Anti-Diabetic Activity of 2,3,6-Tribromo-4,5-Dihydroxybenzyl Derivatives from Symphyocladia latiuscula through PTP1B Downregulation and α-Glucosidase Inhibition.

The marine alga, Symphyocladia latiuscula (Harvey) Yamada, is a good source of bromophenols with numerous biological activities. This study aims to characterize the anti-diabetic potential of 2,3,6-tribromo-4,5-dihydroxybenzyl derivatives isolated from S. latiuscula via their inhibition of tyrosine phosphatase 1B (PTP1B) and α-glucosidase. Additionally, this study uses in silico modeling and glucose uptake potential analysis in insulin-resistant (IR) HepG2 cells to reveal the mechanism of anti-diabetic activity. This bioassay-guided isolation led to the discovery of three potent bromophenols that act against PTP1B and α-glucosidase: 2,3,6-tribromo-4,5-dihydroxybenzyl alcohol (1), 2,3,6-tribromo-4,5-dihydroxybenzyl methyl ether (2), and bis-(2,3,6-tribromo-4,5-dihydroxybenzyl methyl ether) (3). All compounds inhibited the target enzymes by 50% at concentrations below 10 µM. The activity of 1 and 2 was comparable to ursolic acid (IC50; 8.66 ± 0.82 µM); however, 3 was more potent (IC50; 5.29 ± 0.08 µM) against PTP1B. Interestingly, the activity of 1⁻3 against α-glucosidase was 30⁻110 times higher than acarbose (IC50; 212.66 ± 0.35 µM). Again, 3 was the most potent α-glucosidase inhibitor (IC50; 1.92 ± 0.02 µM). Similarly, 1⁻3 showed concentration-dependent glucose uptake in insulin-resistant HepG2 cells and downregulated PTP1B expression. Enzyme kinetics revealed different modes of inhibition. In silico molecular docking simulations demonstrated the importance of the 7⁻OH group for H-bond formation and bromine/phenyl ring number for halogen-bond interactions. These results suggest that bromophenols from S. latiuscula, especially highly brominated 3, are inhibitors of PTP1B and α-glucosidase, enhance insulin sensitivity and glucose uptake, and may represent a novel class of anti-diabetic drugs.

Isolation and synthesis of a new benzylated alkamide from the roots of Lepidium meyenii.

A new benzylated alkamide, N-(3,4-dimethoxybenzyl)-9Z-oleamide (1), along with two known ones (2 and 3) were isolated from the roots of Lepidium meyenii collected from Lijiang, Yunnan Province of China. Their structures were elucidated by extensive spectroscopic analyses and the new compound further confirmed by a one-step synthesis. All the isolated alkamides were evaluated for their cytotoxicity against five human cancer cell lines. However, no significant activities were detected at concentrations up to 40 µM.

Arundinosides A-G, new glucosyloxybenzyl 2R-benzylmalate derivatives from the aerial parts of Arundina graminifolia.

Seven new glucosyloxybenzyl 2R-benzylmalate derivatives, arundinosides A-G (1-7) were isolated from the aerial parts of the bamboo orchid Arundina graminifolia. This is the first occurrence of this class of compounds in the genus Arundina. Their planar structures and absolute configuration were determined by extensive NMR spectroscopic data as well as chemical conversion. Their neuroprotective properties were also evaluated on their potential ability to reduce the beta amyloid damage on PC12 cell model.

Insecticidal Activity of the Leaf Essential Oil of Peperomia borbonensis Miq. (Piperaceae) and Its Major Components against the Melon Fly Bactrocera cucurbitae (Diptera: Tephritidae).

The essential oil from the leaves of Peperomia borbonensis from Réunion Island was obtained by hydrodistillation and characterized using GC-FID, GC/MS and NMR. The main components were myristicin (39.5%) and elemicin (26.6%). The essential oil (EO) of Peperomia borbonensis and its major compounds (myristicin and elemicin), pure or in a mixture, were evaluated for their insecticidal activity against Bactrocera cucurbitae (Diptera: Tephritidae) using a filter paper impregnated bioassay. The concentrations necessary to kill 50% (LC50 ) and 90% (LC90 ) of the flies in three hours were determined. The LC50 value was 0.23 ± 0.009 mg/cm2 and the LC90 value was 0.34 ± 0.015 mg/cm2 for the EO. The median lethal time (LT50 ) was determined to compare the toxicity of EO and the major constituents. The EO was the most potent insecticide (LT50  = 98 ± 2 min), followed by the mixture of myristicin and elemicin (1.4:1) (LT50  = 127 ± 2 min) indicating that the efficiency of the EO is potentiated by minor compounds and emphasizing one of the major assets of EOs against pure molecules.

New Cytotoxic Bibenzyl and Other Constituents from Bauhinia ungulata L. (Fabaceae).

A new bibenzyl, 2'-hydroxy-3,5-dimethoxy-4-methylbibenzyl (1) and four known compounds identified as 2'-hydroxy-3,5-dimethoxybibenzyl (2), liquiritigenin (3), guibourtinidol (4) and fisetinidol (5) were isolated from the roots of Bauhinia ungulata L. Phytochemical investigations of the stems of B. ungulata led to the isolation of the known compounds identified as liquiritigenin (3), guibourtinidol (4), fisetinidol (5), taraxerol (6), betulinic acid (7), taraxerone (8), glutinol (9), a mixture of sitosterol (10) and stigmasterol (11), pacharin (12), naringenin (13) and eriodictyol (14). The structures of these compounds were elucidated on the basis of their spectral data (IR, MS, 1D- and 2D-NMR). The cytotoxicity of the bibenzyl 1 has been evaluated against four human cancer cell lines, showing the IC50 values of 4.3 and 6.5 µg ml-1 against pro-myelocytic leukemia (HL-60) and cervical adenocarcinoma (HEP-2) cell lines, respectively. This article also registers for the first time the 13 C-NMR data of the known bibenzyl 2.

A New Bibenzyl-phenanthrene Derivative from Dendrobium signatum and its Cytotoxic Activity.

From the whole plant of Dendrobium signatum, a new bibenzyl-dihydrophenanthrene derivative, named dendrosignatol was isolated, together with the known compounds 3,4-dihydroxy-3,4'-dimethoxybibenzyl, dendrocandin B, dendrocandin I and dendrofalconerol A. The structure of the new compound was elucidated through analysis of its spectroscopic and mass spectrometric data. All of the isolates showed appreciable cytotoxic activity against three human cancer cell lines, including MDA-23 1, HepG2 and HT-29 cells.

A new isoflavanone from the trunk of Horsfieldia pandurifolia.

A new isoflavanone, 2,2'-epoxy-4'-methoxy-3,7-dihydroxyisoflavanone (1), and a new natural coumaranone, 2-hyroxy-2-(4'-methoxybenzyl)-6-methoxy-3-coumaranone (2), along with 26 known compounds, were first isolated from the trunk of Horsfieldia pandurifolia. Their structures were elucidated by the means of spectroscopic analysis. Compound 1 was assessed for its cytotoxicity against five human tumour lines (HL-60, SMMC-7721, A-549, MCF-7 and SW-480), and the result showed that it has no activity.

Identification of a New Class of Antifungals Targeting the Synthesis of Fungal Sphingolipids.

UNLABELLED: Recent estimates suggest that >300 million people are afflicted by serious fungal infections worldwide. Current antifungal drugs are static and toxic and/or have a narrow spectrum of activity. Thus, there is an urgent need for the development of new antifungal drugs. The fungal sphingolipid glucosylceramide (GlcCer) is critical in promoting virulence of a variety of human-pathogenic fungi. In this study, we screened a synthetic drug library for compounds that target the synthesis of fungal, but not mammalian, GlcCer and found two compounds [N'-(3-bromo-4-hydroxybenzylidene)-2-methylbenzohydrazide (BHBM) and its derivative, 3-bromo-N'-(3-bromo-4-hydroxybenzylidene) benzohydrazide (D0)] that were highly effective in vitro and in vivo against several pathogenic fungi. BHBM and D0 were well tolerated in animals and are highly synergistic or additive to current antifungals. BHBM and D0 significantly affected fungal cell morphology and resulted in the accumulation of intracellular vesicles. Deep-sequencing analysis of drug-resistant mutants revealed that four protein products, encoded by genes APL5, COS111, MKK1, and STE2, which are involved in vesicular transport and cell cycle progression, are targeted by BHBM. IMPORTANCE: Fungal infections are a significant cause of morbidity and mortality worldwide. Current antifungal drugs suffer from various drawbacks, including toxicity, drug resistance, and narrow spectrum of activity. In this study, we have demonstrated that pharmaceutical inhibition of fungal glucosylceramide presents a new opportunity to treat cryptococcosis and various other fungal infections. In addition to being effective against pathogenic fungi, the compounds discovered in this study were well tolerated by animals and additive to current antifungals. These findings suggest that these drugs might pave the way for the development of a new class of antifungals.

A new benzyl ester and ergosterol derivatives from the fungus Gymnoascus reessii.

A new benzyl ester, reessiate (1), anthraquinone, islandicin (2), ergosterol and seven ergosterol derivatives (3-9) were isolated from the fungus Gymnoascus reessii. All structures were identified by spectroscopic methods. This is the first report of their isolation from this fungus. Compounds 4-7 and 9 exhibited antimalarial activity against Plasmodium falciparum with IC50 values in the range of 3.3-4.5 µg/mL. In addition, 4 showed cytotoxicity against KB, MCF7 and NCI-H187 cancer cell lines. It was found that 4 has cytotoxic effect to MCF7 (IC50 = 7.9 µg/mL) lower than Doxorubicin (IC50 = 8.5 µg/mL).

GC/GC-MS analysis, isolation and identification of bioactive essential oil components from the Bhutanese medicinal plant, Pleurospermum amabile.

We have hydrodistilled the essential oil (EO) from the aerial parts of the Bhutanese medicinal plant, Pleurospermum amabile using a Clevenger apparatus and evaluated this EO by GC/GC-MS and NMR analysis followed by testing for bioactivity. The GC-MS analysis identified 52 compounds with (E)-isomyristicin as a major component (32.2%). Repeated purification yielded four compounds; (E)-isomyristicin (1), (E)-isoapiol (2), methyl eugenol (3) and (E)-isoelemicin (4). Compound 2 and the mother EO showed the best antiplasmodial activity against the Plasmodium falciparum strains, TM4/8.2 (chloroquine and antifolate sensitive) and K1CB1 (multidrug resistant). They exhibited mild antibacterial activity against Bacillus subtilis. None of the test samples showed cytotoxicity.

[Bibenzyl from Dendrobium inhibits angiogenesis and its underlying mechanism].

Bibenzyl is a type of active compounds abundant in Dendrobium. In the present study, we investigated the inhibitory effects of six bibenzyls isolated from Dendrobium species on vascular endothelial growth factor (VEGF)-induced tube formation in human umbilical vascular endothelial cells (HUVECs). All those bibenzyls inhibited VEGF-induced tube formation at 10 micromol x L(-1) except tristin, and of which moscatilin was found to have the strongest activity at the same concentration. The lowest effective concentration of moscatilin was 1 micromol x L(-1). Further results showed that moscatilin inhibited VEGF-induced capillary-like tube formation on HUVECs in a concentration-dependent manner. Western blotting results showed that moscatilin also inhibited VEGF-induced phosphorylation of VEGFR2 (Flk-1/KDR) and extracellular signal-regulated kinase 1/2 (ERK1/2). Further results showed that moscatilin inhibited VEGF-induced activation of c-Raf and MEK1/2, which are both upstream signals of ERK1/2. Taken together, results presented here demonstrated that moscatilin inhibited angiogenesis via blocking the activation of VEGFR2 (Flk-1/KDR) and c-Raf-MEK1/2-ERK1/2 signals.

Two new C-benzylated dihydrochalcone derivatives from the leaves of Melodorum siamensis.

Two new C-benzylated dihydrochalcone derivatives, 4,2',4'-trihydroxy-6'-methoxy-3'(2''-hydroxybenzyl)dihydrochalcone (1) and 2',4'-dihydroxy-4,6'-dimethoxy-3'(2''-hydroxybenzyl)dihydrochalcone (2), along with six known flavonoid derivatives (3-8), a known dihydrochalcone dimer (9), three known aromatic esters (10-12), and one known aromatic amide (13), were isolated from the leaves of Melodorum siamensis. The structures of the compounds were elucidated by spectroscopic analysis, mainly 1D and 2D NMR techniques (1H, 13C, COSY, HMQC, and HMBC), as well as by comparison with literature data. The isolated compounds with a sufficient amount for biological assays were evaluated for their antimalarial, antimycobactirial, and cytotoxic activities. Compounds 1, 2, and 13 exhibited strong cytotoxicity against human tumor cell lines KB and NCI-H187, with IC50 values in the range of 0.66-7.16 µg/mL.

Biocatalytic resolution of benzyl glycidyl ether and its derivates by Talaromyces flavus: effect of phenyl ring substituents on enantioselectivity.

Talaromyces flavus containing a constitutive epoxide hydrolase (EH) resolved racemic benzyl glycidyl ether and nine derivatives into their (R)-enantiomers. After optimization of the fermentation conditions, the specific EH activity and biomass concentration were improved from 13.5 U/g DCW and 14.8 g DCW/l to 26.2 U/g DCW and 31.3 g DCW/l, respectively, with final values for e.e. ( s ) of 96 % and E of 13 with (R)-benzyl glycidyl ether. Substituents on the phenyl ring, however, gave low enantioselectivities.

New bibenzyl glycosides from leaves of Camellia oleifera Abel. with cytotoxic activities.

Studies on the chemical constituents of leaves of Camellia oleifera Abel. led to the isolation of 3 new bibenzyl glycosides. Their structures have been elucidated as 1-(3',5'-dihydroxy)phenyl-2-(4″-O-ß-D-glucopyranosyl)phenylethane (1), 1-(3',5'-dimethoxy)phenyl-2-(4″-O-ß-D-glucopyranosyl)phenylethane (2) and 1-(3',5'-dimethoxy)phenyl-2-[4″-O-ß-D-glucopyranosyl(6→1)-O-α-L-rhamnopyranosyl]phenylethane (3) through spectral studies including HR-ESI-MS, ((1))H NMR, ((13))C NMR and 2D NMR experiments. All the above 3 bibenzyl glycosides showed cytotoxic activities to Hela and hep2 cell lines.

[GC-MS analysis of essential oil from nutmeg processed by different traditional methods].

OBJECTIVE: To analyze the chemical components of the essential oil extracted from the seeds of Myristica fragrans (nutmeg) processed by different methods (steamed with water steam, roasted with flour, sauted with flour, roasted with talcum powder, roasted with loess, and roasted with bran) and to provide quality control foundations in the sciences. METHOD: The essential oil was extracted by steam distillation and separated with GC capillary column. The relative content of every compound was determined with area normalization method and the structures were elucidated by GC-MS technique. RESULT: Fifty-eight to one hundred and four of chromatographic peaks were detected, among them seventy-six compounds accounting for 98.32% to 99.99% of the total essential oil in nutmeg were identified, which were composed of 69.15% to 97.24% for monoterpenoids and 2.06% to 25.51% for aromatic compounds of the total essential oil, respectively. CONCLUSION: It was shown that monoterpenoids and their derivatives were main composition, and aromatic compounds were secondary composition in the total essential oil of nutmeg grows in Indonesia and processed by different traditional methods on the basis of theory of traditional Chinese medicine. In addition, it was suggested that we should be careful to use processed nutmeg owing to contain safrole and a-asarone induced genetoxicity in animals and mutagenicity in the Ames Salmonella assay, and myristicin and elemicin induced narcotism in human. The processed method roasted with bran for nutmeg may be better and will be developed.

The protective effects of phenolic constituents from Gastrodia elata on the cytotoxicity induced by KCl and glutamate.

Seven phenolic compounds (1-7) were isolated from the tubers of Gastrodia elata. Their structures were elucidated on the basis of MS and NMR spectral data. p-Ethoxymethyl phenyl-O-beta-D-glucoside (1) was proved to be a new compound, with N-(p-hydroxybenzyl)-adenosine (7) isolated from this plant for the first time. In this study, the protective effects of the six constituents (1-6) on PC12 cells against the cytotoxicity induced by KCl and glutamate were also investigated. The viability of the PC12 cells was significantly enhanced by pretreatment with the six phenolic constituents.

Insecticidal activity of the essential oil of Ligusticum mutellina roots.

The essential oil obtained from roots of different collections of Ligusticum mutellina was tested against 3rd instar armyworms, Pseudaletia unipuncta (Lepidoptera: Noctuidae), for insecticidal activity. The main compounds were isolated and their structures were elucidated using 2D-NMR techniques. Our collections contained dillapiole, ligustilide and myristicin as major compounds. The previously reported sarisan was not present, moreover its occurrence in L. mutellina should be revised based on our findings.

Identification of a novel factor, vanillyl benzyl ether, which inhibits somatic embryogenesis of Japanese larch (Larix leptolepis Gordon).

In contrast to angiosperms, some gymnosperms form well-developed suspensors in somatic embryogenesis. This characteristic makes it easy to study suspensor biology. In cultures with high cell densities, somatic embryogenesis of Japanese larch, especially the suspensor development, is strongly inhibited due to factor(s) that are released by the cells into the culture medium. In this study, we purified and identified one of the inhibitory factors present in high-cell-density conditioned medium (HCM) of larch cells. The factor with the strongest inhibitory activity was purified by dialysis, extraction by ethyl acetate, octadecylsilyl (ODS) column chromatography and high-performance liquid chromatography (HPLC). The inhibitory factor was identified as vanillyl benzyl ether (VBE) by physicochemical analysis. This compound was first isolated from natural resources. Authentic VBE inhibited somatic embryo formation in Japanese larch, and the inhibitory effect in the suspensor was stronger than in the embryo proper. Furthermore, quantification of VBE by HPLC demonstrated that VBE accumulates at high concentrations in HCM. These results suggest that VBE is a novel negative regulator of somatic embryogenesis.

Hepatoprotective effect of myristicin from nutmeg (Myristica fragrans) on lipopolysaccharide/d-galactosamine-induced liver injury.

To evaluate the hepatoprotective activity of spices, 21 different spices were fed to rats with liver damage caused by lipopolysaccharide (LPS) plus d-galactosamine (D-GalN). As assessed by plasma aminotranferase activities, nutmeg showed the most potent hepatoprotective activity. Bioassay-guided isolation of the active compound from nutmeg was carried out in mice by a single oral administration of the respective fractions. Myristicin, one of the major essential oils of nutmeg, was found to possess extraordinarily potent hepatoprotective activity. Myristicin markedly suppressed LPS/D-GalN-induced enhancement of serum TNF-alpha concentrations and hepatic DNA fragmentation in mice. These findings suggest that the hepatoprotective activity of myristicin might be, at least in part, due to the inhibition of TNF-alpha release from macrophages. However, further studies are needed to elucidate the hepatoprotective mechanism(s) of myristicin.