Antiamylase, Antiglucosidase, and Antiglycation Properties of Millets and Sorghum from Sri Lanka

Abstract

The present study evaluated a range of biological activities of selected millet types and sorghum varieties in Sri Lanka in relation to diabetes and its complications management. Five millet types, namely, proso millet, white finger millet, kodo millet, foxtail millet, and finger millet (Oshadha and Rawana), and two sorghum varieties, namely, sweet sorghum and sorghum ICSV 112, were used in this study. Methanolic extracts of whole grains were studied for antiamylase, antiglucosidase, and early- and middle-stage antiglycation and glycation reversing activities in vitro. Tested millets and sorghum showed significant ( $p$  < 0.05) and dose-dependent antiamylase (IC50: 33.34 ± 1.11–1446.70 ± 54.10 μg/ml), early-stage antiglycation (IC50: 15.42 ± 0.50–270.03 ± 16.29 μg/ml), middle-stage antiglycation (135.08 ± 12.95–614.54 ± 6.99 μg/ml), early-stage glycation reversing (EC50: 91.82 ± 6.56–783.20 ± 61.70 μg/ml), and middle-stage glycation reversing (393.24 ± 8.68–1374.60 ± 129.30 μg/ml) activities. However, none of the studied millet and sorghum showed antiglucosidase activity. Out of the samples studied, pigmented samples, namely, sweet sorghum, Oshadha, and Rawana, exhibited significantly high ( $p$  < 0.05) antiamylase and early- and middle-stage antiglycation and glycation reversing activities compared to other millet and sorghum samples. Interestingly, sweet sorghum exhibited nearly four times potent antiamylase activity compared to the standard drug acarbose (IC50 111.98 ± 2.68 μg/ml) and sweet sorghum, kodo millet, Oshadha, and Rawana showed comparable early-stage antiglycation activities in comparison to the reference standard Rutin (IC50 21.88 ± 0.16 μg/ml). Therefore, consumption of whole grains of pigmented millet and sorghum in Sri Lanka may play an important role in the prevention and management of diabetes and its complications. Interestingly, this is the 1st study to report all the tested biological activities for millet and sorghum in Sri Lanka and the 1st study to report both early- and middle-stage glycation reversing activities of millet and sorghum worldwide.