J Pharm Pharmacogn Res 2(Suppl. 1): S84, 2014
Special supplement with the abstract book of LATINFARMA 2013
C 029: NEW PROMISING CANDIDATES FOR DIABETES TYPE 2 TREATMENTS OBTAINED FROM NATURAL SOURCES: INHIBITORY EFFECTS ON PTP1B, DPPIV AND GLUCOSE UPTAKE IN VITRO ASSAY
Marrero Faz E1, Sánchez Calero E1, Young L2 and Harvey A.2
The present study is aimed to determine the underlying mechanism of the antidiabetic efficacy of seven medicinal Cuban plants: Allophylus cominia (L.) Sw., Ocimum tenuiflorum, Persea americana, Sechium edule green and white varieties, Momordica charantia and Jatropha aethiopica, some of them reported in Cuban ethnomedicine. The aqueous extracts from these plants and their fractions were evaluated on type 2 diabetes therapeutic targets: protein tyrosine phosphatase 1B (PTP1B) and dipeptidyl peptidase-IV (DPPIV) enzymatic activities and glucose uptake, in order to identify the candidate plants that can be used more effectively in treating diabetes. All in vitro assays were performed on 96 micro well plates. In PTP1B enzymatic assay (6, 8-difluoro-4-methylumbelliferyl phosphate) (DiFMUP) was used as substrate and as standard inhibitor [Bis(4-Trifluoromethylsulfonamidophenyl)-1,4-diisopropylbenzine] (TFMS); in DPPIV enzymatic assay [Gly-Pro-7-amido-4-methylcoumarin hydrobromide] (Gly-proAMC) was used as substrate and as standard inhibitor [(3N-[(2S, 3S)-2amino-3-methyl-pentanoyl]-1,3-thiazolidine) hemifumarate] (P32/98); in both assays, the enzymatic activity inhibition was calculated with the fluorescence values using an excitation wavelength of 360 nm and an emission wavelength of 460 nm. Glucose uptake studies were performed on fully differentiated 3T3-L1 adipocytes using 2-deoxy-D[3H] glucose and insulin as a positive control, the radioactivity incorporated into the cells was measured with a microplate scintillation counter. The results revealed that only aqueous extracts from A cominia, O tenuiflorum and P americana inhibited the enzymatic activity of PTP1B in an extract concentration dependent manner, resulting more active the more polar fractions from A. cominia and P. americana extracts and fraction 2 from O. tenuiflorum extract. All the extracts and fractions showed only a slight inhibition of enzymatic activity of DPPIV, at higher concentrations, A cominia aqueous extract also inhibited the enzymatic activity of this protease in an extract concentration dependent manner, only fraction 1 from P americana aqueous extract showed a moderate inhibitory effect. A. cominia, O. tenuiflorum and P. americana extracts exhibited a moderate enhance of glucose uptake in 3T3-L1 adipocytes, resulting more active fractions 6 and 10 from A. cominia extract and fraction 10 from P. americana extract. The present research demonstrated that aqueous extracts from A. cominia, P. americana and O. tenuiflorum and some of its fractions (AcF6, AcF10 and PaF10), are promising candidates for the development of antidiabetic phytopharmaceuticals and for drug discovery issues as well. Further research will be necessary in order to explore new molecular targets related with this metabolic disorder, such as: biomarkers of carbohydrates and lipids metabolism as well as to identify the secondary metabolites responsible of antidiabetic activity.