The triplet energy levels of UVA and UVB sunscreens

Gonzenbach, H.; Hill, Thomas J.; Truscott, T. George

doi:10.1016/1011-1344(92)80025-q

Cited by 55 publications

(36 citation statements)

References 3 publications

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“…50 The triplet state energies of PABA is 75 kcal mol Ϫ1 (313.5 kJ mol Ϫ1 ) and that of OMC is 57 kcal mol Ϫ1 (238.3 kJ mol Ϫ1 ). 51 Evidence of singlet oxygen formation was also reported for padimate-O. 18a To our knowledge, the energy of the triplet excited state of oxybenzone has not been reported, but Allen and coworkers 18a found no significant formation of singlet oxygen with this sunscreen.…”

Section: Influence Of Molecular Oxygen On the Photostability Of Chemimentioning

confidence: 59%

An in vitro systematic spectroscopic examination of the photostabilities of a random set of commercial sunscreen lotions and their chemical UVB/UVA active agents

Serpone

Salinaro

Emeline

et al. 2002

Photochem Photobiol Sci

156

112

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The photostabilities of a random set of commercially available sunscreen lotions and their active ingredients are examined spectroscopically subsequent to simulated sunlight UV exposure. Loss of filtering efficacy can occur because of possible photochemical modifications of the sunscreen active agents. Changes in absorption of UVA/ UVB sunlight by agents in sunscreen lotions also leads to a reduction of the expected photoprotection of human skin and DNA against the harmful UV radiation. The active ingredients were investigated in aqueous media and in organic solvents of various polarities (methanol, acetonitrile, and n-hexane) under aerobic and anaerobic conditions The UV absorption features are affected by the nature of the solvents with properties closely related to oil-in-water (o/w) or water-in-oil (w/o) emulsions actually used in sunscreen formulations, and by the presence of molecular oxygen. The photostabilities of two combined chemical ingredients (oxybenzone and octyl methoxycinnamate) and the combination oxybenzone/titanium dioxide were also explored. In the latter case, oxybenzone undergoes significant photodegradation in the presence of the physical filter TiO2.

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Section: Influence Of Molecular Oxygen On the Photostability Of Chemimentioning

confidence: 59%

An in vitro systematic spectroscopic examination of the photostabilities of a random set of commercial sunscreen lotions and their chemical UVB/UVA active agents

Serpone

Salinaro

Emeline

et al. 2002

Photochem Photobiol Sci

156

112

View full text Add to dashboard Cite

show abstract

“…The energy required to promote molecular oxygen from the ground state triplet to the excited singlet state is only 22.7 kcal mol -1 (10). The energy of the triplet excited state of PABA has been reported as 75 kcal mol -1 (11). Thus, this excited state triplet of PABA clearly has enough energy to promote O 2 ( 3 Σ g ) to 1 O 2 .…”

Section: Resultsmentioning

confidence: 98%

Photochemical Formation of Singlet Molecular Oxygen in Illuminated Aqueous Solutions of Several Commercially Available Sunscreen Active Ingredients

Allen

Gossett

Allen

1996

Chem. Res. Toxicol.

103

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Evidence is presented for the photochemical formation of singlet molecular oxygen (1O2) in air-saturated aqueous solutions of several sunscreen active ingredients using sunlight-range illumination. This is of significance because (1) 1O2 is known to be cytotoxic, and (2) there have been several reports of toxic effects associated with the use of some sunscreens; most notably, with p-aminobenzoic acid (PABA). Illuminated aqueous solutions of PABA, 2-ethylhexyl p-(dimethylamino)benzate (ODPABA), 2-hydroxy-4-methoxybenzophenone (BZ3), 2,2'-dihydroxy-4-methoxybenzophenone (BZ8), 2-ethylhexyl 2-cyano-3,3-diphenylacrylate (OCR), 2-ethylhexyl p-methoxycinnamate (OMC), and 2-ethylhexyl salicylate (OCS) were evaluated individually for 1O2 formation. Furfuryl alcohol (FFA), a well-known chemical trap for 1O2, was added to each of the aqueous sunscreen solutions. The FFA was consumed when solutions of PABA, ODPABA, OMC, and OCR were illuminated, but no loss of FFA other than by direct photolysis occurred in solutions of BZ3, BZ8, or OCS. There was also no significant loss of FFA in any of these solutions kept in the dark. Further evidence for the formation of 1O2 in illuminated aqueous sunscreen solutions is provided by the results of experiments in which individual solutions containing sunscreen active ingredients and FFA that were diluted with D2O exhibited an increased rate of FFA consumption while the addition of azide ion (N3-) reduced the rate of FFA consumption. Continuous sunlight-range illumination of aqueous PABA solutions produced significantly higher steady-state concentrations of 1O2 than in solutions containing any of the other sunscreen active ingredients evaluated. The substituted benzophenone compounds (BZ3 and BZ8) and the salicylate-based compound (OCS) not only appear to produce no 1O2, but they also appear to produce no other reactive oxidant species that are capable of consuming FFA. This indicates that BZ3, BZ8, and OCS may be peferable, from the standpoint of toxic oxidant formation, for use as sunscreen active ingredients when compared to the other compounds evaluated in this study.

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“…The relative transition wavelengths compare favorably with the predicted transitions for DESM and avobenzone of 399 and 366 nm, respectively. The reliability of the calculated absolute excitation energies and transition wavelengths is questionable, as higher‐level methods are computationally demanding and beyond the scope of this study (26).…”

Section: Resultsmentioning

confidence: 99%

Design of a Photostabilizer Having Built‐in Antioxidant Functionality and Its Utility in Obtaining Broad‐spectrum Sunscreen Formulations†

Chaudhuri¹,

Lascu²,

Puccetti³

et al. 2006

Photochem & Photobiology

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Di-2,2'-diethylhexyl-3,5-dimethoxy-4-hydroxy-benzylidenemalonate (INCI name diethylhexyl syringylidene malonate, DESM), the target photostabilizer, was synthesized in one step by condensation of 3,5-dimethoxy-4-hydroxy benzaldehyde (Syringaldehyde) with di-2,2'-diethylhexyl malonate. Photostability data in sunscreen formulations showed that DESM is photostable and improves the photostability of avobenzone significantly when compared to control (without a photostabilizer). Photostable broad-spectrum sunscreen formulations with high SPF (>30) have been achieved by combining avobenzone, DESM and UV-B sunscreens, such as homosalate, octisalate or other UV-B sunscreens. It seems that (a) triplet-state energy transfer from avobenzone to DESM and (b) scavenging of reactive species are responsible for the observed stabilization of avobenzone. In vitro study of the two formulations containing DESM clearly showed critical wavelength of well over 370 nm and can thus be categorized as broad-spectrum sunscreens. DESM does not have any contribution to in vivo SPF; instead it boosts SPF by about 5 units in high-SPF products. DESM was found to be an excellent singlet-oxygen quencher, thereby reducing photodegradation of avobenzone caused by singlet oxygen. In short, the multiplicity of effects and formulation benefits seen with DESM makes it an ideal choice as a unique antioxidant photostabilizer for a variety of cosmetic products targeting young and mature skin alike.

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The triplet energy levels of UVA and UVB sunscreens

Cited by 55 publications

References 3 publications

An in vitro systematic spectroscopic examination of the photostabilities of a random set of commercial sunscreen lotions and their chemical UVB/UVA active agents

An in vitro systematic spectroscopic examination of the photostabilities of a random set of commercial sunscreen lotions and their chemical UVB/UVA active agents

Photochemical Formation of Singlet Molecular Oxygen in Illuminated Aqueous Solutions of Several Commercially Available Sunscreen Active Ingredients

Design of a Photostabilizer Having Built‐in Antioxidant Functionality and Its Utility in Obtaining Broad‐spectrum Sunscreen Formulations†

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