Saponins from Solanum nigrum L. Fruit: Extraction Optimization, Structural Characterization, and Dual-Functional...

Area of Science:

• Food Science
• Natural Products Chemistry
• Pharmacology

Background:

• Solanum nigrum L. is a traditional edible plant with potential bioactive compounds.
• Saponins are a class of compounds known for various biological activities.
• Functional foods require natural preservatives with antioxidant and antimicrobial properties.

Purpose of the Study:

• To optimize saponin extraction from Solanum nigrum fruits.
• To isolate and structurally elucidate saponins from Solanum nigrum.
• To evaluate the antioxidant and antibacterial activities of purified saponins for food applications.

Main Methods:

• Optimized saponin extraction from S. nigrum fruits.
• Column chromatography for saponin isolation.
• Spectroscopic analyses (IR, NMR, MS) for structural elucidation.
• DPPH, hydroxyl, and ABTS radical scavenging assays for antioxidant activity.
• Antimicrobial assays against foodborne pathogens.

Main Results:

• Achieved 8.59% total saponin yield.
• Identified three saponins: γ2-Solamargine, Diosgenin, and β-Solanine.
• The n-butanol-purified fraction showed potent antioxidant activity (DPPH IC50 = 0.0096 mg/mL).
• Saponins demonstrated selective antimicrobial efficacy, particularly against Escherichia coli.
• Synergistic suppression of lipid oxidation and microbial growth observed.

Conclusions:

• Solanum nigrum fruit saponins possess dual-functional preservative properties.
• These saponins are effective natural antioxidants and selective antimicrobials.
• They represent a promising, multi-mechanistic alternative to synthetic food additives.
• Findings support their use in clean-label functional foods.