title: Design, synthesis, characterization, and biological evaluation of triazine dendrimers bearing paclitaxel using ester and ester/disulfide linkages.
abstract: The design, synthesis, characterization, and preliminary biological assessment of three dendrimers are reported. All three dendrimers, 1-3, present twelve paclitaxel groups linked by acylation of the 2'-hydroxyl group. The linker for dendrimers 2 and 3 also includes a disulfide. Installation of the paclitaxel group relies on reacting twelve primary amines of a second generation triazine dendrimer, a scaffold available on kilogram scale, with a dichlorotriazine bearing the drug. This dichlorotriazine is available in four steps by (i) reacting paclitaxel with glutaric anhydride, (ii) activating with N-hydroxysuccinimide (NHS), (iii) treating the resulting ester with either 1,3-diaminopropane (for 1) or cystamine (for 2 and 3), and (iv), finally, reacting with cyanuric chloride. After reaction with the dendrimer, the resulting monochlorotriazine groups are reacted with 4-aminomethylpiperidine (AMP) and then a poly(ethylene glycol) (PEG) group of molecular weight 2 kDa. Two different PEG-NHS esters are employed that differ in lability. For 1 and 2, the PEG incorporates an ester-linked succinic acid group. For 3, the PEG incorporates an ether-linked acetic acid group. Both mass spectrometry and 1H NMR spectroscopy prove valuable for determining the final ratios of dendrimer:paclitaxel:AMP:PEG. These values are typically 1:12:12:9. Cytotoxicity of these constructs using an MTT-based assay and PC-3 cells reveals IC(50) values in the low nanomolar range with dithiothreitol and glutathione enhancing the toxicity of the disulfide-containing constructs 2 and 3. Preliminary toxicology assessment of 1 suggests that it is well tolerated in vivo with preferential renal clearance. The elimination half-lives of all of the dendrimers appear shorter than predicted from the previous results. Tumor localization is observed for all the three dendrimers.
authors.affiliation: Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, USA.
authors.forename: Jongdoo
authors.initials: J
authors.lastname: Lim
authors.forename: Abdellatif
authors.initials: A
authors.lastname: Chouai
authors.forename: Su-Tang
authors.initials: ST
authors.lastname: Lo
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Xiankai
authors.initials: X
authors.lastname: Sun
authors.forename: Eric E
authors.initials: EE
authors.lastname: Simanek
mesh_terms: D000215:Acylation; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000493:pharmacokinetics; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003432:Cross-Linking Reagents; D050091:Dendrimers / Q000737:chemistry*; D004220:Disulfides; D016503:Drug Delivery Systems; D015195:Drug Design; D004952:Esters; D006207:Half-Life; D006801:Humans; D020128:Inhibitory Concentration 50; D008297:Male; D017239:Paclitaxel / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000473:pathology; D014227:Triazines / Q000737:chemistry*
chemical_list: D000970:Antineoplastic Agents; D003432:Cross-Linking Reagents; D050091:Dendrimers; D004220:Disulfides; D004952:Esters; D014227:Triazines; D017239:Paclitaxel