Identification and quantitation of phenolic compounds from the seed and pomace of perilla frutescens using HPLC/PDA and HPLC-ESI/QTOF/MS/MS

Introduction - Perilla frutescens (L.) Britt., an essential traditional Asian crop and Chinese medicine, potentially exerts antioxidation effects through its phenolic compounds. These compounds have already been reported in perilla seed, however, little is reported in Perilla pomace, the primary waste during oil production of Perilla seed.

Objective - To investigate major phenolic compounds in perilla seeds and pomaces in order to check whether the pomace could be an alternative resource to the seed for nutritional and medical purposes.

Methods - Compounds in extracts of perilla seeds and pomaces were separated by high-performance liquid chromatography and detected by photodiode array, and by electrospray ionisation with quadrupole time-of-flight tandem mass spectrometry. Herb-markers selected by principal components analysis were then quantified in both seeds and pomaces. Moreover, a fingerprinting approach and multiple discriminant analysis were applied to screen the phenolic markers in 22 samples.

Conclusion - The results indicated perilla pomace is a promising alternative source of phenolic compounds that could be recovered and potentially used as natural anti-oxidants.

Results - Ten phenols were tentatively identified, among which four (rosmarinic acid, luteolin, apigenin and rosmarinic acid-3-O-glucoside) were selected as herb-markers. Perilla seeds and pomaces showed similar phenol profiles, however, the pomaces contained almost two times the amount of the four herb-markers than the seeds.