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Revisiting the absolute chirality and polymorphism of (–)‐Istanbulin A
Author(s) -
Arancibia Luz,
Naspi Mariana,
Pucci Graciela,
Rodriguez Maricel,
Di Salvo Florencia
Publication year - 2020
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229620011493
Subject(s) - chirality (physics) , absolute (philosophy) , polymorphism (computer science) , genetics , physics , philosophy , biology , epistemology , allele , gene , particle physics , chiral symmetry , nambu–jona lasinio model , quark
The terpenoid (−)‐Istanbulin A is a natural product isolated from Senecio filaginoides DC, one of the 270 species of Senecio (Asteraceae) which occurs in Argentina. The structure and absolute configuration of this compound [9a‐hydroxy‐3,4a,5‐trimethyl‐4a,6,7,8a,9,9a‐hexahydro‐4 H ,5 H ‐naphtho[2,3‐ b ]‐furan‐2,8‐dione or (4 S ,5 R ,8 R ,10 S )‐1‐oxo‐8β‐hydroxy‐10β H ‐eremophil‐7(11)‐en‐12,8β‐olide, C 15 H 20 O 4 ] were determined by single‐crystal X‐ray diffraction studies. It proved to be a sesquiterpene lactone showing an eremophilanolide skeleton whose chirality is described as 4 S ,5 R ,8 R ,10 S . Structural results were also in agreement with the one‐ and two‐dimensional (1D and 2D) NMR and HR–ESI–MS data, and other complementary spectroscopic information. In addition, (−)‐Istanbulin A is a polymorph of the previously reported form of (−)‐Istanbulin A, form I; thus, the title compound is denoted form II or polymorph II. Structural data and a literature search allowed the chirality of Istanbulin A to be revisited. The antimicrobial and antifungal activities of (−)‐Istanbulin A, form II, were evaluated in order to establish a reference for future comparisons and applications related to specific crystal forms of Istanbulins.