Isolation and Quantification of Palmatine from Fibraurea tinctoria Lour: In Vitro Antioxidant Activity and In Silico Antidiabetic Activity Evaluation.

PURPOSE: This study aimed to isolate and characterize palmatine from Fibraurea tinctoria Lour stems, quantify its content, and determine its antioxidant and antidiabetic activities.

PATIENTS AND METHODS: Palmatine was isolated from the methanol extract of Fibraurea tinctoria Lour stems by silica gel column chromatography. Structural elucidation of the isolated compounds was performed using spectral data analysis and comparison with the literature. High-Performance Liquid Chromatography (HPLC) was used to quantitatively determine palmatine in the crude methanol extract and fractions. The DPPH and non-enzymatic SOD mimic methods were used to assess the antioxidant activity of the methanol extract, fractions, and isolated compounds. The antidiabetic activity was evaluated in silico by the molecular docking method of alpha-glucosidase and DPP-IV enzymes. Palmatine was used as a test ligand and was compared with berberine and its native ligand or standard compounds.

RESULTS: The isolated compound was identified as palmatine. Quantification of palmatine compound by HPLC showed that palmatine was found in the extract and all fractions. In the in vitro antioxidant activity test using the DPPH method, fraction 4 showed the highest activity, with an IC50 value of 91 ppm. In contrast, using the non-enzymatic SOD mimic method, the methanol extract, fraction 5, and isolated compound (palmatine) exhibited very strong antioxidant activity, with IC50 values of 18, 20, and 28 ppm, respectively. The in silico antidiabetic activity of palmatine is thought to have the potential to inhibit these two enzymes.

CONCLUSION: These results showed that Fibraurea tinctoria Lour stems have potential as an antioxidant and antidiabetic agent. Further research on phytochemical and pharmacological is required to validate the use of this plant species for the treatment of various diseases, especially diabetes mellitus.