New Photosensitizers from MushroomsAustrian, Swiss and Dutch scientists claim to have discoved a natural substance derived from mushrooms that is as potent a photosensitizer as
TLD1433. It's noteworthy that they chose
TLD1433 as the standard with which to compare these new photosensitizers. The full article is here.:
Targeted isolation of photoactive pigments from mushrooms yielded a highly potent new photosensitizer: 7,7′-biphyscion Abstract
Pigments of fungi are a fertile ground of inspiration: they spread across various chemical backbones, absorption ranges, and bioactivities. However, basidiomycetes with strikingly colored fruiting bodies have never been explored as agents for photodynamic therapy (PDT), even though known photoactive compound classes (e.g., anthraquinones or alkaloids) are used as chemotaxonomic markers. In this study, we tested the hypothesis that the dyes of skin-heads (dermocyboid Cortinarii) can produce singlet oxygen under irradiation and thus are natural photosensitizers. Three photosensitizers based on anthraquinone structures were isolated and photopharmaceutical tests were conducted. For one of the three, i.e., (–)-7,7′-biphyscion (1), a promising photoyield and photocytotoxicity of EC50 = 0.064 µM against cancer cells (A549) was found under blue light irradiation (λexc = 468 nm, 9.3 J/cm2). The results of molecular biological methods, e.g., a viability assay and a cell cycle analysis, demonstrated the harmlessness of 1 in the dark and highlighted the apoptosis-inducing PDT potential under blue light irradiation. These results demonstrate for the first time that pigments of dermocyboid Cortinarii possess a so far undescribed activity, i.e., photoactivity, with significant potential for the field of PDT. The dimeric anthraquinone (–)-7,7′-biphyscion (1) was identified as a promising natural photosensitizer.
.
.
.
....With these results, 1 is one of the most potent AQ-based PS so far known: With its average EC50, BL of approx. 0.05 µM 1 exceeds the photocytotoxicity of the reported monomeric AQs rubiadin (EC50, MCF7 = 74 µM) and soranjidiol (EC50, MCF7 = 37 µM)31 by more than 1300 fold. Thus, 1 represents a natural compound with a true potential as PDT hit structure. Furthermore, 1 demonstrated in vitro activities not inferior to those of transition metal complexes already used in clinical trials (i.e., Ru(II) polypyridiyl complex TLD1433 with an EC50 of 51 nM against cells of the U87 human glioblastoma cell line, activated by green light (530 nm, 45 J/cm2))32,33. Finally, the apoptosis-inducing character of 1 under irradiation rendered this new natural photosensitizer highly promising.