Synthesis and biological evaluation of (−)-6-O-desmethylcryptopleurine and analogs

AgOTf-catalyzed sequential synthesis of 4-isoquinolones via oxidative ring opening of aziridines and aza-Michael addition

An efficient AgOTf-catalyzed sequential reaction involving the oxidative ring-opening of aziridines by DMSO and aza-Michael addition has been developed. A series of 2,3-dihydro-4(1H)-isoquinolones were afforded in moderate to good yields by the formation of one new C[double bond, length as m-dash]O bond and one new C-N bond. The features of this sequential reaction include high bonding efficiency, use of a catalytic amount of catalysts, a broad substrate scope and mild conditions. This methodology provides a good choice for constructing the libraries of 2,3-dihydro-4(1H)-isoquinolones.

6-OH-Phenanthroquinolizidine Alkaloid and Its Derivatives Exert Potent Anticancer Activity by Delaying S Phase Progression

To discover new phenanthroindolizidine and phenanthroquinolizidine alkaloids as potential anticancer drug candidates, non-natural 6-O-desmethylcryptopleurine (2) and its derivatives were prepared. Most of the new compounds exhibited potent antiproliferative activity against A549 and BEL-7402 cells, with the lowest IC₅₀ being 3 nM. Optically pure 2-R was further evaluated against a panel of 30 cancer cell lines and found to inhibit the proliferation of all tested cell lines, including three multidrug-resistant cell lines, with an average IC₅₀ value of 2.1 nM, which is much lower than that of previously reported phenanthroindolizidine DCB-3503 (1, IC₅₀: 166.7 nM). A mechanistic evaluation showed that 2-R potently inhibited cell growth and colony formation, which are associated with a delay in S phase progression through the inhibition of DNA synthesis. These results along with further study on the safety profile of these compounds will facilitate the discovery of new phenanthroindolizidine and phenanthroquinolizidine alkaloids for use as anticancer drug candidates.

Design, Synthesis, and Biological Activity of Sulfonamide Analogues of Antofine and Cryptopleurine as Potent and Orally Active Antitumor Agents

Due to their profound antiproliferative activity and unique mode of action, phenanthroindolizidine and phenanthroquinolizidine alkaloids, represented by antofine and cryptopleurine, have attracted attention recently as potential therapeutic agents. We have designed, synthesized, and evaluated the methanesulfonamide analogues of these natural alkaloids with the hope of improving their druglikeness. The analogues showed enhanced growth inhibition of human cancer cells compared with the parent natural products. In particular, a methanesulfonamide analogue of cryptopleurine (5b) exhibited improved bioavailability and significant antitumor activity, which suggests that 5b is a promising new anticancer agent. Our studies suggest that the inhibition of cancer cell growth by 5b is associated with the induction of G0/G1 cell cycle arrest via nicotinamide N-methyltransferase-dependent JNK activation in Caki-1 renal cancer cells. In addition, compound 5b significantly inhibited the migration and invasion of Caki-1 cancer cells by modulating the p38 MAPK signaling pathway.