Comparative analysis of phenolics, flavonoids and anthocyanins in pigmented and non-pigmented maize cultivars (Zea mays L.) in Bangladesh

doi:10.21203/rs.3.rs-3984209/v1

In this investigation, we determined the compositions of phenolics, flavonoids and anthocyanins in a newly released maize (SAU purple maize) variety and compared its phytonutrients with those of other maize varieties cultivated in Bangladesh. The SAU purple maize contained 105.82 ± 8.3 and 165.05 ± 7.5 mg FAE/100 g sample of free and bound phenolics, respectively. The SAU purple maize had the greatest amount of flavonoids (76.49 ± 9.5 mg CE/100 g dry weight) and anthocyanins (68.58 ± 5.3 C3G equv./100 f of dry weight sample) compared with the other pigmented maize varieties used in the investigation. The phenolic content of a hilly indigenous deep red maize cultivar was similar to that of SAU purple maize, but the former contained less flavonoids and anthocyanins than did the later. Nevertheless, the SAU white maize variety had 30.55 ± 1.61, 46.85 ± 4.4 mg FAE/100 g and 8.82 mg CE/100 g of free and bound phenolics and total flavonoids, respectively, which were lower than those of the SAU purple maize. Again, the BARI hybrid maize variety 9 (yellow maize) contained the lowest level of total anthocyanin (4.7 ± 1.1 mg C3G/100 g). The percentages of insoluble phenolics relative to total phenolics and of flavonoids relative to insoluble phenolics were greater in the SAU purple maize. Overall, the SAU purple maize contained relatively high amounts of phenolics, flavonoids and anthocyanins; thus, this maize variety has great promise for future use as a human food and for industrial use.

Phenolics

flavonoids

anthocyanin

pigmented maize

Maize kernels are the largest seed-storage food among cereals. Maize kernels come with pigmented and nonpigmented pericarps. Pigmentation of the maize pericarp is due to the presence of various colored phytochemical compounds and secondary metabolites. The major pigments or compounds present in maize pericarp are different types of phenolics, flavonoids, anthocyanins, carotenoids, etc. Among the color compounds, phenolics are abundant in maize [1,2]. The main classes of polyphenols might include phenolic acids, flavonoids, anthocyanins, stilbenes and lignans [3]. Flavonoids have the widest color range from pale yellow to blue and are responsible for pericarp color [4,5]. The major types of flavonoids identified in cereal grains are flavonols, anthocyanins and proanthocyanidins. Anthocyanins are water-soluble phenolics that result in red, purple and blue coloration in cereal grains [6]. Several studies have shown that consumption of phenolic-rich diets is healthy and beneficial. They are anticancer, cardioprotective, anti-inflammatory, neurodegenerative, hypercholesterolemic, hyperglycemic, and hyperlipidemic and have shown antitumor activity or reduced oxidative stress [1,7,8]. The color of maize also has many industrial uses, for example, for preparing drinks and producing edible colors [9,10].

In Bangladesh, maize is mainly used as flour, grit, and semolina at the home scale. Corn on cobs (roasted) is used as a street food, and corn starch and syrup are used in the food, paper, and medicine industries. However, there is increasing annual demand for maize, and increasing maize production has been observed in recent years (2022-23) [11,12,13]. To meet demand, several maize varieties have been released by the government, nongovernmental organizations, universities, and agro-seed industries in Bangladesh [14,15]. In recent years, at Sher-e-Bangla Agricultural University, Dhaka has released a purple maize named ‘SAU Bhutta 3’, which has a purple pericarp, to meet the continuously increasing demand for maize. However, yellow or white maize is usually cultivated and utilized for various purposes in Bangladesh. There are also some available pigmented and non-pigmented indigenous cultivars that are mainly grown in the hilly regions of Bangladesh for consumption as food by the indigenous people of the country. Estimation of phenolic compounds in such pigmented maize cultivars is necessary to explore their nutritional potential for health benefits as food as well as for industrial purposes. Therefore, the objectives of this investigation were to determine the methanol-soluble, acidic methanol-soluble, total flavonoid and anthocyanin contents in pigmented and non-pigmented whole-grain maize cultivars grown in Bangladesh.

Sample collection and sample description

Seeds of SAU white maize, SAU red maize and SAU purple maize (SAU Bhutta 3) varieties were collected from the Department of Genetics and Plant Breeding, Sher-e-Bangla Agricultural University, Dhaka. The pericarp colors of the SAU white maize, SAU red maize and SAU purple maize were identified as white, red and purple, respectively. Interestingly, the endosperm color of all the kernels of the maize varieties used was white. A yellow maize variety, BARI hybrid maize-9, whose yellow pericarp and endosperm were collected from the Bangladesh Agricultural Research Institute (BARI) was also used. Among the samples, deep red maize and multicolored maize were hilly indigenous varieties collected from southern-eastern hilly regions of Bangladesh. The pericarp color of the deep-red maize kernels ranged from deep red to blackish. The pericarp color of the multicolored maize kernels varied from yellow to deep red. The endosperms of both samples were white (Table 1 & Fig. 1).

Table 1. Different maize cultivars used in the study.

Sl. no.	Maize cultivars	Source*	Pericarp color
1.	SAU white maize	SAU	white
2.	SAU red maize	SAU	red
3.	SAU purple maize	SAU	purple
4.	BARI hybrid maize 9	BARI	yellow
5.	Deep red maize	Bhandarbhon district	red to blackish
6.	Multicolored maize	Bhandarbhon district	Yellow to deep red

* SAU: Sher-e-Bangla Agricultural University, BARI: Bangladesh Agricultural Research Institute, Bhandarbhon district is a hilly region of Bangladesh

Sample preparation and storage

Sundried and cleaned maize kernels were pulverized to flour with a grinder (Miyako, model no: YT-4677A-S). The maize flours were stored under airtight conditions and refrigerated at −20 °C.

Extraction of polyphenols with methanol and acidic methanol

The methanolic extracts of the samples were prepared following this method. One gram of each sample was placed in 15 mL centrifuge tubes. Four milliliters of HPLC-grade methanol was added to each tube. Then, the sample was mixed properly using a vortex mixture. Later, the tubes were mixed properly on a mixing machine for 1 hour at 120 rpm. The tubes were then centrifuged for 5 minutes at 2500 rpm. After centrifugation, the supernatants were transferred to Eppendorf tubes. The pellets of the samples were then mixed with 4 mL of acidic methanol solvent and then mixed well by vortexing. After mixing the samples with solvent, the supernatants were collected as described above. The methanolic and acidic methanolic extracts of the samples were preserved at 4 ^°C [16].

Extraction of flavonoids from defatted maize flour

A defatted sample was used for the extraction of flavonoids. For defatting, one gram of maize flour was mixed with petroleum ether. Then, the total content was centrifuged at 3000 rpm for 5 min. Afterwards, the petroleum ether was removed, and no sample was removed. Another portion of petroleum ether was added to the residue, and the process was repeated. Finally, the sample was dried in an oven. For flavonoid extraction, four mL of acidic methanol solvent was added to the dried defatted maize flour. The total content was mixed well by vortexing. Later, the mixture was mixed for 1 h and subsequently centrifuged at 3500 rpm for 7 min at room temperature. The supernatant was collected in an Eppendorf tube through filtering using a 0.45 µm membrane filter. The extracts were stored at −4^°C until analysis. These extracts were used for total flavonoid estimation.

Anthocyanin extraction

One gram of maize flour and 4 mL of acidic methanol were added to a 15 mL centrifuge tube. It was mixed well by vortexing and later allowed to mix for 1 hour in a mixture machine. After 1 h, the tube was centrifuged at 2500 rpm for 10 min at room temperature. The supernatant was collected in an Eppendorf tube through filtration through a 0.45 µm membrane filter. Finally, the supernatant was stored in an Eppendorf tube at −4 °C [16].

Estimation of polyphenols

The content of methanol-soluble polyphenols in maize was determined by the Folin-Ciocalteu reagent method [17]. Briefly, methanolic extracts (of different volumes) were added, and the volume was adjusted to 250 µL with distilled water. Then, an equal volume of Folin-Ciocalteu reagent was added. Then, 20% Na₂CO₃was added to each sample at an equal volume, and the mixture was shaken well. The final volume was made up of distilled water. The total content was mixed well and kept undisturbed in the dark for 30 min. After incubation, the mixture was centrifuged at 2500 rpm for 5 min. The absorbance of the solution was recorded at 760 nm by a spectrophotometer. Finally, the soluble polyphenol content in the maize sample was calculated from the standard curve of ferulic acid. Acidic methanol soluble polyphenols in maize samples were determined from acidic methanol extracts of maize following the same procedure. The methanol-soluble and acidic methanol-soluble polyphenol content of the maize sample was expressed as mg of ferulic acid equivalent/100 g sample dry weight. The total polyphenol content was calculated as the sum of the methanol-soluble and acidic methanol-soluble polyphenols.

Estimation of total flavonoids in maize by the AlCl₃ method

The total flavonoid content in maize was estimated following a previously described method. In brief, different amounts of acidic methanolic extract were taken in an Eppendorf tube, and the volume was adjusted to 500 µL by using distilled water. Next, 75 µL of NaNO₂and 150 µL of AlCl₃.6H₂O were added, mixed well and kept aside for 6 min. After this period, 0.5 mL of NaOH (1 N) was added, and the solution was mixed well. The total content was kept in the dark for 15 min. After incubation, the mixture was centrifuged at 2500 rpm for 5 min and then kept in the dark for another 15 min. Then, the absorbance was recorded at 512 nm against the reagent blank. Total flavonoids in maize were calculated from the standard curve of catechin and expressed as mg of catechin equivalent/100 g sample dry weight [18].

Estimation of Anthocyanins

To estimate the anthocyanin content, different volumes of the acidic methanolic extract of maize were removed from an Eppendorf tube, and the total volume was adjusted to 1.5 mL by adding buffers (pH 1 and pH 4.6). The contents were mixed properly and allowed to rest for 20 minutes. After incubation, the tubes were centrifuged, and the absorption was measured at two different wavelengths, 515 nm and 700 nm [19]. The total anthocyanin content was expressed as mg cyanidin-3 glucoside (C3G)/100 g sample dry weight.

Statistical analysis

All of the values are presented as the mean ± standard deviation (SD) of three repetitions of each experiment and were calculated on a dry weight basis. The means of the components in the samples were compared by one-way ANOVA and Tukey’s test at a confidence level of 95% using IBM SPSS 20 statistical software (IBM Corp. Released 2011. IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp.).

Methanol-soluble phenolics

The free phenolic (methanol soluble) content in the different maize varieties ranged from 30.55 ± 1.61 mg FAE/100 g of flour to 105.82 ± 8.3 mg FAE/100 g of flour (Table 2). The SAU purple maize and the deep red maize had the highest free phenolic contents, which were 105.82 ± 8.3 mg FAE/100 g of flour and 105.18 ± 8.7 mg FAE/100 g of flour, respectively.

Table 2. Total phenolics (mg FAE/100 g dry weight basis) in different pigmented maize varieties

Maize sample	Methanol soluble phenolics (mg FAE/100 g)	Acidic methanol soluble phenolics (mg FAE/100 g)	Total phenolics (mg FAE/100 g)
SAU purple maize	105.82 ± 8.3^a	165.05 ± 7.5^a	270.87 ± 15.80^a
SAU white maize	30.55 ± 1.61^c	46.85 ±4.4^b	77.41 ± 5.7^c
BARRI hybrid maize 9	73.22 ± 1.39^b	57.96 ± 4.16^b	131.18 ± 2.96^b
SAU red maize	75.63 ± 4.2^b	55.63 ± 8.44^b	131.26 ± 4.35^b
Deep red maize	105.18 ± 8.7^a	153.11 ± 9.6^a	258.29 ± 5.4^a
Multicolored maize	75.01 ± 0.87^b	92.9 ± 8.9^b	167.92 ± 9.4^b

All values are presented as the mean ± standard deviation (SD) on a dry weight basis; different letters in each column indicate significant differences (p < 0.05).

The SAU white maize variety had the lowest amount (30.55 ± 1.61 mg FAE/100 g of flour) of free phenolics. The BARI hybrid maize 9, SAU red maize and multicolored maize varieties had similar free phenolic contents. The lower level of free phenolics in the present study was similar to other findings [20]. However, the level of free phenolics was much greater (33-680 mg/100 g of grain flour) than in the present study [20]. We also found a similar trend in which the pigmented maize varieties contained more free phenolics than did the nonpigmented maize varieties. The free phenolic content in the raw corn ranged from 35 to 50 mg/100 g of dry weight, and the range of the values was similar to the lower range of free phenolics found in our study [21].

Acidic methanol-soluble phenolics

The contents of acidic methanol soluble or bound phenolics ranged from 46.85 ± 4.4 mg FAE/100 g of flour to 165.05 ± 7.5 mg FAE/100 g of flour. The SAU purple maize and the deep red maize had the highest bound phenolic contents, which were 165.05 ± 7.5 mg FAE/100 g of flour and 153.11 ± 9.6 mg FAE/100 g of flour, respectively. The BARI hybrid maize 9, SAU red maize, and SAU white maize varieties had similar bound phenolic contents (Table 2). Among the samples, the SAU white maize kernels contained the lowest amount of bound phenolics. Moreover, the content of acidic methanol-soluble phenolics was lower than that of methanol-soluble phenolics in the BARI hybrid maize 9 and SAU red maize varieties, while the phytochemical content was greater in the other maize varieties (Table 2). A higher content of bound phenolics was observed in maize, which ranged from 206 to 270 mg/100 g of dry weight [20, 21]. They observed that the highest phenolic content was found in high-carotenoid raw corn, while the red corn had the lowest phenolic content, which was the opposite of our observation. On the other hand, the bound phenolic content in yellow corn was much lower than the phenolic content found in the present study. Yellow corn contains 13.43 ± 0.59 µmol/g of grain-bound phenolics [1].

Total phenolics

The total phenolic content in the different maize varieties ranged from 77 mg FAE/100 g to 270 mg/100 g flour (Table 2). The SAU purple maize and the deep red maize had the highest total phenolic content, 270.87 ± 15.80 mg FAE/100 g of flour and 258.29 ± 5.4 mg FAE/100 g of flour, respectively. There were no significant differences among the BARI hybrid maize 9, SAU red maize and multicolored maize varieties. The SAU white maize had the lowest total phenolic content in the study. In a separate study, much greater total phenolic content was detected in some maize varieties than in the present study [22].

Flavonoid content in the different maize varieties

The total flavonoid contents in the maize varieties used in the present investigation were significantly different from one another. Here, the total flavonoid content in the maize varieties ranged from 8.82 ± 1.5 mg CE/100 g to 76.49 ± 9.5 mg CE/100 g sample dry basis (Fig. 2).

The SAU purple maize contained the greatest amount of flavonoids (76.49 ± 9.5 mg CE/100 g sample dry basis), followed by the deep red maize (52.1 ± 7.5 mg CE/100 g). The multicolored maize had 18.22 ± 2.7 mg CE/100 g of flavonoids. The SAU red maize, BARI hybrid maize 9 and SAU white maize varieties had similar flavonoid contents (14.51 ± 1.9 mg CE/100 g, 12.4 ± 1.8 mg CE/100 g, and 8.82 ± 1.5 mg CE/100 g of sample, respectively). Among them, white maize had the lowest flavonoid content. According to a similar report, multicolored maize followed by white maize had the lowest amount of total flavonoids, and light and dark blue maize kernels had the highest amount of total flavonoids. It was also observed that lemon yellow, yellow and orange maize kernels had higher flavonoid contents than red and dark red maize kernels [22]. The flavonoid content might vary according to the darkness of the pericarp color of the maize kernel.

Anthocyanin in maize

The total anthocyanin contents of the different maize varieties ranged from 4.7 ± 1.1 mg to 68.58 ± 5.3 mg C3G/100 g sample dry basis (Fig. 3).

The SAU purple maize contained the greatest amount of anthocyanin (68.58 ± 5.3 mg of C3G/100 g sample dry basis) among the maize varieties used in the study. The deep red maize was next to the SAU purple maize (50.14 ± 6.4 mg of C3G/100 g sample dry basis). Compared to the SAU purple maize, the other maize varieties used in the study contained negligible amounts of anthocyanin. The multicolored maize kernels contained 4 times less anthocyanin than did the SAU purple maize kernels (15.1 ± 3.14 mg of C3G/100 g sample dry basis). There was no significant difference among the SAU white, yellow and SAU red maize varieties (5.7 ± 0.8 mg C3G/100 g sample, 4.7 ± 1.1 mg C3G/100 g sample, and 4.11 ± 1.2 mg of C3G/100 g sample, respectively). Anthocyanins were not detected in white, lemon yellow, yellow or orange maize kernels in one study [22]. The highest anthocyanin content was reported in dark red maize, followed by dark blue, light blue and multicolored maize [22]. It has been reported that the amount of anthocyanins is responsible for pericarp color. Similarly, we also observed more anthocyanins in the dark-colored maize varieties and lower amounts of anthocyanins in the nonpigmented maize varieties used in the study. Similar to a previous report [20], we also reported that a low anthocyanin content was found in SAU white maize, and a high anthocyanin content was found in pigmented maize varieties, viz., SAU purple and deep red maize.

Percent contributions of phenolics and correlation analysis

The percentage contributions of soluble and insoluble phenolics to total phenolics, the percentage contribution of flavonoids to insoluble phenolics, and the percentage contribution of anthocyanins to total flavonoids are presented in Table 3.

Table 3. The percentage contributions of the free and bound fractions of maize to total phenolics, total flavonoids, and total anthocyanins

Maize Sample	Phenolic content (%)		Flavonoid content (%)	Anthocyanin content (%)
Maize Sample	soluble	insoluble	Flavonoid content (%)	Anthocyanin content (%)
SAU White maize	39.47	60.53	18.83	64.63
BARI hybrid maize 9	55.82	44.18	21.39	37.90
SAU red maize	57.62	42.38	26.08	28.33
SAU purple maize	39.07	60.94	46.34	89.66
Deep red maize	40.72	59.28	34.03	96.24
Multicolored maize	44.67	55.32	19.61	82.88

The contribution of soluble phenolics to the total phenolic content in maize varieties ranged from 39.07% to 55.82%, while the contribution of insoluble phenolics to the total phenolic content ranged from 42.38% to 60.94%. The percentage contribution of insoluble phenolics to total phenolics was greater than its contribution of soluble phenolics, except for the BARI hybrid maize 9 and SAU red maize varieties. The percentage contributions of soluble phenolics to total phenolics were the lowest for the SAU purple maize, while the soluble phenolic content was high in the SAU purple maize. Notably, we observed that the percentage contributions of insoluble phenolics to the total phenolic content in SAU white maize were similar to those in SAU purple maize. However, the insoluble phenolic content in SAU white maize was the lowest among the samples. The percentage contribution of flavonoids to insoluble phenolics ranged from 18.83% to 46.34%. The highest percentage contribution of flavonoids to insoluble phenolics was observed in SAU purple maize, and the lowest was observed in SAU white maize. Similar observations were also made for the total flavonoid content in the maize samples. The percentage contribution of anthocyanins to flavonoids ranged from 28.33% to 96.24% (Table 3). The highest percentage contribution of anthocyanin to flavonoids was observed in the deep red maize varieties, and the lowest was observed in the SAU red maize variety, although the highest content of anthocyanin was observed in the SAU purple maize variety, and the lowest was observed in the BARI hybrid maize 9.

The contribution of free phenolics to the total phenolic content was 18-23%, while that of bound phenolics was 77-82% [20], while the contribution of bound phenolics was 85%, and that of free phenolics to the total phenolic content in corn was 15% [1]. They also reported that the contribution of bound flavonoids to insoluble phenolics was 91% in corn. Our present findings for free and bound phenolics were similar to previous reports. However, the percentage contribution of total phenolics to bound phenolics was lower than the reported value.

The correlation matrix for all the components analyzed (Table 4) was highly positive.

Table 4. Correlation coefficients between functional constituents

	TP	MSP	AMSP	TF	A
TP	1
MSP	0.933	1
AMSP	0.981	0.849	1
TF	0.936	0.805	0.956	1
A	0.940	0.780	0.975	0.992	1

Pearson’s correlation analysis was conducted using averaged values of each variable (p=0.05). TP-total phenolics; MSP-methanol soluble phenolics; AMSP-acidic methanol soluble phenolics; TF-total flavonoids; A-anthocyanin

The correlation between soluble phenolics and anthocyanin content was lower than the correlation between acidic methanol-soluble phenolics and anthocyanin content. Similarly, in the present study, there was a highly positive correlation (r=0.99) between the total phenolic and total flavonoid contents in the free, esterified and insoluble bound phenolic fractions obtained from herbs used in traditional Chinese medicine [23]. This indicates that the total flavonoids were the major contributors to the total phenolics. However, a moderately positive correlation (r=0.619, p<0.05) between the content of total phenolics and flavonoids in ear sections of sweet corn was observed [24]. A negative correlation between free and bound phenolics and between soluble conjugated and bound phenolics in maize was observed [25]. However, similar to the present study, a small significant positive correlation between free and conjugated phenolics indicated that an increase in bound phenolics resulted in a decrease in both free and conjugated phenolics [25]. A significant positive correlation between total flavonoid content and total phenol content (r=0.730, p=0.01) and total anthocyanin content (r=0.343, p=0.05) in maize was also established [26]. However, they reported a non-significant correlation (r=0.241) between total polyphenol content and total anthocyanin content in pigmented maize.

The present study evaluated the phytochemical properties and secondary metabolites, mainly phenolic compounds, of SAU purple maize, SAU red maize, SAU white maize, BARI hybrid maize 9 (yellow maize), deep red maize, and multi-colored maize varieties. Maize kernels with a dark pericarp color had more polyphenols than those with a nonpigmented pericarp of the kernel. Soluble phenolic content was lower in the BARI hybrid maize 9 and SAU red maize than in the other maize varieties. The multicolored maize varieties with different pericarp-color kernels had greater anthocyanin content than did the other maize varieties, although the phenolic and flavonoid contents were similar to those of the SAU red maize and BARI hybrid maize 9. Overall, among the maize samples analyzed in the present study, the newly released SAU purple maize (SAU Bhutta 3) was superior in terms of methanol-soluble and acidic methanol-soluble polyphenols, flavonoids and anthocyanins. It was also observed that the enrichment of anthocyanins was related to the level of phenolics. The most phenolic-rich variety, SAU purple maize (SAU Bhutta 3), exhibited the greatest levels of phenolics, flavonoids and anthocyanins. The phytochemical contents of deep red maize and multicolored maize kernels were also high. Thus, these varieties should be further studied for other phytonutrient contents and their potential health benefits.

Funding: Partial financial support was received from the Ministry of Science & Technology, Government of Bangladesh, Project no. BS-14, 2019-2020; and the Sher-e-Bangla Agricultural University Research System, 2021-22, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh

Competing interests: The authors have no competing interests to declare that they are relevant to the content of this article.

Authors contribution statements: Israt Jahan Preety, lab work, data collection, drafting of manuscript; Mohammed Ariful Islam, lab facility and instrumentation; Jamilur Rahman, supplied research materials, editing the manuscript; Kamal Uddin Ahmed, editing the manuscript and English grammar correction; Ashrafi Hossain, collection of research materials, conceptualized the experiments, fund collection, writing and editing the manuscript.

Adom, K. K., & Liu, R. H. (2002). Antioxidant activity of grains. J. of Agric. food and Chem., 50(21): 6182-6187.
Pandey, K. B., & Rizvi, S. I. (2009). Plant polyphenols as dietary antioxidants in human health and disease. Oxidative medicine and cellular longevity, 2(5), 270-278.
Rigacci, S. (2015). Olive oil phenols as promising multi-targeting agents against Alzheimer’s disease. Natural compounds as therapeutic agents for amyloidogenic diseases, 1-20.
Tsao, R., & McCallum, J. (2010). Chemistry of flavonoids. Fruit and vegetable phytochemicals, 131.
Santos, E. L., Maia, B. H. L. N. S., Ferriani, A. P., & Teixeira, S. D. (2017). Flavonoids: Classification, biosynthesis and chemical ecology. Flavonoids-From biosynthesis to human health, 13, 78-94.
Bueno, J. M., Sáez-Plaza, P., Ramos-Escudero, F., Jiménez, A. M., Fett, R., & Asuero, A. G. (2012). Analysis and antioxidant capacity of anthocyanin pigments. Part II: Chemical structure, color, and intake of anthocyanins. Critical reviews in analytical chemistry, 42(2), 126-151.
Leuci, R., Brunetti, L., Poliseno, V., Laghezza, A., Loiodice, F., Tortorella, P., & Piemontese, L. (2020). Natural compounds for the prevention and treatment of cardiovascular and neurodegenerative diseases. Foods, 10(1), 29.
Wu, J. C., Lai, C. S., Lee, P. S., Ho, C. T., Liou, W. S., Wang, Y. J., & Pan, M. H. (2016). Anti-cancer efficacy of dietary polyphenols is mediated through epigenetic modifications. Current opinion in Food science, 8, 1-7.
Nuss, E. T., & Tanumihardjo, S. A. (2010). Maize: a paramount staple crop in the context of global nutrition. Comprehensive reviews in food science and food safety, 9(4), 417-436.
Colombo, R., Ferron, L., & Papetti, A. (2021). Colored corn: An up-date on metabolites extraction, health implication, and potential use. Molecules, 26(1), 199.
https://www.cimmyt.org/, Retrieved on 13/01/2024
Ali, M. H., Ahmed, K. U., & Hasanuzzaman, M. (2010). Consumption of Maize-An Alternative Food Habit to Improve Food Security in the Hilly Areas of Bangladesh. National Food Policy Strengthening Programme, Dhaka, Bangladesh.
www.bbs.gov.bd, Retrieved on 25/01/2024
http://www.bwmri.gov.bd/, Retrieved on 13/01/2024
www.mofood.portal.gov.bd Retrieved on 14/02/2024
Hossain, A., & Jayadeep, A. (2022). Impact of extrusion on the content and bioaccessibility of fat soluble nutraceuticals, phenolics and antioxidants activity in whole maize. Food Research International, 161, 111821.
Singleton, V. L., Orthofer, R., & Lamuela-Raventós, R. M. (1999). [14] Analysis of total phenols and other oxidation substrates and antioxidants by means of folin-ciocalteu reagent. Methods in enzymology, 299, 152-178.
Hossain, A., & Jayadeep, A. (2021). Infrared heating induced improvement of certain phytobioactives, their bioaccessible contents and bioaccessibility in maize. LWT, 142, 110912.
Urias-Lugo, D. A., Heredia, J. B., Serna-Saldivar, S. O., Muy-Rangel, M. D., & Valdez-Torres, J. B. (2015). Total phenolics, total anthocyanins and antioxidant capacity of native and elite blue maize hybrids (Zea mays L.). CyTA-J. of Food, 13(3): 336-339.
Lopez-Martinez, L. X., Oliart-Ros, R. M., Valerio-Alfaro, G., Lee, C. H., Parkin, K. L., & Garcia, H. S. (2009). Antioxidant activity, phenolic compounds and anthocyanins content of eighteen strains of Mexican maize. LWT-Food Sci. and Tech. 42(6): 1187-1192.
Liu, R. H. (2007). Whole grain phytochemicals and health. Journal of Cereal Science, 46(3), 207–219.
Žilić, S., Serpen, A., Akıllıoğlu, G., Gökmen, V., & Vančetović, J. (2012). Phenolic compounds, carotenoids, anthocyanins, and antioxidant capacity of colored maize (Zea mays L.) kernels. J. Agric and food and Chem. 60(5): 1224-1231.
Yu, M., Yang, L., Xue, Q., Yin, P., Sun, L., & Liu, Y. (2019). Comparison of Free, Esterified, and Insoluble-Bound Phenolics and Their Bioactivities in Three Organs of Lonicera japonica and L. macranthoides. Molecules (Basel, Switzerland), 24(5), 970. https://doi.org/10.3390/molecules24050970
Yang, T., Guang Hu, J., Yu, Y., Li, G., Guo, X., Li, T., & Liu, R. H. (2019). Comparison of phenolics, flavonoids, and cellular antioxidant activities in ear sections of sweet corn (Zea mays L. saccharata Sturt). Journal of Food Processing and Preservation, 43(1), e13855.
Hadinezhad, M., Harris, L. J., Miller, S. S., & Schneiderman, D. (2023). Genetic variability of kernel phenolics in maize (Zea mays L.) inbreds with differing levels of resistance to gibberella ear rot. Crop Science, 63(4), 2162-2183.
Ku, K. M., Kim, H. S., Kim, S. K., & Kang, Y. H. (2014). Correlation analysis between antioxidant activity and phytochemicals in Korean colored corns using principal component analysis. Journal of Agricultural Science, 6(4), 1.

No competing interests reported.

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Comparative analysis of phenolics, flavonoids and anthocyanins in pigmented and non-pigmented maize cultivars (Zea mays L.) in Bangladesh

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