Advanced Pharmacognosy

PROBLEMS & PROSPECT OF Presented by,
DISCOVERING NEW DRUGS Syed Asif Raza

FROM HIGHER PLANTS.
Advanced
Pharmacognosy,
Cource#804
Overview ‫عمومی جائزہ‬
• Introduction.
• Important Drugs From Higher Plants.
• Drug Development From Plants.
• Challenges in Drug Discovery From Medicinal Plants.
• Problem in discovering new drugs From higher plants.
• WHO Guidelines For Herbal Medicines.
• Pakistan & Herbal Medicines.
• Prospect & Conclusion
INTRODUCTION
• Drug discovery from plants involves a multidisciplinary
approach combining botanical, ethnobotanical, phytochemical
& biological techniques . plants continue to provide us new
chemical entities for the development of drugs against various
pharmacological targets, including HIV/AIDS,malaria,Alzheimer
disease,cancer & pain.
• Many higher plants produce economically important

compounds such as, resins, tannins, gums, flavors, fragrance,
oils, natural rubber etc.
• Apart from the core disciplines related to pharmaceutical

research classical sciences like taxonomy and the newer
discipline ethnobotany have now become an integral part of
drug discovery from plants.
IMPORTANT DRUGS FROM
HIGHER PLANTS.
• Morphine 1. Papaver somniferum.
• Quinine. 2. Cinchona species.
• Cocaine. 3. Erythoxylon coca.
• Reserpine. 4. Rauwolfia serpentina.
• Atropine. 5. Atropa belladonna.
• Vincristine. 6. Catharantus roseus.
• Digitoxine. 7. Digitalis purpurea.
• Digoxine. 8. Digitalis lanata.
• Sennosides. 9. Cassia angustifolia.
• Diosgenine. 10. Dioscorea species.
• Stigmasterol. 11. Glycine soja.
DRUG DEVLOPMENT FROM
PLANTS.
• Selection of
Approaches;
Advantages Disadvantages
Folklore Use High Ratio of Activity. Role of Psychology in

Lower screening Cost. folk medicine. Secrecy
of primitive cultures.
Botanical Discovery of useful Re-isolation of known

Analogs. compounds.
Relationship
Random Best chance to find Low % of active Leads.

novel active High cost per lead.
Collection compounds. Large bioassay
Plants are more readily capacity needed.
available.
PLANTS . [cont]
• Steps Required;
1. Decision on selection method.
2. Preparation of extracts for
bioassay.
3. Recollection of active plants
for activity conformation.
4. Isolation & structural
elucidation.
5. Pharmacological profile.
6. Toxicity studies.
7. Large scale preparation of
active compounds.
8. Formulation studies.
9. New drug application &
clinical trials.
10. Market the new drug.
PLANTS . [cont]
• Ethno-medical /
IMEPLAM
Scientific & 1974
1973
technical Data
bases;
1969
CA SEARCH®
NAPRALERT
AGRICOLA 1978 1975
1970
ic a ting
yr ind rage
te ; e
*No ture cov
1969 1974 litera
.
from
CHALLENGES IN DRUG DISCOVERY
PROCESS FROM PLANTS.
Clinical trial
Drug candidates
Lead development
Pharmacology, toxicology, pharmacokinetics, ADME, Drug delivery
Medicinal chemistry, combinatorial chemistry Lead optimization
Target based qualitative bioassays Lead identification
Plant sample acquisition

PROBLEMS IN DISCOVERING
NEW DRUGS FROM PLANTS.
1. Herbal drugs are usually mixtures of many constituents.
2. The active principle are in most cases unknown.
3. Selective analytical methods or reference compounds may
not be available commercially.
4. Plant materials are chemically and naturally variable.
5. The source and quality of the raw material are variable.
6. The methods of harvesting, drying, storage, transportation,
and processing (for example, mode of extraction and
polarity of the extracting solvent, instability of constituents,
etc.) have an effect.
7. Many of the plant species are rare &difficult to cultivate.
8. Plants contain only small amounts of the required
compounds.
9. The harvest can be destroyed by insects and plant
diseases.
10.The plant are growing in countries with political unrest.
WHO Guidelines For Herbal
Medicines.
According to a World Health Organization (WHO) survey,
the traditional healers prescribe herbal drugs to treat 65%
patients in Sri Lanka , 85% in Burma , 80% in India , 60%
in Indonesia , 75% in Nepal , 90% in Bangladesh and
60% in Pakistan .
According to WHO Guidelines;
2. The manufacturing procedure and the formula including the
amount of excipients should be described in details.
3. A method of identification & where possible quantification of the
plant material in the finished product should be defined.
4. According to WHO herbal medicines should be regarded as
finished labeled medicinal products that contain as active
ingredients or combinations thereof whether in crude state or as
plant preparations. plant material combined with chemically
defined active substances which are not of plant/natural origin not
considered as herbal medicines.
PAKISTAN&HERBAL
MEDICINES
In the Islamic Republic of Pakistan, a national
policy on Traditional medicines is being
developed. Laws and regulations were developed
in 1965 and amended in 1970 and 2002.
The Drugs Act of 1962 controls the regulation of herbal medicines
as regards advertising and prevention of misuse. Herbal medicines
are regulated as over the counter medicines and dietary
supplements. No claims may legally be made about herbal
medicines. The national pharmacopoeia is the Tibbi pharmacopoeia
(1967); the information is not legally binding. The Monographs of
unani medicines (Vol. 1) has been prepared and published.
There is no registration system. Herbal medicines are not included
on an essential drug list. A post marketing surveillance system is
being developed. In Pakistan, herbal medicines are sold in
pharmacies as over the counter drugs, by licensed practitioners,
and in special outlets without any restrictions.
PROSPECT & CONCLUSION
• It is clear that the herbal industry can make great strides in the world
with the co-operation between drug regulatory authorities, scientists
and industries. However, standardisation of methods and quality
control data on safety and efficacy are required for proper
understanding of the use of herbal medicines.
Plant based discovery programme continues to
provide new drug leads.the drug from biological
origin are the back bone of medicinal therapy,
abouth 50% of drugs arrived from natural origin,
such as vitamins, hormones, glycosides, antibiotics,
alkaloids and many more.
© 2009 Department of Pharmacognosy, Uok, Pakistan.
‫اپ کا شکریہ‬. adviapharma@aol.com ‫سید اصف رضا زیدی‬ ‫پیش کیا‬

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What are some important drugs that have been discovered from higher plants?

What are some challenges in discovering new drugs from plants?

PROBLEMS & PROSPECT OF Presented by,

DISCOVERING NEW DRUGS Syed Asif Raza

• Many higher plants produce economically important

• Apart from the core disciplines related to pharmaceutical

Folklore Use High Ratio of Activity. Role of Psychology in

Botanical Discovery of useful Re-isolation of known

Random Best chance to find Low % of active Leads.

Pharmacology, toxicology, pharmacokinetics, ADME, Drug delivery

Medicinal chemistry, combinatorial chemistry Lead optimization

Target based qualitative bioassays Lead identification

Plant sample acquisition

‫اپ کا شکریہ‬. adviapharma@aol.com ‫سید اصف رضا زیدی‬ ‫پیش کیا‬

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