Azaspiracid variability of Azadinium poporum (Dinophyceae) from the China Sea

Mediterranean Azadinium dexteroporum (Dinophyceae) produces six novel azaspiracids and azaspiracid-35: a structural study by a multi-platform mass spectrometry approach

“…A total AZA cell quota of 24.5 fg/cell was estimated from a cross check of the Q-Trap MS data with relative abundances and concentrations measured on the LTQ Orbitrap XL FTMS using AZA-1 CRM as standard. This cell quota is comparable to that of other AZA-producing species such as A. spinosum (5-50 fg/cell) [6] and A. poporum (0-10 fg/cell) [14,16] and is quite different from that reported by Percopo et al (2-3 fg/ cell) for the same strain, based on TOF MS analyses of only three minor components of the A. dexteroporum profile [13]. The available material was not sufficient for even attempting isolation and subsequent full structural elucidation based on NMR spectroscopy.…”

“…However, recently, Krock et al [15] found the 3-hydroxylated derivatives AZA-36 and AZA-37 to be de novo synthesized in A. poporum strains from the North Sea and Korea, respectively. In addition, some strains of A. poporum from the Northwest Pacific region only produced AZA-11, the 3-hydroxylated derivative of AZA-2, without producing AZA-2 itself [14]. Interestingly, also the Mediterranean A. dexteroporum produces 3-epi-AZA-7, the 3-hydroxylated derivative of AZA-1 without producing AZA-1 itself.…”

“…This is consistent with the compound at m/z 858 being the epimer at C3 of AZA-7 (3-epi-AZA-7). Noteworthy, the finding of 3-epi-AZA-7 in the Mediterranean A. dexteroporum represents the second case of de novo biosynthesis of a 3-hydroxylated AZA in a dinoflagellate, the first case being A. poporum, which can produce AZA-11 [14]. Until recently, 3-hydroxylated AZA were regarded exclusively as shellfish metabolites of AZA-1 and AZA-2 [9].…”

“…Over the last years, several analogues of AZA-1 have been discovered either in shellfish [7][8][9][10][11] or in dinoflagellates [6,[12][13][14][15][16][17] and structurally characterized by tandem mass spectrometry (MS/MS) and partly also by nuclear magnetic resonance (NMR) spectroscopy. Some AZAs (AZA-1 and AZA-2, among others) are actually produced by the dinoflagellates, whereas others (e.g., AZA-3 to AZA-19) seem to derive from biotransformation occurring in shellfish [9].…”

Azadinium poporum from the Argentine Continental Shelf, Southwestern Atlantic, produces azaspiracid-2 and azaspiracid-2 phosphate

“…Whereas all three available North Sea isolates only produce AZA-37 (compound 2 in Krock et al, 2012), A. poporum from the Asiatic Pacific region produces more complex AZA profiles including AZA-2, -11, -36, -40, -41 in different combinations, and also strains without any known AZA have been described Krock et al, 2014). AZA-2 as the major AZA produced by the Argentinean isolates thus is in line with a close relation to the Asian clade of A. poporum, for which AZA-2 production was found in 7 out of 22 strains .…”