Phenolic compounds in the leaves and inflorescences of <i>Spiraea baldshuanica</i> B. Fedtsch.

Abstract

For the first time, the composition and content of phenolic compounds in the leaves and inflorescences of Spiraea baldshuanica B. Fedtsch. was investigated. Research material was collected in June 2019 from a natural population in the Republic of Tajikistan. Phenolic compounds were studied in 40% water- ethanol extracts by the method of high-performance liquid chromatography (HPLC). The analytical HPLC system used consisted of an Agilent 1200 (USA) liquid chromatograph equipped with a diode array detector, an autosampler and a ChemStation system for collecting and processing chromatographic data. 15 and 11 compounds of phenolic nature were found in native extracts from inflorescences and leaves, respectively. Among them, the following substances were identified: chlorogenic and cinnamic acids, quercetin, kaempferol, hyperoside, isoquercitrin, avicularin and astragalin. The chromatographic profiles of leaves and inflorescences were found to be different. Such substances as isoquercitrin, avicularin, kaempferol were discovered in the inflorescences of S. baldshuanica , rather than in its leaves. Compared to the leaves, the concentration of all detected phenolic compounds was higher in the inflorescences under study. The major component in the inflorescences was astragalin (3.16 mg/g), whereas its concentration in the leaves was 5 times lower (0.60 mg/g). Flavonoid aglycones were obtained from the water-ethanol extracts of the leaves and inflorescences under study by acid hydrolysis using hydrochloric acid (1:1). The hydrolysates of extracts from the leaves and inflorescences of S . baldshuanica were found to contain 3 flavonoid aglycones: quercetin, kaempferol and isorhamnetin. By recalculating the concentration of aglycone for the corresponding glycoside, it was determined that quercetin glycosides prevails: 6.67 mg/g – in the inflorescences and 1.19 mg/g – in the leaves. S. baldshuanica differs significantly from other representatives of the Spiraea genus, section Calospira , in terms of the chromatographic profile of phenolic compounds contained in the leaves. This information serves as an additional argument for differentiating S. baldshuanica as a separate series of the Decumbentes group by morphological signs.