Phytochemical and biological investigation of Calliandra surinamensis as a potential treatment for diabetes

The International Diabetes Federation (IDF) estimates that there are approximately 387 million people with diabetes worldwide [1]. The current pharmacological management for diabetes has been reported to have some unpleasant side effects such as hypoglycaemia, lactic acidosis, and stomach discomfort [2]. Medicinal plants are considered a good source for mining biologically active compounds. The current study investigates the potential of Calliandra surinamensis to yield anti-diabetic compounds. C. surinamensis leaves and bark were collected from the Cayman Islands in 2015. The plant materials were ground and then Soxhlet extraction was performed using hexane, ethyl acetate, and methanol. Ethyl acetate and hexane extracts were subjected to open column silica gel chromatography, while the methanol extracts were separated by Sephadex column chromatography. Structural elucidation of isolated compounds was carried out using Nuclear Magnetic Resonance (1 H NMR and 13C NMR). Three compounds, not previously reported in C. surinamensis were isolated; these were myricitrin, lupeol, and ferulic acid. Myricitrin is known to possess antioxidant and anti-inflammatory activity [3], lupeol is reported to have anti-inflammatory and anti-cancer activities [4], and ferulic acid has shown anti-microbial activities in previous studies [5]. C. surinamensis and the isolated compounds have not been investigated for anti-diabetic activity before and so in this study, crude extracts of C. surinamensis were biologically tested for anti-diabetic activity using various in vitro assays such as dipeptidyl peptidase-IV (DPPIV) and protein-tyrosine phosphatase 1B (PTP 1B) enzyme assays. These produced negative results (P > 0.05) and so other in vitro assays (α-amylase, and α-glucosidase) as well as the isolated compounds are being assessed for anti-diabetic potential.