Abstract
Yacón is a perennial crop with high insect resistance. Its leaves have many glandular trichomes, which may be related to pest resistance. In order to collect the constituents of glandular trichomes, leaves were rinsed using dichloromethane (DCM) to obtain the rinsate, and the plant residues were subsequently extracted by DCM to obtain a DCM extract containing the internal constituents of yacón leaves. Biologic evaluations revealed that insect antifeedant activity was stronger for the rinsate than for the DCM extract against the common cutworm. The major constituents of rinsate were isolated by silica gel flash chromatography and were identified as sesquiterpene lactones (SLs), uvedalin (1) and enhydrin (2) and uvedalin aldehyde (3), collectively known as melampolides. Although SLs 1 and 2 exhibited remarkably strong insect antifeedant activity, SL 3 and reduced corresponding derivatives (4 and 5) of 1 and 2 exhibited moderate insect antifeedant activity. Additionally, the two analogs, parthenolide (6) and erioflorin (7) showed moderate insect antifeedant activity. The results indicate that the substituent patterns of SLs may be related to the insect antifeedant activities. The insect antifeedant activities of SLs 1 and 2 were similar to that of the positive control azadirachtin A (8), and thus these natural products may function in chemical defense against herbivores.
Highlights
The Asteroideae is a subfamily of the Asteraceae and includes the genera Tanacetum, Senecio, Inula and Helianthus
In a function of glandular trichomes, a tomato cultivar without hairy trichomes produced large amounts of terpenoids compared with its cultivar with a hairy trichomes, and these terpenoids contribute to the herbivore resistance in tomato plants [15]
The antifeedant activity evaluation showed that the rinsate had stronger insect antifeedant The antifeedant activity evaluation showed that the rinsate had stronger insect antifeedant activity activity than dichloromethane (DCM) extract against common cutworms (Spodoptera litura F.)
Summary
The Asteroideae is a subfamily of the Asteraceae and includes the genera Tanacetum, Senecio, Inula and Helianthus. Bartsia trixago L.) produce large amounts of exudates consisting of diterpenes for tiny insect entrapment on the trichomes of their leaf surface. In a function of glandular trichomes, a tomato cultivar without hairy trichomes produced large amounts of terpenoids compared with its cultivar with a hairy trichomes, and these terpenoids contribute to the herbivore resistance in tomato plants [15]. L.) produce large amounts of exudates of active compound Trixago they store various chemicals, and various kinds ofconsisting biologic active diterpenes for tiny insect entrapment on the trichomes of their leaf surface. In a insect antifeedant diterpene, kolavenic acid in glandular trichomes wereproduced both important for function of glandular trichomes, a tomato cultivar without hairy trichomes large amounts herbivore resistance of yellow bartsia [16]. Images of hairy (black a b and glandular (white triangle) trichomes on the yacón leaf surface (×160). (a) adaxial; (b) abaxial
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