Natural Products Articles

Concerns about the safety and efficacy of dietary and herbal products are generating manufacturing requirements and analytical standards for ingredients.

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PC SPES (PC for prostate cancer and SPES in Latin for "hope") is a dietary supplement consisting of extracts of o­ne North American plant [Serenoa repens (Bartram) Small; saw palmetto] and seven Chinese herbs [Dendranthema morifolium (Ramat.) Kitam., Ganoderma lucidum Karst., Glycyrrhiza glabra L., Isatis indigotica Fort., Panax pseudo-ginseng Wall., Rabdosia rubescens (Hemsl.) Hara, and Scutellaria baicalensis Georgi], which has gained popularity as an alternative therapy for advanced prostate cancer (PC) due to its demonstrated clinical efficacy and improvement of quality of life for hormone-refractory PC patients. 

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Biologically active peptides, amines, steroidal bufadienolides, and samandarine alkaloids represent some of the classes of compounds that amphibians elaborate and store in granular skin glands, apparently for chemical defense against microbial skin infections and/or predators. However, the wide variety of lipophilic alkaloids, discovered in skin of dendrobatid frogs, do not appear to be synthesized by such frogs, since captive-raised dendrobatid frogs completely lacked such alkaloids, but could sequester alkaloids unchanged into skin. Ants, beetles, and millipedes were found to represent the dietary source for many of the "dendrobatid alkaloids".

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Dolan examines some options for increasing the retention of polar compounds, which is a goal when using gradient elution scouting runs to screen the retention characteristics of compounds for separation by reversed-phase liquid chromatography.

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The kahalalides are depsipeptides isolated by the Scheuer group from the sacoglossan mollusk Elysia rufescens Pease 1871 (Plakobranchidae) and its green algal diet, a Bryopsis sp. (Bryopsidaceae). Seven cyclic depsipeptides, kahalalides A-F and O, and three linear peptides, kahalalides G, H, and J, ranging from a C₃₁ tripeptide to a C₇₅ tridecapeptide, have been previously described from the mollusk. Kahalalide G, the acyclic analogue of kahalalide F, was found in the diet of the animal. Except for the unusual dehydroaminobutyric acid (Dhb) in kahalalides F and G, all constituent amino acids are of common occurrence. Each peptide also contains an aliphatic acid

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Over the past few years, clinical evidence for the antidepressant activity of St. John's wort (Hypericum perforatum L., Hypericaceae) extracts has sparked great interest in the chemistry and biochemistry of this plant, generating also coverage in the mainstream press. Despite the lack of a clear correlation between the chemical composition of St. John's wort extracts and in vivo activity which would explain the clinical benefits of the plant, Hypericum preparations are licensed in Continental Europe for the treatment of depression and anxiety. They have been suggested for the first-line treatment of mild to severe depression, especially in the primary care setting, and are also available over-the-counter or as food supplements in Great Britain and the United States. St.

This study investigated the effects of some essential oils o­n Limantria dispar (Lepidoptera: Lymantridae, gypsy moth) larvae, o­ne of the most serious pests of cork oak forests. The essential oils were first formulated as oil in water (o/w) emulsions and used in laboratory bioassays to assess their lethal concentration (LC50). Microcapsules containing the most promising oils (Rosmarinus officinalis and Thymus herba-barona) were then prepared by a phase separation process, followed by freeze-drying. The formulations thus obtained, characterized in terms of essential oil content and composition, morphology, storage stability, and release profile, were tested o­n gypsy moth larvae. The results showed that the tested oils possess interesting larvicidal effects that make them suitable for application in integrated control strategies. The microencapsulation process gave high encapsulation yields (over 98%) with both essential oils, which have different chemical compositions.

Valerian is a widely used plant-based medicine (1-3). Valerian (Valeriana officinalis L.) native to Europe and Asia is indicated mostly as a mild sedative and as a sleep aid (4). Valerian improves subjective experiences of sleep when taken nightly over o­ne- to two-week periods but long-term safety studies are lacking (5). Valerian is a member of the Valerianaceae family that includes up to 250 species (6). Common species include, but are not limited to, Valeriana wallichii, Valeriana edulis and Valeriana officinalis. The latter is composed of five subspecies and is the species most likely to be commonly used in North America. The parts of the plant used for therapeutic purposes are the roots and the rhizomes. The constituents of Valerian include valepotriates (iridoids), the components of the volatile oil, including monoterpenes and sesquiterpenes (valerenic acids), as well as a number of other constituents (7).

The epothilones A and B were first discovered as antifungal and cytotoxic metabolites in the myxobacterium Sorangium cellulosum. Later they were rediscovered as inhibitors of the tubulin system in a target-oriented screening designed for the detection of Taxol mimetics. The epothilones like Taxol and other taxoids stabilize microtubules, leading to arrest of the cell cycle and eventually to apoptosis. Although their chemical structures are quite diverse, both groups of compounds appear to bind at the same or closely related binding sites o­n -tubulin. Among several beneficial properties, most interestingly, the epothilones are highly active against cell lines resistant to Taxol and other anticancer agents. This resistance is commonly based o­n the induction of the P-glycoprotein drug-transport system and in case of taxoids also o­n mutations in the -tubulin gene.

Part two of a series about a novel spectrofluorometric method that allows for in vivo observation of division of chloroplast populations in leaves of Arabidopsis thaliana.


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