Healthier skin: It's in the trees

Budding approach to antioxidants

Antioxidants are popular as so-called anti-aging ingredients in skin creams. Now, an analysis of high-performance liquid chromatography, mass spectrometry, proton nuclear magnetic resonance spectroscopy and assay data reveals how these healthful substances might be present in the leaf buds of poplar trees.

The cosmetics and so-called nutraceuticals industries are always on the look out for "active" ingredients that can help it to market products such as anti-ageing face creams to consumers keen to retain smooth and youthful skin throughout life. Of course, the companies must walk a fine line between vague promise, marginal effect and wandering into medicinal territory where their products would then become subject to the same for fear of being subject to the same regulations and clinical testing requirements as genuine pharmaceutical products. To this end, a great deal of research is carried out into products that do not have pharmacological activity per se, but do have physiological effects, such as antioxidants. Moreover, if such ingredients can be derived from natural sources, such as winsome herbs or the most wholesome of origins trees, then the marketing team can make promises and allude to nature's wonders in the same breath.

Arboreal antioxidants

Researchers at commercial nutraceutical company Biolandes in Le Sen and Polyphenols Biotech at the University Victor Segalen Bordeaux in Villenave d'Ornon, France in work supported by the company, explain how several species of Populus have been used in traditional medicine for their anti-inflammatory properties. The species are in the Salicaceae, within which the willow tree (Salix alba) sits, the source of salicylic acid and ultimately aspirin. Researchers have investigated the viscous exudates that coats poplar buds and demonstrated the presence of various phenolic compounds, terpenoids, flavonoid aglycons and their chalcones and phenolic acids and their esters.

More specifically, Populus nigra, perhaps the most widely distributed species of poplar in Europe contains the flavanones pinocembrin and pinostrobin, the flavonols galangin, quercetin and kaempferol and flavones such as chrysin and apigenin in its bud exudates. Intriguingly, related compounds have been identified in the resinous substance propolis used by honeybees to seal their hives and which is made from materials collected from poplar and other tree buds. Propolis has been used in traditional medicines for its purported antimicrobial, anti-inflammatory and antioxidant properties activity.

Team leader Xavier Vitrac and colleagues point out that such compounds are of interest to those hoping to protect the skin. Skin is the outermost barrier of the body, which interacts directly with harmful oxidative environment of the atmosphere. It has its own inbuilt defences, antioxidant enzymes and non-enzymatic antioxidant molecules, such as vitamin E, vitamin C, glutathione and ubiquinone that protect skin from oxidative damage. Unfortunately, these defences seem to decline in efficacy as we get older. Nutraceutical formulations containing potent antioxidants, such as those found in poplar buds, might thus be of benefit.

Chemical assessment

Detailed spectroscopic analysis and assay data reveal the properties and constituents of an aqueous extract of poplar buds. The team found that caffeic and p-coumaric acids are the major antioxidant components, based on ORAC assay; they account for half of the total antioxidant activity. "Our results also indicate a potential beneficial effect of poplar bud extract on skin aging as it showed a strong modulation of transcription of genes involved in antioxidant defences, inflammatory responses and cell renewal," the team explains. They suggest that further research is now needed to ascertain the bioavailability of the phenolics in poplar bud extract and to test whether these compounds and their metabolites show activity in vivo. Success would validate their addition to nutraceutical anti-ageing formulations, the team concludes.