Determination of the Total Phenolic, Flavonoid and Hydroxycinnamic Acid Derivatives Content in Lonicera Caerulea L. Leaves Samples

Abstract

Introduction. Lonicera caerulea L. is also known as blue honeysuckle, belonging to the Caprifoliaceae Juss. family, it is a medium-sized shrub that produces blue edible berries [1]. The leaves contain a wide variety of phytochemical components such as flavonoids, phenolic acids, triterpenic compounds [2]. The aim of the study is to investigate the variation in the quantitative composition of phenolic compounds in Lonicera caerulea L. leaves samples. Materials and methods. Leaves from seven different cultivars of blue honeysuckle were collected in Lithuania. Samples were prepared using 0.25 g (exact weight) of shredded dried raw material, 10 mL of 70% (v/v) ethanol and sonicated for 30 minutes using 1300 W ultrasonic power. After filtration the total phenolic content was determined spectrophotometrically using the Folin-Ciocâlteu reagent and expressed as gallic acid equivalent (GAE) [3]. The total flavonoid content of the samples was estimated also spectrophotometrically using reaction with aluminum chloride and expressed as rutin equivalent (RE) [4]. The total hydroxycinnamic acid derivatives content was determined spectrophotometrically using Arnow's reagent and expressed as chlorogenic acid equivalent (CAE) [5]. All data were recalculated for absolute dry weight (DW). Results and their discussion. In different cultivars of L. caerulea the total phenolic content varied in a range from 4.94 mg GAE/g DW to 11.41 mg GAE/g DW. The analysis showed that the highest total phenolic content (11.41±0.47 mg/g) was determined in 'Amphora' cultivar leaves samples. The lowest total phenolic content (4.94±0.26 mg/g) was found in the leaves samples of the cultivar 'Tundra'. The coefficient of variation (CV) of the total phenolic content of L. caerulea leaves was 26.9%. The total flavonoid content varied in a range from 34.87 mg RE/g DW to 42.26 mg RE/g DW. The highest total flavonoid content (42.26±2.18 mg RE/g DW) was ascertained in the leaves samples of cultivar 'Amphora' and the lowest (34.87±1.32 mg RE/g) – in samples of cultivar 'Nimfa'. The CV of the total flavonoid content of L. caerulea leaves was 7.1%. The total hydroxycinnamic acid derivatives content ranged from 485.22 mg CAE/g DW to 1300.01 mg CAE/g DW. The highest total hydroxycinnamic acid derivatives content (1300.01±45.19 mg CAE/g DW) was determined in the leaves samples of cultivar 'Amphora' and the lowest (485.22±9.68 mg CAE/g DW) – in the samples of cultivar 'Tundra'. The CV of the total hydroxycinnamic acid derivatives content of L. caerulea leaves was 31%. Conclusions. The results revealed that the cultivar has influence on the accumulation of phenolic compounds of L. caerulea leaves. The leaves samples of blue honeysuckle from cultivar 'Amphora' was characterized by the highest total phenolic, flavonoid and hydroxycinnamic acid derivatives content. The highest variation was determined for the total hydroxycinnamic acid derivatives content and the lowest – for the total flavonoid content.