α-Glucosidase Inhibitory Prenylated Anthranols from Harungana madagascariensis.

Four new prenylated anthranols, harunganols C-F (1-4), along with kenganthranol A (5), harunganin (6), and ferruginin A (7), were identified from the leaves of Harungana madagascariensis. The structures of compounds 2, 5, and 7 were confirmed by single-crystal X-ray diffraction analysis. Compound 1 is a unique symmetrical anthranol dimer connected via a CH2 group. Compound 4 possesses a unique C-10 hemiketal group. All anthranols were evaluated for their α-glucosidase inhibitory activities. They displayed a higher potency compared to acarbose except for 3 and 4. In particular, harunganol C (1) showed an IC50 value of 1.2 µM.

Natural anthraquinone derivatives from a marine mangrove plant-derived endophytic fungus Eurotium rubrum: structural elucidation and DPPH radical scavenging activity.

There is considerable interest in the isolation of potent radical scavenging compounds from natural resources to treat diseases involving oxidative stress. In this report, four new fungal metabolites including one new bisdihydroanthracenone derivative (1, eurorubrin), two new seco-anthraquinone derivatives [3, 2-O-methyl-9-dehydroxyeurotinone and 4, 2-Omethyl- 4-O-(alpha-D-ribofuranosyl)-9-dehydroxyeurotinone], and one new anthraquinone glycoside [6, 3-O-(alpha-D-ribofuranosyl)- questin], were isolated and identified from Eurotium rubrum, an endophytic fungal strain that was isolated from the inner tissue of the stem of the marine mangrove plant Hibiscus tiliaceus. In addition, three known compounds including asperflavin (2), 2-O-methyleurotinone (5), and questin (7) were also isolated and identified. Their structures were elucidated on the basis of spectroscopic analysis. All of the isolated compounds were evaluated for 1,1-diphenyl-2-picrylhydrazyl(DPPH) radical scavenging activity.

Antibacterial activities of the methanol extracts, fractions and compounds from Harungana madagascariensis Lam. ex Poir. (Hypericaceae).

ETHNOPHARMACOLOGICAL RELEVANCE: Harungana madagascariensis Lam. ex Poir. (Hypericaceae) is used in folk medicine to treat a variety of human ailments, mainly antibacterial, antifungal, antiviral and viral infections. In the present study, the methanol extract from the leaves (HML) and bark (HMB) of this plant as well as fractions (HMBa-c), sub-fractions (HMBa1-5) and compounds isolated from HMBa and HMBb namely betulinic acid (1), madagascin (2), ferruginin A (3) and Kaempferol-3-O-ß-d-glucopyranoside (4) were tested for their antimicrobial activities against a panel of 28 g-negative bacteria including multidrug resistant (MDR) phenotypes. MATERIALS AND METHODS: The broth microdilution method was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the above samples; column chromatography was used for the fractionation and purification of the bark extract whilst the chemical structures of compounds were determined using spectroscopic techniques. RESULTS: Crude extract HMB together with fraction HMBa and sub-fraction HMBa3 were active on the 28 tested bacterial strains. HML as well as fractions HMBb, HMBc and sub-fractions HMBa1, HMBa2, HMBa4 and HMBa5 were selectively active. MIC values below or equal to 1024µg/mL were recorded with these samples on 92.9% (for HML and HMBa 4), 82.1% (for HMBb), 78.6% (for HMBa2), 50.0% (for HMBa5) and 42.9% (for HMBc) tested bacteria. For crude material, the lowest MIC value below 8µg/mL was obtained with HMB against Escherichia coli ATCC10536 and W3110 strains, and with sub-fraction HMBa3 against Klebsiella pneumoniae K2 strains. MIC values below 10µg/mL were recorded with compound 3 against E. coli ATCC10536, Enterobacter aerogenes ATCC13048 and EA294, Pseudomonas aeruginosa PA01, K. pneumoniae K2 and Kp55 and Enterobacter cloacae BM67. CONCLUSIONS: Harungana madagascariensis is a potential source of antimicrobial drugs to fight against MDR bacteria. The anthranol 3 is the main antibacterial constituents of the bark of the plant. HMB and compound 3 deserve further investigations to develop natural drug to combat Gram-negative bacteria and otherwise MDR phenotypes.

The effect of anthralin and its derivatives on epidermal cell kinetics.

An attempt was made to clarify the effect of anthralin on epidermal cell kinetics. Commercial anthralin powder was separated by column chromatography into three components: pure anthralin, 1,8-dihydroxyanthroquinotne, and anthralin dimer. The effect of these on the diurnal mitotic variation and the cell cycle of the hairless mouse epidermis was studied. Neither anthroquinone nor the anthralin dimer had any influence on these parameters. Both the chromatographically pure and commercial anthralins had similar effects. Mitotic activity was considerably reduced, although not to zero, with concomitant elimination of the diurnal peak. The G2 and S phases of the cell cycle were approximately doubled in length. Application of the pure and commercial anthralin also resulted in some irritation not seen with either the anthroquinone or dimer.

Separation, identification, and quantitation of anthralin and its decomposition products.

Anthralin and its decomposition products were separated by both column chromatographic and TLC techniques. Two decomposition products were characterized by TLC, melting-point data, and UV and IR spectroscopy. Pure anthralin and its decomposition products also were determined quantitatively.

Alpha-glucosidase inhibitory anthranols, kenganthranols A-C, from the stem bark of Harungana madagascariensis.

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.