Fig. 7
Identification by LC–MS of cucurbitacin B and glycosylated cucurbitacin B in aphids and melons. A LC–MS profiles of cucurbitacins (Extracted Ion Chromatogram of ion 499.2). 1: leaf extract, 2: aphid extract, 3: authentic standard of cucurbitacin B. Peak height was normalised to that of the largest peak. Red mark: glycosylated cucurbitacin B, green mark: cucurbitacin B. B LC–MS mass spectra of: 1: cucurbitacin B standard, 2: leaf extract at tR = 7.01 min. The peak heights were normalised to that of the largest peak. C MRM spectra of the two transitions: 576.3 > 499.2 and 499.2 > 481.2 at tR 7.01 min, showing the ratios between the two ions produced, 576 and 499: 1: cucurbitacin B standard (ratio 5.6), 2: aphid extract (ratio 6.7), 3: leaf extract (ratio 6.3)