Establishment of a novel monoclonal antibody based icELISA method to determine the total content of ursolic and oleanolic acids in fruits

The naturally occurring pentacyclic triterpenoid compounds ursolic acid (UA) and oleanolic acid (OA) are commonly found together in various fruits and find broad applications in pharmaceuticals, cosmetics, food and agricultural fields. In this study, a sensitive and practical icELISA method was developed based on a monoclonal antibody (mAb) YC23-101, with a median inhibitory concentration (IC 50 ) of 15.56 ng/mL and a linear range of 5.26 to 54.1 ng/mL. The limits of detection (LOD) ranges from 0.98-5.11 ng/mL in fruit matrices and the recoveries were 94.03-112.21% with coefficients of variation below 5.73%. Cross-reactivity analysis showed that mAb YC23-101 could also specifically recognize OA with similar sensitivity to UA, indicating feasibility for the simultaneously quantification of UA and OA in fruits. The developed icELISA was applied to several fruits, and the results showed good correlation with that of HPLC. Molecular docking analysis predicted equal binding energy of UA and OA to the mAb with hydrophobic interactions playing a predominant role. All these findings demonstrated that this icELISA is reliable, sensitive, and suitable for the high-throughput quantification of total UA and OA content in fruits composition analysis. • A Ursolic acid hapten was initially designed and synthesized. • A specific mAb YC23-101 targeting ursolic acid and oleanolic acid was screened and identified. • The mAb YC23-101-based icELISA was developed with high accuracy, precision and producibility. • This icELISA effectively quantifies total content of ursolic and oleanolic acids in fruits.