This slide contains definition of pharmacognosy and reverse pharmacognosy, steps of pharmacognosy, parts of reverse pharmacognosy, comparison of pharmacognosy and reverse pharmacognosy, Selnergy, Selnergy in reverse pharmacognosy, application and advantages of reverse pharmacognosy, Selnergy on e-viniferin, Conclusion and Reference.

1. Reverse Pharmacognosy
Presented By:
Nursad Jahan Sultana

2. Definition of Pharmacognosy
Pharmacognosy is defined as the study of medicine
obtained from natural sources including plants, animals
and minerals.
The American Society of Pharmacognosy has defined
pharmacognosy as ‘the study of the physical, chemical,
bio-chemical and biologic properties of drugs. Drug
substances of natural origin as well as the search for
new drugs from natural sources.’

3. Steps of Pharmacognosy
It consists of the following steps :
1. Selection of plants 2. Extraction
3. Biological
evaluation
4. Characterization

4. Selection of plants
Plants are selected on Ethnopharmacological knowledge when
specific therapeutic area is desired for treatment. Using
knowledge from different cultures increases the probability and
ability to identify effective materials that correspond to the
therapeutic area. One important consideration is the availability
for enough samples for testing and subsequent development.
Extraction
Extraction can be defined as a process of removal of soluble
materials from an insoluble residue, either liquid or solid, by
treatment with a liquid solvent. Extraction is generally done by
solvents of different polarity.
Steps of Pharmacognosy

5. Biological evaluation
When the estimation of potency of crude drug or its preparation is
done by means of its effect on living organisms like bacteria,
fungal growth or entire animal, it is known as bioassay. Herbal
drugs are screened for their activity by bioassay.
Characterization
Isolation of active compounds from the extract is an important
step; it is generally done by chromatographic techniques like
TLC, HPTLC and HPLC. Main constituents of the drug are
studied with the aid of HPTLC and modern spectroscopic
techniques, using HPLC-coupled spectroscopic techniques such
as HPLC-UV, HPLC-MS as well as HPLC-NMR.
Steps of Pharmacognosy

6. Definition of Reverse Pharmacognosy
Reverse pharmacognosy is a new concept of finding
new biological targets from structurally similar
chemicals and finally finding the natural sources of
the biologically active compounds which contain
them.

7. Parts of Reverse Pharmacognosy
There are various parts of Reverse Pharmacognosy as follows-
1. Structural database for natural compounds:
Natural compounds that appear in the published literature and
compounds found in commercial databases forms the structural
database also called Virtual Chemical Database (VCDB).
The sources of these compounds are available, and frequently
the method applied for their extraction is also described.
CONCORD is a VCDB containing more than 100,000 natural
compounds, along with their 3D coordinates. Chemical
diversity of the compound is the final criterion for the selection
of compounds for virtual screening.

8. 2. TARGET DATABASE:
The target database is composed of 3D protein structures,
determined by X-ray crystallography or by homology
modeling.
Most of the structures are from humans, although is also
contains proteins from other sources(e.g., Viruses, bacteria).
Protein/ Ligand pair interaction energy is obtained and
involves retrieval of actives ligands from a set of 100 non
active compounds; method is explained in detailed by Green
Pharma.

9. 3. Virtual Screening Tools :
The basic goal of virtual screening is the
reduction of the enormous virtual chemical
space of small organic molecules to synthesize
and screen against a specific target protein to a
manageable number of compounds that exhibit
the highest chance to lead to a drug candidate.

10. i. Screening based on ligand properties, i.e., physicochemical
properties, fragmental description and pharmacophores which
are techniques of quantitative structure.
ii. Screening based on target properties, which requires
knowledge of the 3D structure of the target and the ligand which
are techniques of de novo design and docking, which involves
generating new ligands or adjusting ligands in the active site of
the target, respectively.
Methods of Virtual Screening tools
There are two types of methods :-

11. 4. Ethnopharmacological database (ETPHDB) :
In order to develop botanical data, natural chemical
structures, biological tests of extracts and compounds,
ETPHDB has been developed.
Family, genus, species, common names and synonyms of
the plants are included in this database. The database
accelerates the discovery of bioactive ingredients e.g., anti
inflammatory compounds.
The ETPHDB contains botanical information on plants
and their traditional uses, and phytochemistry data
associated with biological activity of plants, database
allows being a link between plants, molecule and activity.

12. Chemical
database
Virtual
screening tools
Virtual hits
Ethnopharma-
cological
database
Real hits
Biological
assays
Natural compound
library
Protein
database
Real hits
plants plants
Real aspect Virtual aspect
Block diagram
of Reverse
Pharmacognosy

13. In the diagram, the simple arrows represent the information
flow, while the bold dark arrows correspond to the process
flow. Data from an ethnopharmacological database
(ETPHDB) are utilized for 'knowledge validation' in
converting virtual hits to real hits, and to retrieve the sources
of compounds. The experimental validation process consists
of internal biological tests and/or data gathered from
scientific literature. Real hits or real inactive candidates
enable the validation of the target models.

14. Comparison of Pharmacognosy and Reverse
Pharmacognosy
Vegetal realm
Plants
Extracts
Biological tests
Bio-guided
identification
Bio-active
molecule(s)
Natural
compounds
Molecule database
Or
Molecular library
Virtual screening
and/or
Biological tests
Knowledge-based
identification
Plant(s)
Ethnopharmacological
and botanical selection
Drug-like criteria
Diversity selection
Pharmacognosy Reverse Pharmacognosy

15. The starting material for pharmacognosy
is raw plants selected by considering their
traditional uses or by biodiversity.
Extracts are made from the plants and
screened on biological assays to find
active ones.
The active compound(s) are characterized
by an iterative bio-guided fractionation. So
pharmacognosy starts with plants and ends
with molecules.
Pharmacognosy

16. On the other hand, reverse pharmacognosy may be undertaken with
or without a virtual component. Molecules are selected by chemical
diversity. They are screened on several biological assays.
Then with the help of compound source database, plants bioactive
molecules can be determined.
Docking and inverse-docking software can be introduced prior to the
biological screenings. This step enables to find ligand/target pairs,
thereby reducing drastically the number of compounds to be
evaluated and the number of biological assays.
The natural sources are then identified by compound source database.
Reverse pharmacognosy begins with molecules to get bioactive plants
with their biological activity characterized at the molecular level.
Reverse Pharmacognosy

17. Selnergy
Selnergy, an inverse docking computer software, is used for
biological applications.
It allows the digital modelling of interactions between
chemical molecules ( active or inactive molecules- ligands)
and their biological targets ( proteins, enzymes etc.)
Reverse Pharmacognosy
Molecules
Biological assays
Selnergy
Compound source
Bio-active plant(s)

18. Selnergy in Reverse Pharmacognosy
Reverse pharmacognosy may be undertaken with or without a
virtual component.
Molecules are selected by chemical diversity. They are
screened on several biological assays.
Then compound source database provides the plants that
contain the bioactive molecules.
Selnergy can be introduced prior to the biological screenings.
This step enables to find ligand/target pairs, therefore reducing
drastically the number of compounds to be evaluated and the
number of biological assays.

19. Selnergy in Reverse Pharmacognosy
Molecules selected by Selnergy are validated with binding
tests which proteins are also chosen by Selnergy.
The natural sources are then identified by our compound
source database.
Reverse pharmacognosy begins with molecules to get bio-
active plants with their biological activity characterized at the
molecular level.

20. APPLICATION
A new tool for Lead Discovery, reverse pharmacognosy aims to
find new biological targets for natural compounds by virtual or real
screening and identifying natural sources that contain the active
molecules. It has been studied on ε-viniferin, an active ingredient
for cosmetic development.
Fig: Structure of (Z) & (E)- ε-viniferin stereoisomers

21. Selnergy on ε-viniferin
Using this inverse docking software, biological targets of
ε-viniferin got identified.
Among 400 screened proteins, two targets were retained.
It showed selectivity for PDE4 and DR; other PDE
subtypes (1,2,3,5,6) were not retained.
This selectivity was confirmed by evaluation of TNFα
and IL-8 secretion.

22. ADVANTAGES
Virtual screening tool and important databases
can play important role in reducing the time
and wealth.
It can accelerate the drug discovery and
development to a considerable extent.
This process decreases plant usage.

23. Conclusion
Reverse Pharmacognosy is a contextual strategy to
develop relevant standards.
Its approaches need to be developed further and
optimized as novel means for fast-track drug discovery
and development of newer, safer and effective drugs.

24. Reference
1. Khan Md. Yaseen, K. V. G. A. V. N. P. S. a. B. A., 2007. Reverse
Pharmacognosy In New Drug Discovery. Current Pharma Research Journal,
01(05), pp. 32-34.
2. Quoc-Tuan Do, I. R. P. A. C. L. C. D. M. a. P. B., 2005. Reverse
Pharmacognosy: Application of Selnergy, a New Tool for Lead Discovery. The
Example of ε-Viniferin. Current Drug Discovery Technologies, 02(03), pp. 1-6.