Monoterpenoid Indole Alkaloids from the Bark ofAlstonia scholaris

Abstract

Six new monoterpenoid indole alkaloids, scholarisines B-G (1- 6), together with 15 known analogues (7- 21), were isolated from the bark of Alstonia scholaris. Their structures were determined by 1D and 2D NMR spectra and MS analyses. The structure of 1 was further supported by the single-crystal X-ray.

Characterization of chemical constituents and rats metabolites of an alkaloidal extract of Alstonia scholaris leaves by liquid chromatography coupled with mass spectrometry

“…Particularly, several pairs of epimers were detected, such as Sch (19S, 5) and Epi (19R, 6) [3,5]. It is usually difficult to separate epimers due to their similar physicochemical properties.…”

“…A water extract of the leaves has been developed into an over-the-counter drug in China [2]. A number of alkaloids, iridoids and terpenoids have been isolated from A. scholaris [3][4][5][6][7][8]. Among them, alkaloids are generally considered as the major bioactive compounds [2].…”

“…Among them, alkaloids are generally considered as the major bioactive compounds [2]. To date, more than 100 monoterpenoid indole alkaloids have been isolated from A. scholaris [3,5]. Three major alkaloids, namely scholaricine, vallesamine and…”

Four new isoflavanones from Tadehagi triquetrum

“…s) and 8.05 (br. s), one methoxyl group at δ H 3.84 (s) and two 2,2-dimethylpyran rings at δ H 5.62 (d, J = 9.9, H-5''), 6.71 (d, J = 9.9, H-4''), 1.48 (s, H-7'',8'') and 5.63 (d, J = 9.9, H-5'''), 6.82 (d, J = 9.9, H-4'''), 1.50 (s, Me-7''' and Me-8''') were observed. In addition, the 13 C NMR spectrum (Table 2) displayed 15 skeletal C atoms: one carbonyl at δ C 181.9, 13 quaternary C-atoms at δ C 104.7-159.1, and as well one CH group at δ C 154.7.…”

“…1,2 Previous phytochemical studies found a few of isoflavones and phenols from this species. 3,4 As a part of our continuing research on medicinal plants of DAI ethnopharmacy, [6][7][8][9][10] we investigated the chemical constituents of the whole plants of T. triquetrum, which led to the isolation of four new isoflavanones, named triquetrumones E-H (1-4). Isoflavanones possessing isoprenoid unit, can be considered as the characteristic constituents in this plant.…”