Biologically active compounds, photosynthetic pigments, and antiradical activity in leaf extracts of Siberian Caragana species (Fabaceae)
E. P. KHRAMOVA, E. V. BANAEV, M. A. TOMOSHEVICH, T. M. SHALDAEVA, A. A. ERST
Central Siberian Botanical Garden, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Caragana, xerophytic conditions, phenolic compound, saponin, pectin, pigment, DPPH, adaptation
Abstract
Our aim was to investigate levels of biologically active compounds and antiradical activity in water-ethanol extracts from the leaves of Siberian species of the genus Caragana [ C. spinosa (L.) DC., C. arborescens Lam., C. bungei Ledeb., C. microphylla (Pall.) Lam., C. frutex (L.) C. Koch, and C. pygmaea (L.) DC.] as a source of medicinal raw material and for chemotaxonomy of these species. The profile of biologically active compounds and antiradical activity of C. frutex are reported for the first time. The leaves of C. spinosa have a high content of catechins (4.88 mg/g). It was shown that the highest concentration of secondary metabolites (tannins, flavonols, and saponins) and high antiradical activity are present in forest-steppe species: C. frutex and C. arborescens . Among all the assayed populations, the highest variation was observed for catechins, and the lowest for saponins. High interpopulation variation of biochemical traits in C. pygmaea was noted (coefficients of variation (%): catechins 119.91, flavonols 74.19, tannins 44.45, and saponins 44.09). Among the analyzed Caragana populations, a correlation was demonstrated between the antiradical activity and levels flavonols (r = -0.61), tannins (r = -0.52), and saponins (r = -0.51). The chlorophyll a /chlorophyll b ratio ranged from 2.3 to 3.8 among the populations, with a median value of 3.0, indicating near-optimal conditions for plant growth. Correlation analysis revealed a positive association between total chlorophyll and carotenoid levels (r = 0.64). The level of pectins among the studied Caragana species varied from 0.7 to 21.7 mg/g, and that of protopectins from 9.0 to 114.0 mg/g. The present paper illustrates substantial antioxidant potential of water-ethanol extracts from Caragana leaves, consistently with high concentrations of phenolic compounds and saponins, and this association was confirmed by correlation analysis. Our results point to potential uses of Siberian Caragana species in nutraceutical and pharmaceutical products and thus offer good industrial applications.
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