Photodynamic therapy for cancer: Role of natural products

Abstract

Photodynamic therapy (PDT) is a relatively new and promising modality for the treatment of cancer. PDT involves administering a photosensitizing dye, i.e. photosensitizer, that selectively accumulates in tumors, and shining a light source on the lesion with a wavelength matching the absorption spectrum of the photosensitizer, that exerts a cytotoxic effect after excitation. The reactive oxygen species produced during PDT are responsible for the oxidation of biomolecules, which in turn cause cell death and the necrosis of malignant tissue. PDT is a multi-factorial process that generally involves apoptotic death of the tumor cells, degeneration of the tumor vasculature, stimulation of anti-tumor immune response, and induction of inflammatory reactions in the illuminated lesion. Numerous compounds with photosensitizing activity have been introduced commercially. Although many papers have been published with regard to PDT in the last decade, there has been relatively little focus on natural medicinal plant extracts and compounds derived therefrom. Herbal plants and their extracts are natural substances, and in comparison with synthetic chemicals are considered "green". This review focuses on the different mechanisms of PDT and discusses the role of various plant extracts and natural compounds either alone or in combination for carrying out PDT on different types of cancers.

Photoinduced damage of AsLOV2 domain is accompanied by increased singlet oxygen production due to flavin dissociation

“…On the other hand, the improved control regarding 1 O 2 production by using genetically-encoded photosensitizers leads to attempts to utilize them as antimicrobial agents 15,16 or in PDT 17 . Up to now, more than 400 individual compounds have been recognized as possible candidates for use as PSs 9 . However, a large fraction of the small organic PSs has unsuitable physico-chemical properties such as low solubility and stability in aqueous solvents, and inherent low specificity for targeted diseased tissue.…”

Role of Photoactive Phytocompounds in Photodynamic Therapy of Cancer

“…The selective nature of these compounds is important in clinical PDT to overcome side effects. Future studies are warranted to isolate and evaluate these specific photoactive compounds from plants to be used as a potent PSs for PDT for cancer and related disorders [ 162 , 163 ].…”

Cervical cancer: a meta-analysis, therapy and future of nanomedicine

“…Improved efficiency in cervical cancer treatment using several proteins, polymers and lysosome nanocomplexes containing cisplatin, paclitaxel and methotrexate was also reported [ 11 ]. The ability of chitosan and methoxypolyethylene glycol-coated nanoparticles were seen to effectively deliver methotrexate both in vivo and in vitro and to reduce HeLa cell proliferation [ 103 ]. Although polyphenols are promising anti-cervical cancer agents, their clinical application is hindered by their poor solubility and low oral bioavailability [ 15 ].…”

“…Most photosensitizers occur naturally in plant extracts such as hypericin ( H. perforatum , 514–593 nm), thiophenes ( E. latifolius Tausch , 225 and 400 nm) and curcumin ( Curcuma longa , 350 to 450 nm). Although these extracts are capable of treating cancer cells, the compounds have poor solubility properties and are ineffective in clinical applications [ 103 ]. Lipid nanocapsules embedded with hypericin were found to improve the solubility and efficiency of the compound in HeLa cells [ 104 ].…”