Riboflavin in Black Pepper

Abstract

Fixen and Boscoe1 quoting Murthy2 place the fresh green berries of Piper nigrum extraordinarily high in the list of riboflavin-containing materials. Commercial black pepper, which consists of the dried berries of this plant also picked in the green stage, was considered as a possible source of riboflavin. When this product was assayed for riboflavin by the method of one of us3 it was found to be devoid of riboflavin. An aqueous extract gave a very strong green fluorescence at high dilutions, but the solubility properties of the fluorescent material were not those of riboflavin but were similar to those of piperine. That this is the substance in black pepper which is responsible for the observed green fluorescence is confirmed by the strong fluorescence obtained with purchased piperine at a dilution in water of 1 in 2 million. Piperine in alcohol solution gives a light blue fluorescence with ultra-violet light, and in chloroform a purple blue fluorescence is seen. The fluorescent material in black pepper behaves in a similar manner to piperine, whilst riboflavin gives a green fluorescence in both water and alcohol, and luminoflavin fluoresces green in alcohol, chloroform or water solutions.