Pigmented maize has been extensively studied due to its high anthocyanin content. This study has been focused mainly on kernel, although the whole plant of purple corn is a potential source of anthocyanins. First, general parameters of extraction (solvent system, solvent-to-solid ratio, number of extractions, and acid type) were established depending on the total anthocyanins content. Then, three extraction methods to access anthocyanins were compared: maceration extraction (ME), ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE). Since the residual material still possessed an intense color, a further treatment was performed by application of enzymatic-assisted extraction (EAE). Three enzymatic cocktails (Xylanases, Celluclast, and Depol), pH, and temperature were evaluated to establish optimal reaction conditions. Subsequent analysis and identification of the anthocyanins obtained by four different extraction techniques were performed using HPLC and HPLC-mass spectrometry, respectively. The most efficient method was UAE using 20 min of ultrasound (100 W) preceded by sample treatment in the following conditions: ethanol/water/lactic acid mixture (80:19:1), two extractions, 1:10 solvent-to-solid ratio. As a result, anthocyanins from corn cob and corn husk were extracted at concentrations of 24.32 and 25.80 mg/gDW, respectively. No difference in the anthocyanins profile for samples extracted by three different methods was observed. However, an enhanced presence of cyanidin-3-(6''malonyl)glucoside was detected in the sample corresponding to the EAE method. Therefore, the Cahuacintle corn husk can be considered as a competitive source of anthocyanins with the available commercial sources.

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Mexico is the center of origin of maize where there is a great variety of pigmented corns with health benefits. These properties are attributed to their high content of phenolic compounds. The most studied compounds are anthocyanins that no matter the variety of corn are mainly six: cyanidin, pelargonidin and peonidin-3-glucoside and their malonated derivatives. Among the pigmented corns, the purple has the most concentration of anthocyanins, these are found in the whole plant but in more quantity in the silk. The health benefits attach to anthocyanins are principally anti-obesity agent and anticancer activity. Regarding the phenolic acids reported in the pigmented corn plant, the most abundant acid in kernel is ferulic acid, in cob is syringic acid while in the silk is chlorogenic acid. This variation, in the phenolic acid profiles according to the organ, indicates the biological function that each of them plays in the plant; meanwhile in humans, they have important antioxidant effects. Flavonoids are the group less studied of bioactive compounds in pigmented corns; however, the concentrations of these compounds are high especially in purple silk; inside the flavonoids described are morin, kaempferol, naringin, maysin, rutin, quercetin and hyperoside; with antioxidant effects, as neuroprotective, apoptosis induction and others.

The syntheses of novel hybrid 2-(3,3'-diindolylmethylphenyl)-1H-benzimidazole regioisomers under ecofriendly, solvent-less, catalyst-free conditions and using microwave energy with good to excellent yields in short reaction times were achieved.