Cholesterol Analogs with Degradation-resistant Alkyl Side Chains Are Effective Mycobacterium tuberculosis Growth Inhibitors

Daniel J Frank,Yan Zhao,Siew Hoon Wong,Debashree Basudhar,James J De Voss,Paul R Ortiz De Montellano

doi:10.1074/jbc.m115.708172

Abstract

Cholest-4-en-3-one, whether added exogenously or generated intracellularly from cholesterol, inhibits the growth ofMycobacterium tuberculosiswhen CYP125A1 and CYP142A1, the cytochrome P450 enzymes that initiate degradation of the sterol side chain, are disabled. Here we demonstrate that a 16-hydroxy derivative of cholesterol, which was previously reported to inhibit growth ofM. tuberculosis, acts by preventing the oxidation of the sterol side chain even in the presence of the relevant cytochrome P450 enzymes. The finding that (25R)-cholest-5-en-3β,16β,26-triol (1) (and its 3-keto metabolite) inhibit growth suggests that cholesterol analogs with non-degradable side chains represent a novel class of anti-mycobacterial agents. In accord with this, two cholesterol analogs with truncated, fluorinated side chains have been synthesized and shown to similarly block the growth in culture ofM. tuberculosis.

Highlights

Mycobacterium tuberculosis (Mtb)[2] is the causative agent of tuberculosis, a disease that the World Health Organization estimates in 2014 caused illness in 9.6 million individuals and killed 1.5 million people (1), with the bulk of this disease burden falling on third world countries
In wild-type Mtb, growth on cholesterol is retarded in the presence of large amounts of cholesterol, or added cholest-4-en-3-one, with growth occurring as the cholest-4-en-3-one concentration decreases
To determine whether cholest-4-en-3-one can inhibit growth on other carbon sources, we investigated its effects on cells growing on acetate or glucose

Summary

Introduction

Mycobacterium tuberculosis (Mtb)[2] is the causative agent of tuberculosis, a disease that the World Health Organization estimates in 2014 caused illness in 9.6 million individuals and killed 1.5 million people (1), with the bulk of this disease burden falling on third world countries. We demonstrate that cholest-4-en-3-one inhibits growth of Mtb on defined media with glycerol, as already reported (14), and with acetate and glucose as the sole carbon source.

Results

Conclusion