Lowbush Blueberry, Highbush Blueberry and Cranberry Extracts Protect Cucumber (Cucumis sativus L.) Cotyledons from Damage Induced by UV-B Irradiation

We prepared water extracts from four dry berries, lowbush blueberry (LBB) (Vaccinium angustifolium L.), highbush blueberry (HBB) (Vaccinium corymbosum L.), cranberry (CB) (Vaccinium macrocarpon Ait.) and grape (Vitis vinifera L.). The four berry extracts were efficient absorbers of ultraviolet (UV) light, primarily UV-B. The treatment of cucumber (Cucumis sativus L.) cotyledons with LBB, HBB and CB extracts attenuated the damage induced by continuous UV-B irradiation (0.58 W m-2) for 11 days and did not cause any side effects. Anthocyanin and polyphenol contents in the four berry extracts were analyzed using high performance liquid chromatography (HPLC) and spectrophotometry. Anthocyanins, which are major UV-absorbing compounds in higher plants, were not the primary polyphenolic compounds in the four berry extracts. A total of 51 specific polyphenols were identified. The LBB extract contained primarily chlorogenic acid, caffeic acid and protocatechuic acid; the HBB extract contained primarily chlorogenic acid, caffeic acid and syringic acid; and the CB extract contained primarily protocatechuic acid, myricetin and p-coumaric acid. These components might contribute to the protection of cucumber plants against UV-B-induced damage.