Studies in natural products chemistry 

About: Studies in natural products chemistry is an academic journal published by Elsevier BV. The journal publishes majorly in the area(s): Total synthesis & Enantioselective synthesis. It has an ISSN identifier of 1572-5995. Over the lifetime, 642 publications have been published receiving 9533 citations.

Biological activity of essential oils and their constituents

Abstract: Recent work in the field of biologically active, essential oils is reviewed Essential oil extraction methods that are covered include cold pressing, extraction with other essential oils, steam distillation, solvent extraction, supercritical fluid extraction, and solid phase extraction Separation methods for the isolation of individual constituents that are covered include GC, LC, and distillation Biological activities of essential oils and their components, including antiallergic, enzyme inhibitory, psychological, anti-inflammatory, antimutagenic, anticarcinogenic, antiviral, insect repellent, molluscicidal, and antimicrobial are also reviewed In particular, several examples of our own and others' work in this area that are discussed include, 1) the structure and antimutagenic activity of new sesquiterpenoid eudesmol derivatives, 2) the biological activity and odor perception of optically active rose oxides, 3) the polyphenol oxidase inhibitory activity of acyclic terpene alcohols, commonly found in essential oils, that are used in cosmetic applications, 4) the effects of the diterpene phenol, totarol, in combination with known antibiotics, on a methicillin resistant Staphylococcus aureus(MRSA) strain, and 5) the synergistic antimicrobial activity of the combination of perillaldehyde and polygodial, constituents of two herbs found in traditional Japanese foods Also reviewed are the various uses and applications of essential oils that have been reported recently; examples included in the discussion are insect and animal repellents, oral care products, pharmaceuticals, drug delivery systems, topical applications, cosmetics, food preservatives, antioxidants, industrial applications, and the uses in packaging and consumer household products

Interference of alkaloids with neuroreceptors and ion channels

Abstract: Alkaloids represent one of the largest classes of natural products produced not only by plants but also by marine animals and amphibia, certain bacteria and fungi Their general function in plants and animals seems to be chemical defence against herbivorous and predating animals In order to fulfil this function alkaloids had to be shaped during evolution (by a process termed “evolutionary molecular modelling”) in such a way that they can interfere with important molecular targets of animals Neuronal signal transduction, especially interference with neuroreceptors, enzymes of neurotransmitter metabolism and signal transduction, and with ion channels represent such animal specific targets This review summarizes the experimental data on the molecular interactions of more than 300 alkaloids with neuroreceptors and ion channels and interprets these results under evolutionary and applied aspects, such as their exploitation as medicinal compounds or biorational pesticides for agriculture

Structure-Activity Relationships of Sesquiterpene Lactones

Abstract: Sesquiterpene lactones (STLs) are one of the largest biogenetically homogenous groups of natural products known. Currently, the Dictionary of Natural Products holds a total of over 11000 entries on sesquiterpenes, of which almost 5000 contain at least one lactone group. One reason for the large number of individual compounds and the associated structural diversity of this class of natural products is most certainly related to their enormously broad spectrum of biological activities, rendering them a highly valuable defense tool for those organisms synthesizing them. It is thus no surprise that the plant family from which most STLs have been isolated, i.e. the Compositae, is among the largest and ecologically most diverse plant families on our planet. Many of the biological activities of the most common types of STLs are known to be mediated by a simple general chemical mechanism, i.e. alkylation of biological macromolecules in terms of Michael type additions. These effects have been surveyed in numerous comprehensive reviews. Moreover, some very specific receptor-mediated activities of less frequent types of STLs are known. Quite surprisingly, despite the plethora of reports on STL bioactivity, only very few systematic studies on structure-activity relationships have been carried out. Detailed studies of this kind, however, would be highly desirable with respect to several aspects of medicinal/pharmaceutical, agrochemical and ecological interest. Most importantly, many STL-containing plants have been used in traditional medicines of all cultures for many centuries and continue to be utilized also in modern phytotherapy. Therapeutic use of STLs as pure chemicals is - in spite of their broad utilization in form of plants or crude extracts-restricted to very few examples, which is mainly due to a lack of knowledge on the structural requirements for selectivity with respect to a desired biological activity. It may, however, be conceived, that STLs could play a valuable role as lead structures to new therapeutic agents, if more information, especially in the form of quantitative structure-activity relationships (QSAR), existed. The present chapter attempts to present an overview on the current knowledge on structure-activity relationships of STLs of different types and different activities. Selected examples of current research in the author’s laboratory on structure-reactivity- and structure-activity relationships of STLs are presented.

Triterpene Glycosides from Sea Cucucmbers (Holothurioidea, Echinodermata). Biological Activities and Functions

Abstract: The holothuroid triterpene glycosides have strong membranolytic action against cellular and model membranes containing Δ5-sterols as result of the formation of single-ion channels and more large pores that is the basis of hemolytic, antifungal, antitumor cytotoxic activities of these compounds. The binding presence of an 18(20)-lactone, and at any rate of one oxygen functional group near it for compounds with 9(11)-double bonds in lanostane aglycon moiety, is very important for the membranotropic action of these substances. A linear tetrasaccharide fragment in the carbohydrate chain is also essential for membranolytic action. A sulfate group at C-4 of the first xylose residue increases the effect against membranes. The absence of a sulfate group at C-4 of the xylose residue in biosides decreases the activities more than one order of magnitude. The presence of a sulfate at C-4 of the first xylose of branched pentaosides having 3-O-methyl group at a terminal monosaccharide increases activity but the same sulfate decreases the activity of branched pentaosides having terminal glucose residues. Sulfate groups attached to a C-6 position of terminal glucose and 3-O-methylglucose residues greatly decrease activity. Some glycosides may inhibit chemokine receptor subtype 5 (CCR 5). This activity is correlated with toxicity. Some glycosides possess immunostimulatory action in subtoxic doses. The most effective immunostimulants are monosulfated glycosides but di- and trisulfated are immunosuppressors. The network diagrams illustrating the relationships between glycoside structural elements and functional components (partial activities) as well as with general glycoside activity are shown to be useful for non-quantative predication of biological activity. The glycosides regulate of oocyte maturation in the sea cucumbers to synchronize maturation processes. This role is caused by the modifying action of the glycosides on the membranes of holothuroid eggs. The absence or very low concentration of Δ5-sterols in oocyte membranes suggests another nature of the modifying action in comparison with that against membranes containing Δ5-sterols. Holothuroid glycosides have defensive function against predators.

Flavonoids as Anti-Inflammatory and Analgesic Drugs: Mechanisms of Action and Perspectives in the Development of Pharmaceutical Forms

Abstract: Flavonoids are polyphenolic compounds with very diverse roles. In this chapter, we examined the bioactivity and potential of flavonoids as anti-inflammatory and analgesic drugs and the perspectives on their applicability and pharmaceutical development. Further, the mechanisms of action of flavonoids are addressed, for example, their effects on cytokine production, oxidative stress, and inhibition of protein kinases. In addition, the role of these mechanisms in inflammation and pain, and the structure–activity relationship are discussed.