Phytotoxic Lignans from Artemisia arborescens

Authors: LABRUZZO, ANDREA - University Of Palermo Italy; Cantrell, Charles; CARRUBBA, A. - University Of Palermo Italy; ALI, ABBAS - University Of Mississippi; Wedge, David; Duke, Stephen

Submitted to: Natural Product Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/9/2017
Publication Date: 3/3/2018
Publication URL: https://handle.nal.usda.gov/10113/6473325
Citation: Labruzzo, A., Cantrell, C.L., Carrubba, A., Ali, A., Wedge, D.E., Duke, S.O. 2018. Phytotoxic Lignans from Artemisia arborescens. Natural Product Communications. 13(3):237-240.

Interpretive Summary: Artemisia includes more than 500 annual, biennial and perennial species that are herbs or small shrubs, mainly distributed in the temperate zones of the Northern hemisphere. Known also as silver sage, large wormwood, tree wormwood and other common names, Artemisia arborescens is a typical species of the Mediterranean wild flora which usually grows in full sun exposure and is very tolerant of heat and drought conditions. Relatively little research has been done on determination of phytotoxic compounds from A. arborescens. A. arborescens has been reported to produce phytotoxic compounds, but the exact compounds have not been reported. A systematic fractionation of extracts of the aerial part of A. arborescens was performed in order to identify its phytotoxic compounds. Two lignans were isolated, sesamin and ashantin, that inhibited growth of bentgrass, a monocot, and lettuce, a dicot, at 1 mg mL-1. In a dose-response screening of these lignans for growth inhibition against duckweed, ashantin was the most active with an IC50 of ca. 224 µM, which is comparable to some commercially available herbicides. The results reported in the present paper add to what is known of the phytotoxicity of lignans.

Technical Abstract: A systematic bioassay-guided fractionation of methylene chloride extracts of the aerial part of Artemisia arborescens was performed in order to identify its phytotoxic compounds. Two lignans were isolated, sesamin and ashantin, that inhibited growth of Agrostis stolonifera (bentgrass), a monocot, and Lactuca sativa (lettuce), a dicot, at 1 mg mL-1. In a dose-response screening of these lignans for growth inhibition against Lemna paucicostata (duckweed), ashantin was the most active with an IC50 of ca. 224 µM. The mode of action of these compounds is still unknown. In mosquito larvicidal bioassays against Aedes aegypti, isolated pure compounds sesamin and ashantin did not show any activity at the highest dose of 125 mg/L against 1-d-old Aedes aegypti larvae. In bioautography bioassays for antifungal activity using Botritis cinerea, Fusarium oxysporum, Colletotrichum fragariae, Colletotrichum acutatum, and Colletotrichum gloeosporioides, ashantin and sesamin were inactive at the highest amount tested, 5 micrograms.