Structural characterization and identification of ecdysteroids from Sida rhombifolia L. in positive electrospray ionization by tandem mass spectrometry

Abstract

Seven ecdysteroids isolated from Sida rhombifolia L. were studied by electrospray ionization multi-stage tandem mass spectrometry (ESI-MS(n)) in the positive ion mode using an ion trap analyzer and high-performance liquid chromatography coupled with a diode-array detector (HPLC/DAD). The HPLC experiments were performed by means of a reversed-phase C(18) column and a binary mobile phase system consisting of water (containing 0.05% formic acid) and acetonitrile (containing 0.05% formic acid) under gradient elution conditions. According to mass spectral features and the substitution at C-2, C-20, C-24 and C-25, ecdysteroids in S. rhombifolia were classified into three sub-groups. Structural identification of these three sub-groups of ecdysteroids was established by LC/multi-stage ion trap mass spectrometry on-line or off-line. The fragmentation patterns of ecdysteroids yielded ions of successive loss of 1-4 water molecules. Furthermore, ions corresponding to the complete loss of the side chain at C-17 will help to identify the sub-groups of ecdysteroids in addition to containing a hydroxyl moiety at one of the above-mentioned positions. Based on the HPLC retention behavior, the diagnostic UV spectra and the molecular structural information provided by ESI-MS(n) spectra, a total of nine naturally occurring ecdysteroids were identified, of these two are identified for the first time in S. rhombifolia.

Ecdysteroids in Sida tuberculata R.E. Fries (Malvaceae): Chemical composition by LC–ESI-MS and selective anti-Candida krusei activity

“…3. The fragmentation patterns for the steroidal compounds are in accordance with the key fragmentation described for ecdysteroids (Kumpun et al, 2011;Stevens, Reed, & Morré, 2008;Wang et al, 2008) compound 2, the same fragmentation related to the loss of water was observed, being identified as 20-hydroxyecdysone. The constituents ecdysone and 20-hydroxyecdysone, among other derivatives, were found in S. rhombifolia and S. spinosa (Darwish & Reinecke, 2003;Dinan et al, 2001).…”

“…Thus, we suggest the presence of the compound 20-hydroxyecdysone-3-O-b-D-xylose, the xylopentose fragment of which was reported by Stevens et al (2008) and Sarker, Girault, Lafont, and Dinan (1997). Compound 4 (unknown compound) showed the same key fragments for ecdysteroid, characteristic of 5,20-dihydroxyecdysterone (Wang et al, 2008). The mass spectrum showed ions corresponding to the loss of water molecules, consistent with a multiply hydroxylated ecdysteroid.…”

“…Considered to be markers and a characteristic chemical class of Sida, ecdysteroids have been determined chromatographically in the seeds and aerial parts of different species, such as S. spinosa and S. rhombifolia (Darwish & Reinecke, 2003;Dinan et al, 2001). Ecdysone, 20-hydroxyecdysone and glycosyl derivatives have been described as among the main components in S. rhombifolia (Wang, Avula, Jadhav, Smillie, & Khan, 2008). Alkaloid derivatives, quinazolines (vasicine and vasicinine) and ephedrine have been reported in S. cordifolia, and the cardiovascular effects observed upon consumption are attributed to these substances (Ghosal et al, 1981).…”

Girard derivatization for LC-MS/MS profiling of endogenous ecdysteroids in Drosophila

“…However, their ionization capacity is low compared with major glycerophospholids, such as phosphatidylcholines and phosphatidylethanolamines. MS/MS spectra of ecdysteroids are dominated by abundant peaks of water-loss fragments ( 21,22 ), which is common for small relatively hydrophilic molecules. Therefore, unequivocal identifi cation of known and discovery of novel endogenous ecdysteroids require alternative approaches relying on molecular forms having more specifi c fragmentation pathways.…”

“…Even at the low (<10 eV) collision energy, protonated molecular ions ([M+H] + ) of ecdysteroids underwent successive loss of multiple (up to fi ve, in the case of muristerone A) water molecules ( 21 ) ( Figs. 3 and 4A ).…”