HPLC-ELSD Quantification and Centrifugal Partition Chromatography Isolation of 8-O-Acetylharpagide from Oxera coronata (Lamiaceae)

INTRODUCTION

Iridoid glycosides possess highly functionalised monoterpenoid aglycon with several contiguous stereocentres. For the most common, they are often present in quantities reaching several percentage of the fresh plant weight, and thus they may be regarded as starting material for the synthesis of a number of new chiral and bioactive molecules.

OBJECTIVE

To quantify and to isolate 8-O-acetylharpagide (AH) from several extracts of Oxera coronata R.P.J. de Kok, a Lamiaceae species endemic to New Caledonia, using HPLC-ELSD (evaporative light scattering detector) and centrifugal partition chromatography (CPC).

METHODOLOGY

Oxera coronata produces high amounts of AH in leaves, twigs and fruits. Water and methanol extracts of these plant parts were prepared. The content of AH in each extract was quantified by HPLC-ELSD, using acetonitrile-water (+0.1% formic acid) gradient elution. The HPLC method was validated for precision, linearity, limit of detection (LOD), limit of quantification (LOQ) and accuracy. A ternary solvent system ethyl acetate/n-propanol/water (3:2:5, v/v/v) was selected and applied to recover the target compound using Spot CPC from the leaves aqueous extract.

RESULTS

HPLC-ELSD analysis followed by CPC purification led to the efficient isolation of AH from O. coronata leaves aqueous extract.

CONCLUSION

HPLC-ELSD has proven to be a well-adapted detection and quantification method for iridoid glycosides, while CPC confirmed to be an efficient technique for the isolation of polar compounds. Copyright © 2016 John Wiley & Sons, Ltd.

Three new trixane glycosides obtained from the leaves of Jungia sellowii Less. using centrifugal partition chromatography

Jungia sellowii (Asteraceae) is a shrub that grows in Southern Brazil and polar extract of its leaves presents anti-inflammatory properties. Cyperane, guaiane, nortrixane, and trixane sesquiterpene types were reported as the main metabolites in Jungia species. This work aims to describe the isolation and identification of sesquiterpenes in the leaves of J. sellowii using liquid-liquid partition and centrifugal partition chromatography. Thus, the crude extract of fresh leaves of J. sellowii was partitioned with hexane, dichloromethane, ethyl acetate and butanol, respectively. The butanol fraction was then subjected to a selected ternary system optimized for the CPC (centrifugal partition chromatography): ethyl acetate-ethanol-water (9:2:10, v/v/v). The separation was carried out isocratically at a flow rate of 25 mL/min at 1200 rpm, affording seven fractions A to G. TLC of fractions B, C and F displayed a single spot corresponding to three new glycosylated sesquiterpenoids. Their structures were established by using spectroscopic data in comparison to those reported in the literature. Furthermore, the isolates were evaluated for their leishmanicidal and cytotoxic effects. No cytotoxic effect was observed against the three cancer cell lines (HL60, JURKAT and REH), but compound 1 showed a weak antiprotozoal activity. Liquid-liquid partition and CPC turned to be a versatile technique of glycoside purification which is environmentally friendly and requires a limited amount of organic solvents.