To obtain a specific cyclic hexapeptide compound containing N- methyltyrosine and alanine and obtained by chemically modifying an extract of Rubia akane Nakai which is a medicinal herb, exhibiting excellent antitumor action and useful as an antitumor agent, etc.
This compound is a new cyclic hexapeptide compound represented by formula I [R is a group represented by formula II (R1 and R2 are each an alkyl, phenyl or benzyl) or a group represented by formula III [(n) is an integer of 4-6], exhibits excellent antitumor action and is useful as an antitumor agent, etc. The cyclic hexapeptide is obtained by reacting RA-V (a compound of formula I wherein R is H) obtained by extraction from Rubia akane Nakai which is a sort of a medicinal herb with 2-chloro ethyldimethylamine hydrochloride in a solvent such as N,N-dimethy lformamide in the presence of potassium carbonate and subjecting the reaction product to column chromatography to purify the reaction product.
ICHIYANAGI YUKIO
YAMAGISHI TAKEHIRO
TAISHO PHARMACEUTICAL CO LTD