BIOLOGICALLY ACTIVE COMPOUNDS AND ANTIOXIDANT ACTIVITY OF BORAGE (Borago officinalis L.) FLOWERS AND LEAVES

Recently the interest in borage as a vegetable and medicinal plant has increased, yet the knowledge about a content of biologically active compounds in borage grown in Poland remains very scanty. In the experiment carried out in the south-eastern part of the country, fresh borage flowers and leaves contained 0.02% and 0.12% of lipids with the highest level of palmitic acid, i.e. 44.5% and 33.4%, respectively. Flower lipids contained stearic, oleic, elaidic, linoleic, linolelaidic, arachidonic, myristic and lauric acid as well. Besides, leaf lipids were rich in α-linolenic acid (17.7%), less in palmitoleic acid with absence of arachidonic acid. Leaves were found to have 0.16% of essential oil, 1.0% of flavonoids, 9.2 mg vitamin C·100 g f.w.–1, 1.9 mg carotenoids·100 g f.w.–1, 0.77 mg chlorophyll a·1 g f.w.–1 and 0.22 mg chlorophyll b·1 g f.w.–1. Flowers contained more essential oil and vitamin C while less carotenoids, chlorophyll a and b and flavonoids. 45 components were found in the flower essential oil and among them 16 were identified with cumene (62.9%) as a major one. The content of other components was below 3%. As for the leaf essential oil, 18 compounds were detected, and 5 were identified with the highest level of cumene (58.5%) and hexenyl (13.3%). Generally, flowers had more polyphenols and their ferric reducing ability was higher than that of leaves. Besides, a content of remaining unreduced DPPH radical was higher in the flowers. Notably, the time necessary for 50% reduction of the initial concentration of DPPH radical was 2.5 times longer in flowers, whereas their antiradical efficiency 3 fold lower compared to leaves.