Back to: Organic Chemistry 500 Level
Welcome to class!
I am delighted to have you here again. Today we begin Natural Product Biosynthesis I. This area is special because it connects chemistry with biology. While chemists can build molecules in the lab, nature has been synthesising complex molecules for millions of years through living organisms. Many of the medicines we use today, such as antibiotics, painkillers, and anticancer drugs, come directly or indirectly from natural product biosynthesis.
Natural Product Biosynthesis I
Think about Nigerian traditional medicine. For centuries, people have used roots, leaves, and barks from plants like neem, bitter leaf, and moringa to treat illnesses. These plants are powerful not by magic, but because they contain natural products—chemicals that the plants themselves make to survive, defend, or communicate. By understanding how nature makes these molecules, chemists can learn to produce new drugs, improve existing ones, or design better farming and health solutions.
What are Natural Products?
Natural products are organic compounds made by living organisms—plants, animals, fungi, and bacteria. They are often secondary metabolites, meaning they are not essential for survival but provide special advantages like protection or attraction. For example, the bitter taste of kola nut comes from alkaloids, which protect the plant from being eaten by pests.
Classes of Natural Products
Terpenes: Made from isoprene units (C₅H₈). They are found in essential oils, rubber, and vitamin A. For instance, menthol in peppermint and limonene in citrus fruits are terpenes.
Alkaloids: Nitrogen-containing compounds with strong physiological effects. Quinine from cinchona bark treats malaria, while caffeine in coffee keeps us alert.
Polyketides: Produced by the successive condensation of acetate units. They include antibiotics like erythromycin.
Shikimate Pathway Products: Lead to aromatic amino acids and compounds like flavonoids, lignin, and alkaloids. For example, morphine comes from this pathway.
Biosynthetic Building Blocks
Nature uses small, simple molecules as building blocks, just as a mason uses blocks to build a house.
Acetyl-CoA: A key two-carbon unit for polyketides and terpenes.
Isopentenyl pyrophosphate (IPP): The five-carbon unit for terpenes.
Shikimic acid: A seven-carbon intermediate leading to aromatic compounds.
Pathways of Biosynthesis
Polyketide Pathway: Works like a tailoring process, stitching acetate units together into long chains that are then folded and cyclised into complex structures.
Mevalonate and MEP Pathways: Both produce isoprene units for terpenes. This is like having two different kitchens producing the same ingredient.
Shikimate Pathway: Produces aromatic rings that become phenols, alkaloids, or lignin.
Significance of Natural Product Biosynthesis
Provides lead compounds for drug discovery.
Offers eco-friendly pesticides and herbicides.
Helps understand how organisms survive in their environments.
Guides chemists in designing synthetic routes.
Summary
- Natural products are secondary metabolites made by plants, animals, and microorganisms.
- Major classes include terpenes, alkaloids, polyketides, and shikimate-derived compounds.
- Key building blocks include Acetyl-CoA, IPP, and shikimic acid.
- Biosynthetic pathways stitch small molecules into complex structures.
- Natural products are important in medicine, agriculture, and chemical research.
Evaluation
- Define natural products and give two examples from Nigerian plants.
- What are terpenes made from, and give one example.
- Which pathway produces aromatic amino acids?
- State one medicinal application of alkaloids.
- Explain why natural product biosynthesis is important in drug discovery.
You have done very well! Understanding how nature builds molecules gives you a deep appreciation of both chemistry and life. Always remember, you are capable of mastering even the most complex ideas. With Afrilearn, you are growing into a scientist who can shape health, agriculture, and industry across Africa and the world.