Antioxidant Effect of Berberine and its Phenolic Derivatives Against Human Fibrosarcoma Cells

Berberine (B1), isolated from stems of Coscinium fenestratum (Goetgh.) Colebr, was used as a principlestructure to synthesize three phenolic derivatives: berberrubine (B2) with a single phenolic group, berberrubinechloride (B3) as a chloride counter ion derivative, and 2,3,9,10-tetra-hydroxyberberine chloride (B4) with fourphenolic groups, to investigate their direct and indirect antioxidant activities. For DPPH assay, compoundsB4, B3, and B2 showed good direct antioxidant activity (IC50 values=10.7±1.76, 55.2±2.24, and 87.4±6.65 μM,respectively) whereas the IC50 value of berberine was higher than 500 μM. Moreover, compound B4 exhibiteda better DPPH scavenging activity than BHT as a standard antioxidant (IC50=72.7±7.22 μM) due to the orthoposition of hydroxyl groups and its capacity to undergo intramolecular hydrogen bonding. For cytotoxicity assayagainst human fibrosarcoma cells (HT1080) using MTT reagent, the sequence of IC50 value at 7-day treatmentstated that B1 < B4 < B2 (0.44±0.03, 2.88±0.23, and 6.05±0.64 μM, respectively). Berberine derivatives, B2 andB4, showed approximately the same level of CAT expression and significant up-regulation of SOD expressionin a dose-dependent manner compared to berberine treatment for 7-day exposure using reverse transcriptionpolymerasechain reaction (RT-PCR) assays. Our findings show a better direct-antioxidant activity of thederivatives containing phenolic groups than berberine in a cell-free system. For cell-based system, berberinewas able to exert better cytotoxic activity than its derivatives. Berberine derivatives containing a single andfour phenolic groups showed improved up-regulation of SOD gene expression. Cytotoxic action might not bethe main effect of berberine derivatives. Other pharmacological targets of these derivatives should be furtherinvestigated to confirm the medical benefit of phenolic groups introduced into the berberine molecule.