Collismycin A is a bacterial metabolite originally isolated from Streptomyces that has diverse biological activities, including antibacterial, antiproliferative, and neuroprotective properties. It is active against a variety of bacteria (MICs = 6.25 and 100 μg ml) and fungi (MICs = 12.5-100 μg ml). It inhibits proliferation of A549 lung, HCT116 colon, and HeLa cervical cancer cells (IC50s = 0.3, 0.6, and 0.3 μM, respectively) and NIH373 fibroblasts (IC50 = 56.6 μM) but not MDA-MD-231 breast cancer cells (IC50 = >100 μM). Collismycin A forms a complex with Fe(II) and Fe(III) at a 2:1 ratio, and the addition of iron ions inhibits the antiproliferative effect of collismycin A on HeLa cells, an effect that does not occur with the addition of zinc, manganese, copper, or magnesium ions. Collismycin A (1 μM) prevents apoptosis in the brain region of zebrafish larvae by 44% in a model of neuronal cell death induced by all-trans retinoic acid .
8-hydroxy Efavirenz is a major oxidative metabolite of the non-nucleoside reverse transcriptase inhibitor efavirenz . 8-hydroxy Efavirenz is formed when efavirenz is metabolized by the cytochrome P450 (CYP) isoform CYP2B6. It induces apoptosis in rat primary hippocampal neurons and loss of dendritic spines in rat primary hippocampal neuronal cultures when used at a concentration of 0.01 μM.