Spectrofluorimetric determination of manzamine A in spiked human urine and plasma

The native fluorescence of manzamine A (a biologically active beta-carboline marine-derived alkaloid) has been studied under different conditions. The highest fluorescence intensity was obtained in methanol. Two wavelength settings were found to be suitable for excitation, 280 nm and 340 nm; while lambdamax emission was constant in both cases at 387 nm. The fluorescence intensity at 340/387 nm setting was 1.6 greater than that obtained at 280/387 nm settings. The calibration curves were rectilinear over the range 0.1-2.0 and 0.5-2.5 microg/ml for the two settings, respectively. The detection limits were 0.05 microg/ml (9.1 x 10(-9) M) and 0.1 microg/ml (1.82 x 10(-8) M) at 340/387 nm and 280/387 nm, respectively. The proposed method was applied to the determination of manzamine A in spiked human urine and plasma samples adopting the 340/387 nm wavelength setting, the % recoveries (n = 6) were 99.61 +/- 0.90 and 100.25 +/- 1.63, respectively.