Abstract: The present invention relates to a method of preparing a porphyrin derivative from a meso-acrylonitrile-substituted porphyrin compound. According to the invention a Vilsmeier reagent carrying an aromatic ring is used, wherein said Vilsmeier reagent is a soft electrophile. The use of this Vilsmeier reagent results in a porphyrin derivative having the ring system of the Vilsmeier reagent condensed to its porphyrin macrocycle via two new 6 membered rings. Thus a new class of porphyrin derivatives is provided, wherein said derivatives are photodynamically more active than the starting compound. The invention also relates to a porphyrin derivative, use of said porphyrin derivative and a pharmaceutical composition containing said porphyrin derivative.

Abstract: The present invention relates to the use of a photosensitizer compound with a specified structural formula for the treatment of a skin-borne fungus, a method of preparing a pharmaceutical composition for the treatment of a skin-borne fungus, and a method of treating a mammal suffering from a skin-borne fungus, such as Trichophyton rubrum.