Introduction Fresh leaves of Perilla frutescens are used in preparation of seafood served as sushi and sashimi in Japanese food, and dry leaves are used as herbal medicine treating diseases such as allergy and cold. Concentrations of bioactive phytochemicals in perilla are important for use of both food and clinical application (Figure 1). Perillaldehyde (1), rosmarinic acid (2), luteolin (3) and apigenin (4) are contained as major compounds which prevent disease, due to their antibacterial, anti-allergic, anti-inflammatory, antidepressant, antioxidant, and anti-Alzheimer’s effects. Plant metabolites change for a short time as plants are placed in different conditions. The concentration of secondary metabolite in perilla leaves may change under stressful conditions, such as dryness and injury, even after harvested. Generally, dry leaves of perilla are used as raw materials for crude drugs, and fresh leaves of perilla are used as food additives such as flavorings and colorants. However, there is little knowledge to guide us how stresses could affect the concentrations of bioactive metabolites. We have examined the effects of abiotic stresses on the concentration of food nutrient in biomaterials and would discuss when and how plants respond to the stress. Methods Fresh leaves of perillas were subjected to treatments: cutting and/or drying. Extracts of leaves after the treatment were extracted from frozen or dried leaves samples with methanol. Quantitative analysis of 1-4 was conducted by HPLC and LC-MS. Results The concentration of 2 and 4 in fresh leaves has increased in 6 hours after cutting treatment. However, the effect of cutting was not observed in the concentrations of 1-4 in dry leaves. The content of 2 decreased significantly by dryness treatment, and the contents of 3 and 4 increased with dryness to the contrary. Discussion The content of bioactive phytochemicals in perilla was affected by effects of cutting and drying. Perilla responded soon to injury stress and cutting was effective to increase antioxidant 2 and 4 in fresh leaves. But the effect of cutting has not lasted or disappeared with dried leaves. The concentrations of 2-4 were affected by dryness, in which the accumulation of flavonoid 3-4 was increased.

Effects of cutting and drying leaves of culinary herbs on contents of bioactive phytochemicals in Perilla frutescens

255th National Meeting (2018)

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