Chemical and biological analyses of the essential oils and main constituents of Piper species

The essential oils obtained from leaves of Piper duckei and Piper demeraranum by hydrodistillation were analyzed by gas chromatography-mass spectrometry. The main constituents found in P. demeraranum oil were limonene (19.3%) and β-elemene (33.1%) and in P. duckei oil the major components found were germacrene D (14.7%) and trans-caryophyllene (27.1%). P. demeraranum and P. duckei oils exhibited biological activity, with IC(50) values between 15 to 76 μg mL(-1) against two Leishmania species, P. duckei oil being the most active. The cytotoxicity of the essential oils on mice peritoneal macrophage cells was insignificant, compared with the toxicity of pentamidine. The main mono- and sesquiterpene, limonene (IC(50) = 278 μM) and caryophyllene (IC(50) = 96 μM), were tested against the strains of Leishmania amazonensis, and the IC(50) values of these compounds were lower than those found for the essential oils of the Piper species. The HET-CAM test was used to evaluate the irritation potential of these oils as topical products, showing that these oils can be used as auxiliary medication in cases of cutaneous leishmaniasis, with less side effects and lower costs.     

Benzyl-substituted titanocene dichloride anticancer drugs: From lead to hit

Through the reaction of Super Hydride (LiBEt₃H) with 6-phenyl-substituted fulvenes followed by transmetallation to TiCl₄ ten novel benzyl-substituted titanocene dichloride derivatives were synthesised. 6(4-morpholinomethyl-phenyl) fulvene (6g) and (bis-[(4-methoxymethyl-benzyl)cyclopentadienyl]titanium(IV) dichloride) (8a) were characterised by single crystal X-ray diffraction. All of the titanocenes had their cytotoxicity investigated through preliminary in vitro testing on the LLC-PK (pig kidney epithelial) cell line and CAKI-1 human kidney cell human carcinoma cell line in an MTT based assay in order to determine their IC50 values. The titanocenes synthesised were found to have IC50 values ranging from 2.3 (±0.3) μM (comparable to cisplatin) to others which show no anti-proliferative activity on this cell line in standard DMSO formulations on LLC-PK cell line. Eight of the titanocenes were found to be completely water-soluble and had IC50 values of 6.5 (±0.7) μM to no activity when using medium only for formulation. On the CAKI-1 cell line, IC50 values of 7.8 (±1.4) μM to no activity were found using DMSO formulation, while IC50 values of 0.55 (±0.32) μM to no activity were measured using just medium as the formulation reagent. Some of the titanocenes show significant cytotoxicity improvement when compared directly to the lead compound Titanocene Y (bis-[(p-methoxybenzyl)cyclopentadienyl] titanium(IV) dichloride) and are more cytotoxic than cisplatin. Bis-[(4-diethylaminomethyl-benzyl)cyclopentadienyl]titanium(IV) dichloride (8d) at this preliminary stage seems to be the most promising of the ten compounds prepared and exhibits nanomolar activity against CAKI-1.     

Design, synthesis and cytotoxicity of novel 2-arylvinyl-4-aminoquinoline derivatives

With an aim to develop promising anti-tumor agents, a novel series of 2-arylvinyl-4-aminoquinoline derivatives were designed, synthesized and evaluated for their cytotoxicity against H-460, HT-29, HepG2 and SGC-7901 cell lines in vitro. The pharmacological results indicated that most compounds were more potent than the positive controls, especially compounds 8, 14 and 16 with IC(50) values ranging from 0.05 to 0.85 μM against all tested cell lines respectively, which were 5.7- to 112-fold better than Iressa. The most active compound 14 (IC(50) values of 0.05, 0.25, 0.16, 0.68 μM), bearing 4-fluorostyryl at C-2 position and 3-(dimethylamino)-1-propylamino at C-4 position, showed great promise as a lead for the development of more effective quinoline analogues.     

Microbial mannosidation of bioactive chlorogentisyl alcohol by the marine-derived fungus Chrysosporium synchronum

The biological transformation of the biologically active chlorogentisyl alcohol (1), isolated from the marine-derived fungus Aspergillus sp., was studied. Preparative-scale fermentation of chlorogentisyl alcohol with marine-derived fungus Chrysosporium synchronum resulted in the isolation of a new glycosidic metabolite, 1-O-(α-D-mannopyranosyl)chlorogentisyl alcohol (2). The stereostructure of the new metabolite obtained was assigned on the basis of detailed spectroscopic data analyses, chemical reaction, and chemical synthesis. Compounds 1 and 2 exhibited significant radical-scavenging activity against 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) with IC(50) values of 1.0 and 4.7 μM, respectively. The compounds 1 and 2 were more active than the positive control, L-ascorbic acid (IC(50), 20.0 μM).     

Bioactive phenolic constituents from the seeds of Pharbitis nil

Two new lignans, termed pharsyringaresinol (1) and pharbilignoside (2), a new phenylethanoid glycoside, termed pharbiniloside (3), and 22 known compounds, were isolated from the ethanol extract of the seeds of Pharbitis nil. The structures of the new compounds (1-3) were determined on the basis of spectroscopic analyses, including 2D-NMR and circular dichroism (CD) spectroscopy studies. Among the isolates, compounds 2, 11, 12, and 24 exhibited significant cytotoxicity against human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-15) with IC(50) values ranging from 8.07 to 28.30 μM. In addition, compounds 11, 12 and 24 potently inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-activated BV-2 cells, a microglia cells with IC(50) values ranging from 14.7 to 19.9 μM.     

Ion channel drug potency assay with an artificial bilayer chip

The potency of pharmaceutical compounds acting on ion channels can be determined through measurements of ion channel conductance as a function of compound concentration. We have developed an artificial lipid bilayer chip for simple, fast, and high-yield measurement of ion channel conductance with simultaneous solution perfusion. Here we show the application of this chip to the measurement of the mammalian cold and menthol receptor TRPM8. Ensemble measurements of TRPM8 as a function of concentration of menthol and 2-aminoethoxydiphenyl borate (2-APB) enabled efficient determination of menthol's EC(50) (111.8 μM ± 2.4 μM) and 2-APB's IC(50) (4.9 μM ± 0.2 μM) in agreement with published values. This validation, coupled with the compatibility of this platform with automation and parallelization, indicates significant potential for large-scale pharmaceutical ion channel screening.     

Tomentosones A and B, hexacyclic phloroglucinol derivatives from the Thai shrub Rhodomyrtus tomentosa

Two phloroglucinols named tomentosones A and B (1 and 2) that each possess a novel hexacyclic ring system were isolated from the CH(2)Cl(2) extract of Rhodomyrtus tomentosa leaves. Their structures were elucidated from analyses of 2D NMR spectroscopic data. Tomentosone A inhibited the growth of chloroquine-resistant and -sensitive strains of the malaria parasite Plasmodium falciparum, with IC(50) values of 1.49 μM and 1.0 μM, respectively, while tomentosone B was significantly less active.     

Design of a heterobivalent ligand to inhibit IgE clustering on mast cells

We describe the design, synthesis, and characterization of a heterobivalent ligand (HBL) system that competitively inhibits allergen binding to mast cell bound IgE antibody, thereby inhibiting mast cell degranulation. HBLs are composed of a hapten conjugated to a nucleotide analog allowing simultaneous targeting of the antigen-binding site as well the "unconventional nucleotide binding site" on IgE Fab domains. Simultaneous bivalent binding to both sites provides HBLs with over 100-fold enhancement both in avidity for IgE(DNP) (K(d) = 0.33 μM) and in inhibition of allergen binding to IgE(DNP) (IC(50) = 0.45 μM) than the monovalent hapten (K(d)(mono) = 41 μM; IC(50)(mono) = 55.4 μM, respectively). In cellular assays, HBL2 effectively inhibits mast cell degranulation (IC(50) = 15 μM), whereas no inhibition is detected by the monovalent hapten. In conclusion, this study establishes the use of multivalency in a novel HBL design to inhibit mast cell degranulation.     

新型苯并咪唑衍生物的合成及生物活性研究

以取代苯酚为原料,合成8个新型的2-苯氧甲基苯并咪唑类化合物,通过1H-NMR和HRMS确认其结构。MTT法测试其抗肿瘤活性,实验结果表明,大部分化合物具有较好的广谱抗肿瘤效果,其中化合物2h对大多数肿瘤细胞株的IC50值均达到了低微摩尔水平,对人胰腺癌(BxPC-3)的IC50达到3.6μM。试管二倍稀释法测试其抗菌活性,实验结果表明,目标化合物显示出抗菌活性,化合物2a对粪肠球菌和金黄色葡萄球菌的MIC达到16μg/mL。     

Synthesis and cytotoxic activity of some novel N-pyridinyl-2-(6-phenylimidazo[2,1-b]thiazol-3-yl)acetamide derivatives

A series of novel compounds bearing imidazo[2,1-b]thiazole scaffolds were designed and synthesized based on the optimization of the virtual screening hit compound N-(6-morpholinopyridin-3-yl)-2-(6-phenylimidazo[2,1-b]thiazol-3-yl)acetamide (5a), and tested for their cytotoxicity against human cancer cell lines, including HepG2 and MDA-MB-231. The results indicated that the compound 2-(6-(4-chlorophenyl)imidazo[2,1-b]thiazol-3-yl)-N-(6-(4-(4-methoxybenzyl)piperazin-1-yl)pyridin-3-yl)acetamide (5l), with slightly higher inhibition on VEGFR2 than 5a (5.72% and 3.76% inhibitory rate at 20 μM, respectively), was a potential inhibitor against MDA-MB-231 (IC(50) = 1.4 μM) compared with sorafenib (IC(50) = 5.2 μM), and showed more selectivity against MDA-MB-231 than HepG2 cell line (IC(50) = 22.6 μM).     

Inhibitory effects of phylligenin and quebrachitol isolated from Mitrephora vulpina on platelet activating factor receptor binding and platelet aggregation

Phylligenine, together with quebrachitol, stigmasterol and two aporphine alkaloids--oxoputerine and liriodenine--were isolated from the twigs of Mitrephora vulpina C.E.C. Fisch. They were evaluated for their ability to inhibit platelet activating factor (PAF) receptor binding to rabbit platelets using 3H-PAF as a ligand and their antiplatelet aggregation effect in human whole blood induced by arachidonic acid (AA), collagen and adenosine diphosphate (ADP). Of all the compounds tested, phylligenin and quebrachitol exhibited potent and concentration-dependent inhibitory effects on PAF receptor binding, with IC(50) values of 13.1 and 42.2 μM, respectively. The IC(50) value of phylligenin was comparable to that of cedrol (10.2 μM), a potent PAF antagonist. Phylligenin also showed strong dose-dependent inhibitory activity on platelet aggregation induced by AA and ADP.     

Prevention of iron- and copper-mediated DNA damage by catecholamine and amino acid neurotransmitters, L-DOPA, and curcumin: metal binding as a general antioxidant mechanism

Concentrations of labile iron and copper are elevated in patients with neurological disorders, causing interest in metal-neurotransmitter interactions. Catecholamine (dopamine, epinephrine, and norepinephrine) and amino acid (glycine, glutamate, and 4-aminobutyrate) neurotransmitters are antioxidants also known to bind metal ions. To investigate the role of metal binding as an antioxidant mechanism for these neurotransmitters, L-dihydroxyphenylalanine (L-DOPA), and curcumin, their abilities to prevent iron- and copper-mediated DNA damage were quantified, cyclic voltammetry was used to determine the relationship between their redox potentials and DNA damage prevention, and UV-vis studies were conducted to determine iron and copper binding as well as iron oxidation rates. In contrast to amino acid neurotransmitters, catecholamine neurotransmitters, L-DOPA, and curcumin prevent significant iron-mediated DNA damage (IC(50) values of 3.2 to 18 μM) and are electrochemically active. However, glycine and glutamate are more effective at preventing copper-mediated DNA damage (IC(50) values of 35 and 12.9 μM, respectively) than L-DOPA, the only catecholamine to prevent this damage (IC(50) = 73 μM). This metal-mediated DNA damage prevention is directly related to the metal-binding behaviour of these compounds. When bound to iron or copper, the catecholamines, amino acids, and curcumin significantly shift iron oxidation potentials and stabilize Fe(3+) over Fe(2+) and Cu(2+) over Cu(+), a factor that may prevent metal redox cycling in vivo. These results highlight the disparate antioxidant activities of neurotransmitters, drugs, and supplements and highlight the importance of considering metal binding when identifying antioxidants to treat and prevent neurodegenerative disorders.     

Remarkable photocytotoxicity of curcumin in HeLa cells in visible light and arresting its degradation on oxovanadium(IV) complex formation

Curcumin (Hcur) as a cellular imaging and PDT agent shows remarkable photocytotoxicity in HeLa cells in visible light of 400-700 nm giving IC(50) = 8.2 ± 0.2 μM and its degradation is arrested on formation of photocytotoxic dipyridophenazine (dppz) complex [VO(cur)(dppz)Cl] (IC(50) = 3.3 ± 0.4 μM), while both are less toxic in the dark.     

Different ortho and para electronic effects on hydrolysis and cytotoxicity of diamino bis(phenolato) "salan" Ti(IV) complexes

Bis(isopropoxo) Ti(IV) complexes of diamino bis(phenolato) "salan" ligands were prepared, their hydrolysis in 1:9 water/THF solutions was investigated, and their cytotoxicity toward colon HT-29 and ovarian OVCAR-1 cells was measured. In particular, electronic effects at positions ortho and para to the binding phenolato unit were analyzed. We found that para substituents of different electronic features, including Me, Cl, OMe, and NO(2), have very little influence on hydrolysis rate, and all para-substituted ortho-H complexes hydrolyze slowly to give O-bridged clusters with a t(1/2) of 1-2 h for isopropoxo release. Consequently, no clear cytotoxicity pattern is observed as well, where the largest influence of para substituents appears to be of a steric nature. These complexes exhibit IC(50) values of 2-18 μM toward the cells analyzed, with activity which is mostly higher than those of Cp(2)TiCl(2), (bzac)(2)Ti(OiPr)(2) and cisplatin. On the contrary, major electronic effects are observed for substituents at the ortho position, with an influence that exceeds even that of steric hindrance. Ortho-chloro or -bromo substituted compounds possess extremely high hydrolytic stability where no major isopropoxo release as isopropanol occurs for days. In accordance, very high cytotoxicity toward colon and ovarian cells is observed for ortho-Cl and -Br complexes, with IC(50) values of 1-8 μM, where the most cytotoxic complexes are the ortho-Cl-para-Me and ortho-Br-para-Me derivatives. In this series of ortho-substituted complexes, the halogen radius is of lesser influence both on hydrolysis and on cytotoxicity, while OMe substituents do not impose similar effect of hydrolytic stability and cytotoxicity enhancement. Therefore, hydrolytic stability and cytotoxic activity are clearly intertwined, and thus this family of readily available Ti(IV) salan complexes exhibiting both features in an enhanced manner is highly attractive for further exploration.     

Flavonoid glycosides from Chromolaena odorata leaves and their in vitro cytotoxic activity

Two new flavonoid glycosides, (1, 2), and eleven known compounds, (3-13), were isolated from from a 70% EtOH extract of the leaves of Chromolaena odorata (Asteraceae). Their structures were elucidated by 1D and 2D NMR spectroscopic interpretation as well as by chemical studies. The newly isolated compounds were tested in vitro for their cytotoxic activities against the LLC and HL-60 cancer cell lines. Compound 1 showed cytotoxicity against LLC and HL-60 cancer cell lines with IC(50) values of 28.2 and 11.6 μM, respectively. Compound 2 exhibited significant cytotoxic activity in the inhibition of HL-60 cancer cell lines with IC(50) value of 10.8 μM.     

A search for BACE inhibitors reveals new biosynthetically related pyrrolidones, furanones and pyrroles from a southern Australian marine sponge, Ianthella sp

Fractionation of a southern Australian marine sponge, Ianthella sp., yielded sixteen metabolites including a new class of pyrrolidone, ianthellidones A-F (1-6), a new class of furanone, ianthellidones G-H (7-8), new and known lamellarins, lamellarins O1 (9), O2 (10), O (11) and Q (12), plus the known 4-hydroxybenzaldehyde (13), 4-hydroxybenzoic acid (14), 4-methoxybenzoic acid (15) and ethyl 4-hydroxybenzoate (16). Structures for all Ianthella metabolites were determined by detailed spectroscopic analysis, supported by a plausible biosynthetic relationship. The ianthellidones were non-cytotoxic towards two human colon cancer cell lines (SW620 and SW620 Ad300), as well as Gram +ve and Gram -ve bacteria, and a fungus. Ianthellidone F (6) and lamellarins O2 (10) and O (11) displayed modest BACE inhibitory properties (IC(50) > 10 μM), while lamellarin O1 (9) was more potent (IC(50) < 10 μM). Lamellarin O (11) exhibited modest cytotoxicity towards SW620 and SW620 Ad300 cell lines (IC(50) > 22 μM), was an inhibitor of the multi-drug resistance efflux pump P-glycoprotein, and displayed selective growth inhibitory activity against the Gram +ve bacterium Bacillus subtilis (ATCC 6633) (IC(50) 2.5 μM).     

Facile synthesis of pegylated zinc(II) phthalocyanines via transesterification and their in vitro photodynamic activities

Treatment of 4,5-bis[4-(methoxycarbonyl)phenoxy]phthalonitrile and 4,5-bis[3,5-bis(methoxycarbonyl)phenoxy]phthalonitrile with an excess of 1,3-diiminoisoindoline in the presence of Zn(OAc)(2)·2H(2)O and 1,8-diazabicyclo[5.4.0]undec-7-ene in triethylene glycol monomethyl ether or polyethylene glycol monomethyl ether (with an average molecular weight of 550) led to "3 + 1" mixed cyclisation and transesterification in one pot, affording the corresponding di-β-substituted zinc(II) phthalocyanines in 7-23% yield. As shown by absorption spectroscopy, these compounds were essentially non-aggregated in N,N-dimethylformamide and could generate singlet oxygen effectively. The singlet oxygen quantum yields (Φ(Δ) = 0.53-0.57) were comparable with that of the unsubstituted zinc(II) phthalocyanine (Φ(Δ) = 0.56). These compounds in Cremophor EL emulsions also exhibited photocytotoxicity against HT29 human colorectal adenocarcinoma and HepG2 human hepatocarcinoma cells with IC(50) values in the range of 0.25-3.72 μM. The analogue with four triethylene glycol chains was the most potent photosensitiser and localised preferentially in the mitochondria of HT29 cells. The bis(polyethylene glycol)-counterpart could form surfactant-free nanoparticles both in water and in the culture medium. The hydrodynamic radii, as determined by dynamic laser light scattering, ranged from 6.3 to 79.8 nm depending on the preparation methods and conditions. The photocytotoxicity of these nanoparticles (IC(50) = 0.43-0.56 μM) was comparable with that of the Cremophor EL-formulated system (IC(50) = 0.34 μM).     

Fischerisin A and B, cytotoxic sesquiterpenoid-geranylhydroquinones from Ligularia fischeri

During the course of screening natural sesquiterpenoids for new antitumor agents, two novel compounds, fischerisin A (1) and fischerisin B (2), were isolated from the roots of Ligularia fischeri. Their structures were elucidated by interpretation of their IR, high resolution-mass spectrometry (HR-MS), 1D- and 2D-NMR data. Fischerisin A and B are the first representatives of a novel sesquiterpenoid-geranylhydroquinone hybrid, and both compounds exhibited in vitro cytotoxicity against cultured human oral epidermoid carcinoma (KB) and human breast cancer (MCF-7) cell lines with IC(50) values of 9.7 and 10.2 μM, and 9.8 and 17.8 μM, respectively.     

Hyaluronidase inhibitory rosmarinic acid derivatives from Meehania urticifolia

Nine new phenylpropanoids, rashomonic acids A-D (1-4) and meehaniosides A-E (5-9), along with four known compounds were isolated from Meehania urticifolia. The structure of each new compound was elucidated based on the results of spectroscopic analyses. Compounds 3-8 showed moderate hyaluronidase inhibitory activity with IC(50) values of 183-1049 μM.     

Inhibitory effects of acetylmelodorinol, chrysin and polycarpol from Mitrella kentii on prostaglandin E₂ and Thromboxane B₂ production and platelet activating factor receptor binding

Acetylmelodorinol, chrysin and polycarpol, together with benzoic acid, benzoquinone and stigmasterol were isolated from the leaves of Mitrella kentii (Bl.) Miq. The compounds were evaluated for their ability to inhibit prostaglandin E? (PGE?) and thromboxane B? (TXB?) production in human whole blood using a radioimmunoassay technique. Their inhibitory effect on platelet activating factor (PAF) receptor binding to rabbit platelet was determined using 3H-PAF as a ligand. Among the compounds tested, chrysin showed a strong dose-dependent inhibitory activity on PGE(2) production (IC?? value of 25.5 μM), which might be due to direct inhibition of cyclooxygenase-2 (COX-2) enzymatic activity. Polycarpol, acetylmelodorinol and stigmasterol exhibited significant and concentration-dependent inhibitory effects on TXB? production with IC?? values of 15.6, 19.1 and 19.4 μM, respectively, suggesting that they strongly inhibited COX-1 activity. Polycarpol and acetylmelodorinol showed strong dose-dependent inhibitory effects on PAF receptor binding with IC?? values of 24.3 and 24.5 μM, respectively.