Interpopulation Variation of Leaf Polyphenol Content in Spiraea aquilegifolia (Rosaceae) from the Republic of Buryatia

The composition and content of polyphenols in leaves was studied in Spiraea aquilegifolia Pall. plants from nine natural populations of the Republic of Buryatia (Western Transbaikalia) by high-performance liquid chromatography (HPLC). At least 24 compounds were detected in hydroethanolic extracts of S. aquilegifolia leaves by HPLC. Of these, three phenol carboxylic acids (chlorogenic, p-hydroxybenzoic, and p-coumaric acids) and six flavonols (hyperoside, isoquercitrin, avicularin, astragalin, quercetin, and kaempferol) were identified. Hyperoside (2.9–8.2 mg/g), avicularin (3.0–5.8 mg/g), and isoquercitrin (0.8–2.5 mg/g) were the main flavonols found in leaf hydroethanolic extracts. Plants from populations located at the northern distribution limit in Western Transbaikalia were found to have higher contents of phenol carboxylic acids (near the village Koma) and flavonols (near the village Klyuchi). Plants from populations located at the eastern limit (near the villages Kusoty and Zagan) showed the lowest concentration of the identified phenolic compounds. The contents of the identified free phenolic acids and flavonols were moderate or high in S. aquilegifolia leaves as compared to other Spiraea species examined, rendering it important to further study the composition of phenolic compounds in S. aquilegifolia.