title: Toxicity of thiophenes from Echinops transiliensis (Asteraceae) against Aedes aegypti (Diptera: Culicidae) larvae.
abstract: Structureactivity relationships of nine thiophenes, 2,2': 5',2″-terthiophene (1), 2-chloro-4-[5-(penta-1,3-diyn-1-yl)thiophen-2-yl]but-3-yn-1-yl acetate (2), 4-(2,2'-bithiophen-5-yl)but-3-yne-1,2-diyl diacetate (3), 4-[5-(penta-1,3-diyn-1-yl)thiophen-2-yl]but-3-yne-1,2-diyl diacetate (4), 4-(2,2'-bithiophen-5-yl)-2-hydroxybut-3-yn-1-yl acetate (5), 2-hydroxy-4-[5-(penta-1,3-diyn-1-yl)thiophen-2-yl]but-3-yn-1-yl acetate (6), 1-hydroxy-4-[5-(penta-1,3-diyn-1-yl)thiophen-2-yl]but-3-yn-2-yl acetate (7), 4-(2,2'-bithiophen-5-yl)but-3-yne-1,2-diol (8), and 4-[5-(penta-1,3-diyn-1-yl)thiophen-2-yl]but-3-yne-1,2-diol (9), isolated from the roots of Echinops transiliensis, were studied as larvicides against Aedes aegypti. Structural differences among compounds 3, 5, and 8 consisted in differing AcO and OH groups attached to C(3″) and C(4″), and resulted in variations in efficacy. Terthiophene 1 showed the highest activity (LC50 , 0.16 μg/ml) among compounds 1-9, followed by bithiophene compounds 3 (LC50 , 4.22 μg/ml), 5 (LC50 , 7.45 μg/ml), and 8 (LC50 , 9.89 μg/ml), and monothiophene compounds 9 (LC50 , 12.45 μg/ml), 2 (LC50 , 14.71 μg/ml), 4 (LC50 , 17.95 μg/ml), 6 (LC50 , 18.55 μg/ml), and 7 (LC50 , 19.97 μg/ml). These data indicated that A. aegypti larvicidal activities of thiophenes increase with increasing number of thiophene rings, and the most important active site in the structure of thiophenes could be the tetrahydro-thiophene moiety. In bithiophenes, 3, 5, and 8, A. aegypti larvicidal activity increased with increasing number of AcO groups attached to C(3″) or C(4″), indicating that AcO groups may play an important role in the larvicidal activity.
authors.affiliation: NARO Institute of Crop Science, 2-1-18 Kannondai, Tsukuba, Ibaraki 305-8518, Japan, (phone: +81-29-8388952; fax: +81-29-8388837); NARO Agricultural Research Center for Kyushu Okinawa Region, 496 Izumi, Chikugo 833-0041, Japan; USDA-ARS, Natural Products Utilization Research Unit, University, Mississippi 38677, USA. nakanohr@affrc.go.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakano
authors.forename: Abbas
authors.initials: A
authors.lastname: Ali
authors.forename: Junaid
authors.initials: J
authors.lastname: Ur Rehman
authors.forename: Leonid K
authors.initials: LK
authors.lastname: Mamonov
authors.forename: Charles L
authors.initials: CL
authors.lastname: Cantrell
authors.forename: Ikhlas A
authors.initials: IA
authors.lastname: Khan
mesh_terms: D000330:Aedes / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D000818:Animals; D004175:Diptera; D031182:Echinops Plant / Q000737:chemistry*; D007306:Insecticides / Q000737:chemistry* / Q000302:isolation & purification / Q000633:toxicity*; D007814:Larva / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D010936:Plant Extracts / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D013876:Thiophenes / Q000737:chemistry* / Q000302:isolation & purification / Q000633:toxicity*
chemical_list: D007306:Insecticides; D010936:Plant Extracts; D013876:Thiophenes
keywords: Aedes aegypti; Asteraceae; Echinops transiliensis; Larvicidal activity; Thiophenes