CAP 3 is a cholic acid-peptide conjugate (CAP) with antibacterial activity. It is active against the Gram-negative bacteria E. coli, K. pneumoniae, and A. baumanii (MIC99s = 8, 16, and 16 μM, respectively). CAP 3 increases the fluidity of model Gram-negative bacterial membranes and binds to LPS in vitro. It reduces the biomass and number of colony-forming units in E. coli biofilms in a concentration-dependent manner. CAP 3 inhibits E. coli biofilm formation on catheters implanted in mice infected with E. coli at the incision site when applied as a coating on the catheters. CAP 3 (40 mg/kg) also reduces bacterial load in E. coli-infected wounds in mice. It is cytotoxic to A459 cells (IC50 = 56.4 μM) and has hemolytic activity against human red blood cells with a 50% lysis (HC50) value of 48 μM.
Terpendole I is a fungal metabolite that has been found in A. yamanashiensis.1 It is a weak inhibitor of acyl-coenzyme A:cholesterol acyltransferase (ACAT; IC50 = 145 μM) and is active against the bacteria B. cereus and B. subtilis (MICs = 100 μg/ml for both) but not S. aureus, P. aeruginosa, or K. pneumoniae (MICs = >200 μg/ml for all) or the fungus C. albicans (MIC = 200 μg/ml).1,2 It is cytotoxic to HeLa cells with an IC50 value of 52.6 μM.3 |1. Tomoda, H., Tabata, N., Yang, D.-J., et al. Terpendoles, novel ACAT inhibitors produced by Albophoma yamanashiensis. III. Production, isolation and structure elucidation of new components. J. Antibiot. (Tokyo) 48(8), 793-804 (1995).|2. Zhao, J.-C., Wang, Y.-L., Zhang, T.-Y., et al. Indole diterpenoids from the endophytic fungus Drechmeria sp. as natural antimicrobial agents. Phytochemistry 148, 21-28 (2018).|3. Nagumo, Y., Motoyama, T., Hayashi, T., et al. Structure-activity relationships of terpendole E and its natural derivatives. ChemistrySelect 2(4), 1533-1536 (2017).
Platensimycin (PTM) is an antibiotic produced by S. platensis that inhibits Gram-positve bacteria by selectively inhibiting cellular lipid biosynthesis (IC50 = 0.1 μM). It targets the β-ketoacyl-acyl-carrier-protein synthase I/II, FabF/B, an enzyme that participates in the biosynthesis of fatty acids (IC50s = 48 and 160 nM for S. aureus and E. coli enzymes, respectively). By specifically targeting fatty acid synthesis in bacteria, PTM is thought to be a promising agent for overcoming antibiotic resistance. PTM is also a selective inhibitor of the mammalian fatty acid synthase and has been shown to reduce liver triglyceride levels and to improve insulin sensitivity in a diabetic mouse model after an oral dose of 30 mg/kg.
α-Conotoxin ImI is a conotoxin that has been found inC. imperialisand has receptor antagonist and anticancer activities.1It is a peptide antagonist of homomeric α7 nicotinic acetylcholine receptors (nAChRs; IC50= 220 nM). α-Conotoxin ImI is selective for α7 nAChRs over α2β2, α3β2, α4β2, α2β4, α3β4, α4β4, and α1β1γδ subunit-containing nAChRs at 5 μM but does inhibit homomeric α9 nAChRs (IC50= 1,800 nM). Administration of paclitaxel in micelles containing α-conotoxin ImI decreases tumor growth in an MCF-7 mouse xenograft model.2Intracerebroventricular, but not intraperitoneal, administration of α-conotoxin ImI (20 nmol/animal) induces seizures in rats.3 1.Johnson, D.S., Martinez, J., Elgoyhen, A.B., et al.α-Conotoxin ImI exhibits subtype-specific nicotinic acetylcholine receptor blockade: Preferential inhibition of homomeric α7 and α9 receptorsMol. Pharmacol.48(2)194-199(1995) 2.Mei, D., Lin, Z., Fu, J., et al.The use of α-conotoxin ImI to actualize the targeted delivery of paclitaxel micelles to α7 nAChR-overexpressing breast cancerBiomaterials4252-65(2015) 3.McIntosh, J.M., Yoshikami, D., Mahe, E., et al.A nicotinic acetylcholine receptor ligand of unique specificity, α-conotoxin ImIJ. Biol. Chem.269(24)16733-16739(1994)
BE-24566B is a polyketide fungal metabolite originally isolated fromS. violaceusniger.1It is active againstB. subtilis,B. cereus,S. aureus,M. luteus,E. faecalis, andS. thermophilus(MICs = 1.56, 1.56, 1.56, 1.56, 3.13, and 3.13 μg/ml, respectively). BE-24566B is an endothelin (ET) receptor antagonist (IC50s = 11 and 3.9 μM for ETAand ETBreceptors, respectively).2 1.Kojiri, K., Nakajima, S., Fuse, A., et al.BE-24566B, a new antibiotic produced by Streptomyces violaceusnigerJ. Antibiot. (Tokyo)48(12)1506-1508(1995) 2.Lam, Y.K.T., Hensens, O., Helms, G., et al.L-755,805, a new polyketide endothelin binding inhibitor from an actinomyceteTetrahedron Lett.36(12)2013-2016(1995)