Patent ID: 8309493

Claim:
A method for increasing the content of polyphenol in a plant, which comprises treating said plant with an effective amount of a 5-aminolevulinic acid or a derivative thereof represented by the following formula (1): R 2 R 1 NCH 2 COCH 2 CH 2 COR 3 (1) wherein R 1 and R 2 each independently represents a hydrogen atom, an alkyl group, an acyl group, an alkoxycarbonyl group, an aryl group, or an aralkyl group; R 3 represents a hydroxyl group, an alkoxy group which may have a substituent, an acyloxy group, an alkoxycarbonyloxy group, an aryloxy group, an aralkyloxy group, or an amino group, or a salt thereof, wherein the plant is selected from the group consisting of peppers, pear, and, parsley.