Mindaugas Liaudanskas

Phenolic Composition and Antioxidant Activity of Malus domestica Leaves

The aim of this study was to determine the composition and content of phenolic compounds in the ethanol extracts of apple leaves and to evaluate the antioxidant activity of these extracts. The total phenolic content was determined spectrophotometrically, as well as the total flavonoid content in the ethanol extracts of apple leaves and the antioxidant activity of these extracts, by the ABTS, DPPH, and FRAP assays. The highest amount of phenolic compounds and flavonoids as well as the highest antioxidant activity was determined in the ethanol extracts obtained from the apple leaves of the cv. Aldas. The analysis by the HPLC method revealed that phloridzin was a predominant component in the ethanol extracts of the apple leaves of all cultivars investigated. The following quercetin glycosides were identified and quantified in the ethanol extracts of apple leaves: hyperoside, isoquercitrin, avicularin, rutin, and quercitrin. Quercitrin was the major compound among quercetin glycosides.

A Comparative Study of Phenolic Content in Apple Fruits

The ethanol extracts of apple fruits harvested from the cultivars Aldas, Auksis, Ligol, and Lodel grown in Lithuania were analyzed by the high-performance liquid chromatography method. Chlorogenic acid was found to be a predominant component in the apple fruits of all the cultivars, except the cultivar Ligol. (–)-Epicatechin was the major compound in the ethanol extracts of apple fruits obtained from all the cultivars, while the amount of (+)–catechin was lower. The following quercetin glycosides were identified and quantified: hyperoside, isoquercitrin, avicularin, rutin, and quercitrin. Hyperoside was the major quercetin glycoside in apple fruits.

Application of an Optimized HPLC Method for the Detection of Various Phenolic Compounds in Apples from Lithuanian Cultivars

A specific analytical procedure including sample preparation and HPLC analysis was developed and validated for the detection of phenolic compounds in the samples of different apples from popular Lithuanian cultivars “Aldas,” “Auksis,” “Ligol,” and “Sampion.” The conditions for phenol extraction were optimized: the solvent of the extraction was 70% (v/v) ethanol, and the extraction was performed in an ultrasound bath for 20 min at the temperature of 40°C. The HPLC mobile phase consisted of 2% (v/v) acetic acid in water and 100% (v/v) acetonitrile. Using the HPLC technique, 11 analytes were identified, and their specificity was confirmed: procyanidin B1, (

Seasonal Variation of Qualitative and Quantitative Composition of Phenolic Compounds and Antioxidant Activity in Apple (Malus domestica Borkh.) Fruits

The aim of this study was to explore the peculiarities of the qualitative and quantitative composition of phenolic compounds and antioxidant activity variation in apple (Malus domestica Borkh.) fruit samples during their growth season. The highest total concentration of phenolic compounds (20.97±0.74 mg g -1 ) was detected during the initial period of the phenological fruit growth stage (31 days after full bloom DAFB), and the lowest (1.61±0.05 mg g -1 ) – during the fruit maturation period (143 DAFB). Chlorogenic acid was the predominant compound in apple samples throughout the Original Research Article Liaudanskas et al.; IJBCRR, 14(3): 1-13, 2016; Article no.IJBCRR.28856 2 vegetation period – it comprised 2432.12% of all identified and quantitatively evaluated phenolic compounds in apples. The highest concentration of chlorogenic acid (20.97±0.74 mg g) was detected at the beginning of the fruit development period. In total, 6 quercetin glycosides were detected in apple samples: hyperoside, isoquercitrin, rutin, reynoutrin, avicularin and quercitrin. The highest total concentration of quercetin glycosides (2.75±0.08 mg g -1 ) was detected at the beginning of the fruit development period (31 DAFB), and the lowest (0.23±0.01 mg g) – during the fruit maturation period. The antioxidant activity in apple sample extracts was analysed by applying 2,2-diphenyl-1picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) spectrophotometric assays. The strongest antiradical and reducing activity (TEDPPH reached 81.02 mol g , and TEFRAP 715.63 mol g) was detected at the beginning of the fruit development period. The statistical correlation analysis showed a very strong positive correlation between the total amount of the identified phenolic compounds and the reducing activity of the apple extracts (Spearman’s correlation coefficient – R=0.927, p0.01). There was also a strong positive correlation between the total amount of phenolic compounds and the antiradical activity of the apple extracts (R=0.770, p0.01). Among individual compounds that have been identified and quantitatively evaluated via high-performance liquid chromatography (HPLC), the strongest correlation with antiradical and reducing activity was observed for quercetin glycosides  isoquercitrin (respectively, R=0.851 and 0.845, p0.01) and hyperoside (R=0.770 and 0.891 p0.01).

Detection and analysis of triterpenic compounds in apple extracts

ABSTRACT A new technique for the rapid detection and analysis of triterpenic compounds in apple extracts using HPLC was developed and validated. The main advantage of this technique is the short duration of the analysis – this makes this technique superior to others currently applied for the routine HPLC analysis of triterpenic compounds. The developed, optimized, and validated technique was used for the evaluation of triterpenic compounds in samples of different cultivars of apples, their peels, and flesh. In total, four triterpenic compounds were isolated and identified. Ursolic acid was the dominant compound in all the tested apple samples. The highest amounts of triterpenic compounds were detected in the peels of the ‘Lodel’ apple cultivar, and thus apples of this cultivar may be potentially useful for the isolation of individual compounds and the production of functional food and dietary supplements.

Seasonal Variation of the Qualitative and Quantitative Composition of Phenolic Compounds in Malus domestica Leaves

Apple (Malus domestica Borkh.) is one of the most widely grown and cultivated fruit trees. Studies on the quantitative and qualitative composition of phenolic compounds in healthy apple leaves and leaves with scabs have been conducted to evaluate the influence of apple scab (Venturia inaequalis (Cooke) Wint.) on the biosynthesis of phenolic compounds [1, 2]. However, there is still a lack of studies of apple leaves, which would allow for their use in medical practice, pharmacy, and food industry. The goal of this study was to determine the quantitative and qualitative compositional variability of flavonoids and phenolic acids in apple leaf samples obtained from apples (Malus domestica Borkh.) grown under Lithuanian climatic conditions during the vegetation period. We studied the leaves of the “Ligol” apple cultivar during the vegetation period. Phenolic compounds of different groups were identified in ethanol extracts of the studied apple leaves, including quercetin glycosides, dihydrochalcones, monomeric flavan-3-ols, and phenolic acids. Of all the identified compounds of the quercetin group, quercitrin (1) predominated during all phenological stages. The highest concentration of this compound (9.53 0.21 mg g–1) was detected at the beginning of the phenological stage of leaf development (the 140th day of the year), and the lowest concentration (6.32 0.10 mg g–1) – during the aging stage of the leaves (the 294th day of the year). Similar regularities in the variation of the quantitative quercitrin content during the vegetation period have also been noticed by other researchers who analyzed leaf samples obtained from “Golden Delicious” and “Jonagold” apple trees [3]. The detected amounts of quercitrin reached 44.5–55.9% of the total amount of the identified quercetin glycosides in apple leaf samples. Research data published in scientific sources confirm our results, i.e., quercitrin is the predominant compound among quercetin glycosides detected in apple leaves [2, 4]. The detected amounts of other quercetin glycosides were lower. The highest amount of hyperoside (2, 4.38 0.11 mg g–1) was detected at the end of the vegetative period (the 308th day of the year), and the highest amount of avicularin (3, 4.62 0.19 mg g–1) – in apple leaf samples collected at the beginning of leaf development (the 140th day of the year). The lowest amount of hyperoside (2, 2.27 0.06 mg g–1) was detected during the stage of intensive sprout growth (the 196th day of the year), and the lowest amount of avicularin (3, 1.29 0.05 mg g–1) – in apple leaf samples collected during the phenological stage of leaf aging (the 294th day of the year). The lowest amounts of rutin (4) and isoquercitrin (5) were detected at the beginning of the phenological stage of leaf development (the 140th day of the year) – 0.85 0.034 mg g–1 and 0.17 0.01 mg g–1, respectively. During the vegetative period, the concentration of these compounds increased. The highest amounts of isoquercitrin (2.74 0.22 mg g–1) and rutin (0.81 0.03 mg g–1) were detected during the phenological stage of leaf aging (the 308th day of the year), when the leaves turned yellow. The amount of rutin detected during the vegetative period was the lowest of all the identified quercetin glycosides.

Composition and Concentration of Phenolic Compounds of ‘Auksis’ Apple Grown on Various Rootstocks

Abstract The trial was carried out at the Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry in 2013-2015. Cv. ‘Auksis’ was tested on 12 rootstocks: B.396, B.9, M.9, M.26, P 22, P 59, P 61, P 62, P 66, P 67, PB.4, and Pure 1. Accumulation of phenolic compounds depended on fruit yield and average fruit weight. On average, significantly lower concentration among rootstocks occurred when apple trees had abundant yield and fruits were smaller. On average chlorogenic acid constituted 50% and total procyanidins 28% of total phenols in ‘Auksis’ fruits. Flavonoid concentration most depended on rootstock and the highest variation was recorded. More than 50% difference occurred between the highest total flavonoid concentration in apples on PB.4 and the lowest on M.9 rootstocks. Low variability of total procyanidin concentration among rootstocks was observed. Differences between the highest and lowest concentration was 15%. Total concentration of phenolic compounds differed among rootstocks by 29-35% depending on the year. Differences in accumulation of phenolic compounds depended on rootstock genotype but not on yield or fruit weight. PB.4 and P 67 rootstocks had the highest, and M.9, P 62 and M.26 had the lowest concentration of total phenol in ‘Auksis’ fruits

Determination of the Phenolic Composition and Antioxidant Activity of Pear Extracts

The specific HPLC analytical procedure was developed and validated for the determination of phenolic compounds in pear samples of different popular cultivars “Conference,” “Concordia,” “Grabova,” and “Patten.” HPLC mobile phase consisted of 0.05% (v/v) trifluoroacetic acid in water and 100% (v/v) acetonitrile. The HPLC method was used to identify and confirm the specificity of 8 analytes: chlorogenic acid, rutin, hyperoside, isoquercitrin, isorhamnetin rutinoside, quercitrin, quercitrin malonyl glucoside, and isorhamnetin glucoside. Repeatability % RSD did not exceed 3.87%, and intermediate precision did not exceed 4.63%. The total content of phenolic compounds varied from  mg/g (cv. “Concordia”) to  mg/g (cv. “Patten”). Chlorogenic acid was the major component in all the tested pear cultivars. The highest amount of chlorogenic acid (  mg/g) was found in pear samples of the cultivar “Grabova,” and the highest amount of flavonol compounds (  mg/g) was found in pear samples of the cultivar “Concordia.”

OPTIMISATION OF THE EXTRACTION OF FLAVONOIDS FROM APPLES USING RESPONSE SURFACE METHODOLOGY

The ultrasound-assisted extraction of flavonoids from apple samples was modelled using response surface methodology. A three-level-three-factor central composite design using the response surface methodology (RSM) was employed to optimise three extraction variables, including temperature, extraction time and ultrasonic power, for the achievement of the highest extraction yield of the flavonoids from lyophilised apple samples. The optimised extraction conditions were 44.61oC, an extraction time of 26.90 min, and ultrasonic power 480 W. The experimental yield of flavonoids was 6.58 mg g-1 expressed as rutin equivalent, which was close to the predicted yield (6.69 mg g-1). Optimised extraction conditions were applied for the analysis of apple samples of six cultivars.