Evaluation of volatile compounds, phenolic acids, antioxidant potential and DFT study of essential oils from different parts of Araucaria columnaris (G. Forst.) Hook. from India

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.

Chemical Characterization and Biological Activity of the Essential Oil from Araucaria brasiliensis Collected in Ecuador

The purpose of this study was to determine the chemical composition, physical properties, enantiomeric composition and cholinesterase inhibitory activity of the essential oil (EO) steam-distilled from the leaves of the plant Araucaria brasiliensis Loud. collected in Ecuador. The chemical composition was determined by gas chromatography coupled to mass spectrometry (GC-MS) analysis on two capillary GC columns (DB5-ms and HP-INNOWax). Thirty-three compounds were identified in the EO; the main compounds were beyerene (26.08%), kaurene (24.86%), myrcene (11.02%), α-pinene (9.99%) and 5,15-rosadiene (5.87%). Diterpene hydrocarbons (65.41%), followed by monoterpene hydrocarbons (21.11%), were the most representative components of the EO. Enantioselective analysis of the EO showed four pairs of enantiomeric compounds, α-pinene, camphene, γ-muurolene and δ-cadinene. In an in vitro assay, the EO showed moderate inhibitory activity towards the enzyme butyrylcholinesterase (BuChE) (95.7 µg/mL), while it was inactive towards acetylcholinesterase (AChE) (225.3 µg/mL). Further in vivo studies are needed to confirm the anticholinesterase potential of the EO.