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.     

The structure of a new cardenolide diglycoside and the biological activities of eleven cardenolide diglycosides from Nerium oleander

A new cardenolide diglycoside (1) was isolated from Nerium oleander together with ten known cardenolide diglycosides 2-11. The structure of compound 1 was established on the basis of their spectroscopic data. The in vitro anti-inflammatory activity of compounds 1-11 was examined on the basis of inhibitory activity against the induction of the intercellular adhesion molecule-1 (ICAM-1). Compounds 2-5 were active at an IC(50) value of less than 0.8 μM. The cytotoxicity of compounds 1-11 was evaluated against three human cell lines normal human fibroblast cells (WI-38), malignant tumor cells induced from WI-38 (VA-13), and human liver tumor cells (HepG2). Compound 3 was active toward VA-13 cells, and compounds 2-5 were active toward HepG2 cells at IC(50) values of less than 1.3 μM. The multidrug resistance (MDR)-reversal activity of compounds 1-11 was evaluated on the basis of the amount of calcein in MDR human ovarian cancer 2780AD cells in the presence of each compound. Compounds 1 and 8 showed moderate effects on calcein accumulation.     

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).     

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.     

Anthraquinones with antiplasmodial activity from the roots of Rennellia elliptica Korth. (Rubiaceae)

Dichloromethane root extract of Rennellia elliptica Korth. showed strong inhibition of Plasmodium falciparum growth in vitro with an IC?? value of 4.04 μg/mL. A phytochemical study of the dichloromethane root extract has led to the isolation and characterization of a new anthraquinone, 1,2-dimethoxy-6-methyl-9,10-anthraquinone (1), and ten known anthraquinones: 1-hydroxy-2-methoxy-6-methyl-9,10-anthraquinone (2), nordamnacanthal (3), 2-formyl-3-hydroxy-9,10-anthraquinone (4), damnacanthal (5), lucidin-ω-methyl ether (6), 3-hydroxy-2-methyl-9,10-anthraquinone (7), rubiadin (8), 3-hydroxy-2-methoxy-6-methyl-9,10-anthraquinone (9), rubiadin-1-methyl ether (10) and 3-hydroxy-2-hydroxymethyl-9,10-anthraquinone (11). Structural elucidation of all compounds was accomplished by modern spectroscopic methods, notably 1D and 2D NMR, IR, UV and HREIMS. The new anthraquinone 1, 2-formyl-3-hydroxy-9,10-anthraquinone (4) and 3-hydroxy-2-methyl-9,10-anthraquinone (7) possess strong antiplasmodial activity, with IC?? values of 1.10, 0.63 and 0.34 μM, respectively.     

3-Hydroxymethylglutaryl flavonol glycosides from a Mongolian and Tibetan medicine, Oxytropis racemosa

Three new flavonol 3-O-glycosides, rhamnetin 3-O-[(S)-3-hydroxy-3-methyl-glutaroyl(1→6)]-β-D-glucopyranoside (1), rhamnocitrin 3-O-[(S)-3-hydroxy-3-methylglutaroyl(1→6)]-β-D-glucopyranoside (2), and isorhamnetin 3-O-[(S)-3-hydroxy-3-methylglutaroyl(1→6)]-α-L-rhamnopyranosyl(1→2)-β-D-glucopyranoside (3), along with 13 known compounds, were isolated from Oxytropis racemosa TURCZ. Their structures were deduced by means of spectroscopic methods and chemical evidence. 2 and 6 showed cytotoxic activities against HCT-8 (IC?? 6.38 μM) and A549 (IC?? 5.20 μM), respectively.     

Anti-inflammatory and antioxidant components from Hygroryza aristata

Twenty-six known compounds and two new compounds, including a new lignan, (7S*,8R*,7'R*,8'S*)-icariol A?-9-O-β-xylopyranoside (1), and a new indole alkaloid, hygarine (2), were isolated from the extracts of Hygroryza aristata (Gramineae). The structures of all compounds were elucidated on the basis of NMR spectral analysis. The compounds (-)-epigallocatechin-3-O-gallate (4) and (-)-epicatechin-3-O-gallate (5) possess free radical scavenging activities and compound 1 could inhibit superoxide anion generation and elastase release by fMLP/CB-induced human neutrophils with IC?? values of 19.33 ± 0.86 and 24.14 ± 1.59 μM, respectively.     

Evaluation of the effects of Mitragyna speciosa alkaloid extract on cytochrome P450 enzymes using a high throughput assay

The extract from Mitragyna speciosa has been widely used as an opium substitute, mainly due to its morphine-like pharmacological effects. This study investigated the effects of M. speciosa alkaloid extract (MSE) on human recombinant cytochrome P450 (CYP) enzyme activities using a modified Crespi method. As compared with the liquid chromatography-mass spectrometry method, this method has shown to be a fast and cost-effective way to perform CYP inhibition studies. The results indicated that MSE has the most potent inhibitory effect on CYP3A4 and CYP2D6, with apparent half-maximal inhibitory concentration (IC(50)) values of 0.78 μg/mL and 0.636 μg/mL, respectively. In addition, moderate inhibition was observed for CYP1A2, with an IC(50) of 39 μg/mL, and weak inhibition was detected for CYP2C19. The IC(50) of CYP2C19 could not be determined, however, because inhibition was <50%. Competitive inhibition was found for the MSE-treated CYP2D6 inhibition assay, whereas non-competitive inhibition was shown in inhibition assays using CYP3A4, CYP1A2 and CYP2C19. Quinidine (CYP2D6), ketoconazole (CYP3A4), tranylcypromine (CYP2C19) and furafylline (CYP1A2) were ACCESSused as positive controls throughout the experiments. This study shows that MSE may contribute to an herb-drug interaction if administered concomitantly with drugs that are substrates for CYP3A4, CYP2D6 and CYP1A2.     

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).     

Pseudoceramines A-D, new antibacterial bromotyrosine alkaloids from the marine sponge Pseudoceratina sp

Bioassay-guided fractionation of the CH(2)Cl(2)/MeOH extract of the Australian marine sponge Pseudoceratina sp. resulted in the purification of four new bromotyrosine alkaloids, pseudoceramines A-D (1-4), along with a known natural product, spermatinamine (5). The structures of 1-5 were determined by spectroscopic methods. Pseudoceramines A (1) and B (2) feature a rare bromotyrosyl-spermine-bromotyrosyl sequence, and pseudoceramine C (3) is the first example of bromotyrosine coupled with an N-methyl derivative of spermidine. Compounds 1-5 were screened for inhibition of toxin secretion by the type III secretion (T3S) pathway in Yersinia pseudotuberculosis. Compounds 2 and 5 inhibited secretion of the Yersinia outer protein YopE (IC(50) = 19 and 6 μM, respectively) and the enzyme activity of YopH (IC(50) = 33 and 6 μM, respectively).     

(1)H and (13)C NMR signal assignments of paecilin A and B, two new chromone derivatives from mangrove endophytic fungus Paecilomyces sp. (tree 1-7)

Two new natural products, named paecilin A (1) and B (2), together with two known compounds secalonic acid D (3) and (11)-cytochalasa-6(12),13-diene-1,21-dione-16,18-dimethyl-7-hydroxy-10-phenyl-(7S*,13E,16S*,18S*) (4), were isolated from the mangrove endophytic fungus, Paecilomyces sp. (tree 1-7) from the South China Sea. 1D and 2D NMR experiments including COSY, HMQC, and HMBC were used for the determination of their structures. In our cytotoxicity assays, secalonic D (3) showed cytotoxicity toward KB cells with IC(50) < 1 microg ml(-1) and inhibiting human topoisomerase I with IC(50) at 0.16 micromol ml(-1). 1, 2, and 4 showed no activity to KB cells.     

Systematic phytochemical investigation of Abies spectabilis

Systematical phytochemical investigations on Abies spectabilis afforded 72 chemical constituents. On the basis of physical and spectroscopic data, including 1D and 2D homo- and heteronuclear NMR experiments (heteronuclear single quantum coherence (HSQC), (1)H-(1)H correlation spectroscopy (COSY), heteronuclear multiple bond connectivity (HMBC), and nuclear Overhauser effect spectroscopy (NOESY)), and by comparison with the literature references, they were identified as 3 triterpenoids, 23 diterpenoids, 1 sesquiterpenoid, 13 flavonoids, 12 lignans, and 20 other components. Among these compounds, three were identified as new including abieta-7,13-diene-12α-methoxy-18-oic acid (1), 7α-methoxy-dehydroabietic acid (2), and 5-hydroxy-6-methyl-7,4'-dimethoxyflavone-8-O-β-D-glucopyranoside (3). These three new compounds (1-3) and all the known terpenoids (4-28) were tested for cytotoxic activities against four tumor cell lines: A549, COLO-25, QGY-25, and THP-1. However, none of them showed a positive effect (IC??>100 μM).     

Cholinesterase inhibiting and antiplasmodial steroidal alkaloids from Sarcococca hookeriana

Bioguided phytochemical investigation of Sarcococca hookeriana with respect to the cholinesterase enzyme inhibitory assay yielded two new pregnane-type steriodal alkaloids hookerianamide H (1) and hookerianamide I (2), along with three known alkaloids N(a)-methylepipachysamine D (3), sarcovagine C (4) and dictyophlebine (5). Their structures were determined with the aid of extensive spectroscopic analysis. All compounds showed good inhibitory activities against the enzymes acetylcholinesterase (IC(50) 2.9-34.1 microM) and butyrylcholinesterase (IC(50) 0.3-3.6 microM). These compounds also showed moderate antiplasmodial activity (IC(50) 2.4-10.3 microM) against the Plasmodium falciparum chloroquine resistant W2 strain.     

Antimicrobial phenalenone derivatives from the marine-derived fungus Coniothyrium cereale

The marine-derived fungus Coniothyrium cereale was isolated from the green alga Enteromorpha sp. and found to produce the new phenalenone derivatives 1-7 as well as the known compounds lactone 8, (-) sclerodin (9), lamellicolic anhydride (10), (-) scleroderolide (11), and (-) sclerodione (12). The structures of these closely related compounds were established from extensive spectroscopic investigations on the basis of one and two dimensional NMR spectroscopic studies ((1)H, (13)C, COSY, NOESY, HSQC and HMBC) as well as mass spectrometric analysis (LC/MS, HREIMS and HRESIMS), UV and IR spectra. Compounds 5 and 11 showed the same antimicrobial activity toward Staphylococcus aureus SG 511 with an MIC value of 24 μM. The presence of a diketo-lactone ring as in compounds 5 and 11 was found to be essential for this activity. In agar diffusion assays with Mycobacterium phlei considerable inhibition zones were observed for compounds 2, 4 and 7. Compounds 1, 5 and 9 showed potent inhibition of human leukocyte elastase (HLE) with IC(50) values of 7.2, 13.3 and 10.9 μM, respectively.     

A new sesquiterpenoid from the rhizomes of Homalomena sagittifolia

A new sesquiterpenoid, 1α,4β,7β-eudesmanetriol (1), was isolated together with the known compounds 1β,4β,7β-eudesmanetriol (2) and oplopanone (3) from the rhizomes of Homalomena sagittifolia. The structures of these compounds were determined by extensive spectral analyses. The compounds 1 and 2 inhibited growth of Pseudomonas stutzeri with a MIC value of 117 μM when evaluated for antibacterial activity using the minimum concentration assay. Both these compounds showed remarkable activities against acetylcholinesterase enzyme with IC(50) values ranging between 25 and 26 μM. The isolation of these sesquiterpenoids and their biological activities observed in this study support the reported traditional uses of H. sagittifolia for the treatment of microbial related diseases and central nervous system disorders.     

Biologically active constituents of Aglaia erythrosperma

From the fruits and leaves of Aglaia erythrosperma (Meliaceae), 10 chemical constituents were isolated and identified, i.e. the dammarane triterpenoids cabraleadiol (1), cabraleahydroxylactone (2), ethyl eichlerianoate (3), eichlerialactone (4), aglinin A (5), cabralealactone (6), the aglaialactone 5,6-desmethylenedioxy-5-methoxy-aglalactone (7), the flavagline 4'-demethoxy-3',4'-methylenedioxy-methyl rocaglate (8) and two coumarins: scoparone and scopoletin. Flavagline 8 exhibited antimalarial activity with an IC(50) value of 7.30 μg mL(-1) and was strongly cytotoxic against small cell lung cancer (NCI-H187), epidermoid carcinoma (KB) and breast cancer (BC) cell lines, with IC(50) values of 2.17, 2.10 and 0.11 μg mL(-1), respectively. Aglinin A (5) displayed moderate cytotoxicity against all the three cancer cell lines, whereas ethyl eichlerianoate (3), cabralealactone (6) and the aglaialactone 7 were exclusively cytotoxic to NCI-H187 cell line. Cabraleahydroxylactone (2) showed antiviral activity against herpes simplex virus type-1 with an IC(50) value of 3.20 μg mL(-1), in comparison with the standard acyclovir (IC(50)?= 1.90 μg mL(-1)). When tested for antimycobacterial activity against Mycobacterium tuberculosis H(37)Ra, compounds 1-4 and 6-8 displayed minimum inhibitory concentration in the range of 25-50 μg mL(-1).     

1H and 13C NMR assignments of three nitrogen containing compounds from the mangrove endophytic fungus (ZZF08)

A new natural product, named phomopsin A, 1-(meta-hydroxyphenyl)-4-hydroxy-3-isoquinolone (1), together with two known compounds cytochalasin H (2) and glucosylceramide (3), was isolated from the mangrove endophytic fungus Phomopsis sp. (ZZF08) obtained from the South China Sea coast. The structures were elucidated by 1D and 2D NMR experiments including COSY, HMQC, and HMBC. According to NMR and single-crystal X-ray diffraction, it was found that some assignments about (1)H and (13)C NMR data for cytochalasin H (2) were probably uncorrected in the previous reports. In our cytotoxicity assays, compound 1 showed moderate cytotoxicity toward KB cells with IC(50) at 28.0 microg ml(-1) and KBv200 cells with IC(50) at 16.8 microg ml(-1), and compound 2 exhibited strong cytotoxicity toward KB cells and KBv200 cells with IC(50) less than 1.25 microg ml(-1).     

Three new phenolic glucosides from the roots of Rheum palmatum

A novel naphthalene glucoside, rheumone A (1), with an unprecedented skeleton containing a seven-membered lactone, and two new compounds, 1-O-phloroglucinyl-2-O-galloyl-6-O-cinnamoyl-β-D-glucoside (2) and chrysophanol 1-O-β-D-(6'-O-malonyl)glucoside (3), together with three known compounds (4-6) were isolated from the roots of Rheum palmatum. Their structures were elucidated mainly by spectroscopic analysis. These compounds were evaluated in vitro for their cytotoxicities towards human hepatocellular cancer cell lines Bel-7402 and Bel-7402/5Fu, and human gastric carcinoma cell line BGC-823. None of them showed cytotoxicity with IC(50) far beyond 50 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.