g tetanus toxin botulinus toxin and diphtheria toxin Toxicity may affect a

E.g. tetanus toxin, botulinus toxin, and diphtheria toxin  Toxicity may affect a variety of organ systems, including the nervous system and the cardiovascular system 39

Mycotoxins  Mycotoxins do not constitute a separate chemical category, and they lack common molecular features  Mycotoxins of most interest are those found in human food or in the feed of domestic animals  They include the ergot alkaloids produced by Claviceps sp. which cause toxicity to the nervous system and also have vasoconstrictors.  Outbreaks of ergotism in livestock do still occur frequently  Aflatoxins produced by Aspergillus are common contaminant of grain, maize, peanuts  Carciogenic  However, the most toxic one aflatoxin 1 has to be activate enzymatically to exert its carcinogenic effect 40

Plant Toxins  Also called phytotoxins  Some toxins may be repellent but not particularly toxic, or they may be acutely toxic to a wide range of organisms  Many of the common drugs of abuse such as cocaine, caffeine, nicotine, morphine, and the cannabinoids are plant toxins 41

Animal Toxins  Some are passively venomous, often following inadvertent ingestion (can be considered as only poisonous)  whereas others are actively venomous, injecting poisons through specially adapted stings or mouthparts (can be referred to as venomous)  Animal toxins may present as enzymes and neurotoxic and cardiotoxic peptides and proteins or as small molecules such as alkaloids, glycosides, terpenes  In many cases the venoms are complex mixtures that include both proteins and small molecules  For example, bee venom contains a biogenic amine, histamine, three peptides, and two enzymes 42

Animal Toxins  Human may have aggressive reaction to venoms in the form of anaphylactic shock  Snake venoms have been studied extensively; their effects are due, in general, to toxins that are peptides with 60 to 70 amino acids  These toxins are cardiotoxic or neurotoxic, and their effects are usually accentuated by the phospholipases, peptidases, proteases, and other enzymes present in venoms. These enzymes may affect the blood clotting mechanisms and damage blood vessels 43

Animal Toxins  Many fish species, over 700 species worldwide, are either directly toxic or upon ingestion are poisonous to humans  A classic example is the toxin produced by the puffer fishes (Sphaeroides spp.) called tetrodotoxin (TTX). Especially when eaten uncooked (as in Japan called “fugu” it causes death within 5 to 30 minutes  TTX is an inhibitor of the voltage-sensitive Na channel (like saxitoxin); it may also be found in some salamanders and may be bacterial in origin 44

Toxins  some of the most widely used drugs and therapeutics like streptomycin, the aminoglycoside antibiotic from soil bacteria, and acetylsalicylic acid (aspirin) from willow tree bark, are used by millions of people everyday to improve health and well-being 45