Bioactive terpenoids

Bioactive polyphenol acids and lignans with 0-heterocyclic fragments and terpenoid 8-lactones as components of traditional Chinese drugs 98PAC547. 

Terpenoids with heterocyclic fragments as bioactive taxoids from Japanese yew Taxsus cuspidata and taxol biosynthesis 98H(47) 1111. 

Synthesis of decalin synthons of bioactive terpenoids Lewis-acid-cataiyzed Dieis-Aider reactions [109]... 

Supercritical fluid extraction — During the past two decades, important progress was registered in the extraction of bioactive phytochemicals from plant or food matrices. Most of the work in this area focused on non-polar compounds (terpenoid flavors, hydrocarbons, carotenes) where a supercritical (SFE) method with CO2 offered high extraction efficiencies. Co-solvent systems combining CO2 with one or more modifiers extended the utility of the SFE-CO2 system to polar and even ionic compounds, e.g., supercritical water to extract polar compounds. This last technique claims the additional advantage of combining extraction and destruction of contaminants via the supercritical water oxidation process."... 

Abstract Recent chemical studies on the marine soft corals and terrestrial plants have lesnlted in the isolation of several novel componnds. The soft corals, Pseudopterogorgia elisabethae and Cladiella species yielded several novel terpenoids, exhibiting antimicrobial activities. New steroids were isolated from terrestrial fungi, Mucor plumbeus and Coprims micaceus. Phytochemical studies on the Buxus hyrcana, collected from Iran, have yielded steroidal bases. This revdew describes the new natiual products exhibiting different bioactivities from the aforementioned sources. 

In this presentation, bioactivity-directed isolation and stmcture elucidation of the active constituents will be given. Structures of the constituents, which form namely terpenoids (sesqni, di- and triterpenoids) were based on spectroscopic tech-niqnes, particnlarly intensive NMR and Mass spectroscopies. 

Monoterpenes, 10-carbon-containing terpenoids, are composed of two isoprene units, and found abundantly in plants, e.g. (+)-limonene from lemon oil, and (—)-linalool from rose oil. Many monoterpenes are the constituents of plant volatile oils or essential oils. These compounds are particularly important as flavouring agents in pharmaceutical, confectionery and perfume products. However, a number of monoterpenes show various types of bioactivity and are used in medicinal preparations. For example, camphor is used in liniments against rheumatic pain, menthol is used in ointments and liniments as a remedy against itching, bitter-orange peel is used as an aromatic bitter tonic and as a remedy for poor appetite and thymol and carvacrol are used in bactericidal preparations. 

There is a huge variety of plant defensive secondary metabolites that has been the subject of major phytochemical [1-6] or pharmacological and toxicological [7-12] compilations. This structural complexity is very briefly reviewed below before considering those plant bioactives with signal transduction targets. The major groups are the phenolics, the terpenoids and the alkaloids as well as bioactives structurally related to... 

Macias, F.A., Torres, A., Galindo, J.L.G., Varela, R., Alvarez, J,A., Molinillo, J.M.G Bioactive terpenoids from sunflower leaves cv. Peredovick (R). Phytochem 2002b 61 687-692. 

This is nicely demonstrated by two contributions to this volume. On one hand, electrochemical strategies for the synthesis of complex bioactive alkaloid structures are developed, and on the other, the electrochemical transformation of readily available bio-molecules (terpenoids and p-lactarns) into enantiomerically pure complex synthetic building blocks is demonstrated. 

ABSTRACT This article reviews the literature published dealing with the synthesis of some bioactive diterpenes. It describes the biological activity and synthesis of only four diterpenes pisiferic acid, camosic acid, triptolide and miltirone. This review excludes the discussions of Taxodione, a bioactive diterpene, because it has already been reviewed [85], The utility of several reagents in the total synthesis of terpenoid compounds has been documented. It can be observed that several routes have been developed for the synthesis of a single diterpene. 

A variety of other plant compounds are bioactive as toxins, pro-toxins, sweet or bitter tas-tants, odorants, semiochemicals, enzyme inhibitors, receptor agonists, receptor antagonists or psychoactive agents. The structure and bioactivity of non-alkaloid, non-phenolic and non-terpenoid plant compounds is briefly reviewed below. Some selected structures of cyclic compounds in this category are shown in the Appendix (Section 4). 

One reason that dominant plants are successful in semi-arid and arid ecosystems is due to the high concentration of terpenoids and prenylated phenolics that repel and/or deter feeding by herbivorous insects. Compounds like sesquiterpene lactones and benzopyrans are present in high quantities in the leaves of species of Pjajl t h ij jn, E n c e l i a and D i c o r i a and have been demonstrated to be effective feeding deterrents against known economic insect pests. Ijt vivo experiments are still needed in the field with bioactive constituents to better understand their effects on native phytophagous insects. 

These pleiotropic multitarget bioactivities are not spedflc, but are nevertheless effective, and this is critical in an ecological context. Compounds with pleiotropic properties have the advantage that they can attack any enemy that is encormtered by a plant, be it a herbivore or a bacterium, fungus, or vims. These classes of compounds are seldom unique constituents quite often plants produce a mixture of secondary metabolites, often both phenolics and terpenoids, and thus exhibit both covalent and noncovalent interactions. These activities are probably not only additive but synergistic [10,25]. 

Mauri, R Migliazza, B. Pietta, P. Liquid chromatography/electrospray mass spectrometry of bioactive terpenoids in Ginkgo biloba L. J. Mass. Spec., 1999, 34 1361-1367. 

Tanacetum species contain mainly sesquiterpenoids and flavonoids, whereas the other terpenoids and phenolic compounds are rarely found. Sesquiterpenoids which are the main constituents of the genus, supposed to be bioactive principles of the plants. Flavonoids and essential oils are also pointed out as active substances in some species. On the other hand, there is a confusion on the systematic position and classification of several species of Asteraceae, therefore chemotaxonomy of the species will help the systematic studies. 

Termite soldiers produce a large number of different chemical defense agents. Several of these molecules are unusual bioactive terpenoids such as the secotrinervitanes that have been isolated and their structure elucidated. In the laboratory of T. Kato, the total synthesis of (+)-3a-acetoxy-7,16-secotrinervita-7,11-dien-15P-ol was accomplished. The Nagata hydrocyanation was used to introduce a carbon at the P-position of a macrocyclic enone intermediate. The substrate was treated with excess diethylaluminum cyanide in dry toluene and the addition resulted in the formation of a 1 1 mixture of diastereomers, which could be readily separated by column chromatography. The cyano group was later converted to the corresponding methyl ester. 

Development of palladium-catalyzed cycloalkenylation and its application to the synthesis of natural bioactive O-heterocycles and terpenoids 02SL1211. 

From the viewpoint of organic synthesis, nature provides us with a number of target molecules, which have novel structures and a variety of biological activities. As already shown in Section II.A, electrochemical oxidation of phenols has been applied successfully to natural products synthesis. Hypervalent (diacyloxyiodo)benzenes have also been proved to be effective for natural products synthesis. Generally, oxidation of o- and p-methoxyphenols in MeOH provides the corresponding o- and p-quinone monoketals, respectively. They are utilized as promising synthons for natural products and related bioactive compounds, as demonstrated by Swenton . Recently, these quinone monoketals have been utilized for syntheses of terpenoids, neolignans, anthraquinones, alkaloids and related compounds. 

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