Maple trees are best known for their maple syrup and beautiful fall foliage. But it turns out that the beauty of these leaves could be skin deep ̵
Researchers present their findings at the 256th National Meeting & Exposition of the American Chemical Society (ACS).
The scientists had previously studied the chemical and health benefits of juice and syrup from sugar maple and red maple. According to Navindra P. Seeram, Ph.D., project manager of the project, historical records suggest that other parts of the trees may also be useful. "The Native Americans used leaves of red maple trees in their traditional system of medicine," he notes, "why should we ignore the leaves?"
The elasticity of the skin is maintained by proteins such as elastin. Wrinkles form when the enzyme elastase degrades elastin in the skin as part of the aging process. "We wanted to see if leaf extracts from red maple trees could block the activity of elastase," says Hang Ma, Ph.D., who presented the work at the meeting and is a senior scientist in Seeram's lab.
Researchers at the University of Rhode Island tested phenolic compounds in leaves known as glucitol nucleus-containing gallotannins (GCGs) and tested each compound's ability to inhibit elastase activity in a test tube. The scientists also conducted computer studies to investigate how the GCGs interact with elastase to block their activity and how the structures of the molecules affect this blocking ability. GCGs containing multiple galloyl groups (one type of phenol group) were more effective than those with a single galloyl group. But these compounds can more than annoy elastase. In earlier work, the Serenam group showed that these GCGs could protect the skin from inflammation and lighten dark spots such as unwanted freckles or age spots.
Seeram and Ma are planning further tests. "One could imagine that these extracts tighten human skin like a herbal Botox, even though it is a topical application, not an injected toxin," says Seeram. And the fact that the extracts come from trees would be appreciated by consumers looking for natural, herbal ingredients in their skincare products.
The researchers have taken steps to bring the extracts into products after they have developed their own patent-source formulation with GCGs from summer and fall maple leaves and maple syrup they called Maplifa (pronounced "Mape-LEAF-uh", to reflect its origin). They have licensed it to Indiana-based plant extract supplier Verdure Sciences and hope that eventually there will be a market for formulation in the cosmetics sector or even in nutritional supplements.
If these products bear fruit, the team's results could benefit from local economies. "Many vegetable ingredients are traditionally from China, India and the Mediterranean, but sugar maple and red maple grow only in eastern North America," says Seeram. Farmers in the region, who are currently harvesting only sap from the maple trees, could use the leaves as a value-added product for an additional source of revenue. Even better, the process would be sustainable because leaves can be collected from the trees during normal pruning or in the fall.
How fresh is your maple syrup?
Inhibitory effects of glucotol nuciferous gallotannins from a proprietary red maple (Acer rubrum) leaf extract on elastase enzyme, the 256th National Meeting and Exposition of the American Chemical Society (ACS)
Abstract [19659005 Skin wrinkles is a decreasing process of skin cell function associated with aging caused by the loss of skin elasticity over time. Skin elasticity is maintained by extracellular skin proteins such as elastin. Elastase, a member of the chymotrypsin family of proteases, is responsible for the breakdown of skin elastin. Therefore, inhibition of the elastase enzyme is a plausible management for dermal elastin degradation, and therefore elastase inhibitors, including natural products, are being studied as anti-wrinkle cosmetic agents. We have already reported skin-protecting effects, including antigenic and anti-melanogenic properties, of a series of glucotol nuciferous gallotannins (GCGs) from a proprietary phenol-enriched maple leaf extract (Maplifa ™) from red maple (Acer rubrum). However, the effect of these GCGs on elastase enzyme is unknown. Here, we investigated the inhibitory effects of MaplifaTM GCGs including ginnalin B (GB), ginnalin C (GC), ginnalin A (GA), maplexin F (MF) and maplexin J (MJ) on elastase enzyme. The GCGs (at 500 μM) showed inhibitory activities ranging from 21.3 to 62.5% and the GCGs with multiple galloyl groups including GA (2 galloyl), MF (3 galloyl) and MJ (4 galloyl) showed superior activity GCGs with a mono-galloyl group (namely GB and GC). The mechanisms of the inhibitory effects of the GCGs on the elastase enzyme were further investigated using an enzyme kinetic assay and a computer docking method. Our data suggest that Maplifa ™ GCGs may have anti-wrinkle activity by inhibiting the elastase enzyme, which justifies further studies on its cosmetic applications.