Comparative evaluation of phenolic phytochemicals from perilla seeds of diverse species and screening for their tyrosinase inhibitory and antioxidant properties

The current work was the first to conduct tyrosinase inhibition and antioxidant properties as well as phenolic phytochemicals in the seeds of Korean perilla species such as cultivated and wild types. The 80% methanol extract (80 μg/mL) of this source showed potent biological activities, especially, P. frutescens var. frutescens had the highest antityrosinase and antioxidant effects with 86 and 87%. To investigate the phenolics on their capacities, the above extract was chromatographed, which yielded six compounds, including caffeic acid (1), rosmarinic acid-3-O-glucoside (2), rosmarinic acid (3), luteolin (4), apigenin (5), and chrysoeriol (6) using UHPLC-ESI-Q-TOF-MS/MS and NMR. Highly absolute tyrosinase inhibitory activities were found in phenolics 3–6 with IC50s of 24.6, 20.8, 17.3, and 15.8 μM compared to positive control (kojic acid; 45.7 μM). Moreover, phenolics 1, 3, and 4 exhibited significant scavenging abilities with IC50 values of 4.6, 5.5, and 8.7 μM (ABTS) as well as 11.7, 15.5, and 14.3 μM (DPPH), respectively. Six phenolics 1–6 also differed considerably with the range of 2273.0–4773.9 μg/g in five species, especially, P. frutescens var. frutescens showed the highest contents and rosmarinic acid (3) was the predominant constituent (703.9–2965.0 μg/g), representing approximately 19–74% of the total phenolics. Our results suggest that perilla seeds may be utilized as a potent natural source of antityrosinase and antioxidant for the development of breeding lines and functional foods.