ii) Exotic, naturalised: these species are brought into a region, outside its natural distribution, accidentally, as for example, US food grain shipments to India, but soon got acclimatised in the new home, and so are called naturalised; since there is no apparent economic use for these species, they are not cultivated but they thrive as weeds, often replacing the weeds that are natural to the region; a celebrated, but not the only, example is Parthenium hysterophorus. It is not always easy to distinguish between the native and the naturalised, with passage of time.

While we have, by and large, recognised the therapeutic uses of the native cultivated species and the weeds, such uses of the exotic, cultivated or naturalised, species are largely unknown. Many of these have scientifically established therapeutic uses, in the countries of their natural distribution. So long as these species are largely available with us, and while there is no other use for them, there is no reason why they should not be used by us for the same purposes as in their native country but unknown in India, or even other new uses.

Some signs are there, in the direction of using the exotic species. From the demand for several tonnes of Ageratum conyzoides and Argemone mexicana from Andhra Pradesh, it looks that someone found a use for these species. Thirty one exotic species, occuring in India as horticultural plants or weeds, are listed in Appendix 24. This list would certainly enlarge with time.

PLANTS USED IN LIVER DISORDERS

Liver is the largest organ in our body (13.5 to 18.5 kg) and is the most important part in the abdomen associated with a variety of metabolic functions that are essential to life.

Liver suffers from infections, and wrong life styles. An impaired liver function is reflected in a gastro-intestinal disturbance.

In view of the importance of this area, we attempted compiling a list of plants used in liver disorders, but this list largely overlapped with the species in the database of plants used in gastro-intestinal disorders (Appendix 7). For this reason, no separate list is included here. Nevertheless, it should be possible to identify, in course of time, species that have influence exclusively, or at least predominantly, on liver function, like Picrorrhiza kurrooa.

PLANTS USED AGAINST HELMINTHIC PARASITES

The word ‘helminths’ includes the flat and round worms. Terms ‘anthelmintic’ and ‘vermicide’ have been used indiscriminately in literature, resulting in an ambiguity between the intestinal parasitic worms and insect larvae. It is necessary to distinguish between them (see Appendices 25 and 26).

The following are the helminthic parasites of mammals:

a) TREMATODAL Blood fluke; Liver fluke.

b) CESTODAL Tapeworm.

c) NEMATODAL Thread, Pin, Hook and Round worms; Filarial worm; Guinea worm. Of these, the blood flukes occur in the blood stream, while the liver flukes infest the bile ducts of the liver. The rest occur in the intestinal track.

Some nematodes are plant pests, occurring in soil. A very interesting group of fungi, the nematophagous fungi, produce snares of three celled inflating rings, to instantaneously catch soil nematodes, that had the misfortune of passing through the noose.

The intestinal worms do not directly cause any serious disease but have a nuisance value of the first order, causing extreme discomfort, embarassment and impaired nutrition, particularly in children.

The intestinal worms have a very long and intricate relationship with their hosts. In fact, one theory proposes that the the IgE antibodies with a principal role in allergy manifestations have actually evolved in response to the intestinal nematodes. A particularly interesting discovery is that, about 70 per cent of human genes applicable to disease states are related to a few (of about 20,000 genes in six chromosomes) of the minute round worm Candadis eleganz.

Intestinal parasitic worms have certainly attracted the attention of all indigenous medical systems and there is a long list of plants that were in use (Appendix 25). Even the earlier allopathic therapeutic works cited Artemisia annua (santonin), Chenopodium ambrossoides (seed oil), Dryopteris felix-mas, Punica granatum, melon and pumpkin (seeds) as the most effective anthelmintics (Gosh, 1936). Unfortunately, in recent times these and the other species suffer from disuse, and the victims suffer from the lack of an effective measure of control.

Intestinal worms have surface lectins (explained in the section on lectins). Certain carbohydrates in food can possibly clump the worms in large masses. On the other hand, lectins in certain foods can be used to the same effect. In either case, the clumped masses of worms would be eliminated through defecati on. Some compounds like saponins (explained in the section on saponins) contained in the seeds of melon and pumpkin and several foods like chickpea, tomato, etc., (see the section on saponins) can solubilise the worms. In fact the phloroglucinol-related compounds in Dryopteris felix-mas (a fern), Mallotus philippinensis (Euphorbiaceae), Agrimonia pilosa (Rosaceae) and Hagenia abyssinica (Rosaceae), do just that. These species are the traditional remedy against intestinal worms in Europe, South Asia, East Asia and East Africa, respectively. The use of botanically unrelated taxa, in such diverse geographical areas, with similar chemical compounds for the same purpose, without knowing what is contained in them, is a tribute to ethnomedicine, as mentioned under the section on ethnopharmacology.