Abstract
Tuberculosis (TB) continues to be one of the world's leading causes of death by the infectious pathogen Mycobacterium tuberculosis, which infects one-third of the global population. The emergence of the COVID-19 pandemic made its spread rapid and the treatment task more daunting. With the havoc of infectious disease expansion, traditional medicines have triggered tremendous interest worldwide. However, less availability of scientific evidence still hinders its practical use. In the present study, we evaluated the potential of the traditional medicinal plant, Justicia adhatoda, which has been used to treat respiratory ailments since ancient times. We have successfully isolated and characterized several bioactive compounds viz- Vasicoline, Vasicolinone, Adhatodine, Adhavasine, Aniflorine, and Vasicinone from J. adhatoda plant leaves, including Vasicine as the principal compound, and showed their anti-tubercular activity on nutrient-starved Mycobacterium smegmatis and Mycobacterium bovis. The study also directs their in-vitro and ex-vivo antimycobacterial potential on THP1 macrophages with internalized Mycobacterium. Our study is one of its first kind, where we assessed the synergistic antimycobacterial effect of the isolated compounds with the first-line drug Isoniazid (INH). Their potential role in promoting phagolysosome fusion and apoptosis of M. bovis infected THP1 macrophages is further evaluated.