3. Chemical characteristics
What are “Natural Products”?
Naturally-occurring small organic compounds
• including heterocyclic compounds, and peptides.
• does not include proteins, carbohydrates, and nucleic acids.
• MW: ~150 ~ <800 amu (“small molecule”)
• Methods of extraction and purification are generally
similar to the techniques used for organic compounds
(e.g., TLC, column chromatography, HPLC, GC)
• Methods of structural determination
• NMR, MS, IR, X-ray, UV
4. Biological characteristics
What are “Natural Products”?
• Compounds are generally characteristic of a particular species
or family, i.e., narrow taxonomic distribution (non-ubiquitous)
• No nutritional or structural function. Functional roles may
include:
• - color (identification) - scent (attraction or repulsion)
• - sexual attraction - social communication
• - defense (e.g., plant toxins and antibiotics)
• but many still have unknown function in the organism in which they are
found.
• Classified as “secondary metabolites” in contrast to “primary
metabolites”
5. Introduce
• Diverse aspects of the Chemistry of Natural Products:
Structural determination of natural products compounds
• Total synthesis or semi-synthesis of natural products; enzyme
synthesis
• Determination of biosynthetic pathways using using plant
tissues, cell culture and isotopic labeling
• Pharmaceutical science: pharmacologic effects
• Functional foods, herbal medicines
• Agricultural science: antipest, allelopathy, IPM
• Ethnobotany
• Plant chemistry and plant development
• Biodiversity and Ecology; Marine natural products
• Chemotaxonomy and genetic classification
• Genomics and metabolonomics
6. Why study Natural Products?
• Natural products are the source of the most complex and
fascinating chemical structures.
• Natural products represent biological diversity.
• Natural products are expressions of the genome.
• Natural products represent natural biological activity, whether as
single compounds or as complex mixtures.
• Natural products are part of the natural wealth of the country,
and can be an important source of livelihood, from agriculture
and food, pharmaceuticals, fine chemicals industry.
• Natural products can be an effective bridge from tradition to
modern scientific developments, including genetics, molecular
biology, biotechnology, and pharmaceutical science.
9. The Changing Landscape of Herbal Medicine,
Food and Wellness
• Herbal Medicine
• Dietary Supplement
• Nutriceutical
• Functional Food
Natural Products Chemistry
is key to all of these!
Introduce
10. Natural products and Ecology
BacteriaFungi Antibacterials
Antifungals
Plants
Antifungals
Symbiosis
Insects
Antipest
Attractants
Animals
Antifeedant
Toxins
Scents
Toxins
Toxins
Pheromones
Communication
Chemotaxis
Communication
Symbiosis
Chemotaxis
Communication
Allelopathy
Communication
13. The process selection
Extract and
separate
compounds
2. Small molecular weight organic
compounds, hydrophilic
1. Small molecular weight organic
compounds, lyophilic
14. The process selection
Small molecular weight organic compounds, lyophilic
• Sythetic, the product is mixture ( 3 compounds)
Using chromatographic method to separate
• Natural products, the isolation is more complex.
Preparing a series of “extracts solid ”with polarization which
gradually increased
15. The process selection
Thesolventhaspolarization
whichgraduallyincreased
Common solvent Solubility Common chemical grouping
Petroleum ether
Hexan
Benzene
Toluen
Diclorometan
Cloroform
Ethyl acetate
Etanol
Metanol
Butanol
Water
Alkan
Alken, alkin
Aromatic compound
Ether
Aldehyde, cetone
Ester, Amide
Hydroxy, Amin
Acid cacbonxylic
17. The process selection
Small molecular weight organic compounds, hydrophilic
• 95% new compounds are lyophilic
Isolating hydrophiclic organic compound is more complex
than lyophilic ones
20. 1.Liquid-Liquid Extraction
• Liquid-liquid extraction (also known as solvent extraction)
involves the separation of the constituents (solutes) of a liquid
solution by contact with another insoluble liquid.
• Solutes are separated based on their different solubilities in
different liquids.
• Separation is achieved when the substances constituting the
original solution is transferred from the original solution to
the other liquid solution
29. 3.Soxhlet extractor
1: Stirrer bar
2: Still pot (the still pot should not be
overfilled and the volume of solvent in
the still pot should be 3 to 4 times the
volume of the soxhlet chamber)
3: Distillation path
4: Thimble
5: Solid
6: Siphon top
7: Siphon exit
8: Expansion adapter
9: Condenser
10: Cooling water in
11: Cooling water out
36. www.themegallery.com
Some tips when isolating organic compounds
1. Dry the sample
- Compounds in extract materials will be stable
- To properly calculate the extract efficiency of the extract materials
- To continue refining high with column chromatography
37. Dried by inert gas in the Rotavap/rotovap
- Using the Evaporation to dry the
sample completely
- Give a slightly inert gas from the top
of the machine (N2)
- If not, saving sample longer in the
machine
38. Dried by vacuum dessicator
- Using pump to remove the air from
the tank (30 - 60 minutes)
- Note: Replace desiccant for high
efficiency
