Biochemical activities of extracts from Hypericum perforatum L. - 2nd Communication: Inhibition of metenkephaline- and tyrosine-dimerization

Extracts from the herb "St. John's wort" (Hypericum perforatum L.), besides other activities such as wound healing, antigout; antirheumatic and diuret ic properties, are widely used to counteract neurological disorders such as depressive situations, nervousness and sleeplessness. The characteristic a nd leading component in these extracts, the dianthraquinone hypericin, is v ery likely not to represent the main active principle mediating the desirab le effects. Thus, standardization of the drug is no longer based on the qua ntification of total hypericin and since several years simply the determina tion of dry matter content is in use instead. As biochemical background of depression the lack of catecholamine neurotransmitters or decreased P-endor phins such as methionine- or leucine-enkephalins have to be envisaged. This communication reports on the inhibition of myeloperoxidase-catalyzed dimer ization of enkephalins by Hypericum extracts. The substitution for enkephal ins by tyrosine and for myeloperoxidase by horseradish peroxidase may repre sent a simple and inexpensive biochemical model reaction of pathological ev ents during the manifestation of depressive events suitable for drug standa rdization.