12 
I. NAGAI : 
and quercitrin yielded a less bright red colour than did myricetin and quercetin 
respectively. 
These observations indicate that the oxidation colours of flavones and 
flavonols are largely influenced by the chemical constitution of the substance 
especially the number and the position of OH group substituted in beta 
phenyl group as in the case of the reduction colours. 
It is now beyond boubt that the action of oxidases and peroxidases on 
flavones bears no direct relation to the chemical changes of flavones to 
anthocyanins ; nevertheless the oxidizing enzymes may play an important part 
in other metabolic changes in the living tissue. 
3. Flavone Derivative as Cheomogenic Substances of Reddish 
Brown Plant Pigments (Phlobaphenes). 1 
The reddish brown and brown pigments are widely distributed in the 
plant kingdom, namely in the bark, rliizome, seed coat, dead leaves and in 
others, some of them are known as phlobaphenes which were originally the 
name given by Stähelin and Hofstetter (1814)’ to certain brownish red 
substances of unknown chemical constitution isolated from the bark of Pinus 
sylvestris, Platanus aceri/olia, Betula alba, Cinchona Calisaya etc. According to 
these authors and others, 3 phlobaphenes are considered to be the oxidation 
product of tannins. Hlasiwetz considered that there are two groups of sub¬ 
stances which may respectively give rise to two groups of phlobaphenes. One 
of the groups of phlobaphenes to which £ china red ’, ‘ chinava red ’, and ‘ oak 
red ’ etc. belong, yields by fusion with alkali, protocatechuic acid alone, and 
the other group to which ‘ filix red ‘ ratanhia red ’ and £ chestnut red ’ be¬ 
long, yields together with protocatechuic acid, phloroglucin. Along with them, 
1. Nagai, I., On some Reddish Brown Plant-Pigments. Bot. Mag. Tokyo, 31:1, 1917. In 
Japanese. 
2. Stäheein, C. and Hofstetter, J., Chemische Untersuchungen einiger Rinden. Liebig. 
Ann 51:63, 1844. 
3. Hesse, O , Ueber die humusaitingen Bestandtheile der China-rinden. Liebig. Ann. 109 : 
341. 1859. Hlasiwetz, H., Ueber die Beziehungen der Gerbsiture, Glucoside, Phlobaphene uni 
Harze. Liebig. Ann. 143: 209, 1867. Nierenstein, M., Beitrag zur Kenntnis der Gerbstoffe H. 
Berich, d.d. ehern. Gesel. 42 : 353, 1909. See also Perkin, A. G. and Everest, A. E., Loc. cit. page 
436 et seq. 
