Synthesis and Biological Evaluation of Reniochalistatins A-E and a Reniochalistatin E Analogue.

The total synthesis of reniochalistatins A-E, along with a reniochalistatin E analogue (inverso-E) was successfully achieved through Fmoc-based solid-phase peptide synthesis and subsequent macrolactamization with PyBOP and DIEA. The biological activities of these reniochalistatins and a key linear peptide intermediate were systematically evaluated. Among these seven synthesized compounds, linear reniochalistatin B was found to have potent activity against several cancer cell lines not shown by the cyclic reniochalistatin B counterpart. In addition, linear reniochalistatin B was found to have antitubercular activity (IC50 =1.4 μm). Inverso-E possesses increasing cytotoxicity against the HeLa and LNCaP cell lines after simple alternation of the sequence of amino acids in reniochalistatin E. The results of these studies provide a feasible method to further investigate the structure-activity relationships (SARs) of reniochalistatins A-E.