Antidiabetic Properties of Nymphaea Species (Water Lilies): A Review

Diabetes mellitus is a highly prevalent metabolic disease specified by increased blood glucose and impaired insulin function. Various antidiabetic drugs are currently being used, but plant sources of antidiabetic agents are of recent scientific interest as they possess multitarget effects and the most negligible side effects. Nymphaea species (water lilies) have long been traditionally taken as food and antidiabetic agents. Growing research evidence suggests that different Nymphaea species exhibit antidiabetic activity. Therefore, we took an endeavor to summarize the available scientific literature on the antidiabetic activity of the genus Nymphaea. We extensively searched in three search engines and selected 27 in vivo, 9 in vitro, and 4 in silico studies regarding antidiabetic properties of 7 Nymphaea species named Nymphaea stellata, Nymphaea pubescens, Nymphaea lotus, Nymphaea alba, Nymphaea nouchali, Nymphaea rubra, and Nymphaea odorata. All these studies coincided with the conclusion that the Nymphaea species have effective antidiabetic properties and safety. Therefore, Nymphaea species are potential candidates for evidence-based complementary and alternative medicine and integrative medicine. The species have shown antidiabetic properties through antihyperglycemic, antihyperlipidemic, pancreatic β cell-regenerating, insulin secretion and sensitivity promoting, glucose uptake and metabolizing protein-expressing, intestinal glucose metabolizing enzyme inhibiting, hepatoprotective, cardiovascular protective, nephroprotective, antioxidant, and anti-inflammatory activities. A variety of antidiabetic compounds have been identified in the 7 Nymphaea species, which can be responsible for the antidiabetic activity exerted by diverse mechanisms. Future studies should be conducted on other Nymphaea species and different plant parts and diabetic parameters to investigate their antidiabetic activity and responsible phytochemical contents.