New hopane triterpene from Eleocharis sellowiana (Cyperaceae)

Abstract

Do extrato hexânico de Eleocharis sellowiana foram isolados o novo triterpeno 3α-hidroxi-13α,17α,21β-hopano-15,19-diona e hexadecanoato de E-fitila, caracterizados por dados de RMN e EM.A new triterpene named 3α-hydroxy-13α,17α,21β-hopan-15,19-dione and E-phytyl hexadecanoate were isolated from the hexanic extract of Eleocharis sellowiana. NMR and MS experiments determined the molecular structures. Keywords: Eleocharis, Cyperaceae, hopane-like triterpene IntroductionThe genus Eleocharis R. Br. (Cyperaceae, Cyperoideae, Scirpeae) includes about 200 species, occurring in wet environments like swamps, lakes and rivers margins. Their aerial parts are formed by simple, not ramified stalks that end in a spiciform inflorescence formed by numerous very inconspicuous flowers. Their subterraneous parts are formed by roots and stem (called rhizome or stolon, depending on its form). E. sellowiana Kunth occurs in Mexico, Colombia, Paraguay and Brazil. This species is widely distributed in São Paulo State. 1 As many other plants from wet environments like swamps, lakes and rivers margins, Eleocharis species are subject of only a few studies. According to the literature 2 only E. dulcis Trin., E. coloradoensis (Britt.) Gilly, E. acuta R. Br., E. microcarpa Torr. and E. smallii L. had been subjected to phytochemical analysis before.In continuation of our phytochemical analysis of Eleocharis genus, 3 the hexanic extracts of E. sellowiana (subterraneous and aerial parts) were subjected to a detailed chromatographic analysis resulting in the isolation of a new pentacyclic triterpene named 3α-hydroxy-13α,17α,21β-hopan-15,19-dione (1) and E-phytyl hexadecanoate (2) (Figure 1). On the other hand, when the hydrogens H-16 were irradiated, only the hydrogen H-17 was observed. The absence of polarization transference between H-17 and H-21 points out to a very small coupling constant between these hydrogens and consequently to a cis-D/E rings fusion with a β-isopropyl group. The C/D rings fusion should be a cis-fusion with the hydrogen H-13 in a α-position. that corroborated with the hydroxyl group at C-3 (m/z 207, 16%, 1a and m/z 189, 100%, 1b) and with carbonyl groups location at D-and E-rings (m/z 318, 85%, 1c; m/z 300, 24%, 1d; m/z 303, 20%, 1e; m/z 277, 32%, 1f) (Figure 4). Compound 2 (C 28 H 48 O), isolated from the hexanic extract of E. sellowiana (aerial part), was identified as Ephytyl hexadecanoate by comparison of their 1 H and 13 C NMR and MS data with those previously published. 7 The occurrence of compound 2 in the genus Eleocharis is described here for the first time. Results and Discussion Experimental GeneralThin layer chromatography (TLC): Silica gel 60 F 254 Al sheets (Merck); detection at 254 and 365 nm and with anisaldehyde in acidic ethanol solution, 8 CC = column chromatography. 1 H, 13 C NMR and 2D experiments Varian Inova-500 (Palo Alto, CA, USA) spectrometer at 11 tesla. Chemical shifts of the compounds were recorded in CDCl 3 solutions and were quoted relative to TMS for 1 H NMR (δ 0.0) and to CDCl 3 (δ 77.0)...

New Hopane Triterpenes and Antioxidant Constituents from Potentilla Fulgens

“…A δc value at 200. 16 [17][18][19], but this is the first record of them in P. fulgens. Further species of Potentilla need to be studied to understand whether these hopane compounds could be considered as chemotaxonomic markers of the genus.…”

New Cycloartane-type Triterpenes from Marcetia Latifolia (Melastomataceae) and In Silico Studies on Candida Parapsilosis Protease

“…The H-4 ( H 3.12) coupling constants (dd, J = 10.0, 8.8 Hz) observed revealed axial-axial interactions with H-3 ( H 3.12) and H-5 ( H 3.12), as shown in 1b. The two doublets (J = 4.1 Hz) at  H 0.47 and 0.13 were attributed to methylene hydrogen cyclopropane (1), which was confirmed in the HSQC spectrum by correlation with the 13 C signal at  C 26.4 (CH 2 -19). Thus, these assignments were confirmed by direct ( 1 J H→C ) and long-range ( 2 J H→C and 3 J H→C ) heteronuclear hydrogen-carbon shift correlations observed in the HMQC and HMBC spectra, respectively, as shown in Table 1.…”

“…Triterpenoids represent an important class of natural products that are widely found and which have been shown to have biological activity [1,2]. In the Melastomataceae, monohydroxylated pentacyclic triterpenoids have been isolated based upon various skeletons, such as ursane, oleanane, fernane and lupane [3][4][5].…”

“…1 H (400 MHz) and13 C (100 MHz) NMR spectroscopic data of triterpene 1 in CDCl 3 , with TMS as internal reference. Chemical shifts (δ, ppm) and coupling constants (J, Hz, in parentheses).…”

“…Superimposed 1 H signals are described without multiplicity and approximated chemical shifts deduced by HMQC, HMBC and 1 H-1 H-COSY spectra. All 1 H and13 C chemical shift assignments of 1 were also based on homonuclear1 H-1 H-COSY and heteronuclear 2D shift-correlated HMQC ( 1 J HC ) and HMBC ( n J HC , n=2 and 3) NMR.…”