Large herbivores must select food from a wide variety of plant parts, species, and strains. These differ in nutritional value (protein, carbohydrate, etc.), toughness, spinosity, etc. Even greater differences are found in types and concentrations of secondary compounds. Every plant produces its own set of secondary chemical compounds, which to a great extent are unique to it or its species. Ingestion of natural concentrations of these compounds can lead to either death or severe physiological impairment. The ubiquitous nature of these compounds would make herbivory impossible unless animals had mechanisms for degrading and excreting them. An animal displaying no obvious symptoms of poisoning is not free of the problem of ridding itself of toxic compounds; if it is eating plants, it almost certainly has this problem. Herbivores are capable of detoxifying and eliminating secondary compounds. Limitations of these mechanisms force mammalian herbivores to consume a variety of plant foods at any one time, to treat new foods with caution, to ingest small amounts on the first encounter, and to sample food continuously. Selection of foods is based on learning in response to adverse internal physiological effects, and herbivores probably cannot predict these from the smell or taste of new foods. Herbivores prefer to eat familiar foods and can seek out and consume foods that rectify specific nutritional deficiencies induced by detoxification. They should prefer to feed on foods that contain small amounts of secondary compounds, and their body size and searching strategies should be adapted to optimize the number of types of foods available with respect to the total amount of food that can be eaten and will be present in the future. Natural selection can increase the efficiency of degrading particular secondary compounds. Specialist herbivores, like koala and mountain viscacha, are expected where a large amount of several related toxic foods is present in a year-round supply. However, few large herbivores are specialized on such a restricted range of foods.

Strategies in herbivory by mammals: the role of

Large herbivores must select food from a wide variety of plant parts, species, and strains. These differ in nutritional value (protein, carbohydrate, etc.), toughness, spinosity, etc. Even greater differences are found in types and concentrations of secondary compounds. Every plant produces its own set of secondary chemical compounds, which to a great extent are unique to it or its species. Ingestion of natural concentrations of these compounds can lead to either death or severe physiological impairment. The ubiquitous nature of these compounds would make herbivory impossible unless animals had mechanisms for degrading and excreting them. An animal displaying no obvious symptoms of poisoning is not free of the problem of ridding itself of toxic compounds; if it is eating plants, it almost certainly has this problem. Herbivores are capable of detoxifying and eliminating secondary compounds. Limitations of these mechanisms force mammalian herbivores to consume a variety of plant foods at any one time, to tr...

Strategies in Herbivory by Mammals: The Role of Plant Secondary Compounds

Self-assembly of bovine epidermal keratin filaments in vitro

Unusual amino acids are fundamental building blocks of modern medicinal chemistry. The combination of readily functionalized amine and carboxyl groups attached to a chiral central core along with one or two potentially diverse side chains provides a unique three-dimensional structure with a high degree of functionality. This makes them invaluable as starting materials for syntheses of complex molecules, highly diverse elements for SAR campaigns, integral components of peptidomimetic drugs, and potential drugs on their own. This Perspective highlights the diversity of unnatural amino acid structures found in hit-to-lead and lead optimization campaigns and clinical stage and approved drugs, reflecting their increasingly important role in medicinal chemistry.

Unusual Amino Acids in Medicinal Chemistry.

Plant secondary metabolites, which include a wide variety of phytochemicals, have always been constituents of the diets of man and other animals. Although a high proportion of these phytochemicals have been considered to be of little value in plants (although this view is changing), they have frequently been shown to have adverse effects on animals when ingested. The effects depend to a great extent on the chemistry of the compounds, their concentration in the diet and the amount consumed, and are further dependent on the health status of the animals. Traditionally, most studies of the effects of these compounds on animals have focused on their adverse effects and how to alleviate them. However, recent public concern about the use of synthetic compounds in animal diets to enhance performance and health and welfare issues, coupled with changes in regulations on the use of synthetic medicaments, has stimulated interest and research in the use and effects of phytochemicals in the diets of farmed animals. Phytochemicals vary in their chemistry but can be divided into hydrophilic and hydrophobic compounds, of which a wide variety of polyphenolic and terpenoid compounds, as well as alkaloids, carbohydrates and non-protein amino acids, invoke special interest. The chemistry, biochemistry and mechanisms of action of these compounds in plants and their effects in animals when ingested will be explored.

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Biochemistry of plant secondary metabolites and their effects in animals.

Loss of hair in animals following ingestion of seeds and foliage of Leucaena glauca was first reported in 18971. Sudden loss of hair in native women has been ascribed to consumption of Leucaena glauca seeds2. The toxic principle contained in this plant is a water-soluble amino-acid termed leucenol, and is identical with mimosine obtained from Mimosa pudica3. Mimosine seems to be the preferred name for the compound, both by historical precedent4 and to avoid confusion with leucinol, an alcoholic derivative of leucine. Mimosine is found primarily in the seeds of Leucaena glauca, lesser amounts being present in the foliage and stems5. Its chemical structure is:

Inhibition of growth of hair by mimosine.

Epidermal keratin: a re-evaluation.

https://www.jidonline.org/article/S0022-202X(15)46921-0/pdf

Robert G. Crounse

Papers

Inhibition of growth of hair by mimosine.

Epidermal keratin: a re-evaluation.

The amino acid composition of protein fractions from normal and abnormal epidermis.

CHAPTER XVIII – Alkali-Soluble Human Epidermal Proteins1