Background: Many studies have shown that Andrographis paniculata (Burm. f.) Nees has a
good anti-tumor effect, but poor solubility in water and poor bioavailability hinder the modernization of it.
Method: To formulate the effective parts (mainly diterpene lactones) of Andrographis paniculata (AEP)
into targeting drug delivery system, a series of poly(ethylene glycol)-poly(D.L-lactic acid)(mPEG-PLA)
with different ratio of hydrophilic and hydrophobic segment was synthetized to encapsulate AEP. AEP
micelles were prepared by a simple solvent-evaporation method. According to the loading capacity, the
best polymer was chosen. mPEG-PLA micelles were characterized in terms of drug entrapping efficiency,
loading capacity, size, the crystalline state of AEP, stability and release profile. Meanwhile, the
cytotoxicity of micelles on mouse breast cancer 4T-1 was investigated.
Results: These micelle (mPEG-PLA-AEP) particles had a size of (92.84±5.63) nm and a high entrapping
efficiency and loading capacity of (91.00±11.53)% and (32.14±3.02)%(w/w), respectively. The
powder DSC showed that drugs were well encapsulated in the core of micelles. mPEG-PLA-AEP had a
good stability against salt dissociation, protein adsorption and anion substitution and the solubility of
andrographolide (AG) and 14-deoxy-11,12-didehydroandrographolide(DDAG) in AEP increased 4.51
times and 2.12 times in water, and the solubility of DAG showed no difference. mPEG-PLA-AEP had
the same release profile in different dissolution medium. Cytotoxicity testing in vitro demonstrated that
mPEG-PLA-AEP exhibited higher cell viability inhibition in mouse breast cancer 4T-1 than free AEP.
Conclusion: mPEG-PLA micelles offer a promising alternative for TCM therapy with higher solubility
and improved antitumor effect.