Sequestration Of Alkaloids Defense Metabolism And Communication

In a sense, alkaloidal sequestration constitutes the transfer of compounds from the producer to the receiver (predator). In effect, this transfer effectively arms the predator with at least some of the alkaloidal defenses of the ingested plant or animal, probably at little energetic expense to the receiver. Significantly, if a specialist herbivore feeds on an alkaloid-rich plant, it is adapted to tolerate these nitrogen heterocycles which usually render it unpalatable to diverse predators. On...

Food Production On Limited Resources

We have 32.5 billion acres of land in the world. Only 24 or 8 billion acres is potentially suitable for cultivation. The important groups of world food crops (cereal, food legumes, and oilseeds) utilize over 2 billion acres, producing over 1 billion metric tons of food per year (Table I.1). About 70 of the land (23 billion acres) cannot be used for food production. This land is located where it is either too cold, too dry, or too steep, or the soil is too thin (Table 2). About 10 , or 3.2...

Extraction and isolation of diterpenes from P natans

The air-dried and powdered plant material (13 kg) was sequentially and exhaustively extracted with light petroleum, EtOAc and MeOH. The light petroleum extract (66 g) was chromatographed on silica gel eluting with hexane and EtOAc solutions to give fraction A-B. Fraction A eluted with hexane - EtOAc (19 1), was chromatographed using hexane - EtOAc (17 3) as eluent to give pure compounds 8 (57 mg) and 11 (125 mg). Fraction B, eluted with hexane - EtOAc (17 3), was filtered on Sephadex LH-20...

Data analysis

Raw data for all bioassays, except algal test, were analyzed using the Toxcalc Toxicity Data Analysis and Database Software, vers. 5.0 (Tidepool Scientific Software). Point estimations were calculated by concentration response regression using Probit Analysis as first choice and Trimmed Spearman-Karber as second, if Probit was not possible. If the raw data did not allow the respective L(E)C50 to be calculated at the highest tested concentrations, then these values were determined by direct...

Physiological And Biochemical Targets For Alkaloids

Since some alkaloids exhibit great mammalian toxicity (e.g., batrachotoxin, samandarine), it is obvious that these compounds are capable of initiating severe biochemical and physiological lesions. However. it should not be overlooked that toxicological evaluations of most alkaloids have been implemented by in vitro studies in which the alkaloids have been introduced subcutaneously. On the other hand, in nature, in the absence of a venom apparatus, these compounds would be introduced into the...

Pharmacological Properties Of Qa

In addition to toxic and repellent properties, lupin alkaloids have a number of pharmacological activities.15,47,52 Sparteine, lupanine, and other QA exhibit antiarrhythmic properties. Since only sparteine can be isolated easily from broom (Cytisus scoparius) it is the only lupin alkaloid that is commercially available and exploited in medicine as an antiarrhythmic drug. However, about 10 of all patients are unable to metabolize sparteine and suffer from sparteine intoxication. Because of these...

Alkaloids For Defense And Exploitation

Plant alkaloids often demonstrate defensive activity against a wide variety of predators and competitors among which are microorganisms, fungi, viruses, invertebrate and vertebrate herbivores, and plants, including immatures of their own species. Since these alkaloids, termed allelochemicals, have been evolved as deterrents for very different classes of organisms, in plants their production and storage often result in mixtures of structurally diverse alkaloids that are stored at specific sites....

Chemical Defense Based On Alkaloids

Overall, plants are quite capable of defending themselves from diverse microorganisms, herbivores, and other plants. Candidates for this protective role are their allelochemicals, which may possess deterrent repellent or toxic properties for a wide range of competitors.37 Included in the allelochemicals are the alkaloids, which are generally considered to be bitter (e.g., quinine, brucine) and in some cases very toxic (e.g., tetrodotoxin, batrachotoxin). Although at a glance the alkaloids...

Allelopathy

CHEMISTRY AND MODE OF ACTION OF ALLELOCHEMICALS EDITED BY Francisco A. Macias Juan C. G. Galindo Jos M. G. Molinillo Horace G. Cutler Boca Raton London New York Washington, D.C. Allelopathy chemistry and mode of action of allelochemicals edited by Francisco A. Macias, Juan C.G. Galindo, Jos M.G. Molinillo, and Horace G. Cutler. p. cm. Includes bibliographical references and index. ISBN 0-8493-1964-1 alk. paper 1. Allelochemicals. 2. Allelopathic agents. 3. Allelopathy. I. Macias, Francisco A.,...

Concentration M

Effect of - -usnic acid - - 0.01-100 M on activity of HPPD. The activity of the herbicide sulcotrione was added for comparison - - . Lichens containing usnic acid may exhibit phytotoxic activity. In nature, - -usnic acid may decrease interspecific competition by inhibiting growth of seedlings in the canopy. Since it is primarily an HPPD inhibitor and secondarily inhibits Protox, there may be a decreased chance for resistance in those competing species. Emodin is a naturally occurring...

References

Standard Guide for Conducting Static 96h Toxicity Tests with Microalgae, E1218-90. American Society for Testing and Materials, Philadelphia, USA 2 Bohlmann, F., Ahmed, M., Borthakur, N., Wallmeyer, M., Jakupovic, J., King, R. M., and Robinson, H., 1985. Diterpenes related to grindelic acid and further constituents from Grindelia species. Phytochemistry 21, 167-17 3 Cangiano, T., DellaGreca, M., Fiorentino, A., Isidori, M., Monaco, P., and Zarrelli, A. 2001. Lactone diterpenes...

Contributors

Dipartimento di Scienze della Vita, II Universit di Napoli, via Vivaldi, 43-81100 Caserta, Italy. e-mail aliotta unina.it A. L. Anaya. Laboratorio de Alelopat a. Instituto de Ecolog a, UNAM. AP. 70-275. Ciudad Universitaria, 04510, M xico, D.F. M xico. e-mail alanaya miranda.ecologia.unam.mx G. Ayala-Cordero. Laboratorio de Alelopat a. Instituto de Ecolog a, UNAM. AP. 70-275. Ciudad Universitaria, 04510, M xico, D.F. M xico. U. Blum. Department of Botany, North Carolina State...

Methodology

Twenty-five lettuce seeds Lactuca sativa cv. iceberg , onion Allium cepa L. cv. Evergreen Bunching , or a small scoop of bentgrass Agrostis tenuis Sibth were placed on sterile 55-mm dia. filter paper fitted to 60 x 15-mm petri dishes. Filter paper was premoistened with 3 mL of the test solutions. Stock solutions of test compounds were prepared in acetone to obtain final assay concentrations of 100, 33, 10, 3, 1, 0.3, 0.1, and 0.03 uM with volume of carrier solvent being lt 1 in the assay....

Introduction

Lichens are a classic example of symbiosis. This partnership may contain up to three kingdoms, including a fungal mycobiont and algal and or cyanobacterial photobiont partners. These organisms produce a variety of secondary compounds, most of which arise from the secondary metabolism of the fungal component and are deposited on the surface of the hyphae rather than compartmentalized in the cells. Many of these compounds are unique to lichens, with a small minority ca. 60 occurring in other...

Results And Discussion

- -Usnic acid is one of two naturally occurring biologically active enantiomers Fig. 1.1 that are found in most yellow-green lichens. This compound is biosynthesized via the polyketide pathway and is categorized as either a dibenzofuran or triketone. The enantiomers, which differ in the orientation of the methyl group at 9b on the otherwise rigid molecule, have been identified as showing different biological activities and mechanisms of action. Usnic acid has been documented to have...