ARS | Publication request: PHYTOTOXIC LIGNANS OF LEUCOPHYLLUM FRUTESCENS

Submitted to: Journal of Natural Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 26, 1999
Publication Date: N/A

Interpretive Summary: Leucophyllum frutescens is an ornamental shrub native to Texas in the Rio Grande Plains. This species tolerates windy locations and extreme temperatures (ranging from 5 to 100 F),and is disease and insect resistant. Leaf extracts of L. frutescens showed strong phytotoxic activity in a general screening program to discover pesticides from natura sources. Following a bioassay-directed chemical study, four phytotoxic constituents were isolated: diayangambin, epiyangambin, diasesartemin, and epiashantin. These compounds inhibited bentgrass seed germination and the development of lettuce seedlings. Diayangambin, epiyangambin, diasesartemin also inhibited all phases of onion root cell division. This study is the first to demonstrate the antimitotic activity of this group of natural products, as well as the first report of their isolation from this species.

Technical Abstract: Bioassay-guided fractionation of the hexane:ethyl acetate (1:1) extract of the leaves of Leucophyllum frutescens (Berl.) I.M.Johst (Scrophulariaceae) led to the isolation of its phytotoxic constituents diayangambin (1), epiyangambin (2), diasesartemin (3), and epiashantin (4). Phytotoxicity was demonstrated as inhibition of seed germination of Agrostis stolonifera cv. penncross (Poaceae) and inhibition of development of Lactuca sativa L. (Asteraceae) seedlings in a microassay using 24-well plates. Compound 1 was the most phytotoxic to L. sativa, showing strong inhibitory activity at 110u. Compound 1 was more active than 2 and 3 in inhibiting the growth of A. stolonifera with I50 values of 160, 670, and 930u. respectively. At a concentration of 500u, these compounds inhibited all phases of onion root cell division. This is the first demonstration of antimitotic activity of these furofuran lignans, and the first report of their isolation from this species.