Back to: Organic Chemistry 400 Level
Welcome to class!
Hello remarkable learner, it’s a pleasure to have you back once again. I truly appreciate your commitment to learning and I’m excited because today we move on to Natural Product Chemistry III. In the previous lessons, we learnt the basics of natural products, their classes, biosynthetic pathways and the analytical methods used to determine their structures. Today, we will focus on biosynthetic relationships, semi-synthetic modification of natural products, and the industrial production of selected natural products. This lesson will help you connect nature with modern pharmaceutical development and industrial applications.
Natural Product Chemistry III
Think of nature as a brilliant master chef who prepares original recipes, while chemists take these recipes and adjust them to create new dishes with improved flavour, safety and effectiveness. That is exactly what happens in advanced natural product chemistry.
Biosynthetic Relationships between Natural Product Classes
Many natural products arise from a few basic building blocks such as acetyl-CoA, amino acids and isoprene units. Understanding the connections between these classes is important in predicting new structures and designing new biologically active agents.
Terpenoids (built from isoprene) often serve as starting points for the biosynthesis of steroid hormones.
Alkaloids may be derived from amino acids such as tryptophan (producing indole alkaloids) or ornithine (producing tropane alkaloids).
Phenylpropanoids, formed via the shikimic acid pathway, can be converted into flavonoids or lignins, depending on the enzymes present in the organism.
These relationships allow chemists to identify where a particular compound came from even when the original organism is not available.
Semi-Synthetic Modification of Natural Products
In many cases, natural products are highly active but unsuitable for clinical use as they may be toxic, unstable or poorly soluble. Chemists improve these compounds by making semi-synthetic derivatives. This involves taking a natural product as a starting material and chemically modifying it to produce a safer or more effective drug.
Examples include:
Aspirin – derived from salicylic acid obtained from willow bark. Acetylation reduces the irritation caused by the natural compound.
Amoxicillin – obtained by modifying the natural antibiotic penicillin to improve oral absorption and broaden its antibacterial spectrum.
Semi-synthetic Artemisinin derivatives (such as artesunate) – developed to increase the solubility and potency of artemisinin against malaria.
This is similar to taking raw yam from the farm and cooking it into pounded yam — the base material is the same, but its usefulness and acceptability are improved.
Industrial Production of Natural Products
Large-scale production involves several steps:
Cultivation or Fermentation – Growing the plant or microorganism in controlled conditions.
Extraction and Isolation – Using solvents to extract the bioactive compound.
Purification – Employing crystallisation or chromatography to remove impurities.
Formulation – Converting the pure compound into a stable pharmaceutical form like tablets, capsules or injections.
For example, quinine is produced industrially by cultivating Cinchona trees, extracting the alkaloid from the bark, purifying it and then formulating it into tablets for malaria treatment. In some cases, fermentation (e.g. for penicillin) is used instead of plant extraction to obtain better yields.
Future Trends in Natural Product Research
Biotechnology and Genetic Engineering are now used to insert biosynthetic genes into fast-growing microorganisms, allowing the production of complex natural products in the lab.
Combinatorial Biosynthesis allows the creation of new natural product analogues by combining pathways from different organisms.
Green Chemistry principles are being applied to reduce waste and improve sustainability when producing natural products.
Summary
- Biosynthetic relationships show how different classes of natural products originate from common precursors such as acetyl-CoA or amino acids.
- Semi-synthetic modification improves natural compounds by altering them chemically to reduce toxicity and increase effectiveness.
- Industrial production of natural products involves cultivation/fermentation, extraction, purification and formulation.
- Examples of semi-synthetic natural product drugs include aspirin, amoxicillin and artesunate.
- Future trends focus on biotechnology, combinatorial biosynthesis and sustainable production techniques.
Evaluation
- What is meant by semi-synthetic modification of natural products?
- Give two examples of semi-synthetic drugs derived from natural products and their uses.
- Outline the general steps involved in industrial production of natural products.
- Mention one future trend in natural product research and briefly explain it.
Great job today! Your ability to move from foundational concepts to advanced applications is impressive. Keep going confidently — Afrilearn is here to support every step of your journey to excellence!