The present invention describes extracts ofPolygonum cuspidatumand related compositions that are capable of photodynamic inactivation (PDI) of microorganisms such as bacteria, viruses, fungi, and protozoa, and capable of killing or inactivating cancer cells. The present invention further describes methods of using saidPolygonum cuspidatumextracts and photodynamic inactivation (PDI) as a therapy for the treatment of microbial infection and as well as the use ofPolygonum cuspidatumextract and related compositions as photodynamic therapy agents for the treatment of cancer.
