An Overview of Potential Natural Photosensitizers in Cancer Photodynamic Therapy

Abstract

Cancer is one of the main causes of death worldwide. There are several different types of cancer recognized thus far, which can be treated by different approaches including surgery, radiotherapy, chemotherapy or a combination thereof. However, these approaches have certain drawbacks and limitations. Photodynamic therapy (PDT) is regarded as an alternative noninvasive approach for cancer treatment based on the generation of toxic oxygen (known as reactive oxygen species (ROS)) at the treatment site. PDT requires photoactivation by a photosensitizer (PS) at a specific wavelength (λ) of light in the vicinity of molecular oxygen (singlet oxygen). The cell death mechanisms adopted in PDT upon PS photoactivation are necrosis, apoptosis and stimulation of the immune system. Over the past few decades, the use of natural compounds as a photoactive agent for the selective eradication of neoplastic lesions has attracted researchers’ attention. Many reviews have focused on the PS cell death mode of action and photonanomedicine approaches for PDT, while limited attention has been paid to the photoactivation of phytocompounds. Photoactivation is ever-present in nature and also found in natural plant compounds. The availability of various laser light setups can play a vital role in the discovery of photoactive phytocompounds that can be used as a natural PS. Exploring phytocompounds for their photoactive properties could reveal novel natural compounds that can be used as a PS in future pharmaceutical research. In this review, we highlight the current research regarding several photoactive phytocompound classes (furanocoumarins, alkaloids, poly-acetylenes and thiophenes, curcumins, flavonoids, anthraquinones, and natural extracts) and their photoactive potential to encourage researchers to focus on studies of natural agents and their use as a potent PS to enhance the efficiency of PDT.

Thiophene BODIPY-substituted cyclotriphosphazene-derived photosensitizers for photodynamic therapy applications

“…31 This heavy atom functionalization of the BODIPY core on 2,6-positions was necessary to support ISC and increase singlet oxygen production. 15 After the synthesis of the starting BODIPY compounds (3)(4)(5), preparation of distyryl derivatives (6)(7)(8) was planned to produce photoactive compounds in the therapeutic perspective. The reason for choosing 3-thiophene carboxaldehyde for this reaction is that the thiophene moieties at the styryl ends of the molecule enhance the ISC activity and do not have a toxic effect.…”

“…1,2 However, non-invasive or minimally invasive alternative treatment methods are tried because of the side effects of these treatment methods including low life quality of the patients and cancer drug resistance. 3 Therefore, new treatment approaches are still required. Photodynamic therapy (PDT) could be an alternative and promising treatment modality based on a light-activated drug molecule called a photosensitizer (PS).…”

Molecular Nanoarchitectonics of Natural Photosensitizers and Their Derivatives Nanostructures for Improved Photodynamic Therapy

“…[12] In recent years, natural PSs and their derivatives have emerged as powerful candidates for their broad range of sources, good biocompatibility, excellent photosensitivity, as well as anti-tumor effects. [13][14][15][16] For instance, porphyrins and their derivatives (Heme, chlorophyll, chlorin e6 et al) are well studied for their outstanding 1 O 2 quantum yields. [17][18][19] Hypericin extracted from Hypericum perforatum L. can not only induce efficient PDT, but also activate strong tumor immune response.…”

“…Moreover, the PSs should have good selectivity towards tumors to further reduce the phototoxicity to normal tissues during PDT [12] . In recent years, natural PSs and their derivatives have emerged as powerful candidates for their broad range of sources, good biocompatibility, excellent photosensitivity, as well as anti‐tumor effects [13–16] . For instance, porphyrins and their derivatives (Heme, chlorophyll, chlorin e6 et al.)…”

Functionalization of a Cortical Membrane with a Photodynamic Protocol

“…Currently, to overcome these complications, many studies are focusing on the coating of membranes with some bioactive materials, such as hydroxyapatite and/or alginate/chitosan, to improve both osteoinductive and antibacterial properties [ 19 , 21 ]. Photodynamic therapy has evolved through the years with developments in photosensitizers and more complex methodologies resulting in alternative treatments employed as cancer therapy [ 22 ], alleviation of autoimmune disease complications [ 23 ], and control or elimination of viral, fungal and bacterial infections in both planktonic and biofilm forms [ 24 ]. However, few studies reported the application of photodynamic treatments during GBR procedures [ 25 , 26 ].…”