Study on isohexenylnaphthazarins polymerization in alkaline media

Area of Science:

• Natural Products Chemistry
• Pharmaceutical Chemistry
• Organic Chemistry

Background:

• Alkannin and shikonin (A/S) are potent hydroxynaphthoquinones (HNQ) with diverse pharmaceutical applications.
• Stability of A/S and their derivatives is critical for their use in drugs, cosmetics, and food.
• Polymerization of IHN esters can impact the efficacy and safety of A/S-derived products.

Purpose of the Study:

• To investigate the influence of alkaline media and IHN ester hydrolysis on IHN polymerization.
• To optimize hydrolysis conditions to minimize polymerization.
• To compare polymerization during hydrolysis from pure pigments versus root extracts.

Main Methods:

• Size exclusion chromatography (SEC) was used to analyze IHN polymerization.
• Experimental investigation of alkaline media and IHN ester hydrolysis.
• Optimization studies for IHN ester hydrolysis conditions.

Main Results:

• Hydrolysis of IHN esters leads to the formation of polymeric alkannin, shikonin (A/S), and IHN.
• Polymerization occurs via semiquinone intermediates in alkaline media and during hydrolysis.
• Hydrolysis from pure pigment mixtures resulted in less polymerization than from root extracts.
• Non-polar solvents are recommended for IHN extraction to minimize polymerization.

Conclusions:

• Hydrolysis conditions significantly influence IHN polymerization.
• Optimized extraction and hydrolysis methods are crucial for preserving A/S integrity.
• Understanding polymerization mechanisms is key to developing stable A/S-based products.