Evaluation of the antioxidant potential of Capsicum annuum L., C. baccatum L. and C. chinense Jacq. cultivars.

BACKGROUND: Economically important vegetables are a strong source of antioxidants with different characteristics. Capsicum L. (pepper) is an important agricultural plant because of its economical, medicinal, and nutritional values. METHODS: This study aimed to test antioxidant parameters in the fruits of 9 cultivars of Capsicum annuum L. (CA 01-09), 7 cultivars of C. baccatum L. (CB 01-07), and 11 cultivars of C. chinense Jacq. (CC 01-11). The antioxidant activity of the investigated Capsicum cultivars was measured, along with the free radical scavenging activity (FRSA), using the DPPH method, and the molybdenum reducing power (MRP) was expressed as mg TE (Trolox equivalent) per g of DW (dry weight). Total polyphenol content (TPC), expressed as mg GAE (gallic acid equivalent) per g of DW, total flavonoid content (TFC), expressed as mg QE (quercetin equivalent) per g of DW, and total phenolic acid content (TPAC), expressed as mg CAE (caffeic acid equivalent) per g of DW, were the basic antioxidant parameters of antioxidant activity in this study. RESULTS: All investigated Capsicum extracts exhibited FRSA from 1.45 (CC-06) to 8.21 (CC-05) mg TE/g and MRP from 24.84 (CA-06) to 198.21 (CB-07) mg TE/g. The TPC of the tested extracts ranged from 10.13 (CB-03) to 38.68 (CB-07) mg GAE/g. The TFC of the studied samples showed values from 5.73 (CB-03) to 27.32 (CB-07) mg QE/g and TPAC from 2.24 (CB-03) to 13.07 (CC-07) mg CAE/g. A very strong correlation was found in the investigated cultivars between TPC and TPAC (r = 0.932, 0.839 and 0.848, respectively), and between TPC and TFC (r = 0.921, 0.982 and 0.939, respectively). Very strong relations were also found between TPC and FRSA (r = 0.820) in the C. annuum cultivars and between TPC and MRP (r = 0.898) in the C. baccatum cultivars. CONCLUSIONS: This study found useful results concerning the antioxidant potential of the fruits of Capsicum cultivars. The data obtained demonstrate the strong antioxidant activity of cultivars of Capsicum, which can be used in the food industry because of the commercial importance of these fruits.

Assessment of antioxidant and antimicrobial activities of Crambe spp. during vegetation.

BACKGROUND: The search for new plant raw material as a potential source of antioxidants is still ongoing. This study aimed to evaluate the antioxidant and antimicrobial capacity of the plant raw material of Crambe spp. during vegetation. METHODS: The free radical scavenging activity and molybdenum reducing power of the extracts were used to determine antioxidant activity. The quantification of polyphenol compounds was conducted with Folin-Ciocalteu reagent. Flavonoids and phenolic acids were also determined. The disc diffusion method was used to determine antimicrobial activity. RESULTS: It was determined that the free radical scavenging activity, assessed using the DPPH-method, was 4.38-8.20 mg TE/g DW, the molybdenum reducing power of the extracts was 40.07-129.12 mg TE/g DW, total polyphenol content was 20.24-70.88 mg GAE/g DW, total flavonoid content was 5.73-29.92 mg QE/g DW, and phenolic acid content was 3.00-10.63 mg CAE/g DW. Antimicrobial activity depended on the stage of growth and the part of the plant used. CONCLUSIONS: Crambe spp. possess the antioxidant and antimicrobial potential to mean that they could be used in pharmaceutical studies and the food industry.

Biological properties of sea buckthorn (Hippophae rhamnoides L.) derived products.

BACKGROUND: Sea buckthorn is a good and possible source of a wide range of bioactive compounds with     a positive effect on the human body, especially polyphenols and carotenoids. METHODS: The present study aimed to evaluate the antioxidant and antimicrobial activities of Hippophae rhamnoides L. products - 100% oil, 100% juice, dry berries, and tea (dry berries, leaves, and twigs). The antioxidant activity was determined by DPPH radical scavenging and molybdenum reducing antioxidant power methods. The content of phytochemicals (polyphenols, flavonoids, carotenoids) was measured by colorimetric methods. The detection of antimicrobial activity was carried out using the disc diffusion method and an evaluation of minimal inhibition concentration against three species of Gram-negative bacteria: Escherichia coli CCM 3988, Salmonella enterica subsp. enterica CCM 3807, Yersinia enterocolitica CCM 5671, and three Gram-positive bacteria: Bacillus thuringiensis CCM 19, Listeria monocytogenes CCM 4699, Staphylococcus aureus subsp. aureus CCM 2461. RESULTS: All the tested sea buckthorn products had a high antioxidant activity. The highest content of total polyphenols (204.26 mg GAE/g), flavonoids (30.00 mg QE/g), and carotenoids (0.34 mg/g) were identified in 100% sea buckthorn juice. Maximal values of the antioxidant activity were found using the DPPH method for 100% oil (8.75 mg TE/g) and molybdenum reducing power for tea (196.41 mg TE/g). All the tested products showed strong antimicrobial activity against the tested bacteria, confirmed by both methods - disc diffusion (especially for Yersinia enterocolitica CCM 5671) and minimal inhibitory concentration. CONCLUSIONS: The pronounced antioxidant and antibacterial properties of sea buckthorn products indicate the importance of sea buckthorn application in health promotion and agricultural practice.

Evaluation of the antioxidant activity and phenolic content of Chinese quince (Pseudocydonia sinensisSchneid.) fruit.

BACKGROUND: Neglected and underutilized plant species could serve as a valuable source of natural bioactive compounds. The objective of this study was to evaluate the biological activity of Chinese quince (Pseudocydonia sinensis Schneid) genotypes of Ukrainian and Slovak origin. METHODS: The content of the total antioxidant activity (DPPH method and molybdenum reducing antioxidant power), total polyphenol, flavonoid and phenolic acid compounds in the pulp and peel of Chinese quince were compared across five genotypes from Slovakia and three from Ukraine. RESULTS: All tested samples exhibited DPPH• radical scavenging activities with values from 6.17 to 9.56 mg TEAC (Trolox equivalent antioxidant capacity) per gram of dry matter (DM). Antioxidant activity, measured using the molybdenum reducing antioxidant power method, ranged from 69.82 to 225.04 mg TEAC per gram of DM. Total polyphenol content was from 34.73 to 82.02 mg GAE (gallic acid equivalent), while total flavonoid content was from 0.50 to 26.72 mg QE (quercetin equivalent) per gram DM. Phenolic acid content varied from 1.12 to 8.39 mg CAE (caffeic acid equivalent) per gram DM. The peel extracts contained the highest content of bioactive compounds when compared with the pulp extract (from 15.30 to 32.60%). All observed parameters differed significantly between the genotypes. Strong positive correlations (p ≤ 0.05) were observed between the content of phenolic acids and flavonoids in the peel in plants from Slovakia (r = 0.951, r = 0.928, respectively); between the phenolic acid and antioxidant capacities detected using the MRP method – r = 0.950 and r = 0.955 for peel and pulp, respectively; between the determination of antioxidant activity by the DPPH and MRP methods in the peel and pulp in plants from Ukraine (r = 0.986, r = 0.998, respectively). Significantly positive correlations were found between all the parameters in the samples of Ukrainian origin. CONCLUSIONS: The results showed that all fruit extracts exhibited strong antioxidant activities, which generally correlated positively with the total phenolic content. This study demonstrates that Chinese quince fruit grown in Ukraine and Slovakia is a perspective source of valuable polyphenol content with high antioxidant activity and is a valuable fruit for use in the agriculture and food industries.

Antioxidant activities and phenolic compounds in fruits of various genotypes of American persimmon (Diospyros virginiana L.).

BACKGROUND: American persimmons (Diospyros virginiana L.) are known as a widespread cultivar which were traditionally used by Native Americans as a food source, and since ancient times have been used in folk medicine. The objective of this study was to evaluate the antioxidant activity and phenolic content of Diospyros virginiana genotypes. METHODS: The content of the total antioxidant activity and phenolic compounds from the fruits of the American persimmon (Diospyros virginiana L.) of six genotypes were compared. Antioxidant activity (AOA) was measured using three different photometric methods – DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) and FRAP (ferric-reducing antioxidant power). Total phenolic content (TPC) was evaluated using Folin-Ciocalteu reagent assay. RESULTS: The results for AOA (μMol Trolox/g) determined by the DPPH method varied from 51.68 (DV-05) to 100.87 (DV-03), those obtained by the ABTS method varied from 65.40 (DV-05) to 142.26 (DV-03), and those obtained by the FRAP method varied from 45.06 (DV-05) to 109.30 (DV-03). The results for TPC varied from 590.75 ±27.98 mg/100 g (DV-05) to 1325.12 ±77.30 mg/100 g (DV-03). The highest results for AOA and TPC were achieved for the fruits of genotypes DV-03 and DV-05. A positive linear correlation was found between antioxidant activity and total phenolic content in the examined plant material. CONCLUSIONS: The results showed that all fruit extracts exhibited strong antioxidant activities, which generally correlated positively with the total phenolic content. This study demonstrates the potential of the fruits of Diospyros virginiana grown in Ukraine as a possible source of valuable polyphenol content, with high anti- oxidant activities and health-promoting properties. The high contents of phenolic compounds and significant linear correlation between the values of the concentration of phenolic compounds and antioxidant activity indicated that these compounds contributed to the strong antioxidant activity.