Composition of Anthocyanins found in pigmented corn plant.
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.
- pigmented corn
- phenolic acids
The oldest macroremains unambiguously identified as maize (
At this time, corn (
In the world, corn is generally used for animal feed and biofuels. In Mexico, this cereal is used for making foods; maize grains are consumed fresh (elotes and esquites, boiled grains) or processed in the form of dough or cornmeal for the preparation of some foods: dishes (tortillas), corn flakes (salads and sweets totopos), starch (atoles and pinole), tamale dough (tamales), fermented foods (pozol and atoles), boiled or steamed corn (pozole), soups (chilaquiles), bakery products and another foods. Some foods and grains of maizes are depicted in Figure 1.
The colorful corns are less common while the white and yellow are the most popular. All parts such as silk, cob, leaves, husk and kernel of corns have been used by people at remote time to Mesoamerican civilization, the pigment corns referred to as blue, red or purple corn are botanically the same species white and yellow. This cereal was used in the preparation to color foods and beverages. The interest on pigmented (blue, red and purple) corn is due to the bioactive compounds; these are anthocyanins,
2. Anthocyanin in pigmented corn
Anthocyanins are the largest group of phenolic pigments responsible for the pink, red, purple and blue corns which is the cereal with most anthocyanin content . For that reason, the pigmented corn has caught attention in research and production. There is a great diversity in types of corn including sweet corn, popcorn, pod corn, flint corn, flour corn, waxy corn and dent corn; everyone is able to have different variety of color as shown in Figure 3, which give us opportunity to get a great source of anthocyanins using the whole plant because, according with the variety of corn, the silk, corn husk and corn cob could have more anthocyanins than kernel, as we will see in later section.
2.1. Anthocyanin in pigmented corn kernel
Anthocyanin in corn is found in kernel, cob, husk, silk, leaves and stem [5, 6]. In terms of anthocyanins, kernel is the most studied and anthocyanins are found in pericarp and aleurone layer. Pericarp can be transparent, orange, red or brown while aleurone layer can be transparent, red or purple . Currently, researches in corn are focused on major production of anthocyanins, so there are some strategies to find new and better source of pigmented corns. One of them is the study of Mexican maize due to an excellent source for the production of anthocyanins because there are more than 60 native races of corn that have been little studied. However, Mendoza had studied the anthocyanins content in different corn lines and found corns with higher anthocyanins . Other strategy is hybrid corn which is also studied; nevertheless, the anthocyanins content is not better than other pigmented native corns.
The later research about anthocyanin characterization shows a similar profile include cyanidin-3-glucoside and cyanidin-3-(6”malonyl) glucoside as the main anthocyanins. Figure 4 shows anthocyanins found in pigmented corn. However, the variety of colors on pigmented corns is due to the difference on the concentration of each anthocyanin depending on genetics . Peonidin-3-glucoside and pelargonidin-3-glucoside and their derivatives are the anthocyanins that have major variability and a major concentration of pelargonidin-3-(6”malonyl)glucoside are found in red corn  while blue corn has neither pelargonidin-3-glucoside nor peonidin-3-glucoside as purple corn has , moreover blue corn has more cyanidin-3-(6″ malonyl)glucoside than purple corn; however, its total concentration is much less than purple corn as shown in Table 1 .
|Part of the corn||Corn phenotype||Anthocyanin||Ref.|
Purple corn bran3
Purple corn pericarp6
|Cy-3-glu (45.8%)2, (45.8%)3, (47.3%)4 (73.62%)6|
Pg-3-gluc (2.0%)2 (3.3%)3, (4.7%)4 (15.50%)6
Pn-3-gluc (9.3%)2, (4.,1%)3, (11.9%)4 (10.88%)6
Cy-3-malonylglu (17.2%)2, (11.9%)4
Pg-3-malonylglu (2.4%)2, (2.1%)4
Pn-3-malonylglu (3.1%)2, (6.0%)4
Condensed form (16.8%)2, (11.2%)4
|4, 2, 3|
|Purple corn V1-V91|
Purple Hybrid (WenveiiR5 R11)5
|Condensed forms1; Cy-3-glu1,2,3,5,6, Pg-3-gluc1,2,6,9; Pn-3-gluc1,2,5,6,9; Cy-3-malonylglu1,2,3,5; Pg-3-malonylglu1,2,3,5; Cy-3-dimalonylglu1; Pn-3-malonylglu1,2,3; Pg-3-dimalonylglu1,2; Pn-3-dimalonylglu1||5, 1, 2, 6, 9|
|Red hybrid corn (Wenwei2 R6 x LH287 R8)5||Cy-3-glu5; Pn-3-gluc5; Cy-3-malonylglu5||5|
|Blue corn||Cy-3-glu (24.4%)7 (61.50%)8|
|Blue hybrid corn (Lfy blue RI)5||Cy-3-glu5; Cy-3-malonylglu5; Pn-3-malonylglu5||5|
|Germ||Purple corn sprouts||Direct condensed|
(Epi)catechin (4-8)-Cy/Pn/Pg 3,5 diglu
(Epi)catechin (4-8)-Cy 3-malonylglu-5 glu
Cy- 3,5 diglu
Purple corn (Peru)10
|Cy-3-glu9, 10; Cy-3-malonylglu9, 10; Pn-3-glu9, 10; Pn-3-malonylglu9, 10; Pg-3-glu9, 10; Pg-3-malonylglu9, 10||9, 10|
|Purple corn (Peru)||Cy-3-glu (75.28%)|
|Husk||Purple corn||Cy-3-glu (11.7%)11 (39.8%)12|
Cy-3-malonylglu (29.0%)11 (8.4%)12
Cy-3-glu monomalonate (1.0%)11
Pg-3-glu (~1.5%)11 (2.0%)12
Cy-3-glu dimalonate (3.9%)11
2.2. Anthocyanin in pigmented corn cob
Cob is considered as a by-product from the corn and represents the 20.6–26.2% of the plant and it is used as animal feed. However, it has a chemical high value due to their high anthocyanin concentration and other phenolic compounds. Purple corn cob anthocyanin concentration is 3–3900 mg/100 g according to the last years’ review (Table 2). Differences are due to corn variety and also, but in a lesser way, extraction method. Anthocyanin composition in cob is similar to the kernel, finding the six main anthocyanins, and identification has made by HPLS-MS [15, 40].
|Part of corn||Maize phenotype||Extraction method||Anthocyanins content (mg/100 g)||Ref.|
|Kernel||Purple/Blue (||Heat water|
|Kernel||Purple Corn||2% formic acid, 2 h|
|Kernel||Purple (AREQ-084)||Alcoholic extraction (Methanol or ethanol) with acid (85:15 v/v)|
|Purple (race Conico)||97–426|||
|Purple corn (ZM01-ZM22)||0.8–111.7|||
|Kernel||Red corn (ZM01-ZM22)||Methanol acid||0.8–33.4|||
|Kernel||Pink (ZM01-ZM22)||Methanol acid||0.3–1.4|||
|Kernel||Blue pericarp||Alcoholic extraction (Methanol or ethanol) with acid (85:15 v/v)|
One to three extractions
|Blue (race Chalqueño)||64.6|||
|Blue (race Conico)||89.2|||
|Blue hybrid corn||73.0–105.2|||
|Blue hybrid corn||27.39–78.28|||
|Cob||Red/Purple waxy corn||Methanol-1% citric acid (80:20 v/v)|
24 h, 4°C
|Cob||Purple waxy corn (red to black)||Methanol|
Shaken for 2 h
|Cob||Purple hybrid corn (KPSC 901)||Conventional heating||3660|||
|Husk||Purple corn husk||0.1 N HCl|
6 h, room temperature
|Husk||Red/Purple waxy corn||Methanol-1% citric acid (80:20 v/v)|
24 h, 4°C
|Silk||Purple (ZPEXP)/Pink (ZP341)|
Purple hybrid (PWC1-5)
|Methanol acidified with 1 N (85:15 v/v)|
Shaking by 30 min
70°C, 1.5 h
|Silk||Purple corn||Ethanol 50%|
Ratio 1:1 w/v
|Silk||Red/Purple waxy corn||Methanol-1% citric acid (80:20 v/v)|
24 h, 4°C
|Germinated||Purple corn (PMW-581)||240|||
|Foliar||Purple corn (Jingzi No. 1)||Ethanol 60% with citric acid 1%|
60°C, 120 min
|Ultrasound assisted extraction|
|Kernel||Purple corn||96% ethanol and 1.5 N HCl (85:15)|
1:25/80 solid-to solvent
|Kernel||Purple corn bran||400 W||362|||
|Cob||Dried cob of purple waxy||65°C, 35 min|
1:20 solid-solvent ratio
|Supercritical fluid technology|
|Kernel||Purple corn pericarp (Peru)||50°C, 400 bar|
|Kernel||Purple waxy corn (||Subcritical solvent extraction method|
Sample-to-solvent ratio 1:20)
|Cob||Purple waxy corn (|
|Subcritical solvent extraction method|
Sample-to-solvent ratio 1:20)
|Silk||Purple waxy corn (||Subcritical solvent extraction method|
Sample-to-solvent ratio 1:30)
|Kernel||Purple waxy corn||High-pressure processing 700 MPa (30–45 min)||116|||
2.3. Anthocyanin in pigmented corn silk
Corn silk can be yellow, green or purple depending on the corn variety. Silk is used in local community as medicinal herbs; however, it does not take advantage and is considered a waste . But silk has a great potential to obtain phenolic compound, among them, anthocyanins. Research of silk is about its quantification and characterization of anthocyanins and results showed that has the highest anthocyanins concentration of the whole plant .
2.4. Anthocyanin in pigmented corn husk
Husk is the least studied part of the corn; there is limited research about their anthocyanin composition; however, they had a high concentration of anthocyanins depending on corn variety . Most recent reports show a deeper studied of the type of anthocyanins in purple husk which has more anthocyanin diacylated  but there is other report that found cyaniding-3-succinylglucoside instead of diacylated anthocyanin . For that reason, more research is needed; due to the low information, it is not possible to ensure that corn husk composition is different from other parts.
2.5. Extraction methods and characterization of anthocyanins in pigmented corn
Extraction of anthocyanin is made with methanol solvent acid and the method most used is ultrasound-assisted extraction that shows better efficiency, although, microwave-assisted extraction, ohmic heating extraction and supercritical solvent extraction are also used. Liquid chromatography techniques are the most used in anthocyanin identification. Table 2 shows the extraction methods used until 2018 and the anthocyanin content.
2.6. Biological activity of pigmented corn anthocyanins
Structural anthocyanins have conjugation that provides stabilization of free radicals. Antioxidant activity is plenty reported in pigmented corn. Additionally, anthocyanin extract of pigmented corn has been used in
|Extract of anthocyanin||Biological activity||Ref.|
|Red corn||Inhibition proliferation of colorectal cancer cell|||
|Purple corn||Inhibition proliferation of colorectal cancer cell|||
|Purple corn (hybrid maize) kernel||Cardioprotective activity||In vitro|||
|Purple maize flour||Reduce visceral adiposity index, total body fat mass, systolic blood pressure, total cholesterol and plasma triglycerides. Improve glucose tolerance, liver and cardiovascular structure and function|
In rats diet
|Purple corn pericarp||Adipogenesis, inflammation and insulin resistance in adipocytes|||
|Purple waxy corn cob||Neuroprotective and memory enhancing effect|||
|Purple corn silk|
|Blue tortillas||Learning capability||In rats diet|||
2.7. Applications of pigmented corn anthocyanins
Purple corn is used traditionally to make tortillas, atole, chips, popcorn and other type of food products. However, chemical studies of these food products are limited. Food industry is more interested in elaboration of products with a major quality and bioactive compounds content; in consequence, the development of new products with purple corn have been the most studied. Some of the developed products are presented in Table 4, where the main purpose was to find the best process to keep the major anthocyanins concentration.
Additionally, the anthocyanins are used to make photosensitizers from different colored parts of the corn including cob, husk and silk.
Furthermore, due to the low stability of anthocyanins, there are some studies related to this topic. The stability of anthocyanins has been improved using intermolecular copigmentation with gallic ferulic, caffeic acids, and results show that those acids do not protect the anthocyanins only have a hypochromic effect. There is a better protection by self-association. Other strategy is the encapsulated of anthocyanins in alginate-pectin hydrogel  and the spray-dried purple corn found that 5% of maltodextrin, 150°C and water are the best condition to obtain a soluble product with the major anthocyanin concentration . Haggard in 2018 also found that beverage with more pelargonidin-3-glucoside concentration has a major half-life .
3. Phenolic acids in pigmented corn
Pigmented corns are good source of phenolic acids; mainly hydroxycinnamic acids but also hydroxybenzoic and chlorogenic acids. These compounds are distributed in whole plant. Table 4 shows the main phenolic acids found in different parts of the plant reported in the literature (Figure 5).
In white, yellow and pigmented maize, ferulic acid is the most abundant phenolic acid. There are reports that in white and yellow corn it can be found in the forms of dimers, trimers and tetramers . Other authors have reported 1.94 mg/100 g  of free diferulic acid in blue Mexican corn which is the most abundant in that variety (Table 5).
3.1. Phenolic acid in pigmented corn kernel
Free ferulic acid concentration in a variety of pigmented kernel is similar among Mexican and Khao Niew Dum varieties (2.02–3.99 mg/100 g) [24, 52]; however, Peruvian variety has the highest concentration with 5.50 mg/100 g .
Also, there are reports that evaluate ferulic concentration among different Mexican corn phenotypes pigmented white and yellow and there are no statistically significant differences. The concentration is between 140 and 160 mg and 94–98% are bounded in cell wall and the rest is free . In the cell wall, ferulic acid plays an important role because it is cross-linked through photochemical reactions or coupling reactions catalyzed by peroxidases with the polysaccharides present in the grains, thus improving the rigidity in the cell wall of corn .
Other acids found in pigmented maize kernel are as follows:
3.2. Phenolic acid in pigmented corn cob
Research about pigmented corn cob is low; nevertheless, they have concentrations of important phenolic acids. The most abundant phenolic acid in cob from four pigmented corn phenotypes is syringic acid (31–202.78 mg/100 g) , followed by ferulic acid (7.34–10.73 mg/100 g) and in minors amounts vanillic acid (1.42–7.05 mg/100 g) and hydroxybenzoic acid (0.73–7.05 mg/100 g).
3.3. Phenolic acid in pigmented corn silk
Other organ from maize plant which has been studied due to their higher concentration of phenolic acids, in particular chlorogenic acids, is the stigma, commonly called silk. Some authors highlight that silk from purple corn have 25.64 mg/100 g of chlorogenic acid  and other studies highlight that from 25 days after emergence from four phenotypes of corn (purple, green, pink and yellow) they have 21.2–29.3 mg/100 g of 3-caffeoylquinic acid, and 5 days after emergence 923.7–1840.8 mg/100 g , also other three chlorogenic acids where studied: 4-caffeoylquinic acid (186.9–362.1 mg/100 g), 5-caffeoylquinic acid (74.4–86.5 mg/100 g) and
3.4. Extraction methods and characterization of phenolic acids in pigmented corn
As already mentioned, most of the phenolic acids in the corn kernel are bound to the cell wall and a minimum amount are free form; for this reason, the way to extract them to identify and quantify them is not simple and is diverse: some authors point to the extraction of free phenolic acids, making an extraction with 80% methanol and centrifuging ; while the solid of the methanol extraction was carried out by a basic hydrolysis (with NaOH) with a water bath at 80°C for 30 min, and in this way the acids bound to the cell wall are obtained. Other authors report successive extraction methods for the recovery of free and bound phenolic acids; first for the free acids, they performed an extraction with 80% ethanol using a high-performance disperser, then the residue was assisted by adding an enzyme cocktail (pectinases, amylases and cellulases). To the residue of this, they made a thermal hydrolysis doing another extraction with methanol and 70°C. Finally, to the solid residue of this extraction, they added NaOH to carry out a basic hydrolysis .
In the case of phenolic acids present in corn silk, they only report extractions with organic solvents; for example, performing a direct extraction of the silk, using 95% methanol, centrifuging and using the supernatant for quantification and characterization ; other studies use 50% ethanol . In the same way, for the case of the phenolic acids of the cob where they describe a simple extraction using methanol and centrifugation .
3.5. Biological activity of pigmented corn phenolic acids
The phenolic acids present in the pigmented corns are of great importance due to the biological effects on human health , such as anticancer properties, antimutagenic, anti-inflammatory and cardiovascular diseases . Table 6 shows the biological properties of each of the phenolic acids present in the pigmented corn plant.
|Corn part||Phenolic acid||Pigmented corn phenotype||Content (mg/100 g)||Ref.|
|Kernel||Ferulic acid||Peruvian purple (INIA-GOI)||5.52|||
|Mexican pigmented Pigmentados||1.97–2.02|||
|Purple corn variety Khao Niew Dum||2.3|||
|Purple corn variety Khao Niew Dum||1.1|||
|Kernel||Diferulic acid||Blue-Queretaro (Mexico)||1.9|||
|Kernel||Caffeic acid||Peruvian purple (INIA-GOI)||3.81|||
|Purple corn variety Khao Niew Dum||0.29|||
|Kernel||Purple corn variety Khao Niew Dum||0.18|||
|Kernel||Vanillic acid||Purple corn variety Khao Niew Dum||0.98|||
|Kernel||Chlorogenic acid||Peruvian purple (INIA-GOI)||1.05|||
|Silk||Silk from Thai purple corn||25.64|||
|Cob||Syringic acid||Purple corn cob from four phenotypes of Thai corn||31–202.78|||
|Phenolic acid||Biological activity||Ref.|
|Ferulic acid||Potential antioxidant||[24, 52]|
|Against cardiovascular diseases|||
|Coumaric acid||Reduction of blood glucose|||
|Diferulic acid||Potential antioxidant|
|Caffeic acid||Immunostimulatory properties|||
|Vanillic acid||Reduction of blood glucose|||
|Chlorogenic acid||Potential antioxidant|||
|Reduce visceral adiposity index||[21, 35]|
|Syringic acid||Effect against cerebral ischemia|
The biological activity that most report is as antioxidant, with phenolic acids having the capacity to reduce the free radical formation and elimination of ROS, inhibition and repair of lesions caused by the oxidation and degradation of other molecules and biomolecules . The effect of antioxidant activity on corn from Bajio and Morelos (Mexico) has been evaluated; wherein the amount of free and bound phenols was measured; concluding that the antioxidant activity increases three times more in the extractions with basic hydrolysis. Therefore, antioxidant increase is attributed to phenolic acids linked mainly to phenolic acid . In other studies, they reported that one-third of the antioxidant activity of the phenolic fraction in Mexican pigmented corn is given by ferulic acid . They have also described the antioxidant activity between phenolic compounds, reporting that the highest antioxidant activity is generally presented by hydroxycinnamic acids, with ferulic acid presenting the highest and hydroxybenzoic acids less activity. In the case of purple and pink corn silk , high antioxidant activity is attributed mainly to chlorogenic acids, these activities being so high that they could be compared with other medicinal plants such as
4. Flavonoids in pigmented corn
Other import group of the bioactive compounds that contain the pigmented corns are of flavonoids; with>4000 compounds, these molecules are most abundant polyphenols present in plant foods. They are characterized by a 15-carbon skeleton, organized as C6-C3-C6, with different substitutions making up the different subclasses. The major groups of the flavonoids of nutritional interest are the flavonols or catechins .
4.1. Flavonoids in pigmented corn kernel
Peruvian purple corn has kaempferol and morin as major flavonoids in kernel (Table 8), the concentration is 202–224 mg/100 g  which represent almost the total flavonoids (Table 9); after kaempferol and morin the naringenin glucoside and in minor amount rutin and quercetin. Meanwhile, Serbian pigmented corn phenotypes  report a lower total flavonoid concentration with 19.90–33.75 mg/100 g.
|Flavonoid||Part of corn||Pigmented corn phenotype||Total flavonoid content (mg/100 g)||Ref.|
|Quercetin||Silk||Thai purple corn silk||20.26|||
|Dark red corn||0.145|
|Kernel||Peruvian purple corn||1.58|||
|Naringenin glucoside||Silk||Thai purple corn silk||6.45|||
|Kernel||Peruvian purple corn||14.8|||
|Maysin||Silk||Serbian purple corn||17.1|||
|Serbien pink corn||12.6|
|Dark red corn||0.010|
|Kernel||Peruvian purple corn||2.74|||
|Dark red corn||0.537|
|Kaempferol||Kernel||Peruvian purple corn||224.0|||
|Morin||Kernel||Peruvian purple corn||202.0|||
|Parts of the corn||Pigmented corn phenotype||Total flavonoid concentration (mg/100 g)||Ref.|
|Silk||Serbian purple corn||3644.9|||
|Serbian pink corn||3594.2|
|Mexican red corn||2602.4|||
|Mexican dark red corn||797.1|
|Mexican white-purple corn||809.5|
|Kernel||Peruvian purple corn||261–266|||
|Corn||Peruvian purple corn||187|||
|Pericarp||Peruvian purple corn||4200|||
|Naringenin glucoside||Antioxidant activity|||
4.2. Flavonoids in pigmented corn silk
Flavonoids are the main bioactive compounds in pigmented corn silk  as shown in Table 9. Some authors reports until 3644.9 mg/100 g in Serbian purple corn and Mexican pigmented corn reports 797.1 a 2602.4 mg/100 g . Among the flavonoids identified and quantified in pigmented corn silk is the maysin with 12.6–17.1 mg/100 g , quercetin (1.58 mg/100 g) and narigenin glucoside (6.45 mg/100) .
4.3. Flavonoids in pigmented corn pollen
Other organ of pigmented corn (blue, red and red dark) which represent higher concentration of total flavonoids is pollen (916.36–1087.69 mg/100 g) Table 9. The flavonoids identified are (Table 8) hyperoside, rutin and quercetin .
4.4. Extraction methods and characterization of flavonoids in pigmented corn
Flavonoid extraction methods in pigmented corn are made using simple extraction using organic solvents (methanol, ethanol and water in different proportions), centrifuge and using aqueous solution for analysis [21, 35, 53, 60].
4.5. Biological activity of pigmented corn flavonoids
The most important biological activities of flavonoids in pigmented corns that are reported in the last 10 years are presented in Table 9.
Flavonoids of pigmented corns have been studied mainly for their antioxidant and neuroprotection activities. Corn flavonoids have also been reported, which can act as inductors of apoptosis and lipolysis of adipocytes.
Pigmented corns and its parts is a food that can be beneficial to the human because of the presence of phytochemicals and biological activities that are present. The studies of pigmented corns have been increased year after year, and they showed that the coloration blue, purple, pink and red is given by anthocyanins. Also, they have a large amount of phenolic acids and flavonoids. These compounds are present in the whole plant (kernel, cob, husk, silk), and their concentration is different depending on the organ.
The most abundant anthocyanins in corn plant are cyanidin-3-glucoside, cyanidin-3- (6″-malonyl) glucoside, peonidin-3-glucoside, peonidin-3- (6″-malonyl) glucoside, pelargonidin-3- glucoside and pelargonidin-3-(6”malonyl) glucoside and the coloration of each corn is depending on the concentration and profile of these.
With reference to phenolic acids, the representatives are ferulic acid in the kernel, syringic acid in the cob and chlorogenic acid in the silk. Finally, the flavonoids are morin, kaempferol, naringin, maysin, rutin, quercetin and hyperoside; the concentrations of these compounds are high especially in purple silk. Each of these compounds has a biological activity, so in the case of anthocyanins is its anti-cancer activity, cardioprotective and anti-obesity activity; according to phenolic acids, the ferulic acid is a potential antioxidant and provides anticancer properties, and in general, flavonoids have antioxidant activity.
Therefore, pigmented corns are important for the development of new functional food products from the grain and for obtaining natural colorants and antioxidants from the other parts of the plant.
This chapter was supported by the PAPIIT-IT202318.