Bioactive phytosteroids from Araucaria columnaris (G. Forst.) Hook.: RP-HPLC-DAD analysis, in-vitro antioxidant potential, in-silico computational study and molecular docking against 3MNG and 1N3U.

Genus Araucaria is globally known for its medicinal, economic, and ornamental values. Most of its species have not been extensively studied yet for their chemical composition and biological activities. Therefore, the phytochemical investigation and antioxidant potential of Araucaria columnaris (G. Forst.) Hook. has been analyzed. This work aims to investigate the isolation, characterization, and antioxidant potential of bioactive compounds from the bark extract of the exemplar plant. Their structures were elucidated by virtue of physicochemical properties and spectroscopic methods. The antioxidant potential was further discussed through various assays including DFT and molecular docking. The isolation of pure compounds from bioactive extract has been carried out chromatographically. Their structures were elucidated by 1D, 2D NMR, FT-IR, UV, MS, and RP-HPLC-DAD data analysis. In vitro, the antioxidant potential was evaluated by the DRSC, FRAP, and TAC assays and in-silico studies by DFT and molecular docking. For the first time, pure compounds such as stigmasterol (IC1) and diosgenin (IC2) were isolated from the bark extract of Araucaria columnaris. In vitro antioxidant activity has been demonstrated that IC2 has higher values of DRSC, FRAP, and TAC than IC1, due to higher reactivity of IC2 than IC1 as represented by quantum reactivity parameters like lower energy gap, higher dipole moment, and higher electron-donor power. Further, antioxidant potential was also confirmed by molecular docking against two stress proteins such as 3MNG (IC2: -7.70 Kcal/mol > IC1: -7.32 Kcal/mol > ascorbic acid: -5.56 Kcal/mol) and 1N3U (heme: -12.42 Kcal/mol > IC2: -11.15 Kcal/mol > IC1: -9.45 Kcal/mol). In conclusion, the phytosteroids exhibited excellent antioxidant potential, which could enlighten their ethnomedical use. The exemplar plant offered powerful and available antioxidant besides significantly active phytoconstituents.