22 | www.CosmeticsandToiletries.com Vol. 130, No. 4 | May 2015
RESEARCH | C&T
Reproduction in English or any other language of
all or part of this article is strictly prohibited.
© 2015 Allured Business Media.
It is not surprising that skin, being the body’s largest organ and having constant exposure to the environment, is an ideal location for bacteria growth. Such growth includes resident and transient pathogenic bacteria, which are capable of invading the host and causing harm, as well
as commensal bacteria, which help to protect the host from pathogens.
The skin provides a first line of defense against pathogens based on its
mechanical rigidity and low moisture content, production of lysozyme,
acidic environment, host defense peptides such as defensins, and as noted,
protective commensal microbes.1 Yet, some organisms can and do evade
cutaneous host defenses, leading to the next line of protection, which
involves the immune system. This leads to the need for preservation and
antimicrobial efficacy, with the ultimate goal of ensuring product stability
and consumer protection.
In the past, cosmetic formulators used preservatives and biocides for the
sole purpose of inhibiting microbes. The Personal Care Products Council,
for example, defined a preservative system as any agent added to a product
to reduce or prevent microbial growth. 2 Antimicrobial protection can be
achieved by preserving the products applied to skin, and/or by eliminating
harmful microorganisms that already inhabit the skin. However, it is essential to bear in mind the skin’s protective microbiome because the choice of
preservative could unintentionally alter the skin’s natural defenses.
Take traditional biocides such as triclosan, for example, which are used
in hand sanitizers to disrupt bacterial cell walls. While providing broad-spectrum bactericidal action, they also have nonspecific targets and disturb
the skin’s microflora balance, killing both pathogenic and commensal
bacteria and leaving the skin defenseless against new destructive microorganisms. 3 Triclosan also can cause dangerous antimicrobial resistance to
medicines, 4 which is a growing threat to health care as a whole. In addition,
traditional preservatives such as parabens and formaldehyde donors historically work well at inhibiting microbial growth, but it is not currently known
whether they affect or alter the body’s protective microbiota. 3
While safety studies and cosmetic research over the past decade have
generally succeeded in analyzing the potential toxicity of preservatives and
biocides to consumers before they reach the market, only more recently
have the effects of those products on skin’s protective commensal micro-
Maureen Danaher, Durant Scholz,
Erica Segura and Meghan Darley
Active Micro Technologies, LLC, Lincolntown, NC USA
Natural vs. Synthetic Antimicrobials and
HDAC as an Indicator
of Microflora Health
microflora • triclosan •
antimicrobial peptides •
This article reviews the
role of skin microflora
in protecting skin, and
assesses how the histone
enzyme is implicated.
From this, HDAC
expression is used as
an indicator to compare
the effects of traditional
biocides and preservatives
with natural antimicrobials
on skin’s microbiome.
Results suggest the
latter effectively preserve
products while maintaining
a healthy microbiome.