Collection is the most important step which comes after cultivation. Drugs are collected from wild or cultivated plants and the tasks for collection depends upon the collector, whether he is a skilled or unskilled labour. Drugs should be collected when they contain maximum amount of constituents in a highly scientific manner.
COLLECTION OF CRUDE DRUGS
Collection is the most important step which comes after
cultivation. Drugs are collected from wild or cultivated plants and the tasks
for collection depends upon the collector, whether he is a skilled or unskilled
labour. Drugs should be collected when they contain maximum amount of
constituents in a highly scientific manner. The season at which each drug is
collected is so important, as the amount, and sometimes the nature, of the
active constituents could be changed throughout the year. For example, Rhubarb
is collected only in summer seasons because no anthraqui-none derivatives would
be present in winter season but anthranols are converted to anthraquinones
during summer. Not only the season but also the age of the plant should be
taken in to great consideration since it governs not only the total amount of
active constituents produced in the plants but also the proportions of the
constituents of the active mixture. High proportion of pulegone in young plants
of peppermint will be replaced by menthone and menthol and reduction in the
percentage of alkaloids in datura as the plant ages are examples of the effect
of aging in plants.
Moreover the composition of a number of secondary plant
metabolites varies throughout the day and night, and it is believed that some
inter conversion would happen during day and night.
Generally the leaves are collected just before the
flowering season, e.g. vasaka, digitalis, etc., at this time it is assumed
that the whole plant has come to a healthy state and contain an optimum amount
of metabolites, flowers are collected before they expand fully, e.g. clove,
saffron, etc., and underground organs as the aerial parts of plant cells die,
e.g. liquorice, rauwolfia, etc. Since it is very difficult to collect the exact
medicinally valuable parts, the official pharmacopoeia’s has fixed certain
amount of foreign matter that is permissible with drug. Some fruits are
collected after their full maturity while the others are collected after the
fruits are ripe. Barks are usually col-lected in spring season, as they are
easy to separate from the wood during this season. The barks are collected
using three techniques, felling (bark is peeled off after cutting the tree at
base), uprooting (the underground roots are dug out and barks are collected
from branches and roots) and coppicing (plant is cut one metre above the ground
level and barks are removed).
Underground parts should be collected and shaken, dusted in
order to remove the adhered soil; water washing could be done if the adhered
particles are too sticky with plant parts. The unorganized drugs should be
collected from plants as soon as they oozes out, e.g. resins, latex, gums, etc.
Discoloured drugs or drugs which were affected by insects should be rejected.
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