444 



Mr. A. E. Everest. 



My thanks are due to Prof. P. F. Frankland, Dr. G. J. Fowler, and Edward 

 Ardern, M.Sc, for the interest which they have taken in this work and to the 

 Rivers Committee of the Manchester Corporation for permission to publish 

 the results of this investigation carried out in the laboratory of their sewage 

 works at Davyhulme. 



The Production of Anihocyanins and Anthocyanidins. 



By Arthur Ernest Everest, M.Sc, Lecturer in Chemistry, University 



College, Reading. 



r 



(Communicated by Prof. F. Keeble, F.R.S. Received February 16, — Read 



March 26, 1914.) 



The idea that the anthocyan pigments are closely related to the flavone and 

 flavonol glucosides is by no means new. Attempts to solve the problem 

 of their relationship have come chiefly from botanists, and, as a result of 

 their researches, a number of hypotheses have sprung up around which 

 quite considerable controversy has been centred. 



Miss Wheldale* puts forward the suggestion that anthocyan pigments are 

 the oxidation products of colourless or faintly coloured chromogens ; and 

 that these chromogens are products of hydrolysis of glucosides present in 

 the tissues of the plant (probably glucosides of flavone or flavonol deriva- 

 tives). The hydrolysis of the glucoside she considers as essential to the 

 production of the anthocyan pigment. She represents the changes taking 

 place by means of the following equations : — 



Glucoside + water J chromogen + sugar. 

 Then — Oxidation of chromogen anthocyan pigment. 



If this hypothesis be accepted, then either the anthocyan so produced will 

 remain a non-glucoside, i.e., it will be an anthocyanidin, or in the presence 

 of sugars the anthocyanidin first formed must unite with sugar to form 

 an anthocyanin (glucoside). Her more recent suggestion that in flavone 

 glucosides all the hydroxyl groups are substituted by sugar molecules, 

 hence partial hydrolysis could produce glucoside anthocyans,f has apparently 

 no foundation upon experimental evidence, most of the flavone and flavonol 

 glucosides containing one or two sugar residues only. 



Now, in view of the fact that it has recently been shown that in no case 



* 'Camb. Phil. Soc. Proc.,' vol. 15, p. 137 (1909) ; ' Journ. Genetics,' vol. 1, p. 133(1911). 

 t ' Biochem. Journ.,' vol. 7, p. 87 (1913). 



