Psoralen from Ficus carica: Fractionation, bioactivity, and toxicological-pharmacokinetic comparison with silymarin

Abstract

Background

Ficus carica (无花果 wúhuāguǒ) is valued in traditional Chinese medicine (TCM) and nutrition for its rich phytochemical content. Our prior research showed a crude fig extract (FLA) selectively fought liver cancer cells (HepG2) in vitro while sparing normal cells.

Purpose

We aimed to isolate an active compound from FLA and analyze the potent bioactivities, particularly anticancer potential, through in vitro and computational studies.

Method

An innovative strategy combined fractionation by vacuum liquid chromatography (VLC) on silica gel (using six non-polar to polar solvent gradients) with thin layer chromatography (TLC) and bioactivity screening on liver (HepG2) and gastric (SGC-7901) cancer cell lines, and antimicrobial assay. The active Fraction 2 (Fr-2) was repeatedly sub-fractionated using Sephadex LH-20 column chromatography and TLC to isolate psoralen. Its mechanism of action against key cancer markers was evaluated via RT-qPCR, molecular docking, and ADMET pharmacokinetic analysis, with silymarin as a comparator.

Results

Fractionation of FLA yielded Fr- 2 (Hexane: Ethyl acetate, 50:50) with the IC50 (mg/mL) against HepG2 (0.31 ± 0.1) and SGC-7901 (0.124 ± 0.05) among the six tested fractions. It also exhibited antimicrobial activity, showing maximum inhibition zones (mm) against Aspergillus flavus FL (18± 0.4 mm), Penicillium chrysogenum FL (20 ± 0.7 mm), and Pseudomonas aeruginosa (17 ± 0.8 mm). Sub-fractionation of Fr- 2 led to the identification of psoralen, which decreased the genetic expression of tumor suppressor Tp53, anti-apoptotic (Bcl2) and Cell cycle kinases (CDK1 and CDK5). Molecular interaction via molecular docking against critical cancer regulators: Tp53, oncoproteins MDM2 and Bcl2, and CDK1/CDK5 also revealed the strong binding affinity of Psoralen. Psoralen demonstrates a novel mechanism of action by dual targeting of the MDM2-p53 axis: it binds p53′s N-TAD (Arg23, -8.8 kcal/mol) to reduce ubiquitination, while competitively inhibiting MDM2 (-5.8 kcal/mol) to stabilize Tp53 and induce apoptosis. Comparative ADMET analysis revealed psoralen's superior water solubility and oral bioavailability (96.67 % absorption) versus silymarin.

Conclusion

The active Fr-2, featuring psoralen, demonstrates broad antimicrobial and anticancer activity by potentially inhibiting the MDM2-p53 pathway to induce apoptosis, and it exhibits a superior ADMET profile compared to silymarin.