SUMMARYResearch backgroundCurcumaspecies (Zingiberaceae) are well known medicinal herbs in India and Southeast Asia. Despite various findings reporting their beneficial biological activities, very little information has been recorded on theCurcuma caesia. Thus, this study aims to determine the phenolic content, antioxidant and α-glucosidase inhibitory activity of both rhizome and leaves ofC. caesia.Experimental approachRhizome and leaves ofC. caesiawere dried with oven (OD) and freeze (FD)-drying methods, and extracted with differentΦ(ethanol,water)=100:0, 80:20, 50:50 and 0:100. The bioactivities ofC. caesiaextracts were evaluated usingin vitrotests; total phenolic content (TPC), antioxidant (DPPH and FRAP) and α-glucosidase inhibitory activity. Proton nuclear magnetic resonance (1H NMR)-based metabolomics approach was employed to differentiate the most active extracts based on their metabolite profiles and correlation with bioactivities.Results and conclusionsThe FD rhizome extracted withΦ(ethanol,water)=100:0 was observed to have potent TPC expressed as gallic acid equivalents, FRAP expressed as Trolox equivalents and α-glucosidase inhibitory activity with values of (45.4±2.1) mg/g extract, (147.7±8.3) mg/g extract and (265.5±38.6) µg/mL (IC50), respectively. Meanwhile, for DPPH scavenging activity, theΦ(ethanol,water)=80:20 and 100:0 extracts of FD rhizome showed the highest activity with no significant difference between them. Hence, the FD rhizome extracts were selected for further metabolomics analysis. Principal component analysis (PCA) showed clear discrimination among the different extracts. Partial least square (PLS) analysis showed positive correlations of the metabolites, including xanthorrhizol derivative, 1-hydroxy-1,7-bis(4-hydroxy-3-methoxyphenyl)-(6E)-6-heptene-3,4-dione, valine, luteolin, zedoardiol, β-turmerone, selina-4(15),7(11)-dien-8-one, zedoalactone B and germacrone, with the antioxidant and α-glucosidase inhibition activities, whereas curdione and 1-(4-hydroxy-3,5-dimethoxyphenyl)-7-(4-hydroxy-3-methoxyphenyl)-(lE,6E)-1,6-heptadiene3,4-dione were correlated with α-glucosidase inhibitory activity.Novelty and scientific contributionC. caesiarhizome and leaf extracts contained phenolic compounds and had varies antioxidant and α-glucosidase inhibitory capacities. These findings strongly suggest that the rhizomes ofC. caesiaare an invaluable natural source of active ingredients for applications in pharmaceutical and food industries.