Comparative Phytochemical Analysis and Antimicrobial Activity of Methanolic and Ethanolic Extracts of Dendrobium thongchai

Abstract

The objective of the study was to assess the phytochemical composition and initial antimicrobial efficacy of the cultivated hybrid orchid Dendrobium thongchai Gold through qualitative and quantitative methodologies. Root and leaf extracts were prepared utilizing methanol and ethanol according to solvent compatibility. Qualitative phytochemical screening was performed to ascertain principal secondary metabolites. Standard colorimetric and gravimetric methods were used to measure the amounts of certain phytochemical groups. The agar well diffusion method was used to test the antimicrobial activity of two extract concentrations against Bacillus subtilis, Escherichia coli and Aspergillus niger. Qualitative analysis indicated the existence of various bioactive compounds, with methanolic and ethanolic extracts exhibiting notably more complex phytochemical profiles. Quantitative analysis revealed elevated concentrations of flavonoids, polyphenols, quinones and cardiac glycosides in methanolic extracts whereas ethanolic extracts produced larger quantities of terpenoid- and coumarin-enriched fractions. During antimicrobial screening, measurable inhibition zones were noted for all tested organisms, with the ethanolic extract exhibiting comparatively larger zones at elevated concentrations. The research establishes foundational data regarding the phytochemical composition and initial antimicrobial efficacy of D. thongchai Gold. The results underscore the impact of solvent choice and facilitate more comprehensive chemical characterization and bioactivity investigations.