No abstract

A series of novel quinoline-based tetracyclic ring-systems were synthesized and evaluated in vitro for their antiplasmodial, antiproliferative and antimicrobial activities. The novel hydroiodide salts 10 and 21 showed the most promising antiplasmodial inhibition, with compound 10 displaying higher selectivity than the employed standards. The antiproliferative assay revealed novel pyridophenanthridine 4b to be significantly more active against human prostate cancer (IC50 = 24 nM) than Puromycin (IC50 = 270 nM) and Doxorubicin (IC50 = 830 nM), which are used for clinical treatment. Pyridocarbazoles 9 was also moderately effective against all the employed cancer cell lines and moreover showed excellent biofilm inhibition (9a: MBIC = 100 µM; 9b: MBIC = 100 µM).

Isocryptolepine (1), a potent antimalarial natural product, was prepared in three steps from 3-bromoquinoline and 2-aminophenylboronic acid hydrochloride. The key transformations were a SuzukiMiyaura cross-coupling reaction followed by a palladium-initiated intramolecular C-H activation/C-N bond formation between an unprotected amine and an aromatic C-H group. The two key reactions can also be performed in one pot.