α-Glucosidase Inhibitory Anthranols, Kenganthranols A−C, from the Stem Bark of Harungana madagascariensis

Abstract

One new prenylated 1,4-anthraquinone and three new prenylated anthranols, named kengaquinone (1) and kenganthranols A (2), B (3), and C (4), were isolated from a hexane extract of the stem bark of Harungana madagascariensis. Six known compounds including anthraquinones, anthrones, and xanthones were also isolated and identified. The structures of the new compounds were determined by analysis of spectroscopic data and comparison with data of previously known analogues. Some isolated compounds (3-5, 7-11) were evaluated for their alpha-glucosidase inhibition activity. Compounds 3, 4, 8, and 11 showed significant activity, whereas compounds 7, 9, and 10 were inactive in this test.

Anti-plasmodial Activity of Some Constituents of the Root Bark of Harungana madagascariensis LAM. (Hypericaceae)

“…[16][17][18] Although some phytochemical and pharmacological studies have been carried out on H. madagascariensis, no investigation has been reported, to the best of our knowledge, on the anti-plasmodial activity of its constituents. In our continuing interest in new anti-plasmodial metabolites from plant sources, we investigated the MeOH-CH 2 Cl 2 (1 : 1) root bark extract of this plant which showed anti-plasmodial activity (IC 50 ϭ25.12 mg/ml) against W2 strain P. falciparum.…”

“…Various phenolic compounds have been isolated from this plant, among them anthraquinones, xanthones, biflavonoids, coumarins and anthrone derivatives. [14][15][16] These compounds have demonstrated a wide range of biological activities. [16][17][18] Although some phytochemical and pharmacological studies have been carried out on H. madagascariensis, no investigation has been reported, to the best of our knowledge, on the anti-plasmodial activity of its constituents.…”

Thermal rearrangement of harunganin and allylations of some compounds from Harungana madagascariensis

“…Harungana madagascariensis from this family is recognized to be a particularly rich source of this type of secondary metabolites. [1][2][3][4] Harunganin (1), harongin anthrone (8), harunganol B (9), kenganthranol A (10) and 1,7-dihydroxyxanthone (14) have been isolated from the stem bark of this plant and their structures were elucidated by means of spectroscopic analysis. [1][2][3][4] Apart from the last compound, all were C-prenylated and showed strong α-glucosidase enzyme inhibition activity.…”

“…[1][2][3][4] Harunganin (1), harongin anthrone (8), harunganol B (9), kenganthranol A (10) and 1,7-dihydroxyxanthone (14) have been isolated from the stem bark of this plant and their structures were elucidated by means of spectroscopic analysis. [1][2][3][4] Apart from the last compound, all were C-prenylated and showed strong α-glucosidase enzyme inhibition activity. 3,4 Harunganin [ (3,8,9-trihydroxy-6-methyl-4,4,5-tris(3-methylbut-2-enyl)anthracen-1(4H)-one] (1), the major constituent of this plant and the most active in this series, was observed to be instable in solution.…”

“…[1][2][3][4] Apart from the last compound, all were C-prenylated and showed strong α-glucosidase enzyme inhibition activity. 3,4 Harunganin [ (3,8,9-trihydroxy-6-methyl-4,4,5-tris(3-methylbut-2-enyl)anthracen-1(4H)-one] (1), the major constituent of this plant and the most active in this series, was observed to be instable in solution. The thermal (neat) rearrangement of harunganin methyl ether was studied by Richtie and Talyor 2 and that of harunganin (1) and the related isomers ferruginin A and B by Monache et al 5 However, in the previous work 2 , only one rearranged product was observed upon heating of harunganin methyl ether whereas several products were formed according to our TLC studies in the solution decomposition of harunganin (1).…”