Patent ID: 8921420

Claim:
A method for preparing compounds of Formula (I) wherein R represents a hydrogen atom or a methyl group, R 1 , R 2 , and R 4 each represent, independently of each other, a hydrogen atom or a caffeoyl group, R 3 represents a hydrogen, a caffeoyl group, or a succinyl group, provided that at least two of R 1 through R 4 represent a caffeoyl group, and that R 3 represents a succinyl group only if R 2 and R 4 represent a caffeoyl group, from nontuberized roots of plants of the genus Ipomoea comprising the following steps: a) taking samples of said nontuberized roots or recovering root exudate thereof, b) extraction of phenolic compounds from said roots or said root exudate using one or several organic solvents, and c) recovery of the raw extract.