Establishment Of Immunoassay For Clinical Pharmacokinetic Studies Of Oligomannurarate(971), A Novel Anti-Alzheimer's Drug Candidate

971, a new kind of marine-derived acidic oligosaccharide, extracted from brown algae Echlonia Kurome Okam, is a linear polyanionic oligosaccharide, with the average molecular weight at 1300Da.As a candidate of anti-AD, our previous works have demonstrated that 971 remarkably improved the learning and memory deficit induced by Aβ25-35, D-galactose or scopolaming in mice. The further studies disclosed its action of mechanisms mainly correlated with the inhibition of amyloid-beta fibril formation, stimulation the depolymerization of fibrous amyloid-beta, and reducing the toxicity of amyloid-beta fibril.As a potent anti-AD candidate, the evaluation of its pharmacokinetics is difficult due to the carbohydrate characters. In this paper, a new method to study the cliniacal pharmacokinetics of 971 was established based on the preparation of its specific monoclonal antibodies.1. Evaluation of Immunoassay for Pharmacokinetic Clinical Studies of 971The pharmacokinetics of 971 was evaluated with its specific McAb by surface plasmon resonance technology including standard curve,recovery rate,precision, stability and protein-binding rates.The results indicated that 971 could concentration-dependently inhibit the binding of its McAb to 971 immobilized on CM5 sensor chip with the concentration ranged 0.049 to 200μg/ml. The recovery rate of the method was 99-101%, and the intra- and inter-day precisions were 1-6% and 1-8% respectively. The protein-binding rate was studied using ultrafiltration method. These data indicated that the method can meet the demands of clinical pharmacokinetic study of 971.2. Preliminary experiment of clinical PharmacokineticOn the basis of former experiments, preliminary experiment was developed in order to verify the immunoassay and to decide the doses of future clinical Pharmacokinetic studies. The results indicated that the concentration-time curve was figured as two-compartmental model after oral of 971 to subjects at dose of 300 and 900mg with the T_1/2(α) values of 0.399 and 2.417h and T_1/2(β) values of 7.455 and 22.215h respectively. And the Tmax is 0.5h. Cmax is 14.02 and 22.78mg/L.The results showed that the protein-binding rates of 971 was about 50% at the concentration of 5 and 10μg/ml and reduced to 34.35% at the concentration of 20μg/ml.In conclusion, it is the first time for us to evaluate the pharamacokinetic profiles of 971 by SPR. And this preliminary experiments ascertained the haemospasia points.Also it would provide a useful method for the clinical pharmacokinetic study of carbohydrates.