There are two methods involved in extraction of medicinal plants;
1. The Traditional Method and
2. The Scientific Method
THE TRADITIONAL METHOD
This involves the following:
Concoction, decoction, infuusion and maceration.
CONCOCTION-This means a preparation
made usually from many ingredients (Sofowora, 1993).
DECOCTION - This is prepared by placing
the plant material in cold water, bringing it to boil, simmering for about 15
minutes ( or up to 1 hr) and then allowing the mixture to stand for further 15
minutes. The aqueous extract is then decanted or filtered as and when due. Such
preparations are often left in a pot and heated up
daily before use at home. As
a result, the aqueous extract gets darker in colour due to more of the
constituents being extracted while the water remains in prolonged contact with
the plant drug. This type of extraction may result in the alteration of many
active plants constituent.
INFUSION –An infusion is prepared by
pouring water on a specific quantity of plant material and allowing the mixture
to stand for 10 – 15 minutes.
MACERATION – This is prepared by
placing the plant material with the whole of the menstrum (extraction liquid
e.g. ethanol) in a closed vessel and allowed to stand for days, shake
occasionally and then strained before filtration, followed by decantation
(Sofowora ,1993).
THE SCIENTIFIC METHOD
In scientific method, the samples to be used are
collected and dried to a constant weight in a hot air oven or direct sunlight.
Homogenization is carried out and the samples extracted with a suitable solvent
usually organic compound like ethanol, ether, etc.An extractor e.g. soxhlet
extractor is used and extraction carried out over a period of time till there
is no more extractable material in the plant materials. This is usually judged
by loss of colour in the filtrate produced. The ethanolic extract is
concentrated to dryness in a vaccum at about 45 °C to 50 °C. The dried extract
is used for the screening (Sofowora, 1993).