"Photo" Chemistry Without Light?

Baader, W. J.; Stevani, Cassius V.; Bechara, Etelvino José Henriques

doi:10.5935/0103-5053.20150257

Cited by 12 publications

(27 citation statements)

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“…In subsequent decades, several investigators noticed metabolites that seemed to require reaction mechanisms forbidden in the ground state by the Woodward-Hoffman rules, and suggested that electronic excitation might be an important feature of biochemistry [35, 36]. These groups identified enzymes capable of generating dioxetanes and electronic excitation in a test tube, including horseradish peroxidase (in the presence of H 2 O 2 ), cytochrome c, and lipoxygenase [37]. …”

Section: Cpds From Chemiexcitationmentioning

confidence: 99%

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Chemical excitation of electrons: A dark path to melanoma

Premi

Brash

2016

DNA Repair

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Sunlight’s ultraviolet wavelengths induce cyclobutane pyrimidine dimers (CPDs), which then cause mutations that lead to melanoma or to cancers of skin keratinocytes. In pigmented melanocytes, we found that CPDs arise both instantaneously and for hours after UV exposure ends. Remarkably, the CPDs arising in the dark originate by a novel pathway that resembles bioluminescence but does not end in light: First, UV activates the enzymes nitric oxide synthase (NOS) and NADPH oxidase (NOX), which generate the radicals nitric oxide (NO•) and superoxide (O2•−); these combine to form the powerful oxidant peroxynitrite (ONOO−). A fragment of the skin pigment melanin is then oxidized, exciting an electron to an energy level so high that it is rarely seen in biology. This process of chemically exciting electrons, termed “chemiexcitation”, is used by fireflies to generate light but it had never been seen in mammalian cells. In melanocytes, the energy transfers radiationlessly to DNA, inducing CPDs. Chemiexcitation is a new source of genome instability, and it calls attention to endogenous mechanisms of genome maintenance that prevent electronic excitation or dissipate the energy of excited states. Chemiexcitation may also trigger pathogenesis in internal tissues because the same chemistry should arise wherever superoxide and nitric oxide arise near cells that contain melanin.

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Section: Cpds From Chemiexcitationmentioning

confidence: 99%

“…The excited carbonyl’s diradical character initiates [2+2] cycloaddition reactions (Paterno-Buchi reaction), as well as facilitating hydrogen abstraction from H donors (e.g., alcohols and 1,4-dienes) and C-C bond homolysis. Modified from [37]. …”

Section: Figmentioning

confidence: 99%

Chemical excitation of electrons: A dark path to melanoma

Premi

Brash

2016

DNA Repair

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“…One potential explanation for this observation is that MPACN, whose concentration in the nucleus would be expected to increase with dose, functions to photosensitize adjacent pyrimidine nucleobases to undergo cyclobutane dimerization. Such a photosensitization mechanism might involve ROS-mediated formation of dioxetane intermediates, as has been postulated for the formation of CPDs in the dark after UVB irradiation of melanocytes followed by exothermic energy transfer of high-energy melanin products to adjacent thymine and cytosine bases ( Baader et al, 2015 ). This explanation is in agreement with the less prominent increase in CPD formation at higher concentrations of MBITC because the concentration of MBITC would not increase in the nucleus as much as MPACN due to MBITC’s reactivity as an electrophile toward proteins in the cell culture medium and in the cytosolic compartment.…”

Section: Discussionmentioning

confidence: 99%

Photoprotective Properties of Isothiocyanate and Nitrile Glucosinolate Derivatives From Meadowfoam (Limnanthes alba) Against UVB Irradiation in Human Skin Equivalent

Carpenter

Miranda

et al. 2018

Front. Pharmacol.

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Exposure to ultraviolet B (UVB) irradiation of the skin leads to numerous dermatological concerns including skin cancer and accelerated aging. Natural product glucosinolate derivatives, like sulforaphane, have been shown to exhibit chemopreventive and photoprotective properties. In this study, we examined meadowfoam (Limnanthes alba) glucosinolate derivatives, 3-methoxybenzyl isothiocyanate (MBITC) and 3-methoxyphenyl acetonitrile (MPACN), for their activity in protecting against the consequences of UV exposure. To that end, we have exposed human primary epidermal keratinocytes (HPEKs) and 3D human skin reconstructed in vitro (EpiDermTM FT-400) to UVB insult and investigated whether MBITC and MPACN treatment ameliorated the harmful effects of UVB damage. Activity was determined by the compounds’ efficacy in counteracting UVB-induced DNA damage, matrix-metalloproteinase (MMP) expression, and proliferation. We found that in monolayer cultures of HPEK, MBITC and MPACN did not protect against a UVB-induced loss in proliferation and MBITC itself inhibited cell proliferation. However, in human reconstructed skin-equivalents, MBITC and MPACN decrease epidermal cyclobutane pyrimidine dimers (CPDs) and significantly reduce total phosphorylated γH2A.X levels. Both MBITC and MPACN inhibit UVB-induced MMP-1 and MMP-3 expression indicating their role to prevent photoaging. Both compounds, and MPACN in particular, showed activity against UVB-induced proliferation as indicated by fewer epidermal PCNA+ cells and prevented UVB-induced hyperplasia as determined by a reduction in reconstructed skin epidermal thickness (ET). These data demonstrate that MBITC and MPACN exhibit promising anti-photocarcinogenic and anti-photoaging properties in the skin microenvironment and could be used for therapeutic interventions.

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“…[47] More radical approaches involve using non-electrical and molecular lumiphores as "internal" light sources. Chemiluminescence has been used to trigger chemical reactions using "dark" photochemistry (direct energy transfer from reactive oxygen species), [48] and for photoexcitation. [49][50][51][52] The application of chemiluminescence to biological systems is hampered by the complexity of co-localizing all of the necessary reagents in the tissue or cell of interest.…”

Section: Internal Luminescent Sources Of Lightmentioning

confidence: 99%

Shining a Light on Bioorthogonal Photochemistry for Polymer Science

Boase

2020

Macromol. Rapid Commun.

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Bioorthogonal chemistry is revolutionizing the fields of biological chemistry and nanomedicine, providing tools to actively probe and perturb native biochemical processes. Photochemistry provides the opportunity to actively and non‐invasively control bioorthogonal reactions, providing sophisticated optochemical tools. Despite the opportunities in bioorthogonal photochemistry, there remain many significant challenges to the clinical translation of current research. This review aims to provide an overview of these challenges and highlight recent examples from the literature that are providing revolutionary solutions to overcoming these barriers. It will highlight new photochemical systems that can be triggered by near infrared light in aqueous solutions and have been demonstrated to function in complex biological systems, including in living animals. It will cover diverse classes of photochemical reactions including photopolymerization, uncaging, conjugation, and photoswitching. The discussion will detail how new approaches are being integrated into polymers or highlight unexploited opportunities. This review intends to showcase how the unique synergy of bioorthogonal photochemistry and polymer science provides vast opportunities in the fields of biomaterials, nanomedicine, and theranostics. This will hopefully provide inspiration to material scientists to integrate bioorthogonal photochemistry into new adaptable materials and ensure translation to solve clinical challenges.

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"Photo" Chemistry Without Light?

Cited by 12 publications

References 0 publications

Chemical excitation of electrons: A dark path to melanoma

Chemical excitation of electrons: A dark path to melanoma

Photoprotective Properties of Isothiocyanate and Nitrile Glucosinolate Derivatives From Meadowfoam (Limnanthes alba) Against UVB Irradiation in Human Skin Equivalent

Shining a Light on Bioorthogonal Photochemistry for Polymer Science

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