Four new sulphur containing amides have been isolated from the methanolic leaf extract of the Malayan Glycosmis chlorosperma. Their structures and stereochemistries were elucidated on the basis of spectroscopic evidence and were shown to represent two pairs of isomers: the dominating (E)-isomer penangin together with traces of the (Z) isomer isopenangin [methyl amides of 3-methylthio-(E) and (Z)-propenic acid] and small amounts of the (E)-and (Z) cinnamic acid derived penimides A and B. Their possible biogenetic relationships with cysteine and the previously isolated sinharines are discussed.