Salicortin is a phenolic glucoside produced in Salicaceae as a chemical defense against herbivory. The specialist lepidopteran herbivorous larvae of Cerura vinula are able to overcome this defense. We examined the main frass constituents of C. vinula fed on Populus nigra leaves, and identified 11 quinic acid derivatives with benzoate and/or salicylate substitution. We asked whether the compounds are a result of salicortin breakdown and sought answers by carrying out feeding experiments with highly 13 C-enriched salicortin. Using HRMS and NMR analyses, we were able to confirm that salicortin metabolism in C. vinula proceeds through deglucosylation and ester hydrolysis, after which saligenin is oxidatively transformed into salicylic acid and, eventually, conjugated to quinic acid. To the best of our knowledge, this is the first report of a detoxification pathway based on conjugation with quinic acid.
In briefZhang et al. show that Manduca sexta prefers to lay its eggs on beetle-infested plants. Caterpillars feeding on these plants have a reduced chance of being parasitized by wasps. The authors show that the beetle-induced plant volatile a-copaene can elicit moth oviposition and the odorant receptor 35 is involved in its detection.
The absolute configuration of salicortin, HCH-salicortin and tremulacin, isolated from leaves of Populus trichocarpa × deltoides Beaupré, was determined by comparing spectroscopic data of these compounds with those of idescarpin, isolated from leaves of Idesia polycarpa. All compounds were characterized by nuclear magnetic resonance spectroscopy, high-resolution mass spectrometry, and circular dichroism spectroscopy. It was found that the hydroxy cyclohexenonoyl (HCH) moiety in all compounds is (S)-configured. In addition, it was shown that leaves of Idesia polycarpa contain high amounts of (−)-idescarpin (1.1%, based on dry weight).
The chemical composition of Populus nigra shoot resin has been investigated by chromatographic and spectroscopic methods. The analyses resulted in identification of 19 known compounds. The resin exhibited low activity against selected microorganisms.
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