Mallotumides A–C: Potent Cytotoxic Cycloheptapeptides from the Roots of Mallotus spodocarpus

Abstract

The structures of potent cytotoxic cycloheptapeptides, mallotumides A−C (1−3, respectively) isolated from the roots of Mallotus spodocarpus Airy Shaw, were elucidated by extensive spectroscopic analysis. The absolute configuration of 1 was determined by single-crystal X-ray crystallographic data. All three cycloheptapeptides exhibited potent cytotoxicity against various cancer cell lines with IC 50 values ranging from 0.60 to 4.02 nM.

General Synthesis of Conformationally Constrained Noncanonical Amino Acids with C(sp3)-Rich Benzene Bioisosteres

“…Although all life on Earth is built from the 20 canonical amino acids, nature’s creativity demonstrates the unlimited potential of peptide natural products bearing noncanonical amino acids (ncAAs). For example, diazonamide A ( 1 ), dynobactin A ( 2 ), and mallotumide C ( 3 ) represent examples of biologically active peptide natural products containing ncAAs (Scheme ).…”