New Hapalindoles from the Cyanophyte Hapalosiphon laingii

Identification, Isolation, and Characterization of Developmental Toxins from the Cyanobacterium Fischerella 52-1 Using the Zebrafish (Danio rerio) Embryo Model

“…From the various analyses and experiments using the IR, NMR, and MS, it was determined that 1 was 12-epi-Hapalindole H Isonitrile. The IR analysis suggested the occurrence of an isonitrile group, the 13 C NMR data matched extremely closely to 12-epiHapalindole H Isonitrile, and the stereochemistry determined by the 1 H NMR matched that observed by Klein et al, (1995).…”

“…The splitting and the chemical shifts suggest that these protons are the equatorial C13 and C14 positions since the observations by Klein et al, (1995) showed the chemical shift of the equatorial hydrogens to be higher than that of the axial hydrogens. The multiplet at 1.15δ was assigned as the axial hydrogen on C14 because of the correlation with the carbon signal at 21.2δ.…”

“…The doublet of multiplets at 1.33δ was shown to correlate in the HMQC to both C13 and C14 (Figure 39). The overlapping doublet of multiplets might be a result of the doublets of triplets and the doublets of quartets produced by the equatorial hydrogens on C13 and C14 observed by Klein et al, (1995).…”

“…The carbon signals were compared to previously identified hapalindoles Klein et al, 1995;Becher et al, 2007) and assigned on the basis of the carbon chemical shifts and comparison of proton chemical shifts and splitting. The carbon signal at 36.6δ was labeled as C13 as previously assigned for other hapalindole structures and the signal at 21.2δ was assigned as C14.…”

“…The compound 12-epi-Hapalindole H Isonitrile (1), as discussed in Chapter 1, was previously isolated from Hapalosiphon laingii by Klein et al, (1995). The toxicological effects of 1 were not evaluated in this paper, rather this compound was isolated from a purified fraction that was shown to be toxic towards Artemia.…”