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Objective: To identify and quantify the bioactive compounds, along with biological activities, of native Thai edible Zingiberaceae. Methods: The bioactive compounds evaluated were phenolic acids, flavonoid, vitamin C, curcumin, 6-gingerol, eugenol and essential amino acids; analyses involved HPLC and LCMS/MS. Antioxidant activities were assessed by DPPH and FRAP assays. Results: Zingiber officinale was the richest source of bioactive compounds, followed by Z. officinale, Alpinia zerumbet and Alpinia conchigera. Total phenolic content and total flavonoid contents ranged widely across these species (17 to 200 mg GAE/100 g DW and 17 to 66 mg RE/100 g DW). All the species studied possessed strong antiglycation properties, ranging from 82 to 98%, with strong positive correlations of total phenolic content and antioxidant activity. The contents of curcumin, 6-gingerol, eugenol and vitamin C were in the range of 1 to 26, 1 to 140 µg/ g DW, 5 to 1600 and 4 to 21 mg/100 g DW, respectively. Seven essential amino acids identified by using LCMS/MS were found in most samples studied ranging from 2 to 6752 µg/100 g DW. Conclusion: Z. officinale is an abundant source of bioactive compounds and antioxidant activity in all these samples. These plants are fresh sources for developing novel functional ingredients in either food or cosmetics.

Effects of drying methods on the stability of phytochemicals and antioxidant properties of ginger (Zingiber officinale) were assessed. The rhizomes were collected at 9 and 12 months after planting and sun-dried, freeze-dried, or oven-dried at 40 • , 50 • , 60 • , or 70 • C. Oven drying at 60 • C resulted in significant gains of phenolics (441.85 mg.100g -1 d.w), antioxidant activities (78.45 ± 2.04% and 650.45 ± 50.04 μmol Fe (II).g -1 dry extract) of ginger rhizomes at 9 months after planting. Oven drying at 70 • C resulted in significant gains of phenolics (450.02 mg.100g -1 dry weight), antioxidant activities (79.34 ± 1.20% and 662.31 ± 17.01 μmol Fe (II).g -1 dry extract) of ginger rhizomes at 12 months after planting.

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