Effect of Chloral Hydrate and Acetaldehyde on Mitochondrial Preparations from Sweet Potato

The inhibitory effects of chloral hydrate and acetaldehyde have been studied on oxidations performed by mitochondrial preparations of sweet potatoes (Ipomea batatas). With a variety of substrates, chloral acts very like amytal but only between a fifth and a tenth as effectively; it affects those reactions which would be expected to depend on the oxidation of intramitochondrial DPNH, more than the oxidation of succinate or of added DPNH. It also acts like amytal when oxygen is replaced by other electron accepting agents. It is more effective, for example, against the malate reduction of cytochrome c than against the malate reduction of 2:6-dichlorophenol-indophenol.Inhibitions producd by acetaldehyde are more complex. Some DPN-dependent oxidations, especially those of pyruvate and alpha-keto-glutarate, are strongly inhibited, while that of citrate is not.It is suggested that chloral affects the electron transport sequence of sweet potato mitochondria at a similar locus to amytal. Although the present work fails to provide unambiguous evidence that acetaldehyde acts in the same manner, experiments described in the literature have been interpreted in this way.