Utilization of UPLC-PDA and GC–MS/MS coupled with metabolomics analysis to identify bioactive metabolites in medicinal turmeric at different ages for the quality assurance

Available monographs often suggest measurement of curcumin or curcuminoids for quality control of turmeric-based medicines/products. However, one compound is not enough to indicate the quality of traditional herbal medicines due to the holistic approach. Furthermore, to ensure high quality of such products, good harvesting practice plays an important role in the quality control of turmeric raw materials.This study aimed to indicate quality markers of turmeric and to suggest optimum harvesting times for turmeric used for medicinal purposes by integration of Thai traditional medicine knowledge.Turmeric rhizomes at 4, 6, 8, 9, 10, and 11 months old were analyzed. UPLC-PDA was used for quantitation of curcumin. GC-MS/MS was used to obtain chemical profiles of turmeric volatile oil. PCA, Volcano plot, and HCA were performed to identify similarities or differences of the data.Turmeric aged between 6 and 10 months old contained > 5%w/w of curcumin, which complied with Thai Herbal Pharmacopoeia 2021. GC-MS/MS analysis suggested suitable chemical markers, namely Ar-turmerone, turmerone, curlone, and zingiberene, because they exhibited pharmacological activities related to the traditional uses of turmeric. Eucalyptol, santalene, β-caryophyllene, cis-β-farnesene, α-caryophyllene, curcumene, β-bisabolene, β-sesquiphellandrene, and cis-sesquisabinene hydrate were also tentatively identified. Later, the multivariate analysis revealed that turmeric aged between 6 and 10 months old showed similar metabolite profiles.Based on curcumin content and chemical profiles, turmeric aged between 6 and 10 months old are appropriate for uses in Thai traditional medicine. Our study suggests additional information in the quality control of turmeric to assure its efficacy, especially for uses in traditional medicines.