Investigating phytochemical and antioxidant activity of free and bound phenolics from brown rice bran and their correlation with enzymatic inhibitory and in vitro starch digestibility
Article Sidebar
Main Article Content
Abstract
Inhibiting the activity of digestive enzymes is a highly effective approach to controlling glucose absorption and, consequently, aiding in controlling type-2 diabetes mellitus. Brown rice bran, a by-product of the rice grain polishing process, represents a natural source rich in bioactive compounds that could be explored as a potential solution to reduce postprandial hyperglycemia. The study focused on evaluating the inhibitory effects of free and bound phenolic compounds on α-amylase and α-glucosidase enzymes, which play significant roles in carbohydrate metabolism. The IC50 values were found to be 0.947±0.05 mg/mL for α-amylase inhibition and 2.188±0.69 mg/mL for α-glucosidase inhibition in the free phenolic compound extract. In contrast, the bound phenolic compound extract displayed higher IC50 values of 13.861±0.03 mg/mL and 16.883±0.15 mg/mL for α-amylase and α-glucosidase inhibition, respectively. These differences in inhibitory potential between the free and bound phenolic compounds were statistically significant (p < 0.005). The superior inhibition observed in the free phenolic extract can be attributed to its higher levels of phenolic, flavonoid, and anthocyanin compounds compared to the bound form. Additionally, the antioxidant content analysis using the DPPH and FRAP methods revealed that the bound phenolic compounds exhibited lower antioxidant levels compared to the free form. Furthermore, the study investigated the impact of these bioactive compounds on starch digestibility by adding 10% sample extracts, both in free and bound forms, to high amylose rice starch. The results showed that the rate of starch digestibility was reduced to 54.04% and 58.2%, respectively, compared to the control (60.52%). Phytochemical content exhibited highly positive correlations with antioxidant activity leading to stronger enzymatic inhibition and slower the digestion rate. These findings suggest that the free phenolic extract from brown rice bran holds promise as a potential antidiabetic agent due to its ability to inhibit enzymatic digestion, leading to reduced postprandial glucose levels.
Article Details
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
References
Aleixandre, A., Gil, J. V., Sineiro, J. and Rosell, C. M. (2022). Understanding phenolic acids inhibition of α-amylase and α-glucosidase and influence of reaction conditions. Food chemistry, 372:131231.
Ali Asgar, M. (2013). Anti-diabetic potential of phenolic compounds: A review. International Journal of Food Properties, 16:91-103.
Bobo‐García, G., Davidov‐Pardo, G., Arroqui, C., Vírseda, P., Marín‐Arroyo, M. R. and Navarro, M. (2015). Intra‐laboratory validation of microplate methods for total phenolic content and antioxidant activity on polyphenolic extracts, and comparison with conventional spectrophotometric methods. Journal of the Science of Food and Agriculture, 95:204-209.
Boue, S. M., Daigle, K. W., Chen, M.-H., Cao, H. and Heiman, M. L. (2016). Antidiabetic potential of purple and red rice (Oryza sativa L.) bran extracts. Journal of agricultural and food chemistry, 64:5345-5353.
Chen, T., Lu, H., Shen, M., Yu, Q., Chen, Y., Wen, H. and Xie, J. (2022). Phytochemical composition, antioxidant activities and immunomodulatory effects of pigment extracts from Wugong Mountain purple red rice bran. Food Research International, 157:111493.
Chusak, C., Chanbunyawat, P., Chumnumduang, P., Chantarasinlapin, P., Suantawee, T. and Adisakwattana, S. (2020). Effect of gac fruit (Momordica cochinchinensis) powder on in vitro starch digestibility, nutritional quality, textural and sensory characteristics of pasta. LWT, 118:108856. https://doi.org/https://doi.org/10.1016/j.lwt.2019.108856
Deng, N., Deng, Z., Tang, C., Liu, C., Luo, S., Chen, T. and Hu, X. (2021). Formation, structure and properties of the starch-polyphenol inclusion complex: A review. Trends in Food Science & Technology, 112:667-675.
Ghasemzadeh, A., Karbalaii, M. T., Jaafar, H. Z. and Rahmat, A. (2018). Phytochemical constituents, antioxidant activity, and antiproliferative properties of black, red, and brown rice bran. Chemistry Central Journal, 12:1-13.
Giuberti, G., Rocchetti, G. and Lucini, L. (2020). Interactions between phenolic compounds, amylolytic enzymes and starch: An updated overview. Current Opinion in Food Science, 31:102-113.
Gonzales, G. B., Smagghe, G., Raes, K. and Van Camp, J. (2014). Combined alkaline hydrolysis and ultrasound-assisted extraction for the release of nonextractable phenolics from cauliflower (Brassica oleracea var. botrytis) waste. Journal of Agricultural and Food Chemistry, 62:3371-3376.
Kaur, B., Chin, R. Q. Y., Camps, S. and Henry, C. J. (2016). The impact of a low glycaemic index (GI) diet on simultaneous measurements of blood glucose and fat oxidation: A whole body calorimetric study. Journal of clinical & translational endocrinology, 4:45-52.
Kazeem, M., Adamson, J. and Ogunwande, I. (2013). Modes of inhibition of α-amylase and α-glucosidase by aqueous extract of Morinda lucida Benth leaf. BioMed research international, 2013.
Kumar, S., Mittal, A., Babu, D. and Mittal, A. (2021). Herbal medicines for diabetes management and its secondary complications. Current diabetes reviews, 17:437-456.
Li, K., Yao, F., Du, J., Deng, X. and Li, C. (2018). Persimmon tannin decreased the glycemic response through decreasing the digestibility of starch and inhibiting α-amylase, α-glucosidase, and intestinal glucose uptake. Journal of agricultural and food chemistry, 66:1629-1637.
Madaan, R., Bansal, G., Kumar, S. and Sharma, A. (2011). Estimation of total phenols and flavonoids in extracts of Actaea spicata roots and antioxidant activity studies. Indian journal of pharmaceutical sciences, 73:666.
Miao, L., Xu, Y., Jia, C., Zhang, B., Niu, M. and Zhao, S. (2021). Structural changes of rice starch and activity inhibition of starch digestive enzymes by anthocyanins retarded starch digestibility. Carbohydrate Polymers, 261:117841.
Mu, J., Wang, L., Lv, J., Chen, Z., Brennan, M., Ma, Q., Wang, W., Liu, W., Wang, J. and Brennan, C. (2022). Phenolics from sea buckthorn (Hippophae rhamnoides L.) modulate starch digestibility through physicochemical modifications brought about by starch–Phenolic molecular interactions. LWT, 165:113682.
Mu, J., Wu, G., Chen, Z., Klosek, A., Brennan, M. A., Hui, X. and Brennan, C. S. (2021). The effects of blackcurrant and strawberry powder on the physicochemical and in vitro glycaemic response of starches derived from sweet potato (Ipomoea batatas) and potato (Solanum tuberosum). International Journal of Food Science & Technology, 56:6062-6072.
Norhazlini, M., Mailina, J., Shalini, M., Nor-Azah, M. and Zulhazman, H. (2021). Total phenolic content, total flavonoid content and antioxidant activity of ethanolic extract of Rafflesia kerri Meijer, Lojing Highlands, Peninsular Malaysia. IOP Conference Series: Earth and Environmental Science,
Pang, Y., Ahmed, S., Xu, Y., Beta, T., Zhu, Z., Shao, Y. and Bao, J. (2018). Bound phenolic compounds and antioxidant properties of whole grain and bran of white, red and black rice. Food chemistry, 240:212-221.
Shao, Y., Xu, F., Sun, X., Bao, J. and Beta, T. (2014). Identification and quantification of phenolic acids and anthocyanins as antioxidants in bran, embryo and endosperm of white, red and black rice kernels (Oryza sativa L.). Journal of Cereal Science, 59:211-218.
Sivamaruthi, B. S., Alagarsamy, K., Thangaleela, S., Bharathi, M., Kesika, P. and Chaiyasut, C. (2023). Composition, Microbiota, Mechanisms, and Anti-Obesity Properties of Rice Bran. Foods, 12:1300.
Sohail, M., Rakha, A., Butt, M. S., Iqbal, M. J. and Rashid, S. (2017). Rice bran nutraceutics: A comprehensive review. Critical reviews in food science and nutrition, 57:3771-3780.
Sun, L. and Miao, M. (2020). Dietary polyphenols modulate starch digestion and glycaemic level: A review. Critical reviews in food science and nutrition, 60:541-555.
Ti, H., Li, Q., Zhang, R., Zhang, M., Deng, Y., Wei, Z., Chi, J. and Zhang, Y. (2014). Free and bound phenolic profiles and antioxidant activity of milled fractions of different indica rice varieties cultivated in southern China. Food Chemistry, 159:166-174.
Wang, M., Chen, J., Ye, X. and Liu, D. (2020a). In vitro inhibitory effects of Chinese bayberry (Myrica rubra Sieb. et Zucc.) leaves proanthocyanidins on pancreatic α-amylase and their interaction. Bioorganic Chemistry, 101:104029.
Wang, Z., Li, S., Ge, S. and Lin, S. (2020b). Review of distribution, extraction methods, and health benefits of bound phenolics in food plants. Journal of Agricultural and Food Chemistry, 68:3330-3343.
Wu, N. N., Li, H. H., Tan, B., Zhang, M., Xiao, Z. G., Tian, X. H., Zhai, X. T., Liu, M., Liu, Y. X. and Wang, L. P. (2018). Free and bound phenolic profiles of the bran from different rice varieties and their antioxidant activity and inhibitory effects on ɑ-amylose and ɑ-glucosidase. Journal of Cereal Science, 82:206-212.
Ye, C., Zhang, R., Dong, L., Chi, J., Huang, F., Dong, L., Zhang, M. and Jia, X. (2022). α-Glucosidase inhibitors from brown rice bound phenolics extracts (BRBPE): Identification and mechanism. Food chemistry, 372:131306.
Yusof, B., Talib, R., Kamaruddin, N., Karim, N., Chinna, K. and Gilbertson, H. (2009). A low‐GI diet is associated with a short‐term improvement of glycaemic control in Asian patients with type 2 diabetes. Diabetes, Obesity and Metabolism, 11:387-396.
Zhang, Y., Bai, B., Yan, Y., Liang, J. and Guan, X. (2022). Bound polyphenols from red quinoa prevailed over free polyphenols in reducing postprandial blood glucose rises by inhibiting α-glucosidase activity and starch digestion. Nutrients, 14:728.
