Thesis (Ph.D.)--Chulalongkorn University, 2012

The nature of Helicobacter pylori to inhabit under the acidic mucus layer of the stomach tissue combined with the increasing rate of acquisition of resistance to antibiotics in clinical isolates of this bacteria have caused failure in the treatment (eradication) of this infectious etiological agent of chronic gastritis and peptic ulcer diseases. Not only are new antibiotics needed, but also an effective method for their localization and controlled release of any such drugs at the site of bacterial residence is also most important. Here, mangosteen extract (GME) and its major active component, α-mangostin, were encapsulated into mucoadhesive nanoparticles fabricated from a 1:1 (w/w) blend of ethyl cellulose (EC) and methyl cellulose (MC). Both prepared nanoparticles showed spherical shape, size around 600 nm, encapsulation efficiency more than 90%, loading capacity 50% approximately and good suspension in water. The GME-loaded EC/MC nanospheres show a sustained release of GME at pH 2.0 and pH 7.4. GME and α-mangostin possessed anti-H. pylori and anti-adhesion activities in vitro. These in vitro activities are also observed and indeed are enhanced when the materials are encapsulated into nanocarriers. Preliminary in vivo tests revealed the ability to combat H. pylori in the stomachs of infected mice following oral administration of the EC/MC encapsulated GME, but not the unencapsulated GME. Moreover, acute toxicity test in mice demonstrated that GME-encapsulated nanoparticles were non-toxic to mice. Thus, nanoencapsulated GME was a potential anti-H. pylori agent.