Filamentous fungi: Potentially useful catalysts for the biohydroxylations of non-activated carbon centers

Filamentous fungi are capable of catalyzing regio- and stereoselective hydr oxylation on an extensive array of natural and synthetic hydrophobic organi c substrates. A significant benefit of fungal hydroxylation is that non-act ivated carbon centers can be functionalized in ways that may not be easily emulated by classical organic means. The enzymes thought to perform the hyd roxylations are: cytochrome P450 monooxygenases. This review presents the e vidence for the role of cytochrome P450's and summarizes the broad spectrum of substrates hydroxylated by various filamentous fungi in the twenty year s prior to August 2000. Whole cell systems are generally preferred because monooxygenases that catalyze these reactions have not been isolated and cha racterized. Optimization of the hydroxylation conditions and the ability to accurately predict the biotransformation product(s) are necessary future d evelopments before widespread synthetic practicality is achieved. Several r ecent developments in optimization techniques are also discussed including the use of protecting groups, varied experimental conditions, and the use o f additives to the whole cell systems.