Acetylcholinesterase and insect growth inhibitory activities of Gutierrezia microcephala on fall armyworm Spodoptera frugiperda J.E. Smith.
From the aerial parts of Gutierrezia microcephala (Asteraceae), four oxyflavones were isolated, namely 5,7,2'-trihydroxy-3,6,8,4',5'-pentamethoxyflavone (1); 5,7,4'-trihydroxy-3,6,8-trimethoxyflavone (2); 5,7,2',4'-tetrahydroxy-3,6,8,5'-tetramethoxyflavone (3); 5,2'-dihydroxy-3,6,7,8,4',5'-hexamethoxyflavone (4), and an ent-clerodane, bacchabolivic acid (5). Compounds 1-5, the synthetic methyl ester (6), n-hexane and MeOH extracts were evaluated against the fall armyworm (Spodoptera frugiperda). Gedunin, a known insect growth regulator isolated from Cedrela spp. was used as a positive control. When tested for activity on neonate larvae into the no-choice artificial diet bioassay, flavone (1), clerodane (5), its methyl ester (6), MeOH and n-hexane extracts caused significant larval mortality with MC50 of 3.9, 10.7, 3.46, 7.95 and 7.5 ppm at 7 days, respectively, as well as growth reduction. They also increased the development time of surviving larvae and a significant delay in time to pupation and adult emergence. Acute toxicity against adults of S. frugiperda was also found, 5, 6, gedunin and n-hexane extract had the most potent activity with LD50 value of 6.59, 15.05, 10.78, and 12.79 ppm, respectively. In addition, MeOH, n-hexane extracts, 5, 6 and gedunin caused acetylcholinesterase inhibition with 93.7, 100, 90.2, 62.0 and 100% at 50.0 ppm, respectively; whereas 1-4 exhibited only moderate inhibitory activity. Compounds 1, 5 and 6 showed inhibitory activities comparable with gedunin. These compounds could be responsible of the insect growth inhibitory activity of this plant.
Calderón
J S
JS
Instituto de Química, Universidad Nacional Autónoma de Mexico, DF, México.
Céspedes
C L
CL
Rosas
R
R
Gómez-Garibay
F
F
Salazar
J R
JR
Lina
L
L
Aranda
E
E
Kubo
I
I
D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D019659:Asteraceae / Q000737:chemistry; D001681:Biological Assay; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D015394:Molecular Structure; D010572:Pest Control, Biological; D018411:Spodoptera / Q000201:enzymology / Q000254:growth & development*; D013329:Structure-Activity Relationship
D002800:Cholinesterase Inhibitors; D005419:Flavonoids; D000110:Acetylcholinesterase