Synthesis and Antiplasmodial Activity of EG-Artemisinin Ethers and Artemisinin–Quinoline Hybrids

The aim of this study was to synthesize a series of ethylene glycol (EG) ethers and quinoline hybrids of the antimalarial drug artemisinin and to evaluate their antimalarial activity in vitro against Plasmodium falciparum strains. The ethers were synthesized in a one-step process by coupling ethylene glycol (EG) moieties of various chain lengths to carbon 10 of dihydroartemisinin, while the artemisinin-quinoline hybrids were obtained by condensation of dihydroartemisinin with different amine-functionalized quinoline moieties. For solubility reasons, part of the hybrids were converted to oxalate salts upon reaction of the free bases with oxalic acid. All the synthesized compounds were tested against chloroquine (CQ) susceptible (CQS) D10 and chloroquine resistant (CQR) Dd2 Plasmodium falciparum strains. The IC50 values revealed that all the ethers were active against both strains but less potent than artemether irrespective of the strain. However, they were more active than CQ against the resistant strain. Ether 8 featuring three EO units was the most active of all ethers. It showed activity similar to that of CQ against D10 and much more potency than CQ against Dd2 strain (IC50, 0.023 vs. 0.473 nM). The hybrids and their salts were also all active against both strains. Hybrid 19 which possessed an isopropyl linker and its oxalate salt 19a were the most active against the Dd2 strain. Theywere more potent than CQ (IC50, 0.009 and 0.011 vs. 0.255 nM, respectively).Keywords: Artemisinin (ART), dihydroartemisinin (DHA), artemether (ARM), chloroquine (CQ), malaria, Plasmodium falciparum, ethyleneglycol) (EG), ethylene oxide (EO), hybri

Carrier-bound Methotrexate. III.‡ Antiproliferative Activity of Macromolecular MTX Conjugates Against the Human HeLa and Colo Carcinoma Cell Lines

In continuation of studies in these laboratories aiming at the bioevaluation of macromolecular anticancer drug models, in vitro cytotoxicity screens are performed on several series of water-soluble polymer-methotrexate  conjugates. The methotrexate drug in these conjugates is bound through amide or ester linkages to water- soluble polyamide- or polyamidoamine-type carriers by previously developed anchoring techniques.Tests were  conducted against the HeLahumancervical carcinoma cell line generally considered to be drug-sensitive, and  against two variants of the rather refractory Colo 320 DM, a human colon adenocarcinoma line.KEYWORDS: Drug conjugation, Colo cell line, HeLa cell line, methotrexate, polyaspartamide,  polyamidoamine

Polyamidoamines as Drug Carriers: Synthesis of Polymers Featuring Extrachain-type Primary Amino Groups as Drug-anchoring Sites

The versatile polymerization of bisacrylamides with mono- and difunctional amines, first investigated and greatly expanded in Ferruti’s laboratory,1–3 is utilized in the present project for the synthesis of  macromolecular drug carriers. Specifically, we report on the preparation of linear polyamidoamines possessing primary amino groups as terminals of short side chains, designed to function as drug  attachment sites. In the first reaction step, performed in aqueous medium, methylenebisacrylamide  (MBA) is copolymerized with two types of comonomer: (1) primary amines bearing solubilizing  functionality, such as tert-amine or hydroxyl groups, and (2) a variety of mono-N-Boc-protected primary diamines (Boc = tert-butoxycarbonyl). In other reactions, MBA is allowed to react with a mono-N-protected diamine to give a macromonomer, which is polymerized with an oligo- or poly(ethylene oxide) terminated at both ends by a primary amino group. The intermediary polymers so obtained, as yet featuring N-protected amino side groups, are treated with trifluoroacetic acid for deprotection. Further work-up by aqueous dialysis (25 000 mwco tubing) and freeze-drying affords the target polymers as water- and methanol-soluble solids in ultimate yields of 10–25%. 1H NMR spectroscopy serves to confirm the structural assignments 1–12. In order to demonstrate the drug-carrying potential of these polymers, an exemplifying polyamidoamine (11) is allowed to react with an active ester of 4-ferrocenylbutanoic acid in methanolic solution. A water-soluble conjugate (11-Fc) is thus obtained, in which 93% of available primary amine side-chain terminals are acylated by the ferrocenylation agent.KEYWORDS: Polyamidoamines., methylenebisacrylamide, macromolecular drug carriers, primary amine side functionality, 4-ferrocenylbutanoic acid

Carrier-bound Methotrexate. IV. Antiproliferative Activity of Polyaspartamide-MTX Conjugates against Leukemic Lymphoblast Cell Lines

Polymeric conjugates of methotrexate (MTX) with macromolecular carriers, obtained from amine-functionalized polyaspartamides by coupling with one of the drug’s carboxyl groups, are used in this  preliminary screening project for in vitro cytotoxicity assessment. The water-soluble conjugates, crudely fractionated by aqueous dialysis, possess mass-average molecular masses in the range of 20000–30000. Screens are performed by standard procedures against cultured CEM/S human leukemic lymphoblast cells, a drug-sensitive line, and against CEM/E, its drug-resistant subline, for comparison also against  unconjugated MTX. All compounds tested, including the unconjugated drug, display decreasing activity on  going from CEM/S to CEM/E, resistance factors (IC50 [CEM/E]/IC50[CEM/S]) being in the vicinity of 15–20 for MTX as well as for the majority of conjugates. On the other hand, comparisons of IC50 values for conjugates versus free drug, both against CEM/S and CEM/E, show vastly superior antiproliferative performance of the drug in the carrier-anchored state over the free form, with activity factors (IC50[free MTX]/IC50 [conjugate]) typically in the 10–50 range and higher. On the basis of these promising in vitro findings, the polyaspartamide-MTX conjugates are considered to be excellent candidates for further cell culture and extended in vivo tests.KEYWORDS: Methotrexate conjugates, polyaspartamide, CEM leukemic lymphoblasts