2. Getting involved in Phytochemistry
Laboratory analysis of medicinal and other useful plant is costly
and time consuming endeavor
Reason Many different chemical compounds , botanical
species and their potential uses
Therefore Before work it is necessary to decide which
species are apt to yield the most promising results before
proceeding with extensive investigation.
3. Approach
•Search for the chemical and ethnobotanical literature to
discover existing knowledge about various species in your
ethnobotanical inventory
•Blind duplication of tests would be waste of time
•‘’ Trease and Evans Pharmacognosy ‘’ are good reference
for well known drug plants.
•Search for the computerized database on plant chemistry,
pharmacognosy and medicinal plants viz. NAPRALERT
DATABASE at University of Illinosis at Chicago, contains
about 115000 articles and books. It includes results of 34000
species of flowering plants, 2200 types of fungi, 2300 kinds
of animals and many other living things.
4. After this research work and consultation with the
colleagues next stage is the start of field work and
collecting samples which can be further tested at research
institutes
•First stage is select through the appropriate Sampling
Method the plant that will be analyzed.
•Small parts of Plants, fruit, seeds, fruits or other parts of
plants are screened to see if they show activity in specific
biological or pharmacological testing system or if they
contain compound which are biologically/ physiologically
active or economically valuable.
•If the plant show promise you can proceed to make a Bulk
collection, gathering several kilogram of material that is
brought to lab for detailed analysis.
5. If you have a specific interest in phyto-chemistry, you can spend
some months in the lab, learning basic techniques, and gaining
familiarity with the specialized equipment.
Carrying out the entire procedure of phytochemical analysis
require advance training and access to the sophisticated lab
equipment.
Colleagues in the Laboratory:
This work needs collaboration with academic fields like
pharmacognosy, ethno-pharmacology and natural product
chemistry.
Pharmacognosy: It is the study of naturally occurring compound
particularly those from plants- that can be used medicinally. In
1800 it starts focusing on identification, preparation and
commercialization of drugs extracted from plants
6. Approach was combined Botany, Chemistry and
anthropology
They need to divide their time between lab and the field.
In order to select plants for chemical analysis they need to
interact with the specialist users such as herbalist, hunters
and the fisher man, who have developed empirical
knowledge of chemical compounds by
tasting and smelling plant
Observing the effects of medicinal herbs on patients and
noting the link between the morphology and the curative
power of plants
Because of their close link with the local people
pharmacognist may seek to apply their knowledge and
discoveries to improve health conditions in the community
7. Some researchers are focused on other chemical constituents of
plants like Nutritional composition .
Nutritional chemist: measure the quantity of the specific
nutrients found in the edible animals and plants in order to
discover the extent to which they fulfill the dietary
requirement.
They may focus on the wild and edible food plants consumed
by the local community not previously tested.
Chemical Ecologist: they study how biological compound
affect the relationship between plant and animals, emphasizing
the plant-insect interaction
This inspires ethno botanist to explore how hoe human diet and
medicine have evolved in response to plant chemicals and how
their concentration have been modified.
8. Natural Product Chemist: They worked on the broad range of
the chemical compound that include latex and the resins
employed in industrial processes, essential oils used in perfumes
and other substances that have diverse application.
Chemist with the interest in agriculture focus on the natural
insecticides , as well as the macronutrients in plants used as a
Green Fertilizers or to enrich the soil
Others use hallucinogenic and narcotic plants employed in
rituals or recreation purposes
Or naturally occurring poison which hunters use for hunting,
fish poisoning or other activities
9. Sampling Method
Choice of the sampling methods should be done first (It is
very important in tropics , where both plants and secondary
compounds are more diverse than in temperate zones)
Some opt Random Sampling Method: Take any plant in
sufficient quality and quantity
Benefit sampling a diverse range of plants and make a
large number of collection
Disadvantage collection of plants with low proportion of
biological and Pharmacognostic potential
Random sampling is done by the researchers
How can we increase the proportion of plants plant that Screen
positively thus saving time and money?
10. One way is Chemotaxonomic Approach
That is: specific secondary compounds like flavonoids are
restricted in distribution being found in only one group of
related plants
For Example Type of Flavonoids known as Is flavones are
common in specific members of family Fabaceae , or 5500
types of alkaloids are confined to the single genus or
subfamily. Only a single is alkaloid is found in many species
of Bombacaceae tested so far.
Efficiency of screening is done by knowing the distribution
of plant chemical you wish to study For example terpenoids
are restricted to Asteraceae Family, you may limit collection
to this family.
If you find an interesting alkaloid in Rubiaceae family you
can proceed to gather closely related species
11.
12.
13. A second way to increase your rate of success is to use Ethno
pharmacological Approach by choosing plant like one use
by local community as a medicinal plant.
This is the most efficient approach as it is efficient way of
testing efficiency, safety and effectiveness and dose of
medicine
This approach is also useful in comparison analysis between
different ethnic group
So hypothesis could be tested in broad range of plants in
multi ethnic groups before accepted as a rule.
Like in many culture plants are use for treatment because of
symbolic representation for example twinning plants are often
employed to snake bite, use is governed by morphology and
not the active ingredients.
14. Ethnopharmacological methos is also employed in other
purpose like in case of analysing link between nutritional
composition of plant and human diet, choose species used
by the local people. Like if you wish to measure level of
macronutrients and micronutrient contribution that certain
species contribute to agroecosystems, collect plants used
as mulch and fertilizers by local farmers
15. Screening
Advantages to the field testing
There are two ways of going about screening
You may go to the field with necessary equipment to test
the sample yourself
Or send them to the pharmacognosist who agree to
advance to the process the material in laboratory
Field testing enable to identify merit investigated in lab,
also plants can be tested fresh
Drawback of Field Screening:
•Field techniques are not precise, sometime loose essential
compounds that can be identified with laboratory
sophisticated instrument.
•Leaves less time for other aspects of ethnobotany
16. Pharmacological and the Biological Screening
Generally carried out in Laboratory. Two important
techniques are
1. Brine shrimp Technique
2. Antibacterial Screening
Brine Technique: Small aquatic animal that is grown in a
special solution that resemble saltwater for the sea. In
order to check the cytotaxicity potential of plant
measure amount of extract is addedd to various
containerholding known number of shrimpsin
solution. After 24 hours shrimps are counted To check
calculations of cytotoxicity measures called LD-50
Value
17. This corresponds to concentration of compound in solution
which kill 50% of the brine shrimps.
Biological activity of plants against numerous type of
bacteria could be tested in different kind of screens
Bacteria are grown on agar medium. Measyred amount of
plant extract are placed on paper disc. ALL IS DONE
UNDER STERILE CONDITIONS. 18-24 hours during
which the plates are incubated. Clear zones of bacteria free
zones are calculated indicating that plant extracts has
inhibited growth.
