Combined in vitro and computational studies on the antioxidant and anticancer effects of Caesalpinia digyna (Rottl.) fruit extracts

Caesalpinia digyna Rottl. is an evergreen shrub traditionally used as an astringent, phthisis, antipyretic, nervine tonic, and diabetes remedy. The goal is to determine the fruit extract's antioxidant, anticancer, and cytotoxic effects through in vitro and computational studies. First, the methanol extract was prepared, and fractionation was performed using petroleum ether, dichloromethane, ethyl acetate, and distilled water. Preliminary screening was done using qualitative techniques, while Folin-Ciocalteu and AlCl₃ techniques were used to measure the total phenol (TPC) and flavonoid content (TFC), respectively. The total antioxidant capacity, DPPH scavenging, and Fe³⁺ reducing power were used to calculate the antioxidant activity using a spectrophotometric technique. Besides, Trypan Blue Exclusion and MTT methods were used to measure cytotoxic and anticancer activities against Vero and various cancer cell lines. GC-MS profiling was performed to identify the plant's phytochemicals. Phytochemical screening revealed various phytoconstituents, and the GC-MS analysis discovered 40 bioactive compounds in the ethyl acetate extract (ECDF). The ECDF exhibited the highest TPC (258.16 ± 4.84 mg GAE/g) and TFC (174.25 ± 8.33 mg QCE/g), and potent antioxidant capacity. In the in vitro anticancer and cytotoxicity studies, the ECDF showed the lowest viability at doses of 800 µg/mL against the lung cancer (43.97 ± 2.95%) and Vero (53.58 ± 3.20%) cell lines. Besides, ECDF extract has strong anticancer effects against breast cancer cell lines MCF-7 and MDA-MB-231 (IC₅₀: 23.53 ± 1.61 and 15.57 ± 3.74 µg/mL). The docking results showed that the selected compounds have a strong binding affinity for several proteins and bind to amino acid residues via hydrogen bonds, non-covalent, and Van Der Waals bonds. Molecular dynamics simulations revealed that the 1,3-dihydroxyanthraquinone (C14) compound forms stable complexes with respective proteins. Additionally, most of these compounds were predicted to have satisfactory ADMET profiles. The findings suggest that C. digyna fruit extracts might be a potential source for discovering cancer medicine. However, further analysis is required to isolate and identify the compounds responsible for these effects.