Twenty three different wild blackberry fruit samples were assessed regarding their phenolic profiles and contents (by LC/MS quadrupole time-of-flight (QTOF) and antioxidant activity (ferric reducing ability of plasma (FRAP) and 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS)) by two different extraction methods. Thirty four phenolic compounds were detected (8 anthocyanins, 15 flavonols, 3 hydroxycinnamic acids, 6 ellagic acid derivatives and 2 flavones). In samples, where pressurized liquid extraction (PLE) was used for extraction, a greater increase in yields of phenolic compounds was observed, especially in ellagic acid derivatives (max. 59%), flavonols (max. 44%) and anthocyanins (max. 29%), than after extraction by the ultrasonic technique extraction (UAE) method. The content of phenolic compounds was significantly correlated with the antioxidant activity of the analyzed samples. Principal component analysis (PCA) revealed that the PLE method was more suitable for the quantitative extraction of flavonols, while the UAE method was for hydroxycinnamic acids.

The basic chemical composition, polyphenols and antioxidant capacity in 22 old apple cultivars grown in Poland were determined. Fruits were analyzed for contents of individual polyphenolics with the ultra-performance liquid chromatography photodiode detector-quadrupole/time-of-flight mass spectrometry (UPLC-PDA-Q/TOF–MS) method, sugar with the high-performance liquid chromatography–evaporative light scattering detector (HPLC-ELSD) method, and antioxidant capacity with the ABTS and FRAP radical method. A total of 29 bioactive compounds, including 26 polyphenolic compounds (7 flavan-3-ols, 2 dihydrochalcones, 4 anthocyanins, 5 phenolic acids, 8 flavonols) and 3 triterpenoids (ursolic, betulinic and oleanolic acids), were identified in fruits. All the apple cultivars were found to be rich in polyphenols [average 2139.21 mg/100 g dry matter (dm)], especially phenolic acid (average 694.12 mg/kg dm), flavan-3-ols (average 1259.80 mg/kg dm), flavonols (average 106.78 mg/kg dm) and triterpenoids (average 2552.20 µg/g dm), particularly ursolic acid (average 2234.50 µg/g dm), with high ABTS and FRAP capacity (average 72.14 and 46.77 µmol Trolox/100 g dm). The apple cultivars were also found to be a good source of pectins (average 1.19%), acids (average 0.67%) and sugars (average 9.11 g/100 g).

Twenty-six different wild blackberry leaf samples were harvested from various localities throughout southeastern Poland. Leaf samples were assessed regarding their phenolic compound profiles and contents by LC/MS QTOF, and their antioxidant activity by ABTS and FRAP. Thirty-three phenolic compounds were detected (15 flavonols, 13 hydroxycinnamic acids, three ellagic acid derivatives and two flavones). Ellagic acid derivatives were the predominant compounds in the analyzed leaves, especially sanguiin H-6, ellagitannins, lambertianin C, and casuarinin. The content of phenolic compounds was significantly correlated with the antioxidant activity of the analyzed samples. The highest level of phenolic compounds was measured for R. perrobustus, R. wimmerianus, R. pedemontanus and R. grabowskii. The study showed that wild blackberry leaves can be considered a good source of antioxidant compounds. There is clear potential for the utilization of blackberry leaves as a food additive, medicinal source or herbal tea.

The aim of the study was the qualitative and quantitative analysis of the bioactive components present in the leaves of 9 sweet potato cultivars grown in the moderate climate in Poland, which were harvested at different growth stages according to the BBCH (Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie) scale (14, 51, 89). It was found that sweet potato leaves contained 7 polyphenolic compounds, including 5 chlorogenic acids—neochlorogenic acid (5-CQA), chlorogenic acid (3-CQA), 4-cryptochlorogenic acid (4-CQA), 34-di-O-caffeoylqunic acid (3,4-CQA), 3,5-di-O-caffeoylqunic acid (3,5-CQA)—and 2 flavonoids, quercetin-3-O-galactoside (Q-3-GA) and quercetin-3-O-glucoside (Q-3-GL). Their content depended on the genotype of the examined cultivars and on the stage of leaf development. The mean content of the identified polyphenolic compounds in the examined cultivars ranged from 148.2 to 14.038.6 mg/100 g⁻¹ DM for the leaves harvested at growth stage 14 according to the BBCH scale. In the case of leaves harvested at BBCH stage 51, the concentration of polyphenolic compounds ranged from 144.76 to 5026.8 mg/100 g⁻¹ DM and at BBCH stage 89 from 4078.1 to 11.183.5 mg/100 g⁻¹ DM. The leaves of the Carmen Rubin cultivar collected at stage 14 contained the highest amount of polyphenolic compounds, while Okinava leaves had the highest amount of these compounds at stage 51. The highest content of polyphenolic compounds in leaves at BBCH growth stage 89 was found in the Radiosa variety. The highest concentration levels were found for 3-CQA at all stages of leaf development. Significant correlations between polyphenol content and antioxidant activity measured by 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing/antioxidant power (FRAP) were found. The results of this experiment revealed that the growth stages and genetic properties of cultivars have a very significant influence on the content of phenolic acids and flavonols in sweet potato leaves. The results are innovative and can have a practical application, as the knowledge of the content of the substances under study makes it possible to determine the optimal management practice of sweet potato leaf harvest in order to obtain more top-quality raw material.

Antioxidant properties and phenolic acid content in the pulp of five pumpkin species were evaluated. The following species cultivated in Poland were included: Cucurbita maxima ‘Bambino’, Cucurbita pepo ‘Kamo Kamo’, Cucurbita moschata ‘Butternut’, Cucurbita ficifolia ‘Chilacayote Squash’, and Cucurbita argyrosperma ‘Chinese Alphabet’. The content of polyphenolic compounds was determined by ultra-high performance liquid chromatography coupled with HPLC, while the total content of phenols and flavonoids and antioxidant properties were determined by spectrophotometric methods. Ten phenolic compounds (protocatechuic acid, p-hydroxybenzoic acid, catechin, chlorogenic acid, caffeic acid, p-coumaric acid, syringic acid, ferulic acid, salicylic acid, kaempferol) were identified. Phenolic acids were the most abundant compounds; the amount of syringic acid was found to be the highest, ranging from 0.44 (C. ficifolia) to 6.61 mg∙100 g⁻¹ FW (C. moschata). Moreover, two flavonoids were detected: catechin and kaempferol. They were found at their highest level of content in C. moschata pulp (catechins: 0.31 mg∙100 g⁻¹ FW; kaempferol: 0.06 mg∙100 g⁻¹ FW), with the lowest amount detected in C. ficifolia (catechins: 0.15 mg∙100 g⁻¹ FW; kaempferol below the limit of detection). Analysis of antioxidant potential showed significant differences depending on the species and the test used. The DPPH radical scavenging activity of C. maxima was 1.03 times higher than C. ficiofilia pulp and 11.60 times higher than C. pepo. In the case of the FRAP assay, the multiplicity of FRAP radical activity in C. maxima pulp was 4.65 times higher than C. Pepo pulp and only 1.08 times higher compared to C. ficifolia pulp. The study findings show the high health-promoting value of pumpkin pulp; however, the content of phenolic acids and antioxidant properties are species dependent.

The aim of the paper was to evaluate the phenolic acid content and antioxidant properties in potato cultivars with coloured flesh and bright flesh. The study material included eight cultivars of edible potato grown in a temperate climate in Poland. Five cultivars were potato tubers with coloured flesh: “Rote Emma”, “Blue Salad”, “Vitelotte”, “Red Emmalie”, and “Blue Congo”; and three were potato tubers with bright flesh: “Bella Rosa”, “Lord”, and “Tajfun”. In all potato samples under study, four phenolic acids were identified: chlorogenic acid, gallic acid, p-coumaric acid, and caffeic acid. The predominant acid was chlorogenic acid, the levels of which ranged from 62.95 mg·100 g⁻¹ FM to 126.77 mg·100 g⁻¹ FM. The total concentration of the identified phenolic acids was diverse and depended on the genotype of the cultivar and the tuber flesh colour, with coloured-fleshed potatoes having higher phenolic acid contents in comparison to bright-fleshed potato cultivars. The average concentration of phenolic acids in the samples was 89.19 mg∙100 g⁻¹ FM, and the average concentrations of the individual phenolic acids identified were as follows: chlorogenic acid (86.19 mg∙100 g⁻¹ FM), gallic acid (1.18 mg∙100 g⁻¹ FM), p-coumaric acid (0.64 mg∙100 g⁻¹ FM), and caffeic acid (1.18 mg∙100 g⁻¹ FM). In addition, three groups of anthocyanins were identified: pelargonidin-3,5-di-O-glucoside, peonidin-3,5-di-O-glucoside, and petunidin-3,5-di-O-glucoside. Anthocyanins were not found in the “Lord” or “Tajfun” varieties characterised by white tuber flesh. The predominant pigment was petunidin-3,5-di-O-glucoside, with an average content of 23.15 mg∙100 g⁻¹ FM, and the highest value was observed in the “Vitelotte” variety (51.27 mg∙100 g⁻¹ FM). The antioxidant activity of the flesh of the potatoes under study was diverse depending on flesh colour. The FRAP (Ferric Reducing Antioxidant Power) assay indicated higher antioxidant activity of coloured-fleshed potato cultivars. The highest concentration was identified in the “Vitelotte” cultivar flesh and was 114% higher than in the “Lord” cultivar. Similar dependencies were found in the case of the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay; however, in this case, the “Vitelotte” cultivar flesh demonstrated nearly 6.4 times higher antioxidant activity than the “Lord” cultivar. Summarizing our own research, we can conclude that potato varieties with coloured flesh are characterised by a higher content of biologically active substances, including phenolic acids, and antioxidant properties compared to potato tubers with bright flesh.