Composition of plant polyphenolics in local cereals and pseudograins and their bioactivity

Abstract

Cereals and pseudocereals are increasingly acknowledged for their abundant polyphenolic chemicals, which exhibit advantageous health-promoting qualities, particularly in the prevention and management of non-communicable illnesses such as hyperlipidemia. Due to their higher profiles of antioxidants, flavonoids, dietary fibers, and other bioactive constituents, these grains are frequently utilized as functional foods globally. Cereal crops, including rice, wheat, maize, oats, barley, bajra, and millets (proso and foxtail), are extensively cultivated and consumed in Bangladesh, supported by established agronomic systems and governmental agricultural initiatives. In contrast, pseudocereals—quinoa (Chenopodium quinoa), chia (Salvia hispanica), buckwheat (Fagopyrum esculentum), and amaranth—exhibit limited production, consumption, and research activity. Despite their nutritional and medicinal benefits, pseudo-cereals are significantly undervalued in Bangladeshi cuisine. Current market trends indicate a probable transition towards an expanded national grain inventory as domestically cultivated pseudograins—such as chia, quinoa, cheena, and kaon—become increasingly accessible. A thorough nutritional and phytochemical analysis of both conventional cereals and novel pseudograins growing in Bangladesh is urgently required to facilitate this transformation. The ethnographic study examined the production, utilization, and socio-cultural significance of several cereals and pseudograins in Bangladesh, alongside their functional potential through biochemical analysis. The research examined the macronutrient composition of grains, total flavonoid and phenolic content, and antioxidant capacity. The in vitro assessment of their lipase inhibitory properties facilitated the determination of their potential function in regulating lipid metabolism. The study intends to ascertain the functional importance of cereals and pseudocereals in dietary management, nutrition-sensitive agriculture, and the prevention of v chronic diseases, particularly hyperlipidemia, in Bangladesh by integrating ethnographic knowledge with biochemical investigation. Methodology A qualitative, exploratory, longitudinal ethnographic study was undertaken to evaluate the production, consumption, and distribution patterns of cereals and pseudocereals throughout Bangladesh. Focus group discussions were employed to identify the patterns in local agriculture and utilization. Laboratory tests were conducted to determine the proximate composition, total phenolic content (TPC), total flavonoid content (TFC), total antioxidant capacity (TAC), total tanin content (TTC), antioxidant activity (via DPPH, ABTS, and FRAP assays), and polyphenol profiles employing HPLC-DAD screening. The lipase inhibitory activity was evaluated using the ELISA technique, and the I ₅₀ values were derived rom the absorbance o sample extracts at varying concentrations. Regression analyses were conducted to ascertain the correlation between the dose-dependent sample concentration and lipase enzyme inhibition. Results Ethnographic research indicated that 85% of black rice, 80% of red rice, and 99% of buckwheat were sold locally, while 100% of quinoa and chia production was still in the experimental phase. Cheena and kaon had the greatest protein content among cereals, at 13.48% and 13.55%, respectively, although chia and quinoa revealed elevated amounts of protein, fat, and dietary fiber, with chia at 22.40% protein. Black rice and yellow buckwheat exhibited enhanced antioxidant capabilities and phenolic contents. The highest concentration of TPC, TFC, TAC and TTC were observed in two pigmented rice sample extracts (red and black) among cereal samples and two types of buckwheat extracts (yellow and black) among pseudograin samples, respectively. HPLC profiling verified elevated concentrations of epicatechin in quinoa and red vi rice. Lipase inhibition experiments indicated that black rice (I ₅₀ = 10.25 ± 1.06 mg/mL) and yellow buckwheat (I ₅₀ = 15.69 ± 1.09 mg/mL) exhibited significant inhibitory effects relative to the standard epicatechin (I ₅₀ = 0.320 ± 0.90 mg/mL). Regression analysis demonstrated substantial correlations (P < 0.05) between polyphenolic content and lipase inhibition in red aman rice (R² = 0.9685), quinoa (F) (R² = 0.9646) and yellow buckwheat (R² = 0.9442), signifying robust predictive associations. Conclusion This extensive investigation shows that Bangladeshi cereal and pseudograins contain bioactive compounds with nutritional and therapeutic significance. Black rice, red aman rice, chia, quinoa, and yellow buckwheat displayed high total phenolic and flavonoid contents, strong DPPH, ABTS, and FRAP tests, and increased reducing power. HPLC profiling identified the presence of distinct polyphenols, including (-) epicatechin in red aman rice and quinoa. Several grains, including black rice (I ₅₀ = 10.25 mg/mL), yellow buckwheat (15.69 mg/mL), and quinoa (23.70 mg/mL), showed significant pancreatic lipase inhibition, suggesting a role in lipid metabolism. A regression research ound strong correlations (R² > 0.94, P < 0.05) between polyphenol content in methanolic extracts and lipase inhibition activity in red aman rice, quinoa, and yellow buckwheat. Despite their health advantages, pseudocereals are underrepresented in national agriculture and food systems. The results clearly imply including nutrient-dense, bioactive-rich cereals and pseudocereals in public nutrition and agro-food policy frameworks in Bangladesh to boost dietary diversity, chronic illnesses (hyperlipidemia) and sustainable agriculture