Recent updates on antidiabetic and antiobesity potential of carnosic acid



Dear Editor,

Rosemary (Rosmarinus officinalis) extracts have been extensively studied for their ability to ameliorate traits of metabolic dyshomeostasis (Sedighi et al., 2015[19]; Naimi et al., 2017[11]). Carnosic acid, ursolic acid and rosmarinic acid are among the major bioactives of the herb (Li et al., 2019[8]). Carnosic acid (CA) is a diterpene that is known for antidiabetic (summarized in Table 1(Tab. 1); References in Table 1: Hasei et al., 2021[3]; Lee et al., 2018[7]; Lipina and Hundal, 2014[9]; Naimi et al., 2017[10]; Ou et al., 2017[12], 2018[13]; Park and Mun, 2013[14]; Park and Sung, 2015[15]; Razavi et al., 2020[17]; Song et al., 2018[21]; Tsai et al., 2014[23]; Wang et al., 2011[25], 2019[24]; Xia et al., 2017[27]; Xie et al., 2017[28], 2018[29]; Zhao et al., 2015[31]), antiobesity (summarized in Table 1(Tab. 1)), antioxidant (Huang et al., 1996[5]; Sahu et al., 2014[18]; Birtić et al., 2015[2]; Thummuri et al., 2017[22]), and neuroprotective (Azad et al., 2011[1]; Hou et al., 2013[4]; Wu et al., 2015[26]) properties. Rosemary is used as source material for preparation of CA-enriched extracts for commercial applications as the herb is known for having high levels of CA (in excess of 2 %). Owing to its antioxidant potential, CA-rich rosemary extracts have now been approved for use as a food additive (E392) (Younes et al., 2018[30]).

Table 1. Summary of experimental reports demonstrating metabolic effects of carnosic acid.

Rosemary or rosemary-derived preparations have been demonstrated to modulate glycemic parameters in human subjects. Consumption of rosemary tea for 90 days has been reported to reduce glycated hemoglobin levels in addition to alleviating insulin resistance in type 2 diabetes subjects (Quirarte-Báez et al., 2019[16]). Reduction in blood glucose levels has been reported following 4-week consumption of rosemary leaf powder (Labban et al., 2014[6]). Similarly, consumption of rosemary powder (3 g/day) for 8 weeks has been reported to decrease glucose and glycated hemoglobin levels in type 2 diabetes patients receiving either metformin or glucomid (Shawabkeh and Jamal, 2017[20]). Considering that CA is abundantly found in rosemary, it is not surprising that the diterpene has been explored for its antidiabetic and antiobesity effects. Table 1(Tab. 1) summarizes experimental reports demonstrating antidiabetic and antiobesity effects of CA. In view of the status of CA-enriched extracts of rosemary as an approved food additive and known antidiabetic and antiobesity effects, we opine that CA has the potential to be investigated for antidiabetic effects in clinical settings.

Acknowledgements

Authors are thankful to Jain (Deemed to be University), Bangalore for the support.

Conflict of interest

None.