Content of Ascorbic Acid in Common Cowslip (Primula veris L.) Compared to Common Food Plants and Orange Juices

Ascorbic acid is a well-known antioxidant found in plants. The content of ascorbic acid was assayed using a normal phase European Pharmacopoeia HPLC method for ascorbic acid in medicinal products. The content of ascorbic acid in herbs was calculated in % for absolutely dry drug. Ascorbic acid was not detected in the roots of P. veris, in aerial parts it was detected in flowers (0.43 ± 0.034%), in blades (1.43 ± 0.11%) and petioles (1.56 ± 0.12%). In fresh leaves collected at weekly intervals the content of ascorbic acid varied from 1.19 to 2.39%, being highest from mid-May to mid-June. The fresh leaves contained 2.35 ± 0.18% of ascorbic acid and when frozen its content was quite stable for one year. The content of ascorbic acid in dried leaves decreased more than ten times in three months, in twelve months it was less than 1/20th of the initial level. Compared to the analyzed common fresh fruits and salads (n=10) the fresh leaves of common cowslip contained considerably more ascorbic acid. Commercial orange juices could be recommended as the most convenient source of ascorbic acid (8.6-50.4 mg/100 ml); 1-5 glasses of orange juice could fulfill the recommended daily intake of vitamin C (60 mg).