DNA microarray gene expression profile of Mycobacterium tuberculosis when exposed to osthole

Tuberculosis (TB), affecting one-third of the global population, kills an estimated two to three million people every year. The development of drug resistance is becoming a serious threat to any attempt to control this disease, which underscores the need for new agents targeting Mycobacterium tuberculosis (M. tuberculosis). Osthole (7-methoxy-8-isopentenoxycoumarin) is a coumarin derivative present in many medicinal plants. Previous studies have shown that osthole possesses antimycobacterial effects, however, the action mechanism of osthole is unclear. In the study, we used a commercial oligonucleotide microarray to determine the overall transcriptional response of M. tuberculosis H37Rv triggered by exposure to osthole. Analysis of the microarray data revealed that a total of 478 genes were differentially regulated by osthole. Of these, 241 genes were upregulated, and 237 genes were downregulated. Some of the important genes that were significantly regulated are related to different pathways such as fumarate reductase, class I peroxidase, cell wall, nitrate respiration, and protein synthesis. Real-time quantitative RT-PCR was performed for chosen genes to validate the microarray results. To our knowledge, this genome-wide transcriptomics approach has produced the first insights into the response of M. tuberculosis when exposed to osthole.