Back to: Organic Chemistry 400 Level
Welcome to class!
Hello amazing learner, it’s great to have you back once again. You’re doing very well and I’m really proud of your consistency. Today we continue with Natural Products Chemistry II, and this time we will look more closely at how natural products are biosynthesised, how their structures are analysed, some useful examples, and also the challenges involved in working with them.
Natural Products Chemistry II
Just like different departments work together in a large factory to produce medicines, foods and other products, living organisms use highly organised biochemical pathways to build complicated natural molecules from very simple starting materials. This is exactly what happens in natural products chemistry.
Biosynthesis of Natural Products
Natural products originate from specific biochemical pathways present in living organisms:
Mevalonate Pathway: Builds terpenoids using repeated isoprene units. Menthol (from mint plants) and natural rubber (from rubber trees) are produced through this pathway.
Shikimic Acid Pathway: Responsible for the biosynthesis of aromatic compounds such as flavonoids and phenolic acids. The pain-relieving compound salicylic acid (precursor of aspirin) and the pleasant smell of cloves are all linked to this pathway.
Polyketide Pathway: Produces many antibiotics and anti-cancer compounds. Macrolide antibiotics such as erythromycin are made through this pathway in microorganisms.
Think of these as specialised “production lines”, where enzymes act like skilled workers assembling complex compounds from smaller building blocks.
Structural Elucidation of Natural Products
To successfully use natural products, it is important to know their exact chemical structure. Chemists do this by combining several analytical techniques:
Nuclear Magnetic Resonance (NMR) Spectroscopy: Shows how atoms are connected in the molecule.
Mass Spectrometry (MS): Determines the molecular weight and gives information on fragments.
Infrared (IR) Spectroscopy: Identifies functional groups such as OH, NH, C=O.
X-ray Crystallography: Gives a full three-dimensional structure, especially when crystals are available.
These different techniques work together like different diagnostic tools in a hospital, each giving part of the full picture until the complete structure is revealed.
Examples and Uses of Important Natural Products
Natural products have a wide range of important applications:
Morphine, obtained from the Papaver somniferum (opium poppy), is used as a strong pain reliever in hospitals.
Artemisinin, isolated from Artemisia annua (sweet wormwood), is a powerful antimalarial drug commonly used in Africa.
Resveratrol, found in grapes and some berries, has antioxidant properties and is studied for heart protection.
Digoxin, obtained from Digitalis purpurea (foxglove plant), is used for treating certain heart conditions.
In Nigeria, kolaviron, a natural flavonoid from bitter kola (Garcinia kola), is traditionally used for liver protection and is known for its antioxidant activity.
Gingerol from ginger is well known for its anti-inflammatory and antimicrobial effects and is widely used in local herbal remedies.
Challenges in Natural Products Research
Working with natural products can be challenging for several reasons:
Low Natural Abundance: Many useful compounds occur in very small amounts in nature, making extraction difficult.
Structural Complexity: Some natural products have extremely complicated structures that require advanced techniques and time to analyse.
Sustainability: Over-harvesting plants for their active compounds can harm the environment, so there is a need for sustainable collection or semi-synthetic alternatives.
Summary
- Natural products are produced through specific biosynthetic pathways (mevalonate, shikimic acid and polyketide pathways).
- Structural elucidation involves techniques such as NMR, MS, IR and X-ray crystallography.
- Important natural products include morphine, artemisinin, resveratrol, digoxin, kolaviron and gingerol, all of which have significant biological or medicinal uses.
- Natural product research faces challenges such as low natural yield, structural complexity and sustainability concerns.
- Understanding biosynthetic pathways and structural analysis techniques is essential for the development and safe use of natural products in medicine and industry.
Evaluation
- Give one natural product biosynthetic pathway and one compound produced through it.
- Mention two techniques used in the structural elucidation of natural products.
- Give two examples of natural products and their uses.
- State one major challenge in natural products research.
You’ve done excellently today! Keep going – your commitment is powerful, and Afrilearn is here to make sure you keep succeeding with confidence.