Background: Rosehips, the fruits of Rosa species, are well known for their various health benefits like strengthening the immune system and treating digestive disorders. Antioxidant, anti-inflammatory, and cell regenerative effects are also among their health enhancing impacts. Rosehips are rich in compounds having antioxidant properties, like vitamin C, carotenoids, and phenolics. Methods: Total polyphenol content (Folin-Ciocalteu’s method), and in vitro total antioxidant capacity (ferric-reducing ability of plasma, FRAP) in rosehips of four Rosa species (R. canina, R. gallica, R. rugosa, R. spinosissima) were determined and compared. Ripe fruits were harvested at two locations. Water and ethanolic extracts of dried fruit flesh were analyzed. Results: R. spinosissima had the highest total phenolic content and antioxidant capacity, significantly higher than the other investigated Rosa species. Both parameters were reported in decreasing order for R. spinosissima > R. canina > R. rugosa > R. gallica. Ethanolic extracts of rosehips showed higher phenolic content and antioxidant activity than water extracts. Antioxidant properties were influenced by the growing site of Rosa species. Conclusions: This study indicates that R. spinosissima exhibited the greatest phenolic and antioxidant content, and therefore can be used as a reliable source of natural antioxidants, and serve as a suitable species for further plant breeding activities. Furthermore, investigations of various Rosa species for their antioxidant properties may draw more attention to their potential as functional foods.

In Europe, blackberry (Rubus fruticosus L.) fruits are cultivated for fresh or processed products, and the leaves are collected for medicinal uses mainly from wild-grown populations. In this study, mineral composition, total phenolic content (Folin-Ciocalteu’s method), and total antioxidant capacity (ferric reducing ability of plasma, FRAP) of blackberries were determined during the harvest period. Leaves and fruits were harvested from wild-grown and cultivated plants at the same locations. Results showed that sampling time and growing place influenced the element composition. Concentration of Ca, Fe, K, Mg, P, Zn was significantly higher in cultivated fruits, however, content of Al, Cu, Mn was higher in wild-grown samples. Total phenolic content (TPC) and FRAP values in the leaves increased slightly during the vegetation period. Fruits were harvested at the same maturity stage, their TPC and FRAP level were not influenced by the harvest time. TPC and FRAP levels were higher in blackberry fruits than that in leaves. Significant differences were obtained for TPC and FRAP between wild and cultivated plants, both parameters were higher in the cultivated blackberries. Positive linear correlation was found between the TPC results of wild and cultivated blackberry leaves and fruits, and the same was true for FRAP values. Between TPC and FRAP also a strong positive relationship was observed both in leaves and fruits. Our findings suggest that cultivated blackberry fruits had higher mineral level and antioxidant properties than the wild ones; however, the antioxidant power of leaves from wild populations was similar to that of cultivated plants.

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Differences in antioxidant properties of ginkgo leaves collected from male and female treesTotal phenolic content and antioxidant capacity (FRAP method) of Ginkgo biloba L. leaves collected from male and female trees were determined and compared. Different water and aqueous ethanolic (water/ethanol 80/20, V/V) extracts were prepared by varying the time of infusing, boiling and steeping in order to determine the effect of the extraction method on the above parameters. Antioxidant activity and phenolic content of ginkgo leaf extracts correlated well with significant correlation coefficients. Slopes of linear regression lines were not statistically different for either sex.

Total polyphenol content and antioxidant/reducing capacity of stinging nettle (Urtica dioica L.) leaves and roots collected from wild-grown plants were investigated during the vegetation period. From both fresh and dried samples of leaves and roots, water extracts were prepared by brewing at 60, 80 and 100 °C for 3 hours, and ethanolic extracts of 20 % (v/v) and 70 % (v/v) by extracting at room temperature for 72 hours. The total polyphenol content was determined spectrophotometrically with Folin-Cioceltau reagent and the antioxidant capacity was measured by ferric reducing ability of plasma (FRAP) assay. Our results showed that the optimal harvest time is in the spring (April). Water extracts had the highest total polyphenol content and antioxidant capacity in this period. The amount of valuable compounds released increased by higher extraction temperature in both plant parts. In water extracts of nettle leaves, two times higher polyphenol content was obtained than in that of roots. Both kind of ethanolic extractions resulted in a higher polyphenol content in the leaves harvested in the spring period. For the roots, it was higher for samples collected in the autumn, which is also reflected in the values of antioxidant capacity. Water extracts of fresh leaves harvested in April had more than twice higher total polyphenol content than in October. For dried samples, raising the temperature did not cause a significant change in the total polyphenol content, however, it has resulted in increased antioxidant capacity both for the dried leaf and root samples.