Comtrifosides A and B, two new triterpenoid saponins from the leaves of Combretum trifoliatum.

The phytochemical composition of the Combretum trifoliatum leaves was studied for the first time. Two new triterpenoid saponins, named comtrifoside A (1) and comtrifoside B (2), together with two other saponins (3-4) were purified by variously chromatographic techniques. For the first time, compound 3 was informed from the Combretum genus, as well as all of the isolated compounds (1-4) were reported from C. trifoliatum. The chemical structures of them were clearly characterised using extensive UV-VIS, IR, HRMS-ESI, and NMR experimental data. The in vitro anti-inflammatory activities of 1 & 2 were examined against NO overproduction in LPS activation of RAW264.7.

Indicuen, a new hopane from Parmotrema indicum Hale growing in Vietnam.

One new hopane-type triterpene, indicuen (1), along with eight known compounds (2-9) were isolated from the n-hexane extract of the lichen Parmotrema indicum Hale. The chemical structures of isolated compounds were identified by interpretation of their spectroscopic data (1D, 2D NMR and HRESIMS) combined with DFT-NMR chemical shift calculations and subsequent assignment of DP4+ probabilities and by comparison with the literature. Indicuen represents for a rare hopane bearing a 1-carboxyethyl substituent at C-21 in lichens. Compounds 1-3 and 5-8 were evaluated for α-glucosidase inhibition and cytotoxicity against K562 and HepG2 cancer cell lines. Compounds 1, 5 and 7 exhibited moderate α-glucosidase inhibition with IC50 values of 201.1, 156.3 and 187.4 µM, respectively. Compound 1 also showed weak cytotoxicity toward K562 cell line while others showed no activity.

Lasibidoupins A and B, two new compounds from the stems of Lasianthus bidoupensis V.S. Dang & Naiki.

From the Lasianthus bidoupensis stems, two new compounds, including one new 9,10-anthraquinone, lasibidoupin A (1), and one new 6,7-benzocoumarin, lasibidoupin B (2), together with one known compound, 11-O-methyldamnacanthol (3) were isolated using chromatographic method. Their structures were determined by extensive HRMS, and NMR assignments. Compound 3 was reported for the first time from this species. New compounds (1 & 2) were tested for the cytotoxicity against three human cancer cell lines (MCF-7, HeLa, and NCI-H460) by SRB assay. As results, 1 & 2 exhibited significant cytotoxic activity against all cancer cell lines (IC50 ranged from 0.058 ± 0.003 to 0.177 ± 0.014 µM).

Two new phenolic compounds from the Vietnamese lichen Parmotrema tinctorum.

Chemical investigation of the lichen Parmotrema tinctorum (Nyl.) Hale led to the isolation of two new phenolic compounds, 2-ethylhexyl orsellinate (1) and tinctorinone (2). The structures were determined by analysis of their MS and NMR data as well as by comparison with literature data. The 2-ethylhexyl ester group of 2-ethylhexyl orsellinate is uncommon among lichen metabolites. Tinctorinone revealed strong inhibition towards α-glucosidase.

Parmosidone K, a new meta-depsidone from the lichen Parmotrema tsavoense.

Further phytochemical investigation on P. tsavoense led to one new meta-depsidone, parmosidone K together with one known compound, barbatic acid. Their structures were determined by 1D and 2D NMR analysis, high resolution mass spectroscopy, and comparison their NMR data with those reported in literatures. Parmosidone K was evaluated for α-glucosidase inhibition and revealed the powerful activity with IC50 value of 3.12 µM.

Ricicomin A, a new alkaloid from the leaves of Ricinus communis Linn.

From the leaves of Ricinus communis Linn., one new alkaloid, named ricicomin A (1) together with three known ones, ricinine (2), N-demethylricinine (3) and 4-[2-formyl-5-(methoxymethyl)-1H-pyrrol-1-yl]butanoic acid (4) were justified by repeated chromatographic methods. Their structures were determined by comprehensive IR, HR-ESI-MS and NMR analyses. Compound 4 was identified for the first time from the genus Ricinus. DFT-NMR chemical shift calculations and subsequent DP4+ probability methods were applied to confirm the chemical structure of 1. Compounds 1-3 did not display cytotoxic effect against three human cancer cell lines (MCF-7, HepG2 and HeLa) using SRB assay.

Three new diphenyl ethers from the lichen Parmotrema praesorediosum (Nyl.) Hale (Parmeliaceae).

Three new diphenyl ethers, named praesorethers E, F and G (1, 2 and 3), were isolated from the lichen Parmotrema praesorediosum. Their chemical structures were elucidated on the basis of extensively spectroscopic analysis including HR-ESI-MS and NMR as well as comparison with previously published data. These compounds were evaluated for the cytotoxicity against three human cancer cell lines (HeLa, NCI-H460 and MCF-7) using SRB assay. As results, 1 and 2 exhibited weak cytotoxic activity against three tested cancer cell lines with the inhibitive percentage of 64-79.9% at the concentration of 100 µg/mL while 3 was inactive.

Three new phenolic compounds from the lichen Ramalina peruviana Ach. (Ramalinaceae).

Three new phenolic compounds, peruvinides A-C were isolated from the lichen Ramalina peruviana Ach. (Ramalinaceae). Their structures were unambiguously determined by extensive spectroscopic analyses and comparison with literature data. Peruvinides A and B bearing unusual moieties were found for the first time among lichen metabolites.

A new depsidone from the lichen Usnea ceratina Arch.

Chemical investigation of the lichen Usnea ceratina Arch led to the isolation of five depsidones, including one new compound ceratinalone (1) along with four known compounds bailesidone (2), stictic acid (3), 8'-O-methylstictic acid (4) and 8'-O-ethylstictic acid (5). The structures were determined by analysis of their MS and NMR data as well as by comparison with literature values. Compounds 1 and 4 were evaluated the cytotoxic activity against HeLa (human epithelial carcinoma), NCI-H460 (human lung cancer), HepG2 (liver hepatocellular carcinoma), and MCF-7 (human breast cancer) cell lines, showing the moderate activity.

Reticulatin, a novel C43-spiroterpenoid from the lichen Parmotrema reticulatum growing in Vietnam.

A novel C43-spiroterpenoid, reticulatin (1), was isolated from the lichen Parmotrema reticulatum (Taylor) M. Choisy (Parmeliaceae). Five previously-reported compounds were also isolated: zeorin (2), leucotylin (3), lupeol (4), betulinic acid (5), and dihydroreynosin (6). The structures were elucidated by 1D, 2D NMR, and HRESIMS spectroscopy and comparison with the literature. We propose that reticulatin is a biosynthetic product of fusicoccadiene and vinapraesorediosic acid A via Diels-Alder addition. Reticulatin is the first C43-spiroterpenoid identified from lichen metabolites. All compounds were evaluated for inhibition of α-glucosidase. Compound 1 showed the most potent inhibition, with an IC50 value of 3.90 µM, much lower than that of the acarbose positive control (IC50 165 µM).

Usneaceratins A and B, two new secondary metabolites from the lichen Usnea ceratina.

Two new compounds, comprising one dibenzofuran, named usneaceratin A (1), and one phenolic acid, named usneaceratin B (2), together with one known dibenzofuran, isousnic acid (3), and two known phenolics, orsellinic acid (4) and methyl orsellinate (5) were clarified from the lichen Usnea ceratina using variously chromatographic methods. Their structures were testified by comprehensive HR-ESI-MS, and NMR spectroscopic analysis, and comparison with published data. Their α-glucosidase inhibitory activity of all compounds was measured. Usneaceratin B (2) possessed better inhibition against α-glucosidase enzyme (IC50 value of 41.8 µM) than the standard drug acarbose (IC50 value of 214.50 µM).

Two new phenolic compounds from the lichen Parmotrema cristiferum growing in Vietnam.

Two new phenolic compounds, cristiferides A-B (1-2) together with six known compounds, 2,4-dihydroxyphthalide (3), lecanoric acid (4), orsellinic acid (5), 5-chloroorsellinic acid (6), methyl haematommate (7), and methyl ß-orsellinate (8) were isolated from the lichen Parmotrema cristiferum (Taylor) Hale (Parmeliaceae). The structures of isolated compounds were identified from its spectroscopic data and by comparison with the literatures. Compounds 1-3 and 6-8 were evaluated for alpha-glucosidase inhibition. Compounds 2 and 7 revealed potent activity with IC50 values of 72.66 µM and 48.73 µM, respectively.

Paresordin A, a new diphenyl cyclic peroxide from the lichen Parmotrema praesorediosum.

From the lichen Parmotrema praesorediosum, one new diphenyl peroxide, named praesordin A (1), together with four depsidones, including virensic acid (2), protocetraric acid (3), 8'-O-methylprotocetraric acid (4), and furfuric acid (5) were purified. Their structures were chacracterized using extensive HR-ESI-MS and NMR spectroscopic methods. The isolated compounds (2-5) possessed stronger α-glucosidase inhibitory activity (IC50 = 43.7-110.1 µM) than the standard drug acarbose (IC50 = 214.5 µM).

A new diphenyl ether from Parmotrema indicum Hale growing in Vietnam.

Chemical investigation of the lichen Parmotrema indicum Hale led to the isolation of one new diphenyl ether, parmetherine D (1), along with eight known compounds (2-9). The structures were determined by analysis of MS and NMR data and by comparison with the literature. Compounds 1, 2, and 7 were evaluated for α-glucosidase inhibition. Only compound 1 exhibited significant inhibition.[Formula: see text].

Cycloartane-type triterpenoids from the whole plants of Macrosolen bidoupensis.

One new cycloartane-type triterpenoid, named macrobidoupoic acid A (as an C-24 epimeric mixture, 4a, 4 b), together with three known ones (1-3), were clarified by different chromatography from the M. bidoupensis whole plants. Triterpenoids (1, 3 & 4) were detected for the first time from the Macrosolen genus. Chemical structures of them were illuminated using HR-ESI-MS, and NMR (1 D & 2 D) assessments. The cytotoxic properties of triterpenoids (3 & 4) were examined against two human cancer cell lines (A549, and RD) by MTT assay. As results shown, triterpenoids (3 & 4) possessed moderate cytotoxic activity against A549 and RD cancer cells (IC50 ranged from 5.44 to 39.52 µM).

α-Glucosidase Inhibition by Usnic Acid Derivatives.

This study investigated a set of new potential antidiabetes agents. Derivatives of usnic acid were designed and synthesized. These analogs and nineteen benzylidene analogs from a previous study were evaluated for enzyme inhibition of α-glucosidase. Analogs synthesized using the Dakin oxidative method displayed stronger activity than the pristine usnic acid (IC50 >200 µM). Methyl (2E,3R)-7-acetyl-4,6-dihydroxy-2-(2-methoxy-2-oxoethylidene)-3,5-dimethyl-2,3-dihydro-1-benzofuran-3-carboxylate (6b) and 1,1'-(2,4,6-trihydroxy-5-methyl-1,3-phenylene)di(ethan-1-one) (6e) were more potent than an acarbose positive control (IC50 93.6±0.49 µM), with IC50 values of 42.6±1.30 and 90.8±0.32 µM, respectively. Most of the compounds synthesized from the benzylidene series displayed promising activity. (9bR)-2,6-Bis[(2E)-3-(2-chlorophenyl)prop-2-enoyl]-3,7,9-trihydroxy-8,9b-dimethyldibenzo[b,d]furan-1(9bH)-one (1c), (9bR)-3,7,9-trihydroxy-8,9b-dimethyl-2,6-bis[(2E)-3-phenylprop-2-enoyl]dibenzo[b,d]furan-1(9bH)-one (1g), (9bR)-2-acetyl-6-[(2E)-3-(2-chlorophenyl)prop-2-enoyl]-3,7,9-trihydroxy-8,9b-dimethyldibenzo[b,d]furan-1(9bH)-one (2d), (9bR)-2-acetyl-6-[(2E)-3-(3-chlorophenyl)prop-2-enoyl]-3,7,9-trihydroxy-8,9b-dimethyldibenzo[b,d]furan-1(9bH)-one (2e), (6bR)-8-acetyl-3-(4-chlorophenyl)-6,9-dihydroxy-5,6b-dimethyl-2,3-dihydro-1H-[1]benzofuro[2,3-f][1]benzopyran-1,7(6bH)-dione (3e), (6bR)-8-acetyl-6,9-dihydroxy-5,6b-dimethyl-3-phenyl-2,3-dihydro-1H-[1]benzofuro[2,3-f][1]benzopyran-1,7(6bH)-dione (3h), (6bR)-3-(2-chlorophenyl)-8-[(2E)-3-(2-chlorophenyl)prop-2-enoyl]-6,9-dihydroxy-5,6b-dimethyl-2,3-dihydro-1H-[1]benzofuro[2,3-f][1]benzopyran-1,7(6bH)-dione (4b), and (9bR)-6-acetyl-3,7,9-trihydroxy-8,9b-dimethyl-2-[(2E)-3-phenylprop-2-enoyl]dibenzo[b,d]furan-1(9bH)-one (5c) were the most potent α-glucosidase enzyme inhibitors, with IC50 values of 7.0±0.24, 15.5±0.49, 7.5±0.92, 10.9±0.56, 1.5±0.62, 15.3±0.54, 19.0±1.00, and 12.3±0.53 µM, respectively.

New erythritol derivatives from the fertile form of Roccella montagnei.

Chemical investigation of the methanol extract of the fertile form of Roccella montagnei collected in Vietnam afforded twelve secondary metabolites, including five new montagnetol derivatives, orsellinylmontagnetols A-D and a furanyl derivative together with seven known compounds. Their chemical structures were elucidated by analysis of 1D and 2D NMR and high resolution mass spectroscopic data. The relative stereochemistry of two chiral centers (C-2 and C-3) of orsellinylmontagnetols A and B was elucidated by comparison of their coupling constants and the specific rotation with those reported in the literature while the absolute stereochemistry was determined by the application of a modified Mosher method for the hydroxy group at C-3. The absolute configuration (2R,3S) of the butanetetraol moiety of these compounds is in accordance with that of erythrin, a recognized chemotaxonomic marker of the genus Roccella. Five of these compounds were evaluated for their cytotoxic activities against four cancer cell lines. Only orsellinylmontagnetol A exerted a moderate activity against MCF-7 cell line with an IC50 value of 68.39 ± 3.46 µM.