1H-Pyrano[3',4':6,7]indolizino[1,2-b]quinoline-3,14(4H,12H)-dione,4-ethyl-4-hydroxy-9-methoxy-, (4S)-

1. Camptothecin (CPT) and its derivatives are potent candidate compounds in treating cancers. However, their clinical applications are largely restricted by severe toxicities. 2. The solute carrier transporters (SLCs), particularly the organic anion transporting polypeptides and organic anion/cation transporters (OATs/OCTs) are widely expressed in human key organs and responsible for the cellular influx of many substances including endogenous substrates and many clinically important drugs. Drug-drug interactions through SLCs often result in unsatisfied therapeutic outcomes and/or unexpected toxicities. 3. This study investigated the inhibitory effects of CPT and its eight derivatives on the cellular uptake of specific substrates mediated by the essential SLCs in over-expressing Human embryonic kidney 293 cells. 4. Our data revealed that CPT, 10-hydroxycamptothecin (HCPT), 10-methoxycamptothecin (MCPT) and 9-nitrocamptothecin (9NC) significantly inhibit the uptake activity of OAT3. 9NC also inhibited the substrate transport mediated by OAT1. The substrate uptakes of OAT1, OCTN1 and OCTN2 were significantly decreased in the presence of CZ112, while CPT-11 potently down-regulated the transport activity of OCT1 and OCT3.

Naturally occurring camptothecins (CPT) are important sources of chemotherapeutic agents for clinical treatment of cancer. Extraction of CPT from Camptotheca acuminata trees remains to be a cost-effective way in the supply equation compared with a total synthesis. This study conducted a series of experiments to determine efficient solvent for the maximal extraction of CPT and its two derivatives, hydroxycamptothecin (HCPT) and methoxycamptothecin, from seeds and leaves of C. acuminata. Methanol as an extraction solvent demonstrated in seeds a significantly higher recovery of these three alkaloids than dichloromethane and acetone. Methanol concentrations at 70% in water resulted in maximum extraction of all the three alkaloids regardless of the type of plant materials. However, other strengths of methanol, lower or higher, either decreased the extracting power or showed no improvement in the extraction. Seed extract contained all the three alkaloids whereas leaf extract was absent of HCPT. A stable ratio of the three alkaloids was discovered but it was dependent upon seed or leaf extract of C. acuminata, which with various compositions can be produced. Ecological and medicinal implications of the leaf and seed extract characterized with different chemical compositions are discussed.

A simple HPLC method to determine the amount of 10-methoxycamptothecin (MCPT) and its major metabolite 10-hydroxycamptothecin (HCPT) in rat liver tissue was developed in the present study. Camptothecin (CPT) was used as internal standard (IS). A piecewise linear function was used over lower and higher concentrations, respectively. The calibration curves were linear (r (2) >0.99) over concentrations from 2.5 to 20 ng/mL and 20 to 320 ng/mL for both MCPT and HCPT. The method had an accuracy of 92.74% to 112.76%, and the intra- and inter-day precision (RSD%) were 11.85% or less for MCPT and HCPT. The stability data showed no significant degradation occurred under the experimental conditions. This method was successfully applied to the tissue distribution study of MCPT and its metabolite HCPT in liver tissue samples after intravenous administration.