New hair dyes avoid allergic reactions

Date:
January 26, 2022
Source:
American Chemical Society
Summary:
Researchers have developed a range of permanent hair dyes that
avoid the allergenic properties of traditional formulations.



FULL STORY ==========================================================================
A bad dye job is bad enough on its own, but an itchy and irritating
allergic reaction to it is even worse. And people who become allergic
to hair dye can develop reactions to many other common substances,
transforming a simple cosmetic treatment into a big problem. Now,
researchers reporting in ACS Sustainable Chemistry & Engineeringhave
developed a range of permanent hair dyes that avoid the allergenic
properties of traditional formulations.


==========================================================================
When applied as hair color, paraphenylenediamine (PPD) -- a common
ingredient in permanent dyes -- undergoes a chemical reaction that
turns the hair a dark color that won't wash out over time. This reaction, however, can also produce compounds that bind proteins in the user's skin, causing allergic responses, such as eczema and facial swelling. PPD can
also sensitize users to other substances, including a compound commonly
found in sunscreens and cosmetics, as well as common pigment and ink
compounds. Alternatives have been proposed, but they generally are
not water-soluble, and the safety of some of the compounds are not well understood. Gopalakrishnan Venkatesan and colleagues wanted to create new alternatives that would avoid the problems of PPD while still providing permanent hair coloring.

The team prepared seven dyes based on PPD with modifications to the
aromatic amine core. The modifications were chosen to potentially
make the compounds less reactive toward proteins and less able to be
absorbed into skin. All seven compounds permanently colored hair samples, producing a range of hues from rosy pinks to deep blacks that did not
fade, even after three weeks of daily washing. The team then examined
the dyes in a test commonly used in the cosmetics industry to determine
if a product is a skin sensitizer. Five of the modified dyes were "weak" sensitizers, whereas PPD was "moderate." Another test showed that the new compounds generated a reduced inflammatory response in cells compared to
PPD. These results suggest that the new dyes can effectively color hair
while also avoiding the potential allergenic and sensitization risks of
more traditional ones.

The authors acknowledge funding from the National University of Singapore.

========================================================================== Story Source: Materials provided by American_Chemical_Society. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Gopalakrishnan Venkatesan, Yuri Dancik, Yub Raj Neupane, Aneesh V.

Karkhanis, Paul Bigliardi, Giorgia Pastorin. Synthesis and
Assessment of Non-allergenic Aromatic Amine Hair Dyes as Efficient
Alternatives to Paraphenylenediamine. ACS Sustainable Chemistry &
Engineering, 2022; 10 (2): 838 DOI: 10.1021/acssuschemeng.1c06313 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220126090454.htm

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