Simultaneous quantitative determination of multiple bioactive markers in Ocimum sanctum obtained from different locations and its marketed herbal formulations using UPLC-ESI-MS/MS combined with principal component analysis

Introduction: Ocimum sanctum L., with phenolic acids, flavonoids, propenyl phenols and terpenoids as active pharmacological constituents, is a popular medicinal herb and is present as an ingredient in many herbal formulations. Therefore, development of a reliable analytical method for simultaneous determination of the pharmacologically active constituents of O. sanctum is of high importance.

Objective: To develop and validate a new, rapid, sensitive and selective UPLC-ESI/MS/MS method for simultaneous determination of 23 bioactive markers including phenolic acids, flavonoids, propenyl phenol and terpenoid in the leaf extract and marketed herbal formulations of O. sanctum.

Methods: An UPLC-ESI/MS/MS method using negative electrospray ionisation (ESI) in multiple-reaction-monitoring (MRM) mode was used for simultaneous determination. Chromatographic separation was achieved on an Acquity UPLC BEH C18 -column using a gradient elution with 0.1% formic acid in water and 0.1% formic acid in acetonitrile. Principal component analysis (PCA) was applied to correlate and discriminate eight geographical collections of O. sanctum based on quantitative data of the analytes.

Results: The developed method was validated as per International Conference on Harmonization guidelines and found to be accurate, with overall recovery in the range 95.09-104.84% (RSD ≤ 1.85%), precise (RSD ≤ 1.98%) and linear (r(2) ≥ 0.9971) over the concentration range of 0.5-1000 ng/mL. Ursolic acid was found to be the most abundant marker in all the samples investigated, except for the marketed tablet.

Conclusion: The method established is simple, rapid and sensitive, hence it can be reliably utilised for the quality control of O. sanctum and derived herbal formulations.