Structure elucidation and NMR assignments of two new triterpenoids from the stems of Paragonia pyramidata (Bignoniaceae)

Abstract

Phytochemical investigation of dichloromethane (DCM) extract from the stems of Paragonia pyramidata var. pyramidata L. Rich. (Bur.) resulted in the isolation and characterization of two new triterpenoids 3β,19β-dihydroxylup-12, 20(29)-diene-28-oic acid (1) and 3β,19β-dihydroxylup-12-en-28-oic acid (2), three known triterpenoids lupeol (3), spinosic acid A (4) and oleanolic acid (5), together with four known steroids (20R)-22E-24-ethylcholesta-4,22-dien-3-one (6), (20R)-24-ethylcholest-4-en-3-one (7), stigmasterol (8) and β-sitosterol (9). HREIMS, GC-MS and NMR experiments including HSQC, HMBC, COSY and NOESY were used for the determination of the structures and NMR spectral assignments. This is the first report about the chemical constituents for this plant.

Structure verification through computer‐assisted spectral assignment of NMR spectra

“…Compound ( 1 ) is a triterpene of C 30 H 46 O 4 molecular formula that was isolated from Paragonia pyramidata (Bignoniaceae) . This compound was also numbered " 1" in the original publication.…”

“…To the best of our knowledge, the structure ( 1a ) has not been previously reported. In the original publication, a second new triterpene, numbered ‘2’ and reported as a member of the lupane family, might also be an ursane triterpene. This problem is left as an exercise to the reader.…”

Antimycobacterial and Nitric Oxide Production Inhibitory Activities of Triterpenes and Alkaloids from Psychotria nuda (Cham. & Schltdl.) Wawra

“…The chromatographic fractionation of leaf and twig extracts of P. nuda led to the isolation of 19 compounds: pomolic acid ( 1 ), spinosic acid ( 2 ), sitosterol ( 3 ), stigmasterol ( 4 ), campesterol ( 5 ), phytol ( 6 ), β -sitosterol-3- O -β- d -glucoside ( 7 ), β -stigmasterol-3- O - β - d -glucoside ( 8 ), cinchonain Ia ( 9 ), cinchonain Ib ( 10 ), N , N , N -trimethyltryptamine ( 11 ), lyaloside ( 12 ), lawsofructose ( 13 ), roseoside ( 14 ), strictosamide ( 15 ), scopoletin ( 16 ), rotungenic acid ( 17 ), strictosidine ( 18 ), and 5 α-carboxystrictosidine ( 19 ) (Figure 1). Substance identification was based on spectral analysis and data comparison with values described in the literature [21,22,23,24,25,26,27,28,29,30,31,32,33,34]. This is the first report of alkaloid ( 11 ) isolation from a natural product, as well as the isolation of the iridoid ( 14 ) and the flavonolignans ( 9 ) and ( 10 ) from the genus Psychotria .…”

Triterpenoids

“…161 Olibanum, the gum resin of Boswellia carterii, is the source of olibanumols F 395 and G 396. 162 Other simple lupane derivatives include lupane-3b,18a,19b-triol 397 from Garcinia tetralata, 163 lup-12-ene-3b,28-diol 398 from roots of Diospyros virginiana, 164 the 3b,19b-dihydroxy derivatives 399 and 400 from Paragonia pyrimidata, 165 and the 23,27,28-trioic acid 401 from Heteropanax fragrans. 166 Pulsatilla triterpenic acid A 402, from Pulsatilla chinensis, is an acetal of 5-hydroxymethylfurfural and 3b,23-dihydroxylup-20(29)-en-28-oic acid.…”