Effect of LED illumination and amino acid supplementation on phenolic compounds profile in Agastache rugosa in vitro cultures

Abstract

Abstract Agastache rugosa (Fischer & C.A.Meyer) O.Kuntze (Lamiaceae) is an East Asian medicinal and aromatic plant. It is rich in polyphenolic compounds such as rosmarinic, chlorogenic, ferulic acids and apigenin glycosides. in vitro shoot cultures were used to study influence of various factors on polyphenol profile using Ultra Performance Liquid Chromatography coupled to high resolution mass spectrometry (UPLC-ESI-qTOF-MS). Large differences in the morphology and polyphenol profile were observed in experiments with various illumination (white fluorescent lamps or white and photosynthetically active radiation LEDs) and supplementation with plant growth regulators and amino acids. Shoots were cultured on the MS basal agar medium with or without plant growth regulators (6-benzylaminopurine - BA, indole-3-acetic acid – IAA), or supplemented with different concentrations of phenylpropanoid biosynthesis precursor - l -phenylalanine or an amino acid mixture (casein hydrolysate). The composition of polyphenols in methanolic extracts was analyzed using UPLC-DAD-qTOF-MS. Three phenolic acids: cryptochlorogenic acid, feruloyl-quinic acid, rosmarinic acid, a rosmarinic acid methyl ester and two isomeric ferulic acid glucosides, as well as one flavonoid – an apigenin derivative were detected. Rosmarinic acid (RA) was the most abundant compound found in the analyzed plant material. Supplementation with amino acids resulted in highest content of RA in shoots cultured for 196 days on media containing either low concentration (1\u2009mg/L) of l -phenylalanine or two of the highest - 20, 50\u2009mg/L. The effect of casein hydrolysate supplementation was noticed from the beginning of shoot culture and reached maximum of 23.3\u2009mg/g on 140 day. On the other hand, shoots that were growing under different illumination produced over 20\u2009mg/g dw of RA after 70 days of culture. In conclusion, the production of phenolic compounds in A. rugosa in vitro shoots was influenced by the age of the shoot cultures, illumination regime and amino acids supplementation.