Turmeric (Curcuma longa L.) extract in different solvents: A comparative study of curcuminoid content, volatile compounds, and antimicrobial activity with molecular docking insights

The search for bioactive compounds has increasingly turned to plants as a promising and cost-effective source. Turmeric ( Curcuma longa L. ) is a widely cultivated rhizome valued as a culinary spice and a key ingredient in traditional medicine, particularly in Bangladesh. Therefore, the current work was conducted to estimate curcuminoids and the relative amount of volatile components in different solvent extracts (n-hexane, dichloromethane, acetone, methanol, ethanol, and water) of turmeric ( Curcuma longa L.), and assess their in-vitro antimicrobial activity and molecular docking. Among the extracts, the methanolic extract exhibited the highest curcuminoid concentration, demonstrating its potential as a rich source of these valuable compounds. Gas Chromatography-Mass Spectrometry (GC-MS) analysis identified turmerone and ar-turmerone as prominent non-curcuminoid volatile components. The n-hexane extract contained 14.82, 29.37, and 151.81 times more ar-turmerone and 08.42, 16.13, and 63.52 times more turmerone than methanol, ethanol, and acetone, respectively, highlighting the extract's superior profile. Although all the extracts (except water) showed potential antibacterial activity against four tested bacteria, only the n-hexane extract showed antifungal activity against Aspergillus niger and Aspergillus flavus. Molecular docking of identified constituents of n-hexane extract revealed the potential binding affinity of these compounds with the relevant proteins responsible for inhibitory activity against bacteria and fungus. Thus, curcuminoids, turmerone, ar-turmerone, and curlone of turmeric are potential bioactive compounds enriched with pharmacological properties. However, the comparative results, especially regarding curcuminoid and volatile compound content and the therapeutic potential of the findings, open the opportunity for further research, such as optimizing extraction techniques and exploring their medical importance.