Molecules

8 pages, 197 KB

Open AccessArticle

Isolation and Identification of Two New Polyynes from a North American Ethnic Medicinal Plant--Oplopanax horridus (Smith) Miq.

by Wei-Hua Huang, Qing-Wen Zhang, Chong-Zhi Wang, Chun-Su Yuan and Shao-Ping Li

Molecules 2010, 15(2), 1089-1096; https://doi.org/10.3390/molecules15021089 - 23 Feb 2010

Cited by 29 | Viewed by 10422

Abstract

Two new polyynes, named oplopantriol A (5) and oplopantriol B (6), were isolated from the root bark of Oplopanax horridus (Smith) Miq, an ethnic medicinal plant of North America, along with four known polyynes: (3S,8S)-falcarindiol [...] Read more.

Two new polyynes, named oplopantriol A (5) and oplopantriol B (6), were isolated from the root bark of Oplopanax horridus (Smith) Miq, an ethnic medicinal plant of North America, along with four known polyynes: (3S,8S)-falcarindiol (1), oplopandiol (2), (11S,16S,9Z)-9,17-octadecadiene-12,14-diyne-1,11,16-triol, 1-acetate (3) and oplopandiol acetate (4). The structures of the new compounds were elucidated by detailed spectroscopic analyses, including 1D and 2D NMR techniques and chemical methods. The absolute configurations of the new compounds 5 and 6 were determined by comparing their optical rotation values with the hydrolysis products of the known compounds 3 and 4, respectively, derived from the same plant. On the basis of an analysis of their physical and chemical properties we show that the alkaline hydrolysis of 3 and 4 afforded the new compounds 5 and 6, respectively. Full article

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7 pages, 165 KB

Open AccessCommunication

Remarkable Iodine-Catalyzed Synthesis of Novel Pyrrole- Bearing N-Polyaromatic β-Lactams

by Debasish Bandyopadhyay, Gildardo Rivera, Isabel Salinas, Hector Aguilar and Bimal K. Banik

Molecules 2010, 15(2), 1082-1088; https://doi.org/10.3390/molecules15021082 - 23 Feb 2010

Cited by 42 | Viewed by 10124

Abstract

Because of their interesting biological properties various methods for the synthesis of substituted pyrroles are described in the literature. However, synthesis of pyrroles fused with a β-lactam ring has not been reported. Our group has demonstrated synthesis and biological evaluation of various β-lactams [...] Read more.

Because of their interesting biological properties various methods for the synthesis of substituted pyrroles are described in the literature. However, synthesis of pyrroles fused with a β-lactam ring has not been reported. Our group has demonstrated synthesis and biological evaluation of various β-lactams as anticancer agents. The anticancer activities of these compounds have prompted us to study the synthesis of pyrroles bound to the β-lactams. We have identified an expeditious synthetic method for the preparation of pyrroles fused with β-lactams by reacting 3-amino β-lactams with acetonylacetone in the presence of catalytic amounts (5 mol%) of molecular iodine at room temperature. It has also been discovered that the reaction gives products under domestic and automated microwave oven irradiation. To our knowledge, there are no other prior reports that describe the synthesis of pyrrole-substituted β-lactams. Full article

(This article belongs to the Special Issue Organic Iodine Chemistry)

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8 pages, 214 KB

Open AccessArticle

Synthesis and Biological activity of 4-(4,6-Disubstituted-pyrimidin-2-yloxy)phenoxy Acetates

by Lin Jiang, Hao Wang, Maorong Wang and Xinhuan Teng

Molecules 2010, 15(2), 1074-1081; https://doi.org/10.3390/molecules15021074 - 23 Feb 2010

Cited by 8 | Viewed by 7440

Abstract

Ten novel 4-(4,6-dimethoxypyrimidin-2-yloxy)phenoxy acetates and 4-(4,6-dimethylpyrimidin-2-yloxy)phenoxy acetates were synthesized with hydroquinone, 2-methylsulfonyl-4,6-disubstituted-pyrimidine and chloroacetic ester as starting materials. The products were characterized by IR, ¹H-NMR, MS spectra and elemental analyses. Preliminary bioassay indicates that the target compounds possess high herbicidal activity against [...] Read more.

Ten novel 4-(4,6-dimethoxypyrimidin-2-yloxy)phenoxy acetates and 4-(4,6-dimethylpyrimidin-2-yloxy)phenoxy acetates were synthesized with hydroquinone, 2-methylsulfonyl-4,6-disubstituted-pyrimidine and chloroacetic ester as starting materials. The products were characterized by IR, ¹H-NMR, MS spectra and elemental analyses. Preliminary bioassay indicates that the target compounds possess high herbicidal activity against monocotyledonous plants such as Digitaria sanguinalis L. at concentrations of 100 mg/L and 50 mg/L. Full article

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33 pages, 1044 KB

Open AccessReview

Synthetic Applications of Chiral Unsaturated Epoxy Alcohols Prepared by Sharpless Asymmetric Epoxidation

by Antoni Riera and María Moreno

Molecules 2010, 15(2), 1041-1073; https://doi.org/10.3390/molecules15021041 - 23 Feb 2010

Cited by 45 | Viewed by 17352

Abstract

An overview of the synthesis and applications of chiral 2,3-epoxy alcohols containing unsaturated chains is presented. One of the fundamental synthetic routes to these compounds is Sharpless asymmetric epoxidation, which is reliable, highly chemoselective and enables easy prediction of the product enantioselectivity. Thus, [...] Read more.

An overview of the synthesis and applications of chiral 2,3-epoxy alcohols containing unsaturated chains is presented. One of the fundamental synthetic routes to these compounds is Sharpless asymmetric epoxidation, which is reliable, highly chemoselective and enables easy prediction of the product enantioselectivity. Thus, unsaturated epoxy alcohols are readily obtained by selective oxidation of the allylic double bond in the presence of other carbon-carbon double or triple bonds. The wide availability of epoxy alcohols with unsaturated chains, the versatility of the epoxy alcohol functionality (e.g. regio- and stereo-selective ring opening; oxidation; and reduction), and the arsenal of established alkene chemistries, make unsaturated epoxy alcohols powerful starting materials for the synthesis of complex targets such as biologically active molecules. The popularization of ring-closing metathesis has further increased their value, making them excellent precursors to cyclic compounds. Full article

(This article belongs to the Special Issue Asymmetric Synthesis)

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13 pages, 190 KB

Open AccessArticle

Synthesis and Characterization of Novel Inorganic-Organic Hybrid Ru(II) Complexes and Their Application in Selective Hydrogenation

by Ismail Warad, Zeid Al-Othman, Saud Al-Resayes, Salem S. Al-Deyab and El-Refaie Kenawy

Molecules 2010, 15(2), 1028-1040; https://doi.org/10.3390/molecules15021028 - 23 Feb 2010

Cited by 21 | Viewed by 12023

Abstract

Novel Ru(II) complex-based hybrid inorganic-organic materials immobilized via a diamine co-ligand site instead of the conventional diphosphine ligand have been prepared. The complexes were prepared by two different methods: sol-gel and surface modification techniques. The structures of the desired materials were deduced by [...] Read more.

Novel Ru(II) complex-based hybrid inorganic-organic materials immobilized via a diamine co-ligand site instead of the conventional diphosphine ligand have been prepared. The complexes were prepared by two different methods: sol-gel and surface modification techniques. The structures of the desired materials were deduced by several available physical measurements like elemental analyses, infrared, FAB-MS and ¹H-, ¹³C- and ³¹P-NMR spectroscopy. Due to a lack of solubility the structures of xerogel 3 and modified 4 were studied by solid state ¹³C-, ²⁹Si- and ³¹P-NMR spectroscopy, infrared spectroscopy and EXAFS. These materials were stable enough to serve as hydrogenation catalysts. Selective hydrogenation of functionalized carbonyls in a,b-unsaturated compounds was successfully carried out under mild conditions in a basic medium using these complexes as catalysts. Full article

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21 pages, 906 KB

Open AccessArticle

Polysaccharides Coatings on Medical-Grade PVC: A Probe into Surface Characteristics and the Extent of Bacterial Adhesion

by Ahmad Asadinezhad, Igor Novák, Marián Lehocký, František Bílek, Alenka Vesel, Ita Junkar, Petr Sáha and Anton Popelka

Molecules 2010, 15(2), 1007-1027; https://doi.org/10.3390/molecules15021007 - 23 Feb 2010

Cited by 81 | Viewed by 13849

Abstract

Medical-grade polyvinyl chloride was coated by polysaccharides through a novel physicochemical approach. An initial surface activation was performed foremost via diffuse coplanar surface barrier discharge plasma in air at ambient temperature and pressure. Then, radical graft copolymerization of acrylic acid through grafting-from pathway [...] Read more.

Medical-grade polyvinyl chloride was coated by polysaccharides through a novel physicochemical approach. An initial surface activation was performed foremost via diffuse coplanar surface barrier discharge plasma in air at ambient temperature and pressure. Then, radical graft copolymerization of acrylic acid through grafting-from pathway was directed to render a well-defined brush of high density, and finally a chitosan monolayer and chitosan/pectin alternating multilayer were bound onto the functionalized surfaces. Surface characteristics were systematically investigated using several probe techniques. In vitro bacterial adhesion and biofilm formation assays indicated that a single chitosan layer was incapable of hindering the adhesion of a Staphylococcus aureus bacterial strain, while up to 30% reduction was achieved by the chitosan/pectin layered assembly. On the other hand, chitosan and chitosan/pectin multilayer could retard Escherichia coli adhesion by 50% and 20%, respectively. Furthermore, plasma treated and graft copolymerized samples were also found effective to diminish the degree of adherence of Escherichia coli. Full article

(This article belongs to the Special Issue Macromolecules: Chemistry, Medicinal and Functional Materials)

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10 pages, 191 KB

Open AccessArticle

Synthesis of 1-(4-Trifluoromethoxyphenyl)-2,5-dimethyl-3-(2-R-thiazol-4-yl)-1H-pyrroles via Chain Heterocyclization

by Mykhaylo V. Vovk, Oleksandr M. Pinchuk, Andrij O. Tolmachov and Andrei A. Gakh

Molecules 2010, 15(2), 997-1006; https://doi.org/10.3390/molecules15020997 - 23 Feb 2010

Cited by 8 | Viewed by 8851

Abstract

The title compounds, (4-trifluoromethoxyphenyl)-2,5-dimethyl-3-(2-R-thiazol-4-yl)-1H-pyrroles, were prepared in four steps starting from commercially available 4-trifluoromethoxyaniline. The pyrrole (second ring) was added in one step using the Paal-Knorr method. The thiazole (third ring) was added in three steps using chloroacylation with [...] Read more.

The title compounds, (4-trifluoromethoxyphenyl)-2,5-dimethyl-3-(2-R-thiazol-4-yl)-1H-pyrroles, were prepared in four steps starting from commercially available 4-trifluoromethoxyaniline. The pyrrole (second ring) was added in one step using the Paal-Knorr method. The thiazole (third ring) was added in three steps using chloroacylation with chloroacetonitrile followed by heterocyclization with thioamides/thioureas. Full article

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9 pages, 139 KB

Open AccessArticle

Synthesis, Cytotoxic and Antimalarial Activities of Benzoyl Thiosemicarbazone Analogs of Isoquinoline and Related Compounds

by Ratchanok Pingaew, Supaluk Prachayasittikul and Somsak Ruchirawat

Molecules 2010, 15(2), 988-996; https://doi.org/10.3390/molecules15020988 - 23 Feb 2010

Cited by 71 | Viewed by 10801

Abstract

Thiosemicarbazone analogs of papaveraldine and related compounds 1–6 were synthesized and evaluated for cytotoxic and antimalarial activities. The cytotoxic activity was tested against HuCCA-1, HepG2, A549 and MOLT-3 human cancer cell lines. Thiosemicarbazones 1–5 displayed cytotoxicity toward all the [...] Read more.

Thiosemicarbazone analogs of papaveraldine and related compounds 1–6 were synthesized and evaluated for cytotoxic and antimalarial activities. The cytotoxic activity was tested against HuCCA-1, HepG2, A549 and MOLT-3 human cancer cell lines. Thiosemicarbazones 1–5 displayed cytotoxicity toward all the tested cell lines, while compounds 2–5 selectively showed potent activity against the MOLT-3 cell lines. Significantly, N(4)-phenyl-2-benzoylpyridine thiosemicarbazone 4 exhibited the most potent activity against HuCCA-1, HepG2, A549 and MOLT-3 cell lines with IC₅₀ values of 0.03, 4.75, 0.04 and 0.004 µg/mL, respectively. In addition, 2-benzoylpyridine thio-semicarbazones 3 and 4 showed antimalarial activity against Plasmodium falciparum with IC₅₀ of 10^-7 to < 10^-6 M. The study demonstrates the quite promising activity of analog 4 as a lead molecule for further development. Full article

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29 pages, 292 KB

Open AccessReview

Revealing the Power of the Natural Red Pigment Lycopene

by Kin-Weng Kong, Hock-Eng Khoo, K. Nagendra Prasad, Amin Ismail, Chin-Ping Tan and Nor Fadilah Rajab

Molecules 2010, 15(2), 959-987; https://doi.org/10.3390/molecules15020959 - 23 Feb 2010

Cited by 229 | Viewed by 24045

Abstract

By-products derived from food processing are attractive source for their valuable bioactive components and color pigments. These by-products are useful for development as functional foods, nutraceuticals, food ingredients, additives, and also as cosmetic products. Lycopene is a bioactive red colored pigment naturally occurring [...] Read more.

By-products derived from food processing are attractive source for their valuable bioactive components and color pigments. These by-products are useful for development as functional foods, nutraceuticals, food ingredients, additives, and also as cosmetic products. Lycopene is a bioactive red colored pigment naturally occurring in plants. Industrial by-products obtained from the plants are the good sources of lycopene. Interest in lycopene is increasing due to increasing evidence proving its preventive properties toward numerous diseases. In vitro, in vivo and ex vivo studies have demonstrated that lycopene-rich foods are inversely associated to diseases such as cancers, cardiovascular diseases, diabetes, and others. This paper also reviews the properties, absorption, transportation, and distribution of lycopene and its by-products in human body. The mechanism of action and interaction of lycopene with other bioactive compounds are also discussed, because these are the crucial features for beneficial role of lycopene. However, information on the effect of food processing on lycopene stability and availability was discussed for better understanding of its characteristics. Full article

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42 pages, 335 KB

Open AccessReview

Organocatalyzed Asymmetric α-Oxidation, α-Aminoxylation and α-Amination of Carbonyl Compounds

by Tirayut Vilaivan and Worawan Bhanthumnavin

Molecules 2010, 15(2), 917-958; https://doi.org/10.3390/molecules15020917 - 11 Feb 2010

Cited by 165 | Viewed by 17910

Abstract

Organocatalytic asymmetric α-oxidation and amination reactions of carbonyl compounds are highly useful synthetic methodologies, especially in generating chiral building blocks that previously have not been easily accessible by traditional methods. The concept is relatively new and therefore the list of new catalysts, oxidizing [...] Read more.

Organocatalytic asymmetric α-oxidation and amination reactions of carbonyl compounds are highly useful synthetic methodologies, especially in generating chiral building blocks that previously have not been easily accessible by traditional methods. The concept is relatively new and therefore the list of new catalysts, oxidizing and aminating reagents, as well as new substrates, are expanding at an amazing rate. The scope of this review includes new reactions and catalysts, mechanistic aspects and synthetic applications of α-oxidation, hydroxylation, aminoxylation, amination, hydrazination, hydroxyamination and related α-heteroatom functionalization of aldehydes, ketones and related active methylene compounds published during 2005–2009. Full article

(This article belongs to the Special Issue Asymmetric Synthesis)

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39 pages, 361 KB

Open AccessReview

3-Nitropropionic Acid as a Tool to Study the Mechanisms Involved in Huntington’s Disease: Past, Present and Future

by Isaac Túnez, Inmaculada Tasset, Verónica Pérez-De La Cruz and Abel Santamaría

Molecules 2010, 15(2), 878-916; https://doi.org/10.3390/molecules15020878 - 10 Feb 2010

Cited by 191 | Viewed by 19867

Abstract

Huntington’s disease (HD) is an inheritable autosomal-dominant disorder whose causal mechanisms remain unknown. Experimental models have begun to uncover these pathways, thus helping to understand the mechanisms implicated and allowing for the characterization of potential targets for new therapeutic strategies. 3-Nitropropionic acid is [...] Read more.

Huntington’s disease (HD) is an inheritable autosomal-dominant disorder whose causal mechanisms remain unknown. Experimental models have begun to uncover these pathways, thus helping to understand the mechanisms implicated and allowing for the characterization of potential targets for new therapeutic strategies. 3-Nitropropionic acid is known to produce in animals behavioural, biochemical and morphologic changes similar to those occurring in HD. For this reason, this phenotypic model is gaining attention as a valuable tool to mimick this disorder and further developing new therapies. In this review, we will focus on the past and present research of this molecule, to finally bring a perspective on what will be next in this promising field of study. Full article

(This article belongs to the Special Issue Neuroprotective Strategies)

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7 pages, 243 KB

Open AccessArticle

A New 1,4-Diazepine from South China Sea Marine Sponge Callyspongia Species

by Ri-Ming Huang, Wei Ma, Jun-De Dong, Xue-Feng Zhou, Tunhai Xu, Kyung Jin Lee, Xianwen Yang, Shi-Hai Xu and Yonghong Liu

Molecules 2010, 15(2), 871-877; https://doi.org/10.3390/molecules15020871 - 10 Feb 2010

Cited by 24 | Viewed by 12852

Abstract

A new 1,4-diazepine, callysponine (1), was isolated from a South China Sea Callyspongia sp. marine sponge, together with four known proline-based diketopiperazines: cyclo-(S-Pro-R-Leu) (2), cyclo-(S-Pro-R-Val) (3), cyclo-(S-Pro- [...] Read more.

A new 1,4-diazepine, callysponine (1), was isolated from a South China Sea Callyspongia sp. marine sponge, together with four known proline-based diketopiperazines: cyclo-(S-Pro-R-Leu) (2), cyclo-(S-Pro-R-Val) (3), cyclo-(S-Pro-R-Ala) (4), andcyclo-(S-Pro-R-Tyr) (5). The new structure was determined on the basis of NMR and MS analysis, and the absolute stereochemistry was defined by NOESY spectroscopy and optical rotation. The structures of the known compounds were identified by comparison of their spectroscopic data with those reported in the literature. Callysponine (1) did not inhibit the growth of HepG2 (hepatoma carcinoma cell), A549 (lung carcinoma cell), and HeLa (cervical cancer cell) cell lines. Full article

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14 pages, 684 KB

Open AccessArticle

Quercetin as a Potential Modulator of P-Glycoprotein Expression and Function in Cells of Human Pancreatic Carcinoma Line Resistant to Daunorubicin

by Sylwia Borska, Miroslaw Sopel, Magdalena Chmielewska, Maciej Zabel and Piotr Dziegiel

Molecules 2010, 15(2), 857-870; https://doi.org/10.3390/molecules15020857 - 9 Feb 2010

Cited by 69 | Viewed by 12936

Abstract

P-glycoprotein (P-gp) is one of the ABC transporters responsible for the resistance of several tumours to successful chemotherapy. Numerous agents are capable of interfering with the P-gp-mediated export of drugs but unfortunately most of them produce serious side effects. Some plant polyphenols, including [...] Read more.

P-glycoprotein (P-gp) is one of the ABC transporters responsible for the resistance of several tumours to successful chemotherapy. Numerous agents are capable of interfering with the P-gp-mediated export of drugs but unfortunately most of them produce serious side effects. Some plant polyphenols, including the flavonol quercetin (Q), manifest anti-neoplastic activity mainly due to their influence on cell cycle control and apoptosis. Reports are also available which show that Q may intensify action of cytostatic drugs and suppress the multidrug resistance (MDR) phenomenon. The study aimed at determination if Q sensitizes cells resistant to daunorubicin (DB) through its effect on P-gp expression and action. The experiments were conducted on two cell lines of human pancreatic carcinoma, resistant to DB EPP85-181RDB and sensitive EPP85-181P as a comparison. Cells of both lines were exposed to selected concentrations of Q and DB, and then membranous expression of P-gp and its transport function were examined. The influence on expression of gene for P-gp (ABCB1) was also investigated. Results of the studies confirmed that Q affects expression and function of P-gp in a concentration-dependent manner. Moreover it decreased expression of ABCB1. Thus, Q may be considered as a potential modulator of P-gp. Full article

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15 pages, 338 KB

Open AccessArticle

Seeking Polymeric Prodrugs of Norfloxacin. Part 2. Synthesis and Structural Analysis of Polyurethane Conjugates

by Marcin Sobczak, Katarzyna Nurzyńska and Waclaw Kolodziejski

Molecules 2010, 15(2), 842-856; https://doi.org/10.3390/molecules15020842 - 5 Feb 2010

Cited by 18 | Viewed by 8527

Abstract

Oligo(ε-caprolactone) and oligolactide were synthesized via ring-opening polymerization of cyclic esters in the presence of creatinine as initiators. Thus obtained oligomers were successfully used in the synthesis of novel polyurethane conjugates of norfloxacin. The structures of the polymers and conjugates were elucidated by [...] Read more.

Oligo(ε-caprolactone) and oligolactide were synthesized via ring-opening polymerization of cyclic esters in the presence of creatinine as initiators. Thus obtained oligomers were successfully used in the synthesis of novel polyurethane conjugates of norfloxacin. The structures of the polymers and conjugates were elucidated by means of MALDI-TOF MS, NMR and IR studies. Full article

(This article belongs to the Special Issue Prodrugs)

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8 pages, 311 KB

Open AccessArticle

Sesterterpenes and a New Sterol from the Marine Sponge Phyllospongia foliascens

by Hong-Jun Zhang, Yang-Hua Yi, Fan Yang, Wan-Sheng Chen and Hou-Wen Lin

Molecules 2010, 15(2), 834-841; https://doi.org/10.3390/molecules15020834 - 5 Feb 2010

Cited by 18 | Viewed by 9111

Abstract

A new scalarane sesterterpene, phyllofolactone M (1), and a new sterol, (24E)-5α,6α-epoxystigmasta-7,24(28)-dien-3β-ol (3), together with a known sesterterpene, phyllofolactone B (2), were isolated from the South China Sea sponge [...] Read more.

A new scalarane sesterterpene, phyllofolactone M (1), and a new sterol, (24E)-5α,6α-epoxystigmasta-7,24(28)-dien-3β-ol (3), together with a known sesterterpene, phyllofolactone B (2), were isolated from the South China Sea sponge Phyllospongia foliascens. Their structures were elucidated by spectroscopic analysis and comparison with known compounds. In addition, previous NMR data assignments for the known sesterterpene phyllofolactone B (2) were revised. Full article

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10 pages, 174 KB

Open AccessArticle

Synthesis and Characterization of Long-Chain Tartaric Acid Diamides as Novel Ceramide-Like Compounds

by Bálint Sinkó, Melinda Pálfi, Szabolcs Béni, József Kökösi and Krisztina Takács-Novák

Molecules 2010, 15(2), 824-833; https://doi.org/10.3390/molecules15020824 - 5 Feb 2010

Cited by 13 | Viewed by 11857

Abstract

Ceramides play a crucial role in the barrier function of the skin as well as in transmembrane signaling. In this study long aliphatic chain tartaric acid diamides able to replace ceramides in an in vitro model of the stratum corneum lipid matrix due [...] Read more.

Ceramides play a crucial role in the barrier function of the skin as well as in transmembrane signaling. In this study long aliphatic chain tartaric acid diamides able to replace ceramides in an in vitro model of the stratum corneum lipid matrix due to their similar physico-chemical properties were synthesized from diacetoxysuccinic anhydride in four steps. Their pro-apoptotic effect on fibroblast cells was also investigated. Full article

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11 pages, 300 KB

Open AccessArticle

Microwave-Assisted and Efficient Solvent-free Knoevenagel Condensation. A Sustainable Protocol Using Porous Calcium Hydroxyapatite as Catalyst

by Siham Mallouk, Khalid Bougrin, Abdelaziz Laghzizil and Rachid Benhida

Molecules 2010, 15(2), 813-823; https://doi.org/10.3390/molecules15020813 - 4 Feb 2010

Cited by 67 | Viewed by 13467

Abstract

A sustainable Knoevenagel condensation of a series of aldehydes with malononitrile and ethyl cyanoacetate is described. The process is based on the combination of microwave activation and hydroxyapatite catalysis under solvent-free conditions. Products are obtained in and high yields after short reaction times. [...] Read more.

A sustainable Knoevenagel condensation of a series of aldehydes with malononitrile and ethyl cyanoacetate is described. The process is based on the combination of microwave activation and hydroxyapatite catalysis under solvent-free conditions. Products are obtained in and high yields after short reaction times. The effects of the specific surface of porous calcium hydroxyapatite and microwave activation are discussed. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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9 pages, 123 KB

Open AccessArticle

Ancient Chinese Methods Are Remarkably Effective for the Preparation of Artemisinin-Rich Extracts of Qing Hao with Potent Antimalarial Activity

by Colin W. Wright, Peter A. Linley, Reto Brun, Sergio Wittlin and Elisabeth Hsu

Molecules 2010, 15(2), 804-812; https://doi.org/10.3390/molecules15020804 - 4 Feb 2010

Cited by 63 | Viewed by 17094

Abstract

Ancient Chinese herbal texts as far back as the 4th Century Zhou hou bei ji fang describe methods for the use of Qing Hao (Artemisia annua) for the treatment of intermittent fevers. Today, the A. annua constituent artemisinin is an important [...] Read more.

Ancient Chinese herbal texts as far back as the 4th Century Zhou hou bei ji fang describe methods for the use of Qing Hao (Artemisia annua) for the treatment of intermittent fevers. Today, the A. annua constituent artemisinin is an important antimalarial drug and the herb itself is being grown and used locally for malaria treatment although this practice is controversial. Here we show that the ancient Chinese methods that involved either soaking, (followed by wringing) or pounding, (followed by squeezing) the fresh herb are more effective in producing artemisinin-rich extracts than the usual current method of preparing herbal teas from the dried herb. The concentrations of artemisinin in the extracts was up to 20-fold higher than that in a herbal tea prepared from the dried herb, but the amount of total artemisinin extracted by the Chinese methods was much less than that removed in the herbal tea. While both extracts exhibited potent in vitro activities against Plasmodium falciparum, only the pounded juice contained sufficient artemisinin to suppress parasitaemia in P. berghei infected mice. The implications of these results are discussed in the context of malaria treatment using A. annua infusions. Full article

(This article belongs to the Special Issue Artemisinin (Qinghaosu): Commemorative Issue in Honor of Professor Youyou Tu on the Occasion of her 80th Anniversary)

11 pages, 206 KB

Open AccessCommunication

The Solubility of Hen Lysozyme in Ethylammonium Nitrate/H₂O Mixtures and a Novel Approach to Protein Crystallization

by Nolene Byrne and C. Austen Angell

Molecules 2010, 15(2), 793-803; https://doi.org/10.3390/molecules15020793 - 4 Feb 2010

Cited by 37 | Viewed by 8996

Abstract

We report on the solubility of hen lysozyme (HEWL) in aqueous ethylammonium nitrate (EAN) as a function of water content. We find the solubility behavior to be complex, exhibiting both a maximum (400 mg/mL) at very high EAN content) and a minimum at [...] Read more.

We report on the solubility of hen lysozyme (HEWL) in aqueous ethylammonium nitrate (EAN) as a function of water content. We find the solubility behavior to be complex, exhibiting both a maximum (400 mg/mL) at very high EAN content) and a minimum at intermediate EAN content. We exploit this solubility profile in a novel approach to generating crystals of hydrophilic proteins, based on rehydration of a high concentration protein solution. We describe the production of crystals of X-ray diffraction quality. Two related ionic liquid solvent systems, with the same solubility profiles but different effective pH characteristics, are identified for future evaluation. Full article

(This article belongs to the Collection Ionic Liquids)

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13 pages, 743 KB

Open AccessArticle

Evaluation of Enoyl-Acyl Carrier Protein Reductase Inhibitors as Pseudomonas aeruginosa Quorum-Quenching Reagents

by Liang Yang, Yang Liu, Claus Sternberg and Søren Molin

Molecules 2010, 15(2), 780-792; https://doi.org/10.3390/molecules15020780 - 3 Feb 2010

Cited by 41 | Viewed by 11644

Abstract

Pseudomonas aeruginosa is an opportunistic pathogen which is responsible for a wide range of infections. Production of virulence factors and biofilm formation by P. aeruginosa are partly regulated by cell-to-cell communication quorum-sensing systems. Identification of quorum-quenching reagents which block the quorum-sensing process can [...] Read more.

Pseudomonas aeruginosa is an opportunistic pathogen which is responsible for a wide range of infections. Production of virulence factors and biofilm formation by P. aeruginosa are partly regulated by cell-to-cell communication quorum-sensing systems. Identification of quorum-quenching reagents which block the quorum-sensing process can facilitate development of novel treatment strategies for P. aeruginosa infections. We have used molecular dynamics simulation and experimental studies to elucidate the efficiencies of two potential quorum-quenching reagents, triclosan and green tea epigallocatechin gallate (EGCG), which both function as inhibitors of the enoyl-acyl carrier protein (ACP) reductase (ENR) from the bacterial type II fatty acid synthesis pathway. Our studies suggest that EGCG has a higher binding affinity towards ENR of P. aeruginosa and is an efficient quorum-quenching reagent. EGCG treatment was further shown to be able to attenuate the production of virulence factors and biofilm formation of P. aeruginosa. Full article

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14 pages, 450 KB

Open AccessArticle

Synthesis and Crystal Structure of Novel Sulfone Derivatives Containing 1,2,4-Triazole Moieties

by Weiming Xu, Baoan Song, Pinaki Bhadury, Yang Song and Deyu Hu

Molecules 2010, 15(2), 766-779; https://doi.org/10.3390/molecules15020766 - 3 Feb 2010

Cited by 13 | Viewed by 10899

Abstract

Some 3-(Substituted methylthio)-4-phenyl-5-(3,4,5-trimethoxyphenyl)-4H-1,2,4-triazole derivatives were synthesized in six steps starting from easily accessible gallic acid. The resulting sulfides were then catalytically oxidized to the title sulfones with H₂O₂. The products were obtained in high yield under mild [...] Read more.

Some 3-(Substituted methylthio)-4-phenyl-5-(3,4,5-trimethoxyphenyl)-4H-1,2,4-triazole derivatives were synthesized in six steps starting from easily accessible gallic acid. The resulting sulfides were then catalytically oxidized to the title sulfones with H₂O₂. The products were obtained in high yield under mild conditions and practically devoid of any by-products. The structures were confirmed by elemental analysis, IR, ¹H- and ¹³C-NMR spectral data. Furthermore, a detailed X-ray crystallography structural analysis of model triazole 7g was carried out. Full article

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19 pages, 737 KB

Open AccessArticle

Catalytic Performance of Ceria Nanorods in Liquid-Phase Oxidations of Hydrocarbons with tert-Butyl Hydroperoxide

by Andreia G. Macedo, Sílvia E. M. Fernandes, Anabela A. Valente, Rute. A. S. Ferreira, Luís D. Carlos and João Rocha

Molecules 2010, 15(2), 747-765; https://doi.org/10.3390/molecules15020747 - 2 Feb 2010

Cited by 35 | Viewed by 11496

Abstract

The CeO₂ nanorods (CeNR) promote the oxidation of ethylbenzene (PhEt) and cyclohexene with t-BuOOH, at temperatures as low as 55 ºC. For both substrates the saturated C-H bonds are preferentially activated over the unsaturated ones. The catalyst seems fairly stable towards leaching [...] Read more.

The CeO₂ nanorods (CeNR) promote the oxidation of ethylbenzene (PhEt) and cyclohexene with t-BuOOH, at temperatures as low as 55 ºC. For both substrates the saturated C-H bonds are preferentially activated over the unsaturated ones. The catalyst seems fairly stable towards leaching phenomena. The liquid-phase oxidation catalysis may be associated with the Ce³⁺/Ce⁴⁺ inter-conversion in the one-electron redox processes mediating the formation of tert-butyl-(per)oxy radicals. CeNR is very effective in H₂O₂ disproportionation. Pre-treatment of CeNR with H₂O₂ or t-BuOOH prior to the catalytic reaction enhances the reaction rate of PhEt with t-BuOOH in comparison to CeNR. Textural characterization and spectroscopic studies suggest that catalytic activation is associated to defect sites. Full article

(This article belongs to the Special Issue Nano-catalysts and Nano-technologies for Green Organic Synthesis)

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12 pages, 178 KB

Open AccessArticle

Chemical Composition and Antigerminative Activity of the Essential Oils from Five Salvia Species

by Laura De Martino, Graziana Roscigno, Emilia Mancini, Enrica De Falco and Vincenzo De Feo

Molecules 2010, 15(2), 735-746; https://doi.org/10.3390/molecules15020735 - 1 Feb 2010

Cited by 48 | Viewed by 13020

Abstract

The chemical composition of the essential oils of Salvia africana L., Salvia elegans Vahl, Salvia greggii A. Gray, Salvia mellifera Green and Salvia munzii Epling, cultivated in Eboli (Salerno, Southern Italy), was studied by means of GC and GC-MS analyses. In all, 88 [...] Read more.

The chemical composition of the essential oils of Salvia africana L., Salvia elegans Vahl, Salvia greggii A. Gray, Salvia mellifera Green and Salvia munzii Epling, cultivated in Eboli (Salerno, Southern Italy), was studied by means of GC and GC-MS analyses. In all, 88 compounds were identified, 54 for S. africana, accounting for 95.4% of the total oil, 55 for S. elegans (92.9%), 50 for S. greggii (96.9%), 54 for S. mellifera (90.4%) and 47 for S. munzii (97.5%), respectively. In S. africana,the amount of monoterpenoids and sesquiterpenoids is very similar. For other species, the monoterpenoid percentage is greater than the amount of sesquiterpenoids. The oils of S. elegans, S. greggii and S. munzii were active inhibitors of germination and radical elongation of Raphanus sativus L. and Lepidium sativum L. Full article

26 pages, 797 KB

Open AccessReview

Enantioselective, Organocatalytic Morita-Baylis-Hillman and Aza-Morita-Baylis-Hillman Reactions: Stereochemical Issues

by Javier Mansilla and José M. Saá

Molecules 2010, 15(2), 709-734; https://doi.org/10.3390/molecules15020709 - 1 Feb 2010

Cited by 94 | Viewed by 15160

Abstract

Conscious of the importance that stereochemical issues may have on the design of efficient organocatalyts for both Morita-Baylis-Hillman and aza-Morita-Baylis-Hillman reaction we have analyzed them in this minireview. The so-called standard reactions involve “naked” enolates which therefore should lead to the syn adducts [...] Read more.

Conscious of the importance that stereochemical issues may have on the design of efficient organocatalyts for both Morita-Baylis-Hillman and aza-Morita-Baylis-Hillman reaction we have analyzed them in this minireview. The so-called standard reactions involve “naked” enolates which therefore should lead to the syn adducts as the major products, irrespective of the E, Z stereochemistry of the enolate. Accordingly, provided the second step is rate determining step, the design of successful bifunctional or polyfunctional catalysts has to consider the geometrical requirements imposed by the transition structures of the second step of these reactions. On the other hand, MBH and aza-MBH reactions co-catalyzed by (S)-proline and a secondary or tertiary amine (co-catalyst) involve the aldol-type condensation of either a 3-amino-substituted enamine, dienamine, or both, depending on the cases. A Zimmerman-Traxler mechanism defines the stereochemical issues regarding these co-catalyzed condensations which parallel those of the well established (S)-proline catalyzed aldol-like reactions. Full article

(This article belongs to the Special Issue Baylis-Hillman Reaction and Related Processes)

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10 pages, 355 KB

Open AccessArticle

Facile Synthesis and Preferred Conformation Analysis of Cyclododeceno[b]indene

by Chunyan Zhang, Shengyan Gong, Li Zhang, Daoquan Wang and Mingan Wang

Molecules 2010, 15(2), 699-708; https://doi.org/10.3390/molecules15020699 - 1 Feb 2010

Cited by 2 | Viewed by 7087

Abstract

Using methanesulfonic acid as a catalyst, a series of cyclododeceno[b]indene derivatives were synthesized by the cyclization of α-benzylcyclododecanones, which were prepared by the reactions of cyclododecanones with a variety of substituted benzyl chlorides or bromides using NaH as a base. Their structures were [...] Read more.

Using methanesulfonic acid as a catalyst, a series of cyclododeceno[b]indene derivatives were synthesized by the cyclization of α-benzylcyclododecanones, which were prepared by the reactions of cyclododecanones with a variety of substituted benzyl chlorides or bromides using NaH as a base. Their structures were confirmed by mp, IR spectra, ¹H-NMR, ¹³C-NMR, MS, and x-ray diffraction. The preferred conformations were analyzed by crystal structure, ¹H-NMR and quantum chemistry calculations, and compared with the x-ray diffraction structure of 2,3,5,6-bis(ortho-1,10-decylidene)dihydropyrazine. The results showed that the cyclododecene moiety adopted a preferred [1ene2333] conformation, and the substituted groups at aromatic ring had no significant influence on the conformation. Full article

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10 pages, 143 KB

Open AccessArticle

Chemical Analysis and Biological Activity of the Essential Oils of Two Endemic Soqotri Commiphora Species

by Ramzi A. Mothana, Adnan J. Al-Rehaily and Wulf Schultze

Molecules 2010, 15(2), 689-698; https://doi.org/10.3390/molecules15020689 - 1 Feb 2010

Cited by 34 | Viewed by 11886

Abstract

The barks of two endemic Commiphora species namely, Commiphora ornifolia (Balf.f.) Gillett and Commiphora parvifolia Engl., were collected from Soqotra Island in Yemen and their essential oils were obtained by hydrodistillation. The chemical composition of both oils was investigated by GC and GC-MS. [...] Read more.

The barks of two endemic Commiphora species namely, Commiphora ornifolia (Balf.f.) Gillett and Commiphora parvifolia Engl., were collected from Soqotra Island in Yemen and their essential oils were obtained by hydrodistillation. The chemical composition of both oils was investigated by GC and GC-MS. Moreover, the essential oils were evaluated for their antimicrobial activity against two Gram-positive bacteria, two Gram-negative bacteria and one yeast species by using a broth micro-dilution assay for minimum inhibitory concentrations (MIC) and for their antioxidant activity by measuring the DPPH radical scavenging activity. A total of 45 constituents of C. ornifolia (85.6%) and 44 constituents of C. parvifolia (87.1%) were identified. The oil of C. ornifolia was characterized by a high content of oxygenated monoterpenes (56.3%), of which camphor (27.3%), α-fenchol (15.5%), fenchone (4.4%) and borneol (2.9%) were identified as the main components. High contents of oxygenated sesquiterpenes (36.1%) and aliphatic acids (22.8%) were found in C. parvifolia oil, in which caryophyllene oxide (14.2%), β-eudesmol (7.7%), bulnesol (5.7%), T-cadinol (3.7%) and hexadecanoic acid (18.4%) predominated. The results of the antimicrobial assay showed that both oils exhibited moderate to high antibacterial activity especially against Gram-positive bacteria. C. ornifolia oil was the most active. In addition, the DPPH-radical scavenging assay exhibited only weak antioxidant activities for both oils at the high concentration tested. Full article

9 pages, 519 KB

Open AccessArticle

A Comparative Identification of Ochratoxin A in Longan Fruit Pulp by High Performance Liquid Chromatography-Fluorescence Detection and Electron Spray Ionization-Mass Spectrometry

by Jing Li, Haihui Xie, Bao Yang, Xinhong Dong, Linyan Feng, Feng Chen and Yueming Jiang

Molecules 2010, 15(2), 680-688; https://doi.org/10.3390/molecules15020680 - 29 Jan 2010

Cited by 8 | Viewed by 10611

Abstract

Harvested longan (Dimocarpus longan Lour.) fruit are susceptible to decay caused by both bacterial and fungal infections. Ochratoxin A (OTA) is a kind of mycotoxin produced by a number of fungi. In this study, OTA was extracted from longan fruit pulp by [...] Read more.

Harvested longan (Dimocarpus longan Lour.) fruit are susceptible to decay caused by both bacterial and fungal infections. Ochratoxin A (OTA) is a kind of mycotoxin produced by a number of fungi. In this study, OTA was extracted from longan fruit pulp by 80% methanol and then loaded on C-18 solid-phase extraction columns. The extract solution was then analyzed by high-performance liquid chromatography - fluorescence detection (HPLC-FD) and an electron spray ionization-mass spectrometry (ESI-MS), respectively. The HPLC-FD analysis showed that a compound similar to OTA might exist in longan fruit pulp, but further analysis by the ESI-MS method demonstrated that OTA was not present in the longan pulp, indicating that the presence of OTA in longan fruit pulp detected by the HPLC-FD analysis needed to be confirmed by the ESI-MS method. Full article

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8 pages, 228 KB

Open AccessCommunication

A New Flavone C-Glycoside from Clematis rehderiana

by Zhi-Zhi Du, Xian-Wen Yang, Hao Han, Xiang-Hai Cai and Xiao-Dong Luo

Molecules 2010, 15(2), 672-679; https://doi.org/10.3390/molecules15020672 - 29 Jan 2010

Cited by 24 | Viewed by 10680

Abstract

A new flavone C-glycoside, isovitexin 6″-O-E-p-coumarate (1) and two known flavonoid glycosides—quercetin 3-O-β-D-glucuronopyranoside (2) and isoorientin (3)—were isolated from an ethanol extract of aerial parts of Clematis rehderiana. Their structures were determined by [...] Read more.

A new flavone C-glycoside, isovitexin 6″-O-E-p-coumarate (1) and two known flavonoid glycosides—quercetin 3-O-β-D-glucuronopyranoside (2) and isoorientin (3)—were isolated from an ethanol extract of aerial parts of Clematis rehderiana. Their structures were determined by spectroscopic methods. The antioxidant effects of the two flavone C-glycosides were evaluated by both the MTT and DPPH assays. Compound 1 showed potent activities against H₂O₂-induced impairment in PC12 cells within the concentration range tested, whereas compound 3 scavenged DPPH radical strongly, with an IC₅₀ value of 13.5 μM. Full article

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12 pages, 228 KB

Open AccessArticle

Antileishmanial, Antimicrobial and Antifungal Activities of Some New Aryl Azomethines

by Yasser M.S.A. Al-Kahraman, Hassan. M.F. Madkour, Dildar Ali and Masoom Yasinzai

Molecules 2010, 15(2), 660-671; https://doi.org/10.3390/molecules15020660 - 28 Jan 2010

Cited by 49 | Viewed by 11854

Abstract

A series of eighteen azomethines has been synthesized by the reaction of appropriate primary aromatic amines with aryl and/or heteroaryl carboxaldehydes. The synthesized azomethines have been evaluated for their in vitro antileishmanial, antibacterial and antifungal activities. The results revealed some antifungal activity of [...] Read more.

A series of eighteen azomethines has been synthesized by the reaction of appropriate primary aromatic amines with aryl and/or heteroaryl carboxaldehydes. The synthesized azomethines have been evaluated for their in vitro antileishmanial, antibacterial and antifungal activities. The results revealed some antifungal activity of most of the synthesized compounds, whereas the antileishmaniasis activity results highlighted that all synthesized azomethines inhibited parasite growth and most of them showed highly potent action towards Leishmania major promastigotes. No remarkable bactericidal activities were observed. Full article

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11 pages, 214 KB

Open AccessArticle

Palladium-Catalyzed Heck Coupling Reaction of Aryl Bromides in Aqueous Media Using Tetrahydropyrimidinium Salts as Carbene Ligands

by Sedat Yaşar, Emine Özge Özcan, Nevin Gürbüz, Bekir Çetinkaya and İsmail Özdemir

Molecules 2010, 15(2), 649-659; https://doi.org/10.3390/molecules15020649 - 28 Jan 2010

Cited by 21 | Viewed by 12318

Abstract

An efficient and stereoselective catalytic system for the Heck cross coupling reaction using novel 1,3-dialkyl-3,4,5,6-tetrahydropyrimidinium salts (1, LHX) and Pd(OAc)₂ loading has been reported. The palladium complexes derived from the salts 1a-f prepared in situ exhibit good catalytic activity [...] Read more.

An efficient and stereoselective catalytic system for the Heck cross coupling reaction using novel 1,3-dialkyl-3,4,5,6-tetrahydropyrimidinium salts (1, LHX) and Pd(OAc)₂ loading has been reported. The palladium complexes derived from the salts 1a-f prepared in situ exhibit good catalytic activity in the Heck coupling reaction of aryl bromides under mild conditions. Full article

(This article belongs to the Special Issue Heck Coupling)

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Molecules, Volume 15, Issue 2 (February 2010) – 35 articles , Pages 606-1096

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