Simultaneous determination of artemisinin and its analogs and flavonoids in Artemisia annua crude extracts with the use of NMR spectroscopy

Abstract

Artemisia annua is a promising and potent antimalarial herbal drug. This activity has been ascribed to its component artemisinin, a sesquiterpene lactone. The ability to determine artemisinin and its known analogs in plant extracts is an especially difficult task because the compounds are present in low concentrations, are thermolabile, and lack ultraviolet or fluorescent chromophores. We report herein a facile and rapid 1-D ¹ H, 1-D total correlation spectroscopy, 2-D ¹ H-¹³ C heteronuclear single quantum coherence, and ¹ H-¹³ C heteronuclear multiple bond correlation nuclear magnetic resonance techniques for the simultaneous identification and quantification of artemisinin and five of its analogs along with five flavonoids, an aromatic ketone, and camphor (in total, 13 compounds) in crude diethyl ether A. annua extract without the need of laborious isolation of the individual analytes. The above method was validated in terms of precision, linearity, and limit of detection. The analytical results were found to be in excellent agreement with those obtained with the use of the time consuming high-performance liquid chromatography with diode-array detection and liquid chromatography with tandem mass spectrometry for the compounds that standards were available.

Keywords: 1-D TOCSY; 1H-13C HMBC; 1H-13C HSQC; Artemisia annua; NMR spectroscopy; artemisinin.