Yeo, W.H., et al. Compound IKD-8344, a selective growth inhibitor against the mycelial form of Candida albicans, isolated from Streptomyces sp. A6792. J. Microbiol. Biotechnol. 15(4), 909-912 (2005).|3. Loutet, S.A., El-Halfawy, O.M., Jassem, A.N., et al. Identification of synergists that potentiate the action of polymyxin B against Burkholderia cenocepacia. Int. J. Antimicrob. Agents 46(4), 376-380 (2015).

Boromycin is a boron-containing macrolide antibiotic that has been found in Streptomyces. Boromycin inhibits growth of B. subtilis (MIC = 0.05 μg ml) and induces efflux of potassium ions from B. subtilis without affecting Na+ K+-ATPase activity. It decreases the synthesis of protein, RNA, and DNA in B. subtilis when used at a concentration of 0.05 μg ml. It inhibits the growth of B. halodurans (MIC = 10 ng ml) and inhibits the futalosine pathway of menaquinone synthesis in B. halodurans. Boromycin (3.4 nM) reverses bleomycin-induced cell cycle arrest at the G2 phase in Jurkat cells. It inhibits replication of the HIV-1 strains LAV-1 and RF and the HIV-2 strain LAV-2 in MT-4 cells (IC50s = 0.008, 0.11, and 0.007 μM, respectively). It also inhibits replication of a clinical isolate of HIV-1, strain KK-1, in MT-4 cells and peripheral blood mononuclear cells (PBMCs; IC50s = 0.14 and <0.1 μM, respectively).

Polymyxin B2是一种抗生素，并且是从B. polymyxa分离出的阳离子脂肽抗生素polymyxin B的主要成分。该化合物对P. aeruginosa、A. baumannii、K. pneumoniae和E. cloacae菌株具有活性（MICs分别为1-2、0.5-1、0.25-0.5和0.25-1 µg/ml）。在体内实验中，以4 mg/kg剂量的Polymyxin B2能显著降低P. aeruginosa血液感染小鼠模型中的血液集落形成单位(CFUs)数量。

4-Trehalosamine是一种在Streptomyces中发现的微生物代谢产物，具有抗生素活性。在杯碟法测试中，当浓度为0.5、1和2 mg/ml时，对E. coli、K. pneumoniae和B. subtilis展现出活性。

MBL-IN-3 (compound 72922413) 作为一种新德里金属β-内酰胺酶-1 (NDM-1) 抑制剂（IC50=54±4 μM），能有效降低Meropenem对表达NDM-1的大肠杆菌及肺炎克雷伯菌临床分离株的最低抑菌浓度（mic）。此化合物亦被用于抗生素增敏剂的相关研究。