ANTI-POLLUTION
to the amount of ROS at basal level. This in vitro study concluded that, once
photoactivated, the active ingredient can prevent the formation of ROS in UVA-exposed skin cells.
Reducing the damage on the mitochondrial DNA Another sensitive marker in photoageing, albeit more unusual, is the measurement of the damage on the mitochondrial DNA (mtDNA).7 The mtDNA is responsible for encoding the thirteen proteins that take part in the oxidative phosphorylation and the regulation of the metabolism of the cell. As mentioned earlier, mechanisms that lead
to photoageing are interconnected. Excessive amounts of ROS can cause mutations on the mtDNA.6
These accumulate rapidly because
their reparation is not as efficient as in the nucleus, which affects the normal metabolism of the cell and results in more oxidative stress. An experiment conducted in a similar
fashion as the one described previously showed the efficiency of the active to protect from mtDNA damage. Figure 4B shows that, after one hour of pre-activation, there is a reduction of the damage of the mtDNA of 51%. Increasing the pre-activation to four hours
only improves the result in 8%. In this case, a too short pre-activation of the active ingredient does not reduce the damage significantly.
Halting the degradation of collagen One of the signs of skin ageing is the
appearance of wrinkles. This is caused by a loss of collagen. Collagen’s degradation is an essential step on the mechanism of the regeneration of the protein. Old collagen is replaced by new collagen, keeping a smooth and firm skin. Matrix metalloproteinase-1 (MMP-1) or collagenase-1 breaks collagen-1 down to start the regeneration process. However, an overactivation of MMP-1 can
lead into an unbalanced mechanism where degradation surpasses the synthesis of new collagen, leading to decomposition of the dermis.8
External factors can contribute to the
activation of the MMP-1. It has been proved that UVA-generated Reactive Oxygen Species are one of the main causes of activation of MMP-1. Figure 4C shows the results of an experiment
conducted in the same way as the ones described before. After one hour of pre-activation of a formulation containing 2% of the active ingredient, there is 23% less active MMP-1 on the studied NHDF than on the negative control. In this case, this refers to the formulation without the active ingredient, but submitted to the same experimental conditions. The result is similar to the one provided by
the positive control (cells completely covered with aluminium foil). This suggests that the active ingredient completely protects from UVA- induced activation of MMP-1.
Blocking the expression of proinflammatory cytokines Inflammation of the skin is a symptom
33
of internal damage. It occurs when the keratinocytes, the most abundant cells on the epidermis and the ones responsible to form a barrier against environmental damage, receive a signal to release proinflammatory cytokines. These small proteins which are also related
to the system effects on the immune system activate the mechanism of migration of inflammatory cells, causing inflammation as redness or lacerations.9 Among the proinflammatory cytokines,
Interleukin-6 (IL-6) relates to the damage caused by UVA.10
IL-6 released from
keratinocytes that underwent UVA-irradiation can induce the production of MMP-1 in fibroblasts. Blocking the expression of IL-6 stops the inflammation of the skin and the mechanisms of skin damage. After the results obtained for the activation
of the MMP-1, an experiment with one hour of pre-activation of the ingredient was carried out on the expression of IL-6. Figure 4D shows that the basal levels of IL-6 (completely covered) are 54% lower than for the sample without the ingredient, when IL-6 counting and, therefore, the skin inflammation, is at its maximum. In a statistically significant result, using a
formula with 3% of ingredient resulted in 43% less expression than for the formula without the active. Observing that the active blocks the expression of IL-6 suggests that it prevents inflammation caused by UVA-exposure from occurring and stops the progression of photoageing.
www.personalcaremagazine.com
July 2024 PERSONAL CARE
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