Crystal structure of diaphorin methanol monosolvate isolated from Diaphorina citri Kuwayama, the insect vector of citrus greening disease

Abstract

The title compound C22 H39 NO9 ·CH3 OH [systematic name: (S)-N-((S)-{(2S,4R,6R)-6-[(S)-2,3-dihydroxypropyl]-4-hydroxy-5,5-dimethyltetrahydro-2H-pyran-2-yl}(hydroxy)methyl)-2-hydroxy-2-[(2R,5R,6R)-2-methoxy-5,6-dimethyl-4-methylenetetrahydro-2H-pyran-2-yl]acetamide methanol monosolvate], was isolated from the Asian citrus psyllid, Diaphorina citri Kuwayama, and crystallizes in the space group P2 1. 'Candidatus Profftella armatura' a bacterial endosymbiont of D. citri, biosynthesizes diaphorin, which is a hybrid polyketide-nonribosomal peptide comprising two highly substituted tetrahydropyran rings joined by an N-acyl aminal bridge [Nakabachi et al. (2013). Curr. Biol. 23, 1478-1484]. The crystal structure of the title compound establishes the complete relative configuration of diaphorin, which agrees at all nine chiral centers with the structure of the methanol monosolvate of the di-p-bromobenzoate derivative of pederin, a biogenically related compound whose crystal structure was reported previously [Furusaki et al. (1968). Tetrahedron Lett. 9, 6301-6304]. Thus, the absolute configuration of diaphorin is proposed by analogy to that of pederin.