Radioimmunoassay for the detection and quantitation of bruceantin

Radioimmunoassay of the phytotoxic compound zinniol

The phytotoxic compound zinniol, produced by phytopathogenic fungi such as Alternaria spp. and Phoma macdonaldii was conjugated to bovine serum albumine by the mixed anhydride method. Antiserum against zinniol was obtained by injection at multiple intradermal sites of rabbits. Sensitivity of the R.I.A. was 0.14 ng/tube, the within and between-assay coefficient of variation were less than 10 and 14% respectively. Negligible binding occurred when analogs of zinniol were tested for cross reactivity. The excellent accuracy of this R.I.A., applied to ethanolic extracts of plants, might allow to determine the production of toxin by the parasite during the infection process.

An enzyme-linked immunosorbent assay for quassin and closely related metabolites

A microtitration plate enzyme-linked immunosorbent assay has been developed for quassin and closely related seco-triterpenes. The method is much more sensitive than conventional chromatographic techniques and enables the routine analysis of large numbers of samples with a detection limit of 5 ng quassin. Antibody production was elicited by injecting a conjugate of iso-quassinic acid linked to bovine serum albumin into rabbits. Important features of the technique are (a) the use of a double-antibody, noncompetitive enzyme-linked immunosorbent assay for a low-molecular-weight, nonantigenic compound using microtitration plates; and (b) that the initial incubation of samples with primary antiserum can be carried out in buffer containing up to 20% (v/v) methanol with minimal loss of sensitivity. The structural requirements for recognition of the hapten by the antiserum are considered based on the levels of cross-reaction found with a wide range of other quassinoids.

Clinical pharmacology of bruceantin by radioimmunoassay

During the phase I clinical trial of a new antitumor agent, bruceantin, the pharmacology was studied in 18 cancer patients. The drug was infused intravenously (IV) for 3 h at doses ranging from 1 to 3.6 mg/m2 per day for 5 days. The plasma drug disappearance curves were biphasic, with a fast initial half-life of less than 15 min. The second half-life (t1/2 beta) varied from 0.7 to 38 h among different patients and was not dose-related. The difference between the t1/2 beta on day 1 and that on day 5 was not significant. In patients with normal liver function, the mean plasma concentration at the end of infusion was 22 ng/ml, and the value of the area under the concentration X time curve (AUC) was 111 (ng/ml)h. In contrast, in patients with abnormal liver function the corresponding values were 115 ng/ml and 830 (ng/ml)h, respectively. In addition, these patients had a slower elimination half-life of 10.9 h and a decreased total clearance of 157 ml/min/m2, as compared with 2.6 h and 671 ml/min/m2, respectively, for the normal group. All these differences were statistically significant. Patients with abnormal liver function developed more severe toxicity, including fever, severe nausea, vomiting, and hypotension. Two patients with severe hepatic dysfunction received a reduced dose and developed no toxicity. These results demonstrated the importance of the effects of liver dysfunction on drug disposition and showed that the dosage should be reduced in patients with hepatic dysfunction.