The antioxidant activity of the methanolic extracts of the leaves of 39 plant species was examined. These leaves were collected from the plants growing on subtropical seashores. The activity was evaluated by three kinds of assay methods, which included the DPPH radical scavenging assay, linoleic acid oxidation assay, and oxidative cell death assay. Two extracts from Excoecaria agallocha and Terminalia catappa showed remarkably potent activity in all assay systems. The HPLC analysis of the extracts indicated the presence of the same antioxidant and isolation work for the compound identified ellagic acid. The isolated ellagic acid showed strong antioxidant activity in the assay systems used.
Vacuolar H + -PPase, a membrane bound protontranslocating pyrophosphatase found in various species including plants, some protozoan and prokaryotes, has been demonstrated to be localized to the vacuolar membrane in plants. Using a GUS reporter system and a green fluorescent protein (GFP) fusion protein, we investigated the tissue distribution and the subcellular localization, respectively, of a novel type H + -PPase encoded by AVP2/AVPL1 identified in the Arabidopsis thaliana genome. We showed that AVP2/AVPL1 is highly expressed at the trichome and the filament of stamen. Furthermore, the fluorescence of GFP-tagged AVP2/AVPL1 showed small dotlike structures that were observed throughout the cytoplasm of various Arabidopsis cells under a fluorescent microscope. The distribution of this dot-like fluorescent pattern was apparently affected by a treatment with brefeldin A. Moreover, we demonstrated that most dot-like fluorescent structures colocalized with a Golgi resident protein. These findings suggest that this novel type H + -PPase resides on the Golgi apparatus rather than the vacuolar membrane. ß
Abstract. To test the possibility that micromolar formaldehyde, a metabolite of methanol derived from aspartame, exerts cytotoxicity, its effect on rat thymocytes was examined under the in vitro condition using a flow cytometer. Incubation of thymocytes with formaldehyde at 100 mM or more for 24 h significantly increased the populations of shrunken cells and cells with hypodiploid DNA. The peak blood concentration of methanol in human subjects administered abuse doses of aspartame has been reported to exceed 2 mg / dL (625 m M). It would increase the population of thymocytes undergoing apoptosis if formaldehyde at 100 m M or more appears in the blood after administration of aspartame.
The cytotoxic activity of methanol extracts of leaves collected from 39 seashore plants in Iriomote Island, subtropical Japan was examined on human leukaemia cells (K562 cells) using a flow cytometer with two fluorescent probes, ethidium bromide and annexin V-FITC. Five extracts (10 microg/mL) from Hernandia nymphaeaefolia, Cerbera manghas, Pongamia pinnata, Morus australis var. glabra and Thespesia populnea greatly inhibited the growth of K562 cells. When the concentration was decreased to 1 microg/mL, only one extract from H. nymphaeaefolia still inhibited the cell growth. A cytotoxic compound was isolated from the leaves by bioassay-guided fractionation and was identified as (-)-deoxypodophyllotoxin (DPT). The fresh leaves of H. nymphaeaefolia contained a remarkably high amount of DPT (0.21 +/- 0.07% of fresh leaf weight), being clarified by a quantitative HPLC analysis. DPT at 70-80 pM started to inhibit the growth of K562 cells in an all-or-none fashion and at 100 pM or more it produced complete inhibition in all cases. Therefore, the slope of the dose-response curve was very steep. DPT at 100 pM or more decreased the cell viability to 50%-60% and increased the number of cells undergoing apoptosis (annexin V-positive cells). The results indicate that DPT contributes to the cytotoxic action of the extract from the leaves of H. nymphaeaefolia on K562 cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.