complex III

HQNO is a natural product isolated from P. aeruginosa,and is a potent inhibitor of electron transport chain(Kd of 64 nM for complex III). It also is a potent mitochondrial NDH-2 inhibitorin many species.

Harzianopyridone is an atpenin-like compound that functions as an inhibitor of mammalian and nematode mitochondrial complex II, also known as succinate:ubiquinone oxidoreductase (SQR), demonstrating IC50 values of 0.017, 0.2, and 2 μM against bovine, rat, and nematode complex II, respectively. Additionally, it inhibits nematode quinol-fumarate reductase (QFR) with an IC50 value of 0.36 μM. Significantly selective for complex II over complexes I and III in rats and cattle, as well as complex I in nematodes, with IC50 values exceeding 100 μM, it exhibits notable antibacterial and antifungal properties, with EC50 values of 35.9, 42.2, 60.4, and 50.2 μg/ml against R. solani, S. rolfsii, M. phaseolina, and F. oxysporum, respectively.

Aquacobalamin, one of the primary forms of Vitamin B12 isolated from mammalian cells, accelerates the oxidation of the diazo dye Orange II in aqueous solutions containing HSO5-. Additionally, Aquacobalamin can reversibly bind with hydrogen peroxide to form a cobalt (III) hydroperoxide complex, with a dissociation constant of 0.25 mM.