[Diversity and selectivity in biomolecules]

Area of Science:

• Natural Product Chemistry
• Organic Chemistry
• Biochemistry

Context:

• Nature produces a vast array of molecular structures through controlled synthesis.
• Monoterpenoid indole alkaloids, found in Apocynaceae, Loganiaceae, and Rubiaceae, represent a large class of natural products.
• Strictosidine serves as a key chiral precursor for over 2200 known alkaloids.

Purpose:

• To demonstrate how kinetic and thermodynamic control shape molecular diversity in natural product biosynthesis.
• To analyze the structural relationships and formation pathways of monoterpenoid indole alkaloids derived from strictosidine.
• To illustrate the fundamental principles governing the selection of existing molecules from potential chemical space.

Summary:

• Graph analysis reveals that strictosidine, formed with high stereoselectivity, is the exclusive precursor to over 2200 homochiral alkaloids.
• Enzymatic deglycosylation under kinetic control yields epimers, while acid hydrolysis under thermodynamic control favors the most stable epimers.
• Subsequent cyclization reactions generate diverse tricyclic, tetracyclic, and pentacyclic aglucone skeletons, leading to rearranged and unrearranged alkaloid families.

Impact:

• Highlights the elegance of Nature's synthetic strategies in generating molecular complexity and diversity.
• Provides insights into the biosynthesis and structural evolution of a significant class of plant-derived alkaloids.
• Underscores the interplay between stereochemistry, reaction control, and the emergence of specific biomolecular structures.