Antifeedant Activity of Fatty Acid Esters and Phytosterols from Echium wildpretii

Abstract

Crude extracts and fractions from Echium wildpretii H. Pearson ex Hook. f. subsp. wildpretii (Boraginaceae) have been tested against insect species Spodoptera littoralis, Leptinotarsa decemlineata, and the aphids Myzus persicae, Diuraphis noxia, Metopolophium dirhodum, Rhopalosiphum maidis, and Rhopalosiphum padi. The EtOH extract and the lipid and steroidal fractions of E. wildpretii exhibited significant antifeedant activities against the aphids and L. decemlineata. Two bioactive mixtures composed of fatty acid esters and n-alkanes were obtained from the lipid fraction. The bioguided fractionation of the steroidal fraction resulted in the isolation of glutinol, β-sitosterol, (3β,7α)-stigmast-5-ene-3,7-diol, and (3β,7α)-7-methoxystigmast-5-en-3-ol. The latter two compounds exhibited potent antifeedant activities against L. decemlineata indicating that the presence of an O-bearing C(7) was responsible for the activities of these molecules.

Differential Deterrent Activity of Natural Products Isolated from <i>Allophylus edulis</i> (Sapindaceae)

“…Noteworthy is the fact that the oxidation state in C3 is the only difference between 3 and 5, which may indicate a correlation of the moiety in such position with the activity of these sterols against insects. Similar correlations have previously been reported involving the activity of phytosterols against insects [53].…”

“…At least a hundred different sterols have been isolated from plants, being them of vital importance for their growing processes [53]. Sitosterol is probably the most abundant and common sterol in plants [54]- [57].…”

Influence of long-chain fatty acids on weight gain of Hylastinus obscurus (Coleoptera: Curculionidae)

“…The significantly greater insect weight loss of H. obscurus individuals fed a diet supplemented with palmitic acid suggests that this fatty acid could play a role as an antifeedant in the host recognition process of this curculionid (Figure 3). A similar antifeedant effect of palmitic acid on Leptinotarsa decemlineata has been reported by Santana et al (2012); the effective antifeedant dose was approximately 50 µg cm -2 of palmitic acid present in Echium wildpretii. Although, there are few reports concerning the antifeedant effect of hexadecanoic acid, its role as an oviposition deterrent has been previously demonstrated.…”

Steroids from the aerial parts of Leonurus japonicus

“…Ten known compounds 3-12 were identified by comparison of their data with those published in literature, as (24R)-5a-stigmast- (Prachayasittikul et al, 2009), b-sitosterol (5) (Ahmed et al, 2011), (24S)-saringosterol (6) (Ukiya et al, 2001), (3b,7a)-stigmast-5-ene-3,7-diol (7) (Santana et al, 2012), (3b,7a)-7-methoxystigmast-5-en-3-ol (8) (Santana et al, 2012), 3b-hydroxy7a-ethoxy-24b-ethylcholest-5-ene (9) (Liu et al, 2011), cyathisterone (10) (Kawahara et al, 1994), 5a,8a-epidioxy-23-methyl-(22E,24R)-ergosta-6,22-dien-3b-ol (11) (Xin et al, 2007), and demethylincisterol A 3 (12) (Mansoor et al, 2005), respectively.…”