RESUMEN
Five selected medicinal plants in the family Zingiberaceae, Alpinia nigra, Boesenbergia maxwellii, Etlingera araneosa, Meistera koenigii, and Wurfbainia biflora, were collected from Thailand. HPLC was used to determine the content of phenolic compounds in their ethanolic extracts. The total phenolic contents and the total flavonoid contents of M. koenigii were found to be higher than that of the others. The antioxidant activity of the extracts was assayed by two methods, namely ABTS and DPPH assays using HPTLC and a microplate spectrophotometer. Anticholinesterase activity was screened by the Ellman method against acetylcholinesterase, the chief enzyme of Alzheimer's disease. The results showed mild acetylcholinesterase effects. The results indicated that these five ginger species, especially M. koenigii have the potential to be a good source of natural antioxidants and anticholinesterase agents that could be further applied in the pharmaceutical industry.
RESUMEN
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.