Phytochemical analysis of baby corn silk extracts

BACKGROUND: Baby corn silk extract can be used as an antioxidant dietary supplement. However, insufficient data exists for this extract to guarantee its quality, efficacy and safety. OBJECTIVE: To determine phytochemical constituents, contents of phenolics and flavonoids, antioxidant activities, heavy metal concentrations, and microbial contamination of baby corn silk extracts. MATERIAL AND METHODS: Baby corn silks including Pacific 271 and Zeba SG 17 hybrids were individually extracted with 40% v/v ethanol and distilled water to obtain Pacific 271 ethanol extract (PE), Zeba SG 17 ethanol extract (ZE), Pacific 271 aqueous extract (PA), and Zeba SG 17 aqueous extract (ZA). The analysis of phytochemical constituents was carried out using phytochemical tests, TLC screening, UV-visible, FTIR, and (1)H NMR experiments. The contents of phenolics and flavonoids were determined using the modified Folin-Ciocalteu and aluminium chloride colorimetric procedures, respectively. Antioxidant activities were investigated using DPPH and FRAP assays. The concentrations of heavy metals were analyzed by ICP-MS. Microbial enumeration tests were carried out according to the United States Pharmacopeia (USP) 41. RESULTS: PE and ZE were composed of flavonoids, tannins, terpenoids, and steroids while PA and ZA contained flavonoids and tannins. PE and ZE exhibited higher total phenolic and flavonoid contents and significantly stronger antioxidant activities than PA and ZA. All extracts conformed to the microbiological and heavy metal requirements according to Association of South East Asian Nations (ASEAN) guidelines. CONCLUSION: PE and ZE were considered appropriate to use as natural extracts of phenolics and flavonoids with antioxidant activities and safety.