Phytochemical, Antimicrobial, And Antioxidant Properties Of Alstonia Macrophylla Leaf Extract: A Comprehensive Analysis Using GC-MS And HPTLC

Abstract

Over centuries, medicinal plants have been vital suppliers of natural products and treatments.  Alstonia macrophylla Wall. ex G. Don emerging as a significant candidate due to its extensive use in traditional medicine across Southeast Asia. This study explores the phytochemical, antimicrobial, and antioxidant properties of Alstonia macrophylla leaf extracts, with an emphasis on ethanolic extract due to its efficacy in extracting a broad range of bioactive compounds. Phytochemical analyses were conducted on extracts prepared using solvents of varying polarities, including Petroleum ether, Ethyl acetate, Methanol, Ethanol, Hexane, and Water, to identify key constituents such as alkaloids, flavonoids, saponins, and reducing sugars. Antimicrobial activity of the ethanolic extract was tested against bacterial and fungal strains (e.g., Staphylococcus aureus and Escherichia coli) at concentrations of 10, 25, 50, and 100 mg/mL. Antioxidant potential was assessed through radical-scavenging assays, and IC50 values were compared to ascorbic acid. High-Performance Thin-Layer Chromatography (HPTLC) and Gas Chromatography-Mass Spectrometry (GC-MS) analyses were performed to identify and characterize major bioactive compounds.

Ethanolic extraction yielded high levels of bioactive compounds, including alkaloids, flavonoids, saponins, and reducing sugars. Antimicrobial testing showed concentration-dependent inhibition, with significant zones of inhibition against S. aureus and E. coli, especially at higher concentrations. DMSO exhibited notable antimicrobial activity, suggesting potential synergistic effects or inherent antimicrobial properties. The ethanolic extract demonstrated moderate antioxidant activity, with IC50 values indicating it as a natural antioxidant but less potent than ascorbic acid. HPTLC and GC-MS analyses revealed key bioactive compounds, such as Benzenemethanol and 19-oxo-12-methoxyechitamidine, with potential antimicrobial, anti-inflammatory, and antioxidant effects.
This study highlights the therapeutic potential of Alstonia macrophylla leaf extracts, especially the ethanolic extract, for antimicrobial and antioxidant applications. The identification of unique bioactive compounds through HPTLC and GC-MS offers insight into Alstonia macrophylla’s bioactive profile, supporting its traditional medicinal use and paving the way for further research on isolated compounds for drug development.