Begleiter der Menschen = Ruderalpflanzen und andere
[Jonathan Reuben Rai Invernizzi]
The term 'Ethnobotany' was coined in 1895 by the American botanist John W. Harshberger to describe the studies of plants used by "primitive and aboriginal people.". In a broader sense, it is
a combination of the study of people ('ethno'), and the study of plants ('botany'). (Balick and Cox, 1996:3.)
Ethnobotany is important for a multitude of reasons. The link between people and plants in primitive societies is usually more clear and direct than in more industrialised ones. This is thought
to be mostly because the mechanisms of production and marketing are so complex in developed society, that the botanical origins of a processed product are rarely known or understood by most individuals. In indigenous cultures however, people often have a greater degree of interaction with the plants they use, and consequently, possess knowledge about the properties of plants which
western society has largely lost (Balick and Cox, 1996:6-7).
The WHO. estimates that 80% of the people living in developing countries almost exclusively use traditional medicine as their primary form of medical care, with medicinal plants forming the principal constituent of these traditional therapeutics (Eloff, 1997: 1). More primitive societies have through necessity maintained and passed on knowledge concerning plant medicine and
cultivation (Balick and Cox, 1996:6-7). Most often, this knowledge is verbal and incorporated in local legend and folklore (Naranjo, 1995: 363).
Although it is often possible to scientifically validate certain medicinal properties or traditional uses of plants by western methods, science cannot explain how it is that certain groups of people around the world look to these plants as sources of medicine in the first place (Wood, 1997:3).
Many modern western drugs also owe their development to the refinement of natural plant products. In 1984, one quarter of American prescription drugs were modelled 011 natural products.
Of this, 74% of pharmacologically active plant derived components were discovered by following up on the ethnomedical use of the plant. Despite this, it has been estimated that to date, only
around 15% of all angiosperms have been investigated chemically. S. Africa contains almost 10% of the worlds plant diversity, however very little chemical work has been done on medicinal
plants in this region. (Eloff, 1997: 1-2.) The South African species remain an untapped reservoir of potentially important biologically-active compounds (Fennel and van Staden, 2001 :23).
2.1.3 African ethnobotany
The ancient African healers have an extensive materia medica comprising various herbs, animal parts, minerals and clays. In traditional African medicine many food plants have medical usage, in contrast to orthodox western medicine where most drugs are viewed as 'poisons' which when administered in small doses, have the ability to heal. Apart from incorporating therapeutic plants into the daily diet, African medicine also contains many powerful drugs, as well as many African varieties of better-known western herbal-based drugs. Preliminary studies of the in vitro antibacterial effectiveness of some indigenous Southern African plants have been completed by people such as Rabe and van Staden (1997), Khan and Nkunya (1991), Lin el ai., (1999) and McGaw, Jager and van Staden (2000). However when compared to the extent of research of the indigenous herbs of countries such as America and Australia, there has been generally little attempt to evaluate African medicinal plants in general for biological activity and medicinal usefulness (Khan and Nkunya, 1991:48).
Homeopathic drug proving of Okoubaka aubrevillei
2.2 ETHNOBOTANICAL RESEARCH METHODOLOGY
2.2.1 Screening methods for natural products with anti-microbial properties
The three principal methods employed to evaluate the anti-microbial properties of natural products are diffusion assays, dilution tests and bioautography tests.
Within these methods, standardisation of technique has been difficult, as many factors have been found to influence results. These factors include culture medium composition, micro-organisms tested, extractive method, pH, and solubility of the sample in the culture medium. (Rios, Recio and Villar, 1988:127.)
188.8.131.52 Diffusion assays
Diffusion methods of screening for anti-microbial properties of natural products classically employ either disc, hole or cylinder methods as reservoirs for the sample substance (Rios, Recio and Villar, 1988: 128). This method is based on the principal that a reservoir containing an aqueous extract is brought into contact with an inoculated medium. The solute will diffuse through the interface into the agar gel until equilibrium is attained. After incubation the diameter of growth-free area around the reservoir can be measured and taken as the anti-microbial ability of that product.
(Hewitt and Vincent, 1989:38.)
Diffusion methods are well suited for the preliminary screening of pure substances, such as alkaloids, terpenaids and flavanoids. These methods however, cannot be used for samples that are difficult to diffuse in the media, as there is no direct correlation between diffusion power and anti-microbial activity. Therefore, when utilising agar plates (which are water-based) as a culture medium, this method is not acceptable for testing samples that are not highly soluble in water, regardless of whether the substance is originally applied in a non-polar solvent or not. Diffusion assays are therefore not suitable for testing the properties of essential oils or other non-polar substances. (Rios, Recio and Villar, 1988: 127.)
Dry discs, as opposed to wet discs which contain a liquid sample, are used to test for anti-microbial properties of ethanol extracts (Rios, Recio and Villar, 1988: 131), and have the advantage of nullifying the unknown effect that the rate of evaporation of the sample off the wet disc has on the results of a disc assay, as noted in the experiments by Reid (2002).
Comparisons of the zones of inhibition of natural products with those of synthetic antibiotics in disc-assay studies are only useful for establishing the sensitivity of test organisms. Comparisons of the anti-microbial potency of natural test substances and synthetic antibiotics cannot be made from these measurements. (Rios, Recio and Villar, 1988: 142.) This is largely due to the fact that many other factors such as diffusion ability can influence the size of the zones of inhibition, resulting in misleading conclusions when comparing the 2 different types of substances (Hewitt and Vincent, 1989:40).
The optimum effectiveness of the disc diffusion method has been found to be obtained using Mueller-Hinton agar and standard micro-organisms (American Type Culture Collection or similar) (Rios, Recio and Villar, 1988: 142).
Ruderalpflanzen zeigen gegen Trittschäden auch gegen Umweltgifte beachtliche Resistenz. Sie vertragen Abgase, Reifenabrieb, metallverseuchte Böden und sauren Regen erstaunlich gut.
In dieser Anpassungsfähigkeit ist auch ihre gemeinsame Signatur verborgen. Damit beweisen sie, dass sie Widerstandskräfte gegen Umweltproblemstoffe in sich aufgebaut haben, die
möglicherweise auch dem Menschen nützlich sind. Die Pflanzen am Wegesrand sind daher als potentielle Heilpflanzen gegen sog. "Zivilisationskrankheiten" anzusehen; bspw. Allergien,
Asthma, Atemwegsreizung durch Benzol oder Ozon, Fettsucht, Infektanfälligkeit und Virusleiden, Hautleiden wie Neurodermitis und Schwermetallbelastung.
Im Grunde genommen sprechen diese Gewächse eine eindeutige Sprache. Betrachtet man einmal die Wegwarte (Cichorium intybus) -
Blat-o. = Kakerlake
Ephestia kuehniella = Mehlmotte Arthropoda.
Felix. = cat domesticated itself for its own survival
Laps. = Gemeinen Rainkohl
Mus muculus. = Maus
Musc-d. = Hausfliege
Onis. = Kellerassel
Pariet. = Aufrechtes Glaskraut/wächst an/in Mauern/sucht Menschennähe
Passer.x domesticus = Spatz
Plan-m. = Breitwegerich
Procyon. = Waschbär
Sanguis-s. = Rattenblut
Thlas. w = Hirtentäschlein/= Sheperd’s purse/Sprossteile/= Blutwurz/= Herzel/= Bauernsenf
Tineola bisselliella = Kleidermotte Arthropoda.
Tyto-alba. = Schleiereule
Städtischen Kulturfolger: fels-/höhlenbewohnende Arten, für die die Gebäude der Menschen „Kunstfelsen“ darstellen: Stadttaube./Mauersegler/Dohle/Turmfalke./Hausrotschwanz/Winkelspinnen./Große Zitterspinne, Heimchen/Silberfischchen./Wanderratte./Eichhörnchen/Amsel