Unnatural endo type-B PPAPs as novel compounds with activity against Mycobacterium tuberculosis.

Before the emergence of SARS-CoV-2, tuberculosis (TB) was the leading cause of infectious disease mortality worldwide. Like all antibiotic-exposed bacteria Mycobacterium tuberculosis (Mtb) developed multidrug-resistant (MDR) and exten-sively drug-resistant (XDR) strains which require new antibiotics with novel mechanism of actions. Hyperforin, a natural type-A polyprenylated polycyclic acylphloroglucinol (PPAP) isolated from St. John’s wort, is known for its antibacterial, antidepressant and antimycobacterial activity. However, hyperforin is not stable and easily degradable in light, heat it and oxidizes. Here we report photo- and benchstable type-B PPAPs with structural similarity to hyperforin and enhanced an-timycobacterial activity. We tested a panel of PPAPs and identified our previously reported molecule PPAP22 as lead compound. Converting PPAP22 into the corresponding sodium salt, PPAP53, enhanced the solubility dramatically. We show that PPAP53 inhibits the growth of virulent, extracellular Mtb. Strikingly, the activity is more pronounced intracel-lular Mtb residing in human primary macrophages without damaging the host cell or lung cells. Importantly PPAP53 was also highly active against drug-resistant Mtb. Additionally, we analysed the in vitro properties of PPAP53 in terms of CYP-induction and PXR interaction. Taken together we introduce type-B PPAPs are a new class of antimycobacterial com-pounds, with remarkable activity and favorouble physical properties.