**Preparation and In Vitro Release of Total Alkaloids from** *Alstonia Scholaris* **Leaves Loaded mPEG-PLA Microspheres**

**Xiangyu Zheng 1, Hongli Li 1, Yi He 1, Mingwei Yuan 1, Meili Shen 2, Renyu Yang 1, Nianfeng Jiang 1, Minglong Yuan 1,\* and Cui Yang 1,\***


Received: 3 April 2019; Accepted: 28 April 2019; Published: 6 May 2019

**Abstract:** Total alkaloids of *Alstonia scholaris* leaves (ASAs) are extracted from the lamp leaves, which have positive anti-inflammatory activity and remarkable e ffects in treating bronchitis. Due to its short half-life, we used a degradable mPEG-PLA to physically encapsulate the total alkali of the lamp stage, and prepared a sustained-release microsphere by double-emulsion method. The ASAs-loaded mPEG10000-PLA microspheres were screened for better performance by testing the morphology, average particle size, embedding rate and drug loading of di fferent molecular weight mPEG-PLA microspheres, which can stably and continuously release for 15 days at 37 ◦C. The results of cytotoxicity and blood compatibility indicated that the drug-loaded microspheres have beneficial biocompatibility. Animal experiments showed that the drug-loaded microspheres had a beneficial anti-inflammatory effect. These results all indicated that mPEG-PLA is a controlled release carrier material suitable for ASAs.

**Keywords:** total alkaloids from *Alstonia scholaris* leaves; mPEG-PLA; microspheres; drug release; biocompatibility
