Selection of the optimal extractant for extracting the complex of biologically active substances from the cowslip leaves and rhizomes with roots

Abstract

Topicality. Since ancient times the species of Primrose (Primula L.) are used in traditional medicine. There are about 500 species, which are distributed around the globe. In the CIS (Commonwealth of Independent States) countries grows 67 species. The most common is cowslip (Primula veris L.; Primula officinalis Hill.). The decoction of cowslip rhizomes with roots is used in traditional and scientific medicine as an expectorant; the infusion of leaves is used as analgesic and diuretic. In the Ukrainian pharmaceutical market there are no domestic drugs from raw cowslip.

Aim. To determine the optimal conditions for obtaining extracts from the cowslip leaves and rhizomes with roots to develop new domestic drugs with anti-inflammatory and expectorant activity.

Materials and methods. The object of the research was the cowslip leaves, which were harvested in Ternopil region in 2015 during the mass plants’ flowering, and rhizomes with roots, which were harvested after the death of aerial parts of the plants. Raw material was crushed to the particles of 3-5 mm size. For extraction of biologically active substances from the cowslip leaves, the following solvents were investigated: 20 %, 40 %, 70 % ethanol and hot purified water (80 °C). The ratio of raw material : extractant was 1 : 10. Infused during the day at room temperature, with constant stirring; filtered and condensed on a rotary vacuum evaporator to a thick state at a temperature of 60-70 °C. To select the extractant to obtain substances from the cowslip rhizomes with roots we took 20 %, 30 %, 40 % ethanol. Additionally we received the extract with 20 % ethanol extraction, having moistened the raw material with 95 % ethanol. The ratio of raw material : extractant was 1 : 8. Infused during seven days with compulsory supply of extractant, stirring; filtered and condensed on a rotary vacuum evaporator. Quantitative determination of flavonoids, hydroxycinnamic acids, phenolic compounds and saponins was conducted with spectrophotometric method. The dry residue was determined by gravimetric method as required by State Pharmacopoeia of Ukraine (SPU), oxidative phenols were determined by permanganatometric method.

Results and discussion. When studying the effect of extractant upon the degree of biologically active substances extraction from the cowslip leaves, we found that the maximum amount of hydroxycinnamic acids, oxidative phenols and saponins was extracted with ethanol 40 %, representing 25.5 %, 12.13 %, 3.25 % respectively; phenolic compounds and flavonoids – with ethanol 70 % (5.40 % and 12.70 %, respectively); extractive substances with cleared hot water (48.51 %). When extracting biologically active substances from the cowslip rhizomes with roots, we found that the maximum amount of hydroxycinnamic acids and flavonoids was extracted with ethanol 40 %, representing 7.93 % and 1.15 % respectively; phenolic compounds, oxidative phenols and saponins – with ethanol 30 % (2.57 %, 5.03 % and 5.25 % respectively). The content of extractive substances in the studied extracts from the cowslip rhizomes with the roots in all objects was approximately equal.

Conclusions. We obtained the extracts from the cowslip leaves and rhizomes with the roots. Thick extract of leaves is a homogeneous viscous brown mass with a greenish tinge, with a bitter and salty taste, with a peculiar pleasant smell, soluble in water and insoluble in ethanol 96 %. Thick extract of rhizomes with roots is a homogeneous viscous dark brown mass, with a bitter taste, with a peculiar pleasant smell, soluble in water and insoluble in ethanol 96 %. It is established that the maximum amounts of hydroxycinnamic acids, oxidative phenols and saponins in extracts from the cowslip leaves was observed with 40 % ethanol extraction; phenolic compounds and flavonoids – 70 % ethanol; extractives – hot clean water. Thus, the optimal content of complex biologically active substances from the cowslip leaves provides 40 % ethanol solution. It is established that the maximum amount of hydroxycinnamic acids and flavonoids in extracts from the cowslip rhizomes with roots was observed with 40 % ethanol extraction; phenolic compounds, saponins, oxidative phenols, extractives – 30 % ethanol. Thus, the optimal content of complex biologically active substances from the cowslip rhizomes with roots provides 30 % ethanol solution.