Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran.
Department of Pharmacology, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Int J Pharm. 2018 Jan 15;535(1-2):293-307. doi: 10.1016/j.ijpharm.2017.11.020. Epub 2017 Nov 11.
The aim of this research work was to explore the possibility of providing multifunctional oral insulin delivery system by conjugating several types of dipeptides on chitosan and trimethyl chitosan to be used as drug carriers.
Conjugates of Glycyl-glycine and alanyl-alanine of chitosan and trimethyl chitosan (on primary alcohol group of polymer located on carbon 6) were synthesized and nanoparticles containing insulin were prepared for oral delivery. Preparation conditions of nanoparticles were optimized and their performance to enhance the permeability of insulin as well as cytotoxicity of nanoparticles in Caco-2 cell line was evaluated. To evaluate the efficacy of orally administered nanoparticles, nanoparticles with the most permeability enhancing ability were studied in male Wistar rats as animal model by measuring insulin and glucose Serum levels.
Structural study of all the conjugates by infrared spectroscopy and nuclear magnetic resonance confirmed the successful formation of the conjugates with the desirable substitution degree. By optimizing preparation conditions, nanoparticles with expected size (157.3-197.7 nm), Zeta potential (24.35-34.37 mV), polydispersity index (0.365-0.512), entrapment efficiency (70.60-86.52%) and loading capacity (30.92-56.81%), proper morphology and desirable release pattern were obtained. Glycyl-glycine and alanyl-alanine conjugate nanoparticles of trimethyl chitosan showed 2.5-3.3 folds more effective insulin permeability in Caco-2 cell line than their chitosan counterparts. In animal model, oral administration of glycyl-glycine and alanyl-alanine conjugate nanoparticles of trimethyl chitosan demonstrated reasonable increase in Serum insulin level with relative bioavailability of 17.19% and 15.46% for glycyl-glycine and alanyl-alanine conjugate nanoparticles, respectively, and reduction in Serum glucose level compared with trimethyl chitosan nanoparticles (p < 0.05).
It seems that glycyl-glycine and alanyl-alanine conjugate nanoparticles of trimethyl chitosan have met the aim of this research work and have been able to orally deliver insulin with more than one mechanism in animal model. Hence, they are promising candidates for further research studies.
本研究工作旨在探索通过在壳聚糖和三甲基壳聚糖上缀合几种类型的二肽来提供多功能口服胰岛素递送系统的可能性，将其用作药物载体。
合成了壳聚糖和三甲基壳聚糖（位于聚合物的伯醇基团上，位于碳 6 位）上的甘氨酰-甘氨酸和丙氨酰-丙氨酸缀合物，并制备了包含胰岛素的纳米粒用于口服递送。优化了纳米粒的制备条件，并评估了它们增强胰岛素渗透性以及纳米粒在 Caco-2 细胞系中的细胞毒性的能力。为了评估口服给予纳米粒的疗效，通过测量雄性 Wistar 大鼠的胰岛素和血糖血清水平，以动物模型研究了具有最佳渗透性增强能力的纳米粒。
通过红外光谱和核磁共振对所有缀合物的结构研究证实了具有理想取代度的缀合物的成功形成。通过优化制备条件，获得了具有预期粒径（157.3-197.7nm）、Zeta 电位（24.35-34.37mV）、多分散指数（0.365-0.512）、包封效率（70.60-86.52%）和载药量（30.92-56.81%）、合适形态和理想释放模式的纳米粒。三甲基壳聚糖的甘氨酰-甘氨酸和丙氨酰-丙氨酸缀合物纳米粒在 Caco-2 细胞系中对胰岛素的渗透性提高了 2.5-3.3 倍，优于其壳聚糖对应物。在动物模型中，三甲基壳聚糖的甘氨酰-甘氨酸和丙氨酰-丙氨酸缀合物纳米粒口服给药后，血清胰岛素水平明显升高，相对生物利用度分别为 17.19%和 15.46%，与三甲基壳聚糖纳米粒相比，血清葡萄糖水平降低（p<0.05）。
似乎三甲基壳聚糖的甘氨酰-甘氨酸和丙氨酰-丙氨酸缀合物纳米粒达到了本研究工作的目的，并能够通过一种以上的机制在动物模型中口服递送胰岛素。因此，它们是进一步研究的有前途的候选物。
