The first chapter describes the oldest method of communication between living systems in Nature, the chemical language. Plants, due to their lack of mobility, have developed the most sophisticated way of chemical communication. Despite that many examples involve this chemical communication process - allelopathy, there is still a lack of information about specific allelochemicals released into the environment, their purpose, as well as in-depth studies on the chemistry underground. These findings are critical to gain a better understanding of the role of these compounds and open up a wide range of possibilities and applications, especially in agriculture and phytomedicine. The most relevant aspects regarding the chemical language of plants, namely, kind of allelochemicals have been investigated, as well as their releasing mechanisms and their purpose, are described in this chapter.
The second chapter is focused on the natural products obtained from Hypericum L., a genus of the family Hypericaceae within the dicotyledones. Hypericum has been valued for its important biological and chemical properties and its use in the treatment of depression and as an antibacterial has been well documented in primary literature and ethnobotanical reports. The present contribution gives a comprehensive summary of the chemical constituents and biological effects of this genus. A comprehensive account of the chemical constituents including phloroglucinol derivatives, xanthones, dianthrones, and flavonoids is included. These compounds show a diverse range of biological activities that include antimicrobial, cytotoxic, antidepressant-like, and antinociceptive effects.
The third chapter addresses microtubule stabilizers, which are a mainstay in the treatment of many solid cancers and are often used in combination with molecularly targeted anticancer agents and immunotherapeutics. The taccalonolides are a unique class of such microtubule stabilizers isolated from plants of Tacca species that circumvent clinically relevant mechanisms of drug resistance. Although initial reports suggested that the microtubule stabilizing activity of the taccalonolides is independent of direct tubulin binding, additional studies have found that potent C-22,23 epoxidated taccalonolides covalently bind the Aspartate 226 residue of β-tubulin and that this interaction is critical for their microtubule stabilizing activity. Some taccalonolides have demonstrated in vivo antitumor efficacy in drug-resistant tumor models with exquisite potency and long-lasting antitumor efficacy as a result of their irreversible target engagement. The recent identification of a site on the taccalonolide scaffold that is amenable to modification has provided evidence of the specificity of the taccalonolide-tubulin interaction and the opportunity to further optimize the targeted delivery of the taccalonolides to further improve their anticancer efficacy and potential for clinical development.
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Author Biography:
Francisco A. Mac�as was born in La L�nea de la Concepci�n, C�diz, Spain (1956). He has been Professor of Organic Chemistry at the University of Cadiz, (Spain) since 2000 and Head of the Institute of Biomolecules (INBIO) since 2014. He has been honored with the 1999 Rh�ne-Poulenc Rorer Award, Amsterdam, The Netherlands, from the Phytochemical Society of Europe (PSE), 2011 Molish Award, Guangzhou, China, from the International Allelopathy Society (IAS) and a Gold Medal, in Recognition of Research Excellence, Dedication, and Humanity, The European 2001 Forum, February 2015. His general philosophy is to learn from Nature. His research interests are related to different aspects of allelopathy dealing with higher plants and microorganisms, involving studies on natural and modified ecosystems, and developing new methodologies for allelopathic studies including mode of action. He heads the "Cadiz Allelopathy Group" a pioneering team in Europe in allelopathic studies from the organic chemistry perspective that has a multidisciplinary structure. Over the years, his group has isolated, identified, characterized, synthesized, and tested the bioactivity of more than 2600 potential allelochemicals and derivatives belonging to a wide range of chemical families including aglycons and/or glycosides (simple phenolics, coumarins, flavonoids, lignans, mono-, sesqui-, di-, spirodi-, mero-, and triterpenoids, steroids, benzoxazinoids among others) to permit their corresponding SAR studies. He has been named as a co-inventor of 12 international patents. His publications exceed 300, inclusive of book chapters. He has co-edited two books on "Recent Advances in Allelopathy" and has supervised 31 doctoral theses, and delivered more than 370 lectures around the world.
Alexandra Garc�a Dur�n -- after earning her Bachelor's degree in Chemistry, she received her Ph.D. degree in Sciences from University of Cadiz. During this period, she has specialized in isolation and synthesis to modify the physico-chemical properties of natural products in order to obtain enhanced biological activities. Furthermore, she was an international visiting scientist at Charles Sturt University in Wagga Wagga (Australia) and a postdoctoral fellow at Universit� degli Studi della Campania "Luigi Vanvitelli" (Caserta, Italy), which introduced her to the isolation and purification of natural products in NMR-based metabolomics studies. Currently, her main research interests are related to bioactivity, modes of action, mass spectrometry, and NMR spectroscopy.
Jos� M. G. Molinillo obtained a Ph.D. degree from the University of Cadiz. He visited the University of T�bingen, to learn new techniques for incorporation into his new research field, allelopathy. One of the main aspects he studied has been the search for new herbicides based on natural product lead compounds. He has investigated different plant species, among which sunflower is noteworthy, from which he isolated numerous sesquiterpene lactones and two new families of natural products, heliannuoles and helispiranes. Another highlight of his work is the study of benzohydroxamic acids and their degradation compounds, which occur in plants of the family Poaceae, such as wheat, corn, and barley. He has published 124 articles and 14 book chapters, and edited two books. His publications cover the organic chemistry of natural products and the search for new herbicides.
