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 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 (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 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
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