Submitted to: Natural Product Communications
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/20/2010
Publication Date: 8/1/2010
Citation: Castro, A., Cantrell, C.L., Hale, A.L., Duke, S.O. 2010. Phytotoxic activity of flavonoids from dicranostyles ampla. Natural Product Communications. 5(8):1233-1237. Interpretive Summary: Current agricultural practices involved in weed management depend strongly on the use of synthetic herbicides. Herbicides and agrochemicals based on natural products are attractive for a variety of reasons, most of which revolve around their minimal effect on the environment. Extracts from aerial parts of 16 Convolvulaceae species were evaluated against both the monocot Agrostis stolonifera (bentgrass) and the dicot Lactuca sativa (lettuce). D. ampla (Convolvulaceae) afforded one of the highest levels of phytotoxic activity and was further studied using a bioassay-guided isolation approach in order to isolate and characterize the bioactive compound(s). Two phytotoxic flavonoids, dihydromyricetin and myricetin-3-O-a-rhamnoside or myricetrin, were found to be responsible for much of the activity of the extract as a whole in the A. stolonifera and L. sativa bioassay.
Technical Abstract: Crude extracts from over 16 species of plants from the family Convolvulaceae were evaluated for phytotoxic activity against Agrostis stolonifera (bentgrass) and Lactuca sativa (lettuce) at 1000 µg/mL. Ethanol extracts of Dicranostyles ampla were among the most active of those species tested. Systematic bioassay-guided fractionation of the ethanol extract of the aerial parts from this species was performed to specifically identify the phytotoxic compounds. Two phytotoxic flavonoids, dihydromyricetin (1) and myricetin-3-O-a-rhamnoside or myricetrin (2), were found to be responsible for much of the activity of the extract as a whole in the A. stolonifera and L. sativa bioassay. In a Lemna paucicostata bioassay, (1) and (2) had no activity at 100 µM.