Phytochemical and biological investigation of gallotannins from red maple (Acer rubrum) species
This study investigated the phytochemical constituents, primarily gallotannins, present in a proprietary extract, namely Maplifa™, from leaves of the red maple (Acer rubrum) species as well as their biological activities and mechanisms of action. Although the red maple species has been traditionally used as folk medicine by Native American Indians for numerous health benefits, the bioactive chemical constituents of the leaves of the red maple still remain unknown. This study carried out the identification of phytochemicals targeting gallotannins, from red maple leaves by using various chromatographic separation techniques and spectroscopic approaches. Furthermore, compounds from red maple species were evaluated for bioactivities including anti-oxidant, anti-diabetic (&agr;-glucosidase inhibition and inhibition of advanced glycation end products, AGEs) and skin lightening effects (anti-tyrosinase and anti-melanogenesis) by using a panel of in-house bioassays. In addition, the mechanisms of the inhibitory effects of red maple phytochemicals on &agr;-glucosidase were characterized by using kinetic assay, fluorescence assay, FTIR and CD (circular dichroism) spectra. Moreover, the mechanisms of inhibition on formation of AGEs were elucidated at each individual stage of AGEs formation by applying MALDI-TOF mass spectroscopy, HPLC-FL analysis, G.K. peptide assays and assessing the conformational changes induced by protein glycation by using CD. Lastly, the mechanisms of the inhibitory effects of ginnalins A-C on melanogenesis in B16F10 cells were elucidated by using real-time PCR and Western blot experiments. The results indicated that ginnalins were able to down-regulate the expression of MITF, TYR, TRP-1 and TRP-2 gene levels in a time and dose-dependent manner and significantly reduce the protein expression of TRP-2 gene. The findings in our study indicate that phytochemicals in red maple leaves possess anti-melanogenic effects and thus may have potential cosmetic skin-whitening applications. (Abstract shortened by UMI.)
"Phytochemical and biological investigation of gallotannins from red maple (Acer rubrum) species"
Dissertations and Master's Theses (Campus Access).