Eid Hoda M, Ouchfoun Meriem, Saleem Ammar, Guerrero-Analco Jose A, Walshe-Roussel Brendan, Musallam Lina, Rapinski Michel, Cuerrier Alain, Martineau Louis C, Arnason John T, Haddad Pierre S
Natural Health Products and Metabolic Diseases Laboratory, Department of Pharmacology, Université de Montréal, Montréal, Québec, Canada; Canadian Institutes of Health Research Team in Aboriginal Antidiabetic Medicines and Montreal Diabetes Research Center, Montreal, Canada; Department of Pharmacognosy, University of Beni-seuf, Beni-seuf, Egypt.
Natural Health Products and Metabolic Diseases Laboratory, Department of Pharmacology, Université de Montréal, Montréal, Québec, Canada; Canadian Institutes of Health Research Team in Aboriginal Antidiabetic Medicines and Montreal Diabetes Research Center, Montreal, Canada.
J Ethnopharmacol. 2016 Feb 3;178:251-7. doi: 10.1016/j.jep.2015.12.021. Epub 2015 Dec 18.
Rhododendron groenlandicum (Oeder) Kron & Judd (Labrador tea) was identified as an antidiabetic plant through an ethnobotanical study carried out with the close collaboration of Cree nations of northern Quebec in Canada.
In a previous study the plant showed glitazone-like activity in a 3T3-L1 adipogenesis bioassay. The current study sought to identify the active compounds responsible for this potential antidiabetic activity using bioassay guided fractionation based upon an in vitro assay that measures the increase of triglycerides content in 3T3-L1 adipocyte.
Isolation and identification of the crude extract's active constituents was carried out. The 80% ethanol extract was fractionated using silica gel column chromatography. Preparative HPLC was then used to isolate the constituents. The identity of the isolated compounds was confirmed by UV and mass spectrometry.
Nine chemically distinct fractions were obtained and the adipogenic activity was found in fraction 5 (RGE-5). Quercetins, (+)-catechin and (-)-epicatechin were detected and isolated from this fraction. While (+)-catechin and (-)-epicatechin stimulated adipogenesis (238±26% and 187±21% relative to vehicle control respectively) at concentrations equivalent to their concentrations in the active fraction RGE-5, none afforded biological activity similar to RGE-5 or the plant's crude extract when used alone. When cells were incubated with a mixture of the two compounds, the adipogenic activity was close to that of the crude extract (280.7±27.8 vs 311± 30%).
Results demonstrate that the mixture of (+)-catechin and (-)-epicatechin is responsible for the adipogenic activity of Labrador tea. This brings further evidence for the antidiabetic potential of R. groenlandicum and provides new opportunities to profile active principles in biological fluids or in traditional preparations.
通过与加拿大魁北克北部克里族密切合作开展的一项民族植物学研究，格陵兰杜鹃（Rhododendron groenlandicum (Oeder) Kron & Judd，即拉布拉多茶）被确定为一种抗糖尿病植物。
在之前的一项研究中，该植物在3T3-L1脂肪生成生物测定中显示出类噻唑烷二酮活性。当前研究旨在基于一项体外测定法，通过生物测定指导的分级分离来鉴定负责这种潜在抗糖尿病活性的活性化合物，该体外测定法可测量3T3-L1脂肪细胞中甘油三酯含量的增加。
对粗提物的活性成分进行分离和鉴定。80%乙醇提取物采用硅胶柱色谱进行分级分离。然后使用制备型高效液相色谱法分离各成分。通过紫外光谱和质谱确认分离出的化合物的身份。
获得了9个化学性质不同的馏分，在馏分5（RGE-5）中发现了脂肪生成活性。从此馏分中检测并分离出了槲皮素、（+）-儿茶素和（-）-表儿茶素。虽然（+）-儿茶素和（-）-表儿茶素在相当于其在活性馏分RGE-5中的浓度时刺激脂肪生成（相对于溶剂对照分别为238±26%和187±21%），但单独使用时均未产生与RGE-5或该植物粗提物相似的生物活性。当细胞与这两种化合物的混合物一起孵育时，脂肪生成活性接近粗提物的活性（280.7±27.8对311±30%）。
结果表明，（+）-儿茶素和（-）-表儿茶素的混合物是拉布拉多茶脂肪生成活性的原因。这为格陵兰杜鹃的抗糖尿病潜力提供了进一步的证据，并为分析生物体液或传统制剂中的活性成分提供了新的机会。
