http://www.mdpi.com/journal/molecules/special_issues/phytochemicals_mol/ Dear Colleagues, As the endogenous constituents of plants, phytochemicals often play essential roles in plant survival, growth and reproduction. A variety of phytochemicals are involved in protection against herbivores, microorganisms, and competitors; regulate growth; and control pollination, fertilization and the rhizosphere environment. Moreover, many isolated phytochemicals and their derivatives also promote human health. Indeed, extensive amount of clinical trials have evaluated phytochemicals for their efficacy in preventing various diseases, such as some types of cancer. The Special Issue on "Phytochemicals with signaling, medicinal and therapeutic properties", therefore, will contain the original research and review articles on the all areas of phytochemicals, mainly including extraction, isolation, characterization, cellular signaling and transport pathways, medicinal applications, and therapeutic effects of phytochemicals. Dr. Jean W. H. Yong Dr. Liya Ge Dr. Swee Ngin Tan Guest Editors {snippet name="submission_info"} http://www.mdpi.com/1420-3049/15/12/9214/ An improved method for determining the relative biosynthetic rate of isoprenoid cytokinins has been developed. A set of 11 relevant isoprenoid cytokinins, including zeatin isomers, was separated by ultra performance liquid chromatography in less than 6 min. The iP-type cytokinins were observed to give rise to a previously-unknown fragment at m/z 69; we suggest that the diagnostic (204-69) transition can be used to monitor the biosynthetic rate of isopentenyladenine. Furthermore, we found that by treating the cytokinin nucleotides with alkaline phosphatase prior to analysis, the sensitivity of the detection process could be increased. In addition, derivatization (propionylation) improved the ESI-MS response by increasing the analytes' hydrophobicity. Indeed, the ESI-MS response of propionylated isopentenyladenosine was about 34% higher than that of its underivatized counterpart. Moreover, the response of the derivatized zeatin ribosides was about 75% higher than that of underivatized zeatin ribosides. Finally, we created a web-based calculator (IZOTOP) that facilitates MS/MS data processing and offer it freely to the research community. http://www.mdpi.com/1420-3049/15/12/9214/ Wed, 15 Dec 2010 00:00:00 CET Molecules 2010-12-15 15 12 Article 9214 9229 1420-3049 An Improved in Vivo Deuterium Labeling Method for Measuring the Biosynthetic Rate of Cytokinins 2010-12-15 doi: 10.3390/molecules15129214 Petr Tarkowski Kristýna Floková Kateřina Václavíková Pavel Jaworek Martin Raus Anders Nordström Ondřej Novák Karel Doležal Marek Šebela Jitka Frébortová http://www.mdpi.com/1420-3049/15/10/7090/ Members of the family Bignoniaceae are mostly found in tropical and neo-tropical regions in America, Asia and Africa, although some of them are cultivated in other regions as ornamentals. Species belonging to this family have been extensively studied in regard to their pharmacological properties (as extracts and isolated compounds). The aim of this review is to summarize the reported scientific evidence about the chemical properties as well as that of the extracts and isolated compounds from species of this family, focusing mainly in insect-plant interactions. As it is known, this family is recognized for the presence of iridoids which are markers of oviposition and feeding preference to species which have became specialist feeders. Some herbivore species have also evolved to the point of been able to sequester iridoids and use them as defenses against their predators. However, iridoids also exhibit anti-insect properties, and therefore they may be good lead molecules to develop botanical pesticides. Other secondary metabolites, such as quinones, and whole extracts have also shown potential as anti-insect agents. http://www.mdpi.com/1420-3049/15/10/7090/ Thu, 14 Oct 2010 00:00:00 CEST Molecules 2010-10-14 15 10 Review 7090 7105 1420-3049 Bignoniaceae Metabolites as Semiochemicals 2010-10-14 doi: 10.3390/molecules15107090 Lucía Castillo Carmen Rossini http://www.mdpi.com/1420-3049/15/9/6365/ Spices and herbs are known not only for their taste, aroma and flavour, but also for their medical properties and value. Both spices and herbs have been used for centuries in traditional medical systems to cure various kinds of illnesses such as common cold, diabetes, cough and cancers. The aim of this work was the comparison between two different extractive techniques in order to get qualitative and quantitative data regarding bioactive compounds of four different spices (Cinnamomum zeylanicum, Coriandrum sativum, Cuminum cyminum, Crocus sativus). The plants were extracted employing ultrasonication and microwave-assisted extractions. The efficiency of extraction of bioactive compounds obtained with the microwave extraction process was in general about four times higher than that resulting from sonication extraction. The various extracts obtained were analyzed for their antioxidant activity using ABTS, DPPH and FRAP assays and for their total polyphenolic content. It can be concluded that microwave-assisted extractions provide significant advantages in terms of extraction efficiency and time savings. http://www.mdpi.com/1420-3049/15/9/6365/ Thu, 09 Sep 2010 00:00:00 CEST Molecules 2010-09-09 15 9 Article 6365 6374 1420-3049 Microwave Assisted Extraction of Phenolic Compounds from Four Different Spices 2010-09-09 doi: 10.3390/molecules15096365 Monica Gallo Rosalia Ferracane Giulia Graziani Alberto Ritieni Vincenzo Fogliano http://www.mdpi.com/1420-3049/15/8/5734/ The essential oils of four Guarea species collected at Manaus (Amazonas, Brazil) were obtained by hydrodistillation and analyzed by GC-MS. Except for one diterpene detected, the compounds identified in the essential oils were hydrocarbons and oxygenated sesquiterpenes. The major sesquiterpenes were α-santalene (26.26%) and α-copaene (14.61%) from G. convergens branches; caryophyllene epoxide (40.91%) and humulene epoxide II (14.43%) from G. humaitensis branches; cis-caryophyllene (33.37%) and α-trans-bergamotene (11.88%) from G. scabra leaves; caryophyllene epoxide (36.54%) in leaves and spathulenol (14.34%) in branches from G. silvatica. The diterpene kaurene (15.61%) was found in G. silvatica leaves. Larvicidal activity assay of essential oils against third-instar Aedes aegypti larvae revealed that at higher concentrations (500 and 250 μg/mL), all the essential oils caused 100% mortality after 24 h of exposure. The most active essential oils were those of G. humaitensis branches (LC50 48.6 μg/mL), G. scabra leaves (LC50 98.6 μg/mL) and G. silvatica (LC50 117.9 μg/mL). The differences in the toxicity of essential oils of Guarea species on A. aegypti are due to qualitative and quantitative variations of the components, therefore the larvicidal effect may be due to higher amount of the sesquiterpenes with caryophyllane skeleton. http://www.mdpi.com/1420-3049/15/8/5734/ Thu, 19 Aug 2010 00:00:00 CEST Molecules 2010-08-19 15 8 Article 5734 5741 1420-3049 Chemical Composition and Larvicidal Activity against Aedes aegypti Larvae of Essential Oils from Four Guarea Species 2010-08-19 doi: 10.3390/molecules15085734 Lyege Amazonas Maciel Amazonas Maciel Magalhães Maria da Paz Da Paz Lima Marcia Ortiz Mayo Ortiz Mayo Marques Roselaine Facanali Ana Cristina da Silva Pinto Wanderli Pedro Pedro Tadei http://www.mdpi.com/1420-3049/15/6/4227/ Free and polymeric carbohydrates in Cordyceps, a valued edible mushroom and well-known traditional Chinese medicine, were determined using stepwise pressurized liquid extraction (PLE) extraction and GC-MS. Based on the optimized PLE conditions, acid hydrolysis and derivatization, ten monosaccharides, namely rhamnose, ribose, arabinose, xylose, mannose, glucose, galactose, mannitol, fructose and sorbose in 13 samples of natural and cultured Cordyceps were qualitatively and quantitatively analyzed and compared with myo-inositol hexaacetate as internal standard. The results showed that natural C. sinensis contained more than 7.99% free mannitol and a small amount of glucose, while its polysaccharides were usually composed of mannose, glucose and galactose with a molar ratio of 1.00:16.61~3.82:1.60~1.28. However, mannitol in cultured C. sinensis and cultured C. militaris were less than 5.83%, and free glucose was only detected in a few samples, while their polysaccharides were mainly composed of mannose, glucose and galactose with molar ratios of 1.00:3.01~1.09:3.30~1.05 and 1.00:2.86~1.28:1.07~0.78, respectively. Natural and cultured Cordyceps could be discriminated by hierarchical clustering analysis based on its free carbohydrate contents. http://www.mdpi.com/1420-3049/15/6/4227/ Fri, 11 Jun 2010 00:00:00 CEST Molecules 2010-06-11 15 6 Article 4227 4241 1420-3049 Evaluation of Carbohydrates in Natural and Cultured Cordyceps by Pressurized Liquid Extraction and Gas Chromatography Coupled with Mass Spectrometry 2010-06-11 doi: 10.3390/molecules15064227 Guan Yang Li http://www.mdpi.com/1420-3049/14/12/5144/ Coconut water (coconut liquid endosperm), with its many applications, is one of the world’s most versatile natural product. This refreshing beverage is consumed worldwide as it is nutritious and beneficial for health. There is increasing scientific evidence that supports the role of coconut water in health and medicinal applications. Coconut water is traditionally used as a growth supplement in plant tissue culture/micropropagation. The wide applications of coconut water can be justified by its unique chemical composition of sugars, vitamins, minerals, amino acids and phytohormones. This review attempts to summarise and evaluate the chemical composition and biological properties of coconut water. http://www.mdpi.com/1420-3049/14/12/5144/ Wed, 09 Dec 2009 00:00:00 CET Molecules 2009-12-09 14 12 Review 5144 5164 1420-3049 The Chemical Composition and Biological Properties of Coconut (Cocos nucifera L.) Water 2009-12-09 doi: 10.3390/molecules14125144 Jean W. H. Yong Liya Ge Yan Fei Ng Swee Ngin Tan