Photodynamic and cytotoxic activities of Onosma aucheriana extract: Molecular interactions and antioxidant potential

Introduction

This study investigates the anticancer, photodynamic, antioxidant efficiency and molecular interaction profiles of Onosma aucheriana methanol extract.

Method

The cell viability of normal (HEK293) and gastric cancer (MKN28) cell lines was evaluated using IC₅₀ values, including photodynamic activity under green light. Antioxidant potential was assessed through DPPH radical scavenging, while phytochemical contents were quantified spectrophotometrically. Gas chromatography-mass spectrometry (GC–MS) analysis identified major compounds, and molecular docking studies explored their interactions with target proteins.

Results

Cell viability assays showed a dose-dependent reduction in cell viability, with IC₅₀ values of 1036 μg/mL for HEK293 and 951.8 μg/mL for MKN28. To assess photodynamic activity, green light was used, revealing IC₅₀ values of 56.62 μg/mL for normal cells and 32.53 μg/mL for cancer cells. A more pronounced reduction in cell viability was observed in cancer cells compared to normal cells. However, it demonstrates significant photodynamic activity at a concentration approximately 1/18th of the IC₅₀ value for normal cells and about 1/29th of the IC₅₀ value for cancer cells. The extract, with a DPPH radical scavenging IC₅₀ value of 154.15 ± 1.04 µg/mL, exhibits strong antioxidant activity, which is greater than that of BHT (230 ± 10 µg/mL). The total flavanol, flavonoid, phenolic, proanthocyanidin, and tannin contents are quantified as 24.30 ± 1.23 mg QE/g, 32.96 ± 3.23 mg QE/g, 6.31 ± 0.79 mg GAE/g, 83.41 ± 12.95 mg CAE/g, and 27.32 ± 2.30 mg GAE/g, respectively. GC–MS analysis reveals inositol (30.47 %), 4-((1E)‑hydroxy-1-propenyl)-2-methoxyphenol (23.04 %), 3-amino-2,6-dimethylpyridine (7.41 %), and 3-buten-2-one, 4-(4‑hydroxy-2,2,6-trimethyl-7-oxabicyclo[4.1.0] hept‑1-yl) (5.99 %) as major components. Molecular docking studies reveal that 3-buten-2-one, 4-(4‑hydroxy-2,2,6-trimethyl-7-oxabicyclo[4.1.0] hept‑1-yl) exhibits strong binding interactions with BAF complex (6LTJ), inositol shows substantial hydrogen bonding, and 4-((1E)‑hydroxy-1-propenyl)-2-methoxyphenol demonstrates significant binding with several receptors.

Conclusion

The O. aucheriana extract exhibited strong antioxidant activity and a novel photodynamic cytotoxic effect that became prominent under green light exposure. These findings suggest that the extract may possess versatile therapeutic potential.