split-face study involving 33 Asian males, participants were divided
into three groups. Each group applied one of the following
formulations onto half of their face: green tea only, lotus only,
or a combination of green tea and lotus. The other half of the
face was treated with a placebo. Although both green tea and
lotus independently improved the appearance of rhytides, combination
treatment with green tea and lotus most significantly
improved the appearance of rhytides (P = 0.003 at 60 days).12
The combination appeared to have a synergistic effect, allowing
for lower concentrations of each ingredient to be utilized
in the combination formulation. Again, the methods by which
the lotus and green tea extracts were obtained were not further
characterized by the authors.
Licorice
Licorice extract is derived from Glycyrrhiza glabra and active
compounds of licorice extract include licochalcone A, glabridin,
liquiritin, and glabrene. Glabridin has an anti-inflammatory
effect while liquirtin has been used for the treatment of hyperpigmentation.
7 Licochalcone A is a phenolic compound with
antibacterial, anti-inflammatory, and antitumor effects.
Twelve volunteers had test sites on their back treated with a 1.4
minimal erythemal dose of UV light. Directly following treatment
and 5 hours after treatment, a control (vehicle) formulation or
a test formulation containing 0.05% licochalcone A extract was
applied. This extract was composed of 20% licocalchone A, contained
no terpenes or flavonoids, and was produced via aqueous
extraction. As compared to the vehicle-treated sites, participants
treated with licochalcone A showed significantly reduced erythema
(P < 0.05). This same study evaluated the use of licochalcone
A on the irritated shave sites of 45 subjects and found that prostaglandin
E2, leukotriene B4, IL-6, and TNF-alpha were all reduced
by the extract.13 These findings support an anti-inflammatory as
well as a photoprotective role for licorice extract.
Olive Oil
Olive oil (Olea europaea) is considered one of the healthiest
forms of dietary fat, has anti-inflammatory effects, and may be
useful in a variety of dermatologic conditions.
Ichihashi et al divided 75 hairless female mice into 5 groups,
the control group of which was treated with UVB radiation only.
Two groups were treated with either extra virgin olive oil or
regular olive oil after UVB radiation and two groups were treated
with either extra virgin olive oil or regular olive oil before
UVB radiation. Only extra virgin olive oil applied to the skin
of mice immediately after UVB exposure was shown to delay
the onset and reduce the incidence of skin cancer development.
The mechanism of action was believed to be via reduction of
8-hydroxy-deoxyguanosine (8-OHdG) formation, based on the
reduced number of 8-OHdG positive cells in mice treated with extra virgin olive oil. Cyclobutane pyrimidine dimers and (6-4)
photoproducts were not reduced by any of the treatment arms.
The authors postulated that extra virgin olive oil applied to human
skin after sun exposure could play a role in the prevention
of skin cancer, although further research would be necessary in
order to support this hypothesis.14
Much like feverfew, olive oil is believed to protect against oxidative
stress via upregulation of antioxidant response elements.
Olive oil derived fatty acid ethoxylates were found to increase
transcription of an ARE reporter cell line to levels four to five
times higher than the control as measured by luminescence.15
In addition, human skin keratinocytes and fibroblasts treated
with fatty acid ethoxylates displayed increased heme oxygenase
1 (Ho-1), an enzyme thought to monitor and repair damage
by reactive oxygen species.15 Therefore, not only does olive oil
appear to increase endogenous antioxidant levels, it also allows
the cells to better manage oxidative stress.
Chamomile
Chamomile is a medicinal herb with anti-inflammatory and
emollient properties and bisabolol is a sesquiterpene alcohol
extract from chamomile. Chamomile has been utilized to treat
pruritus, modulate photodamage, and improve the texture and
elasticity of the skin.16 Bisabolol application at concentrations
ranging from 0.01-0.0001% displayed significant inhibition of
hydrogen peroxide-induced reactive oxygen species in fibroblasts.
17 These findings support the antioxidant properties of
chamomile and suggest that it may be a useful ingredient to
treat photoaging. As clinicians, it is important to recognize that
chamomile cross-reacts with ragweed, and should therefore be
used with caution in patients with ragweed allergy.16
Colloidal Oatmeal
Fine grinding of oat (Avena sativa) and subsequent boiling produces
colloidal oatmeal. It is best known for its use in atopic
dermatitis and its ability to hydrate the skin. Oats also display
antioxidant properties, and are believed to protect and repair
the skin and hair from UV radiation, free radicals, and smoke.18
Colloidal oatmeal is composed of polysaccharides, proteins,
lipids, saponins, flavonoids, vitamins, and avenanthramides.7
The main antioxidants in oats are polyphenolic alkaloids called
avenanthramides. Avenanthramides consumed orally are
bioavailable and have been shown to enhance antioxidant defenses.
19 Although the topical antioxidant benefits of colloidal
oatmeal have not been studied extensively, this may be a promising
agent to treat photoaging.
Criquet et al found that personal care products containing
oatmeal were very tolerable, with a low potential to cause irritation
and sensitization. Only 1% of subjects (23 out of 2291)
experienced a transient, low-level erythema. Participants also
