As with the Plant Kingdom, animals are classified into Phyla, Classes, Orders, Families, Genera and Species. Although the number of phar- macognostical products derived from animal sources is limited there has been, in recent years, an immense interest in the chemistry of many marine creatures as potential sources of drugs and biologically active materials. In this respect much research has been published on the simpler marine organisms, see G. Blunden in Trease and Evans 2002 Pharmacognosy, 15th ed., p. 18.
Listed below are selected animal phyla which embrace species of interest (the many animal products used in traditional medicines of Africa, India and the Orient are not included).
PROTOZOA
Unicellular microorganisms including parasites causing malaria (Plasmodium), sleeping sickness (Trypanosoma) and dysentery (Entamoeba). Some dinoflagellates (Prorocentrum, Dinophysis) produce polyether toxins responsible for some shell-fish poisoning.
A TAXONOMIC APPROACH TO THE STUDY OF MEDICINAL PLANTS AND ANIMAL-DERIVED DRUGS 43
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PORIFERA (Sponges)
Metabolites include bromophenols (antibacterial properties), cyclic peroxides and peroxyketals (antimicrobial, ichthyotoxic, cytotoxic activities), modified sesquiterpenes (antimalarial, antifungal, antibac- terial, anticancer activities). Siliceous sponge spicules are often found in samples of kieselguhr and agar (q.v.).
COELENTERATA
(Jellyfishes, sea anemones, corals)
The soft coral Plexaura homomalla is a rich source of prostaglandin A2 and Sarcophyton glaucum contains diterpenoids (sarcophytols A and B) which inhibit tumour promotion. As with the sponges there is much current biochemical interest in this phylum.
PLATYHELMINTHES (Flatworms)
This phylum includes the Trematodes (the parasitic flukes such as the liver fluke and Schistosoma) and the Cestoda (tapeworms).
NEMATODA (Roundworms)
Some are parasitic in man and animals.
MOLLUSCA
Class Gastropoda includes the snails, slugs and limpets. Some snails are vectors of parasites such as Schistosoma.
Class Lamellibranchia includes scallops, mussels, oysters and clams.
Class Cephalopoda includes the squids, cuttlefishes and octopuses.
Cuttlefish bone (from Sepia officinalis) has been employed in denti- frices and as an antacid.
ANNELIDA
(Segmented worms)
Earthworms, lugworms and leeches (q.v.) belong to this phylum. The potent neurotoxic agent nereistoxin is obtained from the Japanese species Lumbriconereis heteropoda.
ARTHROPODA
A very large phylum of jointed animals including the crustaceans, insects and arachnids.
Class Crustacea includes the shrimps, crabs, lobsters, centipedes and millipedes. Of little medicinal significance, nevertheless brine shrimps are being increasingly used in place of higher animals for the preliminary testing of phytochemicals for toxicity.
Class Insecta. Of the many orders of this taxon the following have medicinal interest:
1. Order Anoplura (Lice): Commonly infest birds and mammals.
Important from human standpoint is Pediculus humanus encoun- tered as the body louse (corporis) and the head louse (capitis); it is a proven carrier of typhus fever and an indirect transmitter of relapsing fever.
2. Order Hemiptera (Bugs): The cochineal beetle (q.v.) is an impor- tant colourant and shellac is a resinous substance prepared from a secretion that encrusts the bodies of a scale insect Laccifer lacca.
3. Order Coleoptera (Beetles): Beetles of the genera Cantharis and Mylabris, known as blistering beetles contain cantharidin deriv- atives and possess vesicant properties. Preparations of C. vesi- catoria were at one time used in Western medicine in the form of plasters, collodions etc. as rubefacients and vesicants. Their use continues in the traditional medicine of Eastern Asia (R. W.
Pemberton, J. Ethnopharmacology, 1999, 65, 181). The Chinese blister beetle, M. phalerata, is used in Chinese traditional med- icine for the treatment of cancer; various novel cantharidin- related compounds have recently been described (T. Nakatani et al., Chem. Pharm. Bull., 2004, 52, 8079; 2007, 55, 92).
A number of small beetles are important infestants of stored drugs (see Chapter 15).
4. Order Lepidoptera (Butterflies and moths): Some moths infest stored drugs (see Chapter 15). Silk has been traditionally used in pharmacy in the form of oiled silk.
5. Order Hymenoptera (Ants, bees, wasps, etc.): Hive products derived from Apis mellifica include honey, beeswax, royal jelly and propolis (q.v.).
6. Order Diptera (Flies, gnats and midges): The successful use of maggots in the treatment of wounds infected with antibiotic- resistant Staphylococcus aureus has received recent attention.
Sterile larvae of the common greenbottle Lucilia sericata are used.
For a report see Pharm. J., 1999, 262, 422.
Class Arachnida. Arthropods with two divisions to the body (cephalothorax and abdomen) including spiders, scorpions and mites.
Order Acarina (Mites): the common housemite (q.v.) is a cause of allergy in humans; other species infest stored drugs (see Chapter 15).
CHORDATA
The most important subphylum of the Chordata is the Vertebrata (Craniata) composed of all those animals with backbones; a number of classification schemes will be found in the literature and two major groupings often referred to as superclasses are the Pisces (aquatic ver- tebrates) and the Tetrapoda (terrestrial vertebrates) each divided into four classes. The following four classes have medicinal significance:
1. Class Osteichthyes (Bony fish). The following families and species are important:
Gadidae: Cod Pleurnectidae: Halibut Engraulidae: Anchovies Carangidae: Jacks and pompanos Clupeidae: Herrings
Osmeridae: Smelts
Scombridae: Mackerels and tunas Ammodytidae: Sand eels Salmonidae: Trout, salmon, whitefish and graylings
Liver oils, sources of vitamins A and D
Body oils, rich in omega-3 acids O
O Cantharidin
O O
ü ý þ
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2. Class Amphibia (Frogs and toads). Dried and powdered toadskins contain cardioactive principles and were used for the treatment of dropsy before the widespread adoption of digitalis.
3. Class Reptilia (Crocodiles, snakes and lizards). Snake venoms are important products.
4. Class Mammalia (Warm-blooded animals which suckle their young). Variously divided into subclasses, infraclasses and orders.
Subclass Eutheria embraces the placental mammals, e.g. bats, rodents, carnivores, whales, ungulates and primates. Formerly important was the whale-product spermaceti but its collection is now illegal. Other pharmaceuticals include lard, suet, wool fat, wool, gelatin, musk, catgut, heart-replacement valves from the pig, insulin, hormones, blood and liver products, vaccines and sera.
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DRUGS ACTING ON THE NERVOUS