ABSTRACT
Napthodianthrones are derivatives of anthracene. The napthodianthrones of Hypercium perforatum includes hypericin, pseudohypericin and isohypericin. The fresh plant contains protohypericin and protopseudohypericin and in presence of light, they are converted into hypericin and pseudohypericin. The total amount of napthodianthrones ranges from 0.05-0.15%. According to Upton, the hypericin content of dried flowers can be upto 1.8%. H. perforatum extract used in most of the clinical trials has been standardized to contain at least 0.3% hypericin. However, poor bioavailability of hypericin is a limiting factor and as a result nanohypericin has been developed.
