Polyphenolic compounds and ascorbic acid of plants of the genus Arctium L. introduced in the M. M. Hryshko National Botanical Garden

Abstract

Purpose. To study the accumulation of catechins, anthocyanins, leucoanthocyanins and ascorbic acid in plants of the genus Arctium, introduced to the M. M. Hryshko National Botanical Garden. Methods. Introduced plants of the genus Arctium were used for the study, namely A. lappa L. (greater burdock), A. tomentosum Mill. (woolly burdock), A. nemorosum Lej. (wood burdock) and A. minus Bernh (lesser burdock). Phytochemical analyses of plant organ samples were carried out at different stages of ontogeny. Free catechins, anthocyanins and leucoanthocyanins were determined by the photocolorimetric method. Results. It was found that second year plants accumulate more catechins than first year plants. Their maximum amount is found in the leaf plates of A. lappa and A. minus in the budding phase (180.0 ± 0.3 and 144.0 ± 0.1 mg%, respectively). The content of leucoanthocyanins in the leaf plates of one­year­old plants varied from 72.0 ± 0.4 (A. lappa) to 660.0 ± 0.6 mg% (A. minus); two­year­old plants – from 18.0 ± 0.6 (A. nemorosum) to 165.0 ± 0.5 mg% (A. lappa). Most of these compounds were found in the leaf blade of A. minus in the first year of vegetation. The amount of anthocyanins in leaf plates of one­year­old plants varied from 9.0 ± 0.1 (A. nemorosum) to 42.0 ± 0.4 mg% (A. minus), in petioles from 9.8 ± 0.06 (A. tomentosum) to 117.0 ± 0.6 mg% (A. minus). In the second year of vegetation, their accumulation ranged from 12.0 ± 0.3 (A. minus) to 42.0 ± 0.6 mg% (A. tomentosum) in leaf plates and from 9.6 ± 0.1 (A. tomentosum) to 48.0 ± 0.1 mg% (A. nemorosum) in petioles. Most anthocyanins were found in the petioles of A. minus from the first year of vegetation. Conclusions. The phytochemical studies established that plants of the Arctium genus, introduced to the M. M. Hryshko National Botanical Garden, accumulate varying amounts of phenolic compounds during the growing season. The proportion of flavonoids in leaves was found to be related to air temperature. An increase in temperature leads to a decrease in the content of anthocyanins, while an increase in catechins occurs due to a decrease in temperature. The leaf plates of annual plants belonging to the Arctium genus accumulate the highest levels of ascorbic acid.