B-292 Detection of natural toxins derived from potatoes by biotin-streptavidin direct ELISA

Abstract Background α-solanine (SO) and α-chaconine (CHA) are natural toxins of potato and often cause food poisoning worldwide. We have previously developed a polyclonal antibody (anti-Sold antibody) that bind to SO and CHA and used it in an enzyme-linked immunosorbent assay (ELISA). Our previously constructed ELISA (conventional ELISA) has a weak point of low sensitivity in detecting SO and CHA, we have tried to improve it in this study. Methods Solanidine, a chemical compound found in both SO and CHA, was conjugated with bovine albumin, and this complex was repeatedly injected into two rabbits for two months. Anti-Sold antibody was then purified from rabbit serum using affinity column chromatography. In our ELISA method, named “B-S direct ELISA”, biotin-labeled anti-Sold antibody is bound to SO and CHA in the sample, followed by the binding of peroxidase-labeled streptavidin. To simulate biological samples from patients with potato food poisoning, SO and CHA powders were mixed with commercially available human serum and urine, and SO and CHA levels were then measured using ELISA. Lastly, SO and CHA levels were detected in extracts from rotten potato (Irish Cobbler) sprouts, peels, and tubers. Results The absorbance of the samples containing SO and CHA prepared in 10 mM phosphate buffer saline (PBS) was about 5-fold higher than that of the conventional ELISA. Furthermore, the absorbance of the samples containing SO and CHA prepared in human serum and urine was enhanced about 2.5- and 1.6-fold, respectively, compared to that of the conventional ELISA. The limit of detection in B-S direct ELISA was 0.32 ng/mL in 10 mM PBS, 2.08 ng/mL in serum, and 4.88 ng/mL in urine, respectively. Using this ELISA, it was also possible to measure the content of SO and CHA in extracts of potato tubers, peels, and sprouts. Both SO and CHA in the extracts from rotten potato tubers and peels were detected as approximately 1.4- and 2.2-fold higher, respectively, in each part than those in the extracts from fresh potatoes. Furthermore, the potato sprout extract contained approximately 50-fold more SO and CHA than the tuber and 9-fold more than the peel. On the other hand, B-S direct ELISA cross-reacted with solanidine and solasodine, which have similar chemical structures to SO and CHA, and also with cholesterol and vitamin D3 in serum. Conclusions Based on our results, B-S direct ELISA presented greater performance in detecting SO and CHA than our conventional ELISA. The non-s