Standardization of hazel leaf]

Dried leaves of 9 harvested batches and 5 batches of commercial origin from Corylus avellana L. were examined. The levels of principal polyphenolic compounds averaged respectively: total flavonoids 2.58 and 2.58%, myricitrin 1.09 and 1.35%, quercitrin 0.30 and 0.40%, tannins 5.2 and 6.5%. Specifications were discussed for a French Pharmacopoeial monography.