Secondary metabolic responses to treatment of 2-aminoindan-2-phosphonic acid in cell lines from Arnebia euchroma

Abstract

The accumulation of rosmarinic acid, acetylshikonin, deoxyshikonin, β, β'-dimethylacrylshikonin and isovalerylshikonin was investigated in cell suspension cultures of Arnebia euchroma (Royle) Johnst under the influence of 2-aminoindan-2-phosphonic acid (AIP), an inhibitor of phenylalanine ammonia lyase (PAL), and of the effector methyl jasmonate (MeJA). The results showed that methyl jasmonate promoted the accumulation of rosmarinic acid and shikonin derivatives. Conversely, 2-aminoindan-2-phosphonic acid suppressed the formation of rosmarinic acid, which indicated that AIP, indeed, was able to inhibit the phenylpropanoid pathway in A. euchroma. Meanwhile, the content of total shinkonins and other four kinds of shikonin derivatives, though varied in degrees, was also inhibited. And the inhibition was dose-dependent and time-dependent. Acetylshikonin responsed most rapidly to the treatment of AIP, the content reduced after 24 h of treatment and decreased to only half of those untreated control 48 h after teratment. β, β'-Dimethylacrylshikonin, difffer from acetylshikonin, responded much slowly to the treatment, inhibition could only be observed 96 h later. These suggest that phenylpropanoid pathway plays an important role in the shikoninsbiosynthesis, and this study provides a reference for the further research in metabolic regulation of producing shikonins by cell culture technology and biosynthesis pathways of shikonin derivatives. Still, shikonins biosynthesis pathways is complicated, the exact dose- and time-effect relationship of AIP and interaction between AIP and other effectors like MeJA need further research.