Résumé
Forty three species of marine algae belonging to Chlorophyta, Phaeophyta and Rhodophyta collected from Alexandria sea shore during the summer season of 1989 were analyzed for their content of vitamin C [Ascorbic acid AA and Dehydroascorbic acid DHA]. The spectrophotometric analyses showed that considerable amounts of vitamin C were observed in the brown algae: Cystoseira tamariscifolia, C. foeniculacea, Dictyot dichotoma and Taenia atomaria [average value 240.6 ug g[-1]fresh weight "f.w."] followed by the green alga Chaetomorpha linum [165.6 ug g[-1]f.w.] and the red alga Corallina mediterranea [141.01 ug g[-1]f.w.]. Generally the brown algae contained the highest amounts of vitamin C. With few exception, most species have DHA higher than AA. The AA/DHA ratio varied considerably from one alga to the other. This ratio may play an important role in controlling the growth of algae