A pentacyclic triterpene from Maytenus imbricata: structure elucidation by X-ray crystallography

Abstract

A pentacyclic triterpene, 3β,30-dihydroxy-lup-20(29)-ene, was isolated from the powder extract of Maytenus imbricata. The structure and stereochemistry of the compound were established by spectroscopic techniques and unambiguously determined by single crystal X-ray crystallography. The crystal structure shows one molecule in the asymmetric unit. The crystal packing is stabilized by O-H···O intermolecular hydrogen bonds, which give rise to infinite helical chains along the c unit cell axis. The intramolecular geometry was analyzed using MOGUL, a knowledge base of molecular geometry derived from the Cambridge Structural Database (CSD).

Lupeol

“…All geometrical values agree with those of other reported PCTT structures (e.g. Pimenta et al, 2006;Madureira et al, 2004;Silva et al, 2002;Nakai et al, 1985). Compound (I) contains an intermolecular O-HÁ Á ÁO hydrogen bond (Fig.…”

“…Interestingly, another PCTT recently determined by us, namely 3,30-dihydroxylup-20(29)-ene, (II) (Pimenta et al, 2006), which differs chemically from (I) due to the hydroxy group present at C30, was reported in the enantiomorphous P4 1 (or P4 3 ) space group [a = 19.038 (1) Å and c = 7.2290 (4) Å ]. It is also important to mention that space groups P4 3 and P4 1 are rare for organic and organometallic compounds.…”

On the relationships between molecular conformations and intermolecular contacts toward crystal self-assembly of mono-, di-, tri-, and tetra-oxygenated xanthone derivatives

“…In a recent article, we reported that the isomorphism phenomenon is also present in other natural products, as the case of lupeol [7], a pentacyclic triterpene derivative. This compound shows to be isomorph to 3b,30-dihydroxylup-20(29)-ene [24], a triterpenoid which differs chemically from lupeol due to an additional hydroxyl group.…”

Experimental and theoretical investigation of molecular structure and conformation of the 4-isopropylthioxanthone

“…In a recent paper, we reported a similar behavior of isomorphism occurring in natural products, such as the case of Lupeol [29], a pentacyclic triterpene derivative. Lupeol proved isomorphic to 3b,30-dihydroxylup-20(29)-ene [30], which differs chemically due to an additional hydroxyl group.…”