Alkaloids of a new type from Elaeocarpus polydactylus Schl. (family elaeocarpaceae)

Abstract

No structural information regarding alkaloids of the family Elaeocarpaceae has previously been reported. We now report that two new alkaloids, elaeocarpine, C,,H,,NO,, m.p. 81-82',[a], ca. + O s l o in CHCl,, and an isomer, isoelaeocarpine, m.p. 51-52', [a], ca. f0-4" in CHCl,, isolated from the leaves of a New Guinea species Elaeocarpus Polydactjhs Schl., are the first members of a new class of indolizidine alkaloids. The complete stereochemistry of elaeocarpine (I) has been established by an X-ray crystal structure analysis of elaeocarpine hydrobromide which crystallizes in the triclinic system with two formula units in a unit cell of dimensions a = 12.46, b = 7.38, and c = 8.05 A, a = 961", = 92-8" and y = 94.0'. The N ( z ) versus z test1 clearly shows the space group to be Pi, indicating that the crystals are essentially racemic. The electron-density map, based on the bromine atom co-ordinates derived from the Patterson function, shows the position of all C, N, and 0 atoms, and the complete structure is shown in perspective in the Figure.The isomeric alkaloid, isoelaeocarpine (11) , has been shown to be closely related to elaeocarpine by interconversion of the two alkaloids in methanolic potassium hydroxide solution a t room temperature. Both alkaloids show carbonyl absorption bands (I), v(CC1,) 1694 cm.-l; (11) v(CC1,) 1680 cm.-l, and their mass spectra are closely similar (hf+, m/e %7), differing only in the relative intensities of some peaks. The 100 Mc./sec. n.m.r. spectra of both (I) and (11) show a sharp three-proton singlet assigned to the aryl C-methyl group [a 2.60 in (I) and 8 2.63

Indolizidine Alkaloids with δ-Opioid Receptor Binding Affinity from the Leaves of Elaeocarpus fuscoides

“…We report herein the isolation, structure determination, and human δ-opioid receptor binding affinity of a new indolizidine alkaloid, elaeocarpenine (1), together with the known compounds isoelaeocarpicine (2), isoelaeocarpine (3), and elaeocarpine (4), 5 from E. fuscoides Knuth., a rainforest tree collected from the Kirene Forest, Ialibu, in the Southern Highlands Province of PNG. 2D NMR assignment of the new compound and the three known compounds (2)(3)(4) is reported here for the first time.…”

“…Their structures were determined by 1D and 2D NMR spectroscopy. Since treatment of elaeocarpenine (1) with ammonia produced a 1:1 mixture of the diastereomers 3 and 4, we propose that elaeocarpenine (1) is the biogenetic precursor of isoelaeocarpine (3) and elaeocarpine (4). Compounds 1-4 demonstrated binding affinity for the human δ-opioid receptor with IC 50 values of 2.7, 35.1, 13.6, and 86.4 µM, respectively.…”

“…In the first chemical investigation of the Papua New Guinean plant Elaeocarpus fuscoides, one new indolizidine alkaloid, elaeocarpenine (1), and three known alkaloids, isoelaeocarpicine (2), isoelaeocarpine (3), and elaeocarpine (4), were isolated from the leaves. Their structures were determined by 1D and 2D NMR spectroscopy.…”

“…The family Elaeocarpaceae is a major producer of plant alkaloids. [1][2][3][4][5][6][7][8][9][10][11] Early investigations of the genus Elaeocarpus uncovered a new class of alkaloids, the indolizidines. [1][2][3][4][5][6][7][8][9] Indolizidine alkaloids have been identified in seven species of Elaeocarpus.…”

“…In their original isolation studies on E. polydactylus, Johns et al reported the isolation of 3 and 4 as racemates. 3,5 Dragendorff's reagent in conjunction with positive electrospray MS was used to identify alkaloids in extracts from plants from the Elaeocarpaceae. The leaves, roots, and bark of E. fuscoides were surveyed, but only the leaves returned a positive test for alkaloids.…”