A Melanin Derivative to Shield the Skin
from High Energy Visible Light
N. Dayan, PhD
KEY WORDS: fractionated melanin, HEV light, viscosity, stability,
aesthetics
ABSTRACT: High energy visible (HEV) light recently has been
suspected of causing as much damage as UVA and
UVB combined. Thus, the present paper describes a
fractionated melanin tailored to absorb light in the
visibile 400–500 nm range. In addition, because
the material exhibits color, the authors focus on
formulation techniques to incorporate it into semi-solid formulations.
into semi-solid formulations. Overall,
this material is presented as a novel
means to maximize photoprotection
and phototherapy while minimizing its
color footprint.
While the industry and general public are highly educated about
the dangers associated with excessive
exposure to sunlight, especially the
UVA and UVB wavelengths, findings
in recent years reveal that the full
spectrum of benefits and harm related
to sun exposure are yet to be explored.
One of the more striking recent discoveries is that while UVA and UVB are
indeed responsible for skin damage,
high energy visible (HEV) light, i.e. in
the violet and blue range, may cause
as much damage as UVA and UVB
combined.1–4 However, developing a
compound to shield the skin by the
selective filtration of violet and blue
light presents challenges in molecular
design as well as formulation because an
effective compound must exhibit color.
UV absorbers in skin care formulas
do not impart color because the retina
does not respond to the range of photon
energies they absorb. However, since
HEV absorbers selectively reduce, for
example, violet and blue light from the
visible spectrum, the eye perceives this
as a change in color as the remaining
spectrum is expressed; in this case, it
appears brown or yellow-brown.
HEV light, i.e. in the
violet and blue range,
may cause as much
damage as UVA and
UVB combined.
In this paper, the authors present the
rationale behind the development of a
fractionated melanin (FM) that is tailored to absorb light in the HEV blue to
violet wavelength range of 400–500 nm,
with minimal absorption in the red
range. Since it provides UV as well as
HEV photoprotection, it imparts color
to formulations. Therefore, the present paper also suggests approaches to
cope with the aesthetic challenges this
molecule presents when introduced
HEV Light and Skin
HEV light is in the blue to violet
band, 400–500 nm, of the visible
spectrum. The effects of HEV light on
macular degeneration have been studied
and results suggest it may be a key
factor in this age-related disorder.5 The
mechanism by which the light damages
the lens and retina of the eye is believed
to be the generation and accumulation
of reactive oxygen species (ROS) that
lead to oxidative damage to cells and
their organelles. These changes are
irreversible and should therefore be
minimized as much as possible. In relation to skin, two independent studies
were conducted to evaluate the effects
of HEV light, which demonstrated
photodegradative effects similar to those
found in the eye to the epidermal and
dermal tissues.
Animal model: Researchers studied
the effects of blue light (450–500 nm)
on the tape-stripped skin barrier of
hairless mice first and discovered a significantly delayed barrier recovery rate
in comparison with the control. Notably,
green light had no effect, while red
light increased the recovery rate.1 This
barrier recovery rate was measured by
transepidermal water loss (TEWL)—a
common practice to assess cutaneous
barrier function in a quantitative manner. This technique is based on the fact
that when the stratum corneum (SC)
186 | Cosmetics & Toiletries® magazine www.CosmeticsandToiletries.com
Vol. 126, No. 3/March 2011
