A HR-MS Based Method for the Determination of Chorismate Synthase Activity.

Chorismate synthase (Cs) catalyzes the last step of Shikimate pathway involving a unique biochemical reaction of anti-1,4 elimination of 3-phosphate group and the C-(6proR) hydrogen from 5-enolpyruvylshikimate-3-phosphate (EPSP) leading to the formation of chorismate, which is the common precursor for aromatic amino acid, ubiquinone, and folate biosynthesis in plants and several bacterial, fungal, and parasitic pathogens. Absence of Shikimate pathway in the vertebrate host, make Cs an appealing target for drug discovery against these pathogens. Here, we report a new method for detection of chorismate through a specific liquid chromatography, coupled with negative electrospray ionization high-resolution tandem mass spectrometry (ESI-HRMS) for determination of Cs enzyme activity.

Quantification of sesquiterpene lactones in Parthenium hyterophorous by normal-phase HPLC.

This paper describes the development of a normal-phase liquid chromatography ultraviolet-diode array detection method for the simultaneous quantification of parthenin and coronopilin in the leaves and flowers of Parthenium hysterophorous. The compounds were analyzed on a Merck Si60 silica column (5 µm, 250 × 4 mm) using an isocratic 15:85 mixture of isopropyl alcohol and hexane. The calibration curves resulting from the reference compounds in the concentration range of 200-2,000 ng exhibited acceptable linearity (r > 0.