Determination of free phenolic acids from leaves within different colored maize

Abstract

Along with other plant parts, maize leaves are widely used for making fermented food for cattle, known as silage. Since there have only been a few reports on studies concerning the extraction and determination of phenolic acids from maize leaves, the main goal of this investigation was to evaluate the content of free phenolic acids in the leaves of fifteen different maize inbred lines. Reverse-phase, high performance liquid chromatography (RP--HPLC), with a photodiode array detector (DAD), was performed. Under the optimized chromatographic conditions, referring to short time of sample preparation, small quantities of solvent and direct injection of the extract into HPLC, phenolic acids (i.e., gallic, protocatechuic, caffeic, p-coumaric and ferulic acid) were successfully separated in less than 25 min, indicating that the method could be applied for routine analysis. The efficiency and validation of the method was evaluated by measuring the rate parameters: linearity, limit of detection and quantification, accuracy and precision. The obtained results showed that the most abundant free phenolic acid was p-coumaric acid (23.57 µg g -1 dry weight), followed by ferulic and caffeic acids (21.27 and 20.78 µg g -1 dry weight, respectively). Principal Component Analysis (PCA) revealed the existence of a link.

Evaluation of the nutritional profile of sweet maize after herbicide and foliar fertilizer application

“…The extraction of carotenoids (lutein + zeaxanthin (L+Z) and β-carotene) was performed by adding (2 × 6 mL) the mixture of methanol and ethyl acetate (6:4, v/v), (Rivera and Canela, 2012). The extraction of free phenolic acids (protocatechuic (PA), caffeic (CA), p-coumaric (p-CoumA), ferulic (FA) and cinnamic acid (CIN)) was achieved by using (2 × 5 mL) 80% methanol (Mesarović et al, 2017a). After homogenization in the ultrasound bath (30 min at 25 ºC) for all analyses, the extracts were centrifuged, filtered (0.45 µm nylon syringe filter) and directly injected into the Dionex UltiMate 3000 HPLC system (Thermo Scientific, Germany).…”

“…The detection of tocopherols and carotenoids was conducted by fluorescence (λ ex 290 nm; λ em 325 nm) and photodiode array (at 450 nm and 470 nm) detector, respectively. The mobile phase used for the separation of free phenolic acids and the wavelengths for detection were the same as reported by Mesarović et al, (2017a). The concentrations of the analyzed phytochemicals are expressed as µg per g of dry weight (DW) and reported as the mean value of three independent injections.…”