MS/MS-Guided Isolation of Clarinoside, a New Anti-Inflammatory Pentalogin Derivative

Re-investigation of the chemical composition of the annual plant Mitracarpus scaber Zucc. led to the identification of a new pentalogin derivative containing a rare quinovose moiety. While the planar structure has been fully determined using tandem MS and quantum mechanics calculations (QM), the tridimensional structure was unraveled after isolation and NMR analysis. The absolute configuration was assigned by comparison of experimental and theoretical SRCD spectra. Both compounds were tested for anti-inflammatory activity and compound 1 showed the ability to inhibit the production of interleukin-8 (Il-8) with an IC₅₀ of 9.17 µM.