Characterisation of phenolic phytochemicals and quality changes related to the harvest times from the leaves of Korean purple perilla ( Perilla frutescens)

Abstract

The objective of this study was to investigate the profiles of phenolic phytochemicals in the leaves of Korean purple perilla (cv. Bora, Perilla fructescens) using reversed-phase C 18 column chromatography and HPLC with DAD-ESI/MS analysis. Changes in their contents were also the first reported through eight different harvest times during two months. They were characterised as five anthocyanins and three phenolic acids including cyanidin-3,5-di- O-glucoside ( 1), cyanidin-3- O-glucoside ( 2), cyanidin-3- O-(6- O-caffeoyl)glucoside-5- O-glucoside ( 3), cyanidin-3- O-(6- O-coumaroyl)glucoside-5- O-glucoside ( 4), cyanidin-3- O-(6- O-coumaroyl)glucoside ( 5), caffeic acid ( 6), rosmarinic acid ( 7), and rosmarinic acid methylester ( 8). Significant differences were observed between individual and total phytochemical contents, especially, cyanidin-3- O-(6- O-coumaroyl)glucoside-5- O-glucoside ( 4) and rosmarinic acid ( 7) exhibited the predominant constituents. Among different harvest times, the highest content was found with 82.473 mg/g on 21st September, while the lowest was 39.000 mg/g on 17th August. These results may be useful in determining the optimal harvest time at which phenolic phytochemicals reaches a maximum level in mid-September.