Iridoids, Flavonoids, and Antioxidant Capacity of Cornus mas, C. officinalis, and C. mas × C. officinalis Fruits.

The fruits of Cornus mas and Cornus officinalis have been known and appreciated in folk medicine for years and have a high biological value, which is mainly connected with their polyphenols and iridoids content. However, hybrids of C. mas × C. officinalis have not been investigated. The aim of this study was to evaluate the iridoids, anthocyanins, and flavonols content, and antioxidant capacity of Cornus mas, Cornus officinalis, and C. mas × C. officinalis. Iridoids and flavonoids were quantified by the High-Performance Liquid Chromatography (HPLC) method. Antioxidant capacity (AC) was measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH•), 2,2'-azino-bis (3-ethyl benzothiazoline-6-sulfonic acid (ABTS•+), and ferric reducing antioxidant power (FRAP) tests. Total phenolic content (TPC) was evaluated using the Folin-Ciocalteu reagent. Among the C. mas cultivars and C. officinalis genotypes, there was considerable variation in the content of iridoids, flavonoids, and AC. Interspecific hybrids C. mas × C. officinalis contained more iridoids than C. mas and more anthocyanins than C. officinalis and additionally had higher AC and TPC than C. officinalis and most C. mas. AC, TPC, and the presence of iridoids, anthocyanins, and flavonols in hybrids C. mas × C. officinalis are reported for the first time. The Cornus species deserve special attention due to their highly biologically active substances, as well as useful medicinal properties.

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.