Long-wave UVA1 radiation (375 nm – 400 nm) is often ignored when assessing sun protection due to its low sunburning potential, but it generates reactive oxygen species (ROS) and is poorly attenuated by sunscreens. This study aimed to investigate if α-tocopherol phosphate, (α-TP) a promising new antioxidant, could protect against long-wave UVA1 induced cell death and scavenge UVA1 induced ROS in a skin cell model.
HaCaT keratinocytes cell viability (24 h) was assessed with Alamar blue® and neutral red assays. Radical scavenging efficacy of α-T and α-TP in vitro was monitored by the dichlorodihydrofluorescein (H2DCFDA) ROS detection assay over 2 h. The mechanism of α-TP ROS scavenging was determined using chemical DPPH and ORAC assays.
In HaCaT keratinocytes, irradiated with 226 J/cm2 UVA1 in low-serum (2%, starved) cell culture medium, pretreatment with 80 µM α-TP significantly enhanced cell survival (88%, Alamar blue) compared to control, whereas α-T pre-treatment had no effect survival (70%, Alamar blue). Pre-treatment of cells with 100 μM α-TP or 100 μM α-T before 57 J/cm2 UVA1 also significantly reduced ROS generation over 2 h (24.1% and 23.9% respectively) compared to the control. However, α-TP displayed weak antioxidant activity in cell free assays suggesting its photoprotection was due to bioconversion to α-T by cellular phosphatases.
Treatment with α-TP prevented long-wave UVA1 induced cell death and scavenged UVA1 induced ROS in skin cells when added to the starved cell culture medium before UVA1 exposure by bioconversion into α-T.
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No competing interests reported.
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Posted 06 Mar, 2021
Received 22 Mar, 2021
On 14 Mar, 2021
On 14 Mar, 2021
On 14 Mar, 2021
On 14 Mar, 2021
Invitations sent on 14 Mar, 2021
On 08 Mar, 2021
On 26 Feb, 2021
On 26 Feb, 2021
On 24 Feb, 2021
Posted 06 Mar, 2021
Received 22 Mar, 2021
On 14 Mar, 2021
On 14 Mar, 2021
On 14 Mar, 2021
On 14 Mar, 2021
Invitations sent on 14 Mar, 2021
On 08 Mar, 2021
On 26 Feb, 2021
On 26 Feb, 2021
On 24 Feb, 2021
Long-wave UVA1 radiation (375 nm – 400 nm) is often ignored when assessing sun protection due to its low sunburning potential, but it generates reactive oxygen species (ROS) and is poorly attenuated by sunscreens. This study aimed to investigate if α-tocopherol phosphate, (α-TP) a promising new antioxidant, could protect against long-wave UVA1 induced cell death and scavenge UVA1 induced ROS in a skin cell model.
HaCaT keratinocytes cell viability (24 h) was assessed with Alamar blue® and neutral red assays. Radical scavenging efficacy of α-T and α-TP in vitro was monitored by the dichlorodihydrofluorescein (H2DCFDA) ROS detection assay over 2 h. The mechanism of α-TP ROS scavenging was determined using chemical DPPH and ORAC assays.
In HaCaT keratinocytes, irradiated with 226 J/cm2 UVA1 in low-serum (2%, starved) cell culture medium, pretreatment with 80 µM α-TP significantly enhanced cell survival (88%, Alamar blue) compared to control, whereas α-T pre-treatment had no effect survival (70%, Alamar blue). Pre-treatment of cells with 100 μM α-TP or 100 μM α-T before 57 J/cm2 UVA1 also significantly reduced ROS generation over 2 h (24.1% and 23.9% respectively) compared to the control. However, α-TP displayed weak antioxidant activity in cell free assays suggesting its photoprotection was due to bioconversion to α-T by cellular phosphatases.
Treatment with α-TP prevented long-wave UVA1 induced cell death and scavenged UVA1 induced ROS in skin cells when added to the starved cell culture medium before UVA1 exposure by bioconversion into α-T.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
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