The nutritional compositions and phytochemical properties of eight edible flowers of the ginger family (Zingiberaceae) commonly found in Thailand are reported herein. The plant genera investigated were Zingiber (Ginger, Phlai Dam, Krathue), Hedychium (two morphological filament forms), Curcuma (Ao), Etlingera (Torch ginger), Amomum (Chi Kuk), and Alpinia (Galangal), which are eaten fresh or cooked as ingredients in the preparation of many Thai dishes. The proximate compositions (moisture, ash, fiber, protein, fat, and carbohydrate contents) varied among the different genera. The plants sampled were generally low in fat content (<1%), which contributed as little as 30% of the total caloric energy. Edible plant parts contained substantially high amounts of potassium (max. 737.21 mg/100 g), calcium (max. 140.15 mg/100 g), and iron (~0.32 mg/100 g). Among the tested samples, torch ginger had the highest vitamin C content (1.05 mg/100 g), total phenolic and total flavonoid contents, as well as 2,2-diphenyl-1-picrylhydrazyl activity. On the other hand, the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) assay suggested that Hedychium species possessed the highest antioxidant activity (~5.38 mg TEAC/g extract). Our results prove that edible plants of the Zingiberaceae family found in Thailand are rich sources of potentially important nutrients.

Background: Some of Zingeberaceae are not widely used for medicine of food, although in Thailand have been used them for many reasons about health or the diet. This study evalued the phytochemicals and anti-tyrosinase activities of 16 plant species of Alpinia, Amomum, Curcuma, Etlingera and Kaemferia (Zingiberaceae). Methods: The extractions of dried powdered rhizomes were performed using n-hexane, ethylacetate and ethanol. Percentage extract yield of the samples varied among species and solvent extracts. Chemical groups (alkaloids, flavonoids, tannins, polyphenols, steroids and terpenoids) were identified using phytochemical screening. The total phenolic contents (TPC) were analyzed using the Folin-Ciocalteu's reagent, while antioxidant activities were detected using 2,2-diphenyl-1picrylhydrazyl (DPPH) and the 2,2'-azino-bis (3-ethylbenzothizoline-6-sulphonic acid) (ABTS .+ ). The anti-tyrosinase was expressed to the half maximal inhibitory concentration (IC 50 ) value (mg/mL). Results: The ethyl acetate extract of Amomum showed the highest value of TPC. The strongest antioxidant activity were found in Amomum and Kaemferia extracts, while ethyl acetate and ethanol extracts of all samples have a better antioxidant properties than the n-hexane extracts. On the other hand, the n-hexane extracts have the highest anti-tyrosinase potential in all samples and of these, Curcuma extracts were the best group. Conclusion: Our research indicated that plants of the Zingiberaceae would be new sources of antioxidants and anti-tyrosinase for further natural product developments in cosmetics, food or nutraceuticals.

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