Improved procedure for the quality control of Hypericum perforatum L.

A new, fast and reliable procedure for the quantification of the major comp ounds of Hypericum perforatum L. has been developed. Four naphthodianthrone s (protopseudohypericin, pseudohypericin, protohypericin, hypericin) and tw o phloroglucinols (hyperforin, adhyperforin) were assayed by HPLC using a s hort (17 min) linear gradient, with hypericin and hyperforin as external st andards. Extraction of dried plant material with methanol in the dark at ro om temperature for 2 h led to a complete recovery of phloroglucinols but on ly a partial recovery of the naphthodianthrone derivatives. Treatment of pl ant material with water:ethanol (40:60, v/v) in a water bath shaker at 80 d egreesC led to the total extraction of hypericins, but a 10% loss of total hyperforins was also observed. The two extraction methods, applied successi vely to the same sample, allowed the complete extraction of all compounds o f interest. A 5 min exposure of the crude extract of H. perforatum to sunli ght (1 E/m(2)) induced a 96% loss of hyperforins, whereas the dry plant mat erial lost only 20% of hyperforins after 2 h exposure to sunlight (24 E/m(2 )). Copyright (C) 2001 John Wiley & Sons, Ltd.