Published on August 20, 2021
Written by sciencedirect.com
Alkaloids is a term used collectively to describe a large and diverse group of chemicals that have alkali-like properties and at least one nitrogen atom in a heterocyclic ring structure.
Breeding genetics and biotechnologyD.J. Murphy, in Encyclopedia of Applied Plant Sciences (Second Edition), 2017
Reasons for Engineering Alkaloid BiosynthesisAlkaloids have been isolated as crude extracts from plants for many millennia as part of folk medications. Since the twentieth century, however, individual alkaloids with defined and scientifically verified pharmacological properties have been purified and produced commercially as fine chemicals.
The complexity of alkaloid molecules means that they are in most cases impossible to produce de novo by chemical synthesis, so extraction from a crude plant mixture remains the most economically viable strategy.
However, plants normally produce highly complex mixtures of alkaloids with the desirable types often at low levels, with the result that commercially produced specific alkaloids are very expensive.
As the genetic manipulation of plants becomes more sophisticated, research has focused on the engineering of alkaloid biosynthesis to generate transgenic plants or cell lines that overproduce specific alkaloids. This can be achieved by increasing the synthesis of a particular alkaloid and/or inhibiting the synthesis of related compounds to increase the ease of purification.
Understanding the nutritional and biological constranits of ingredients to optimise their application in aquaculture feedsBrett Glencross, in Aquafeed Formulation, 2016
188.8.131.52.1 AlkaloidsAlkaloids are generally bicyclic, tricyclic, or tetracyclic derivatives of the molecule quinolizidine (Petterson et al., 1999). Data on the influence of alkaloids on fish, show that alkaloids are generally considered a feeding deterrent because of their bitter taste (Glencross et al., 2006; Serrano et al., 2011, 2012).
While the alkaloids are found primarily in the legumacae family (peas and beans), high levels are found in some varieties of lupins (Glencross et al., 2006). Present levels of alkaloids in commercial lupin varieties, such as Lupinus angustifolius are usually less than 200 mg/kg.
Botanical pesticides with virucidal, bactericidal and fungicidal activityLuminita Marutescu, … Mariana Carmen Chifiriuc, in New Pesticides and Soil Sensors, 2017
2.2 AlkaloidsAlkaloids are widely distributed in species belonging to several families within angiosperms. They are versatile heterocyclic nitrogen compounds with reported antimicrobial activity against fungal or bacterial phytopathogens.
Furoquinoline alkaloids, quinolizidine alkaloid extracts, isoquinoline alkaloids (corynoline and acetylcorynoline), pyrrolizidine alkaloids have been mentioned as active compounds (Joosten and van Veen, 2011; Pérez-Laínez et al., 2008).
The multitarget mechanisms of action are represented by the outer membrane or cytoplasmic membrane disruption, respiratory inhibition, the Z-ring perturbation, and nucleic acid synthesis/cell division inhibition (Bardin et al., 2015; Cushnie et al., 2014).
Toxicological profile of Indian foods – ensuring food safety in IndiaS.P. Singh, … D. Singh, in Food Safety in the 21st Century, 2017
184.108.40.206.3 AlkaloidsAlkaloids are nitrogenous compounds of low molecular weight. They are mainly produced by plants and animals for defense. Examples of alkaloids include morphine, codeine, coniine, quinine, scopolamine, hyoscamine, atropine, caffeine, sangunarine, berberine, etc.
About a fifth of total plant species are believed to produce them. Frogs, for example Bufo marinus, contain large quantities of morphine in their skin. Many of these alkaloids have been in use in modern medicine for various purposes. For example, morphine and codeine are used to produce analgesia, while caffeine is used as a central nervous stimulant.
New light on Alkaloid biosynthesis and future prospectsSergey B. Zotchev, in Advances in Botanical Research, 2013
1 IntroductionAlkaloids are structurally diverse compounds generally classified as such due to the basic character of the molecule (from Latin alkali) and a presence of at least one nitrogen atom, preferably in a heterocycle. Many of the naturally occurring alkaloids have biological activity, and some of them are being used as drugs in modern medicine (e.g. morphin, codeine, reserpine, etc.).
Although originally discovered in plants and then in marine sponges, many alkaloids have recently been identified in cultivable microorganisms, which provide opportunities for their sustainable production.
A large number of biologically active alkaloids, many of which contain highly reactive halogen atom(s), have been isolated from marine sources, such as sponges, tunicates and other marine animals (Blunt, Copp, Keyzers, Munro, & Prinsep, 2013).
However, a growing body of evidence suggests that these compounds are most likely produced not only by the macro-organisms themselves but also by their symbiotic or associated bacteria and fungi (Hentschel, Piel, Degnan, & Taylor, 2012).
Challenges in cultivation of such microorganisms, however, make it difficult to unequivocally determine the true origin of some alkaloids. Metagenomics approach can be used in such cases to identify alkaloid biosynthesis genes, which can be traced to their microbial host (Freeman et al., 2012).
This chapter reviews alkaloids recently identified in marine bacteria as well as biosyntheses and biological activities of some representative compounds.
Levels and potential health impacts of nutritionally relevant phytochemicals in organic and conventional food productionEduardo A.S. Rosa, … Alfredo Aires, in Handbook of Organic Food Safety and Quality, 2007
AlkaloidsAlkaloids are present in a wide range of plant families and have a variety of biological effects (Roberts and Wink, 1998). They are divided into two major classes: the proto-alkaloids (nitrogen-containing but not heterocyclic in structure, e.g. phenylethylamines) and the true alkaloids (nitrogen-containing heterocyclic compounds).
Their function in plants is primarily as defence compounds against insect pests and herbivorous animals. Other than the known medicinal plant species, there are few food plants that contain significant levels of alkaloids.
However, members of the Solanaceae have the potential under stress conditions, such as potato tubers exposed to light, to accumulate high concentrations of alkaloids. Examples include a-solanine (Fig. 15.3, structure 27), the related a-chaconine and also a-tomatine in tomatoes (Fig. 15.3, structure 28) (Beier and Nigg, 1992).
Alkaloid exposure can also occur from consumption of some herbal preparations that have been contaminated with weed species that have high levels of alkaloids. This is a possible risk with both organic and conventional cultivation, i.e. weed species could inadvertently be harvested and incorporated into the food material.
The alkaloids causing greatest concern are the highly toxic/mutagenic pyrrolizidine alkaloids (Prakash et al., 1999; Lin et al., 2002b). Examples include heliotropine from Heliotropus species and senecionine from Senecio (groundsel) species (Fig. 15.3, structures 29 and 30, respectively).
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