Isolation, structural elucidation and bioactivity evaluation of phytochemicals from New England plants: Cornus amomum Mill. (silky dogwood) and Rhus copallinum L. (winged sumac).

摘要

Medicinal plants have been used for the treatment of various human ailments for centuries by traditional cultures. Modern studies have revealed that plant compounds (phytochemicals) have a wide range of biological properties and may provide human health benefits. Several plants native to North America have been used traditionally by the Native Americans for medicinal purposes but have not been examined for their phytochemical constituents. Based on preliminary studies of several such plant candidates, our laboratory selected two native and previously un-investigated plants, namely, Cornus amomum Mill. (silky dogwood) and Rhus copallinum L., (winged sumac) for further detailed study. Compounds were isolated using a series of chromatographic methods and identified on the basis of extensive nuclear magnetic resonance (NMR) and mass spectral data. Also, the plant extracts and their purified isolates were evaluated for antioxidant (using the DPPH radical scavenging assay) and human cancer cell cytotoxicty (using the MTS assay) activities.;In the first study our objectives were: 1) to evaluate silky dogwood fruit extract (SDFE) for antioxidant potential and cytotoxicity effects against human breast (MCF7, MDA-MB-231) and colon (HT29, HCT116) tumor cells, and 2) to identify the phenolic constituents present in SDFE. Three phenolic compounds that included two flavonoids, quercetin (1) and 3-O-methylquercetin (2), as well as tyrosol (3), were isolated and identified from SDFE. In addition, two anthocyanins, though not isolated, were identified from SDFE using tandem liquid chromatography mass spectrometry methods as delphinidin-trihexoside and delphinidin-dihexoside. In the antioxidant assay, the compounds had IC 50 values ranging from 70-188 muM.;The second study details the phytochemical and biological examination of winged sumac fruit and leaves. A new phenolic compound, 1',2'-di(methoxycarbonyl)ethyl 3,4,5-trihydroxybenzoate, along with other thirteen known compounds were obtained including a butanedioic acid derivative, ten phenolics and two triterpenes. All of the isolated compounds were assayed for their antioxidant and human cancer cell cytotoxicity activities. The best anticancer effects against two human cancer colon cell lines (Caco-2, HCT-116) were observed with betulinic acid and pentagalloyl glucose with IC50 values ranging from 84.6-102.1 muM. The other metabolites showed IC50 values ranging from 100.2-180.1 muM. In the antioxidant assay, the compounds had IC50 values ranging from 23-70 muM.;Taken together, these results suggest that silky dogwood and winged sumac may be explored as sources of bioactive compounds with potential nutraceutical values given their prevalence and underutilization in North America. Also, this is the first phytochemical investigation of these two plants.