Identification and Synthesis of (Z,Z)-8,11-Heptadecadienyl Formate and (Z)-8-Heptadecenyl Formate: Unsaturated Aliphatic Formates Found in the Unidentified Astigmatid Mite, Sancassania sp. Sasagawa (Acari: Acaridae)

Abstract

We identified two aliphatic formates, ( Z , Z )-8,11-heptadecadienyl formate and ( Z )-8-heptadecenyl formate in the opisthonotal gland secretions of an unidentified acarid species, namely Sancassania sp. Sasagawa. Both compounds were isolated using silica gel column chromatography and the structures were elucidated by 1 H-NMR and GC/FT-IR. Further information on the double bond positions was obtained by GC-MS analysis of the corresponding dimethyl disulfide derivatives. Based on the estimated structures of the two formates and using linoleic and oleic acids as the respective starting materials, a simple four-step synthesis was achieved via Barton decarboxylation as the key step. The aliphatic formates identified in acarids thus far are neryl formate (( Z )-3,7-dimethylocta-2,6-dienyl formate) and lardolure (1,3,5,7-tetramethyldecyl formate), and both have been reported to have pheromone functions. The biological function of the two formates isolated in this study is currently being investigated. Although we can speculate that the two compounds were biosynthesized from linoleic and oleic acid, there is a possibility that the synthetic processes featured a novel chain shortening and formic acid esterification mechanism.

Biosynthetic pathway of aliphatic formates via a Baeyer–Villiger oxidation in mechanism present in astigmatid mites

“…Two formates 8,11-F17 and 8-F17 were synthesized to establish unbiased structures (14). Two hydrocarbons, 6,9-C17 and 8-C17, have been previously identified (32,33).…”

“…Sasagawa) (14). Based on the double-bond position, LA was hypothesized to be the biosynthetic precursor of 8,11-F17 and, similarly, oleic acid (OA) for 8-F17.…”

“…In mite lipid-derived 13 C-labeled OAME, odd-numbered carbon atoms 1, 3, 5, 7, 9, 11, 13, 15, and 17 were strongly labeled by 13 C. The 13 C-isotopic abundances of these nine carbon atoms were 689-919%. Conversely, 13 C-isotopic abundances of even-numbered carbon atoms-that is, 2 (standard signal), 4,6,8,10,12,14,16, and 18-were low at −15 to 37%, and these were judged to not be enriched by 13 C.…”

Life as a fortress – structure, function, and adaptive values of morphological and chemical defense in the oribatid mite Euphthiracarus reticulatus (Actinotrichida)

“…The biochemical origin of δ-acaridial is ambiguous. Considering the biosynthetic pathways described for mites [66][67][68][69][70][71] and compounds detected in species closely related to E. reticulatus two seem possible: the terpenoid synthesis via the mevalonic acid pathway, or the fatty acid synthesis pathway (and derived compounds). Terpenoid synthesis is unlikely, since δ-acaridial lacks any isoprenoid subunit, which is the defining structural element for all terpenes, but δ-acaridial may be a highly modified derivative or a product by an extremely altered terpenoid biosynthesis pathway.…”

“…However, also a natural derivate arising from fatty acid synthesis seems possible, because in mites some fatty acid derivatives appear to constitute some rather usual substances [71]. Yet, mites are prone to use extraordinary ways to produce their chemicals and thus novel biochemical reactions or unexpected modifications from a known pathway would be not surprising [67,70,71].…”