Sesquiterpene acids from Shellac and their bioactivities evaluation.

Area of Science:

• Natural Product Chemistry
• Organic Chemistry
• Phytochemistry

Background:

• Shellac, a natural resin, is widely used in pharmaceutical and food industries.
• The chemical constituents of Shellac, particularly sesquiterpenes, are not fully characterized.
• Understanding Shellac's composition is crucial for its safe and effective application.

Purpose of the Study:

• To isolate and elucidate the structures of sesquiterpenes from Shellac.
• To evaluate the cytotoxic and antibacterial activities of the isolated compounds.
• To propose a biogenetic relationship among the identified sesquiterpenes.

Main Methods:

• Isolation of compounds using chromatographic techniques.
• Structure elucidation via High-Resolution Electrospray Ionization Mass Spectrometry (HR-ESI-MS), UV, IR, 1D, and 2D Nuclear Magnetic Resonance (NMR) spectroscopy.
• Determination of absolute configurations using Mosher's method, Circular Dichroism (CD), and optical rotation analysis.

Main Results:

• Seven sesquiterpenes were isolated, including six previously unknown compounds: four α-cedrene types (Shellolic acids A-C, Laccishellolic acid), two R-curcumene types (Shellolic acids D-E), and Shellolic acid F.
• No cytotoxic activity was observed for any of the isolated compounds.
• Compound 1 exhibited notable antibacterial activity against Bacillus subtilis, with a Minimum Inhibitory Concentration (MIC) of 0.1 mg/mL.

Conclusions:

• The study successfully identified novel sesquiterpenes from Shellac, contributing to the understanding of its chemical diversity.
• The lack of cytotoxicity aligns with Shellac's established safety profile for food and pharmaceutical applications.
• The antibacterial activity of compound 1 suggests potential for developing new antimicrobial agents from natural sources.