Review on rosmarinic acid extraction, fractionation and its anti-diabetic potential.

Rosmarinic acid is a bioactive phytochemical that can be found in many herbs as ethnomedicines. It possesses remarkable pharmacological activities, and thus leading to its exploration as a therapeutic drug in diabetes treatment recently. This article reviews the extraction and fractionation techniques for plant-based natural rosmarinic acid and its anti-diabetic potential based on literature data published in journals, books, and patents from 1958 to 2017. Factors affecting the performance of rosmarinic acid extraction and fractionation such as operating temperature, time, solvent to sample ratio and eluent system are compiled and discussed in detail. The inhibitory action of rosmarinic acid against sugar digestive enzymes, and protective action towards pancreatic β-cell dysfunction and glucolipotoxicity mediated oxidative stress are also critically reviewed. The optimal parameters are largely dependent on the applied extraction and fractionation techniques, as well as the nature of plant samples. Previous studies have proven the potent role of rosmarinic acid to control plasma glucose level and increase insulin sensitivity in hyperglycemia. Although rosmarinic acid is readily absorbed by human body, its mechanism after consumption is remained unclear. Intensive studies should be well planned to determine the dosage and toxicity level of rosmarinic acid for efficacy and safe consumption.