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Siripong P*, Yahuafai J*, Shimizu K**, Ichikawa K**,
Yonezawa S**, Asai T**, Kanokmedakul K***, Ruchirawat S****, Oku N.**
*Natural Products Research Section, Research Division, National Cancer Institute.
**Department of Medical Biochemistry and COE Program in the 21th Century, Graduate School of Pharmaceutical
Sciences, University of Shizuoka.
***Department of Chemistry, Khon Kaen University
****Laboratory of Medicinal Chemistry, Chulabhorn Research Institute
Email: pongpun8@yahoo.com
Abstract
We previously observed that rhinacanthins-C, -N and -Q, three main naphthoquinone esters isolated from the roots of Thai medicinal plant; Rhinacanthus nasutus KURZ. (Acanthaceae) induced apoptosis of human cervical carcinoma HeLaS3 cells. Since these rhinacanthins showed limited solubility in aqueous medium, we attempted to entrap them into liposomal membrane: Liposomalization enabled injection of the drugs and the drugs were expected to transfer to lipoproteins in the bloodstream. Liposomal formulations of rhinacanthins-C, -N and -Q showed strong antiproliferative activity against HeLaS3 cells with the IC50 values of 32, 17, 70 microM; 19, 17, 52 microM and 2.7, 2.0 and 5.0 microM for the exposure time of 24, 48, and 72 h, respectively. These liposomes suppressed the tumor growth in Meth-A sarcoma-bearing BALB/c mice at the dose of 5.0 mg/kg/d for 10 d. Among rhinacanthins, liposomal rhinacanthin-N significantly suppressed solid tumor growth. Based on these results, our findings demonstrated that rhinacanthin-N suppressed tumor growth in vivo, and suggested that liposomes are useful for preparing injectable formulation of hydrophobic drugs.
Keywords : Rhinacanthus nasutus; naphthoquinone ester; rhinacanthin; liposome; antitumor activity
Biol Pharm Bull. 2006 Nov;29(11):2279-83.
