A comprehensive study of phytochemical composition and shikimate dehydrogenase, quinate dehydrogenase and phenylalanine ammonia-lyase activities in three Cornus species

Abstract

The plants of Cornaceae family are a promising source of hydrolysable tannins which are known for their pharmacological properties. However, there are a lot of gaps in biosynthetic mechanisms of this class of phenolic compounds in different species and timepoints This study examines the qualitative composition, total content, and accumulation dynamics of phenolic compounds, as well as the activity of shikimate dehydrogenase, quinate dehydrogenase, and phenylalanine ammonia-lyase in the leaves of three promising Cornus species: Cornus alba, Cornus sericea, and Cornus sanguinea. In the species studied, we discovered monomeric (isomers of gemin D, tellimagrandin I and II), dimeric (isomers of camptothin A, cornusiin A, D or camptothin B, the isomers of cornusiin E, G), and trimeric ellagitannins (an isomer of cornusiin F, C, and trapanin A). The highest level of the total caffeic acid derivatives and total flavonoid content together with the lowest of total hydrolysable tannins content was observed in C. alba samples. The performed principal component analysis revealed the differentiation among Cornus species based on content of phenolic compounds. The highest shikimate dehydrogenase activity was observed in C. sericea leaves in August and lowest in C. sangunea in June. Activity of quinate dehydrogenase was higher in C. sanguinea than that C. alba in June. There was no difference in phenylalanine ammonia-lyase activity between the studied species. The observed differences in the total hydrolysable tannins content in C. alba, C. sanguinea and C. sericea could be related to different quinate dehydrogenase activity. Some cross-species differences were observed in shikimate- and quinate dehydrogenase activity. The performed study of metabolite profiles and an analysis of enzyme activity would be useful for elucidating the regulatory mechanisms governing tannin synthesis in non-model species, such as Cornus species.