Dendrocyin: An isocucurbitacin with novel cyclic side chain from Dendrosicyos socotrana

Abstract

From the chloroform extract of Dendrosicyos socotrana Balf.f. stems, A new isocucurbitacin (Dendrocyin) with unusual cyclization in the side chain; 24β-ethoxy-20-25-epoxy-3α,16α-dihydroxy-9-methyl-19-norlanost- 5(6) ene-2,11,22-trione has been isolated alongside isocucurbitacin R. Dendrosicyos socotrana Balf.f. is a unique species (Cucurbitaceae) native to Socotra island in the horn of Africa. From the chloroform extract of the stems, A new isocucurbitacin (Dendrocyin) with unusual cyclization in the side chain; 24β-ethoxy-20-25-epoxy-3α,16α-dihydroxy-9-methyl-19-norlanost- 5(6) ene-2,11,22-trione has been isolated alongside isocucurbitacin R. Their structural configuration were established by usual spectroscopic ( 1H NMR, 13C NMR and DEPT) and two-dimensional NMR techniques ( 1H- 1H Cosy, HMBC and HMQC). © 2004 Elsevier Ltd. All rights reserved.