Maple water (Acer saccharum sap), a traditional North American beverage: anti-inflammatory activity and potential functional relevance for skin health

Maple water (Acer saccharum sap) is a traditional North American sap-derived beverage consumed seasonally; however, its biological functions as a dietary resource remain insufficiently characterized. This study investigates the potential functional properties of maple water extract by assessing its anti-inflammatory activity and its relevance to skin-related cellular responses. In RAW264.7 macrophages, maple water extract significantly inhibited lipopolysaccharide (LPS)-induced nitric oxide production in a dose-dependent manner without inducing cytotoxicity. The treatment downregulated the mRNA expression of key pro-inflammatory mediators, including inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin (IL)-1β, and IL-6, and suppressed nuclear factor-kappa B (NF-κB) signaling. In UV-irradiated HaCaT keratinocytes, maple water extract modulated cellular responses by regulating matrix metalloproteinases (MMP-1 and MMP-2) and their tissue inhibitors (TIMP-1 and TIMP-2), indicating potential relevance to extracellular matrix regulation. Furthermore, maple water enhanced the expression of epidermal differentiation markers, including filaggrin, involucrin, and loricrin. Hydration-related responses were observed, including reduced hyaluronidase expression and increased hyaluronan synthase expression. These findings suggest that maple water, when considered as a traditional dietary beverage, may provide bioactive components that modulate inflammatory responses and support skin-related cellular functions.