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. 2005 Nov 10;7(23):5261-4.
doi: 10.1021/ol052121f.

Antineoplastic diterpene-benzoate macrolides from the Fijian red alga Callophycus serratus

Julia Kubanek  1 , Anne C Prusak, Terry W Snell, Rachel A Giese, Kenneth I Hardcastle, Craig R Fairchild, William Aalbersberg, Carmen Raventos-Suarez, Mark E Hay
Affiliations

Antineoplastic diterpene-benzoate macrolides from the Fijian red alga Callophycus serratus

Julia Kubanek et al. Org Lett. .

Abstract

[structures: see text] Three diterpene-benzoate natural products, with novel carbon skeletons and an unusual proposed biosynthesis, were isolated from extracts of the Fijian red alga Callophycus serratus and identified by a combination of X-ray crystallographic, NMR, and mass spectral analyses. Bromophycolide A (1) displayed cytotoxicity against several human tumor cell lines via specific apoptotic cell death. This represents the first discovery of natural products incorporating a diterpene and benzoate skeleton into a macrolide system.

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Figures

Figure 1
Figure 1
Novel natural products of Callophycus serratus.
Figure 2
Figure 2
Perspective drawings of 1 (left) and 2 (right) from X-ray crystallographic data.
Scheme 1
Scheme 1
Proposed Biogenesis of Diterpene Carbocyclic Rings for 1–3a aAtom numbering as in Figure 1.
See this image and copyright information in PMC

References

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    1. Bromophycolide A (1): white crystals recrystallized from methanol (39.7 mg; 0.80% plant dry mass); [α]23D −35 (c 0.21 g/100 mL, CHCl3); UV (MeOH) λmax 229 nm (log ∊ = 3.73), 265 nm (log ∊ = 4.27); IR (thin film) νmax 3350 (br), 2970, 2930, 1683-1721, 1608, 1455, 1372, 1338, 1265, 1246, 1108, 769, 738 cm−1; 1H NMR (CDCl3, 500 MHz) and 13C/DEPT NMR (CDCl3, 125 MHz) data, Table 1; NOE, COSY, HMBC NMR data, Supporting Information; HRESIMS [M – H]− m/z 661.0194 (calcd for C27H36O4Br3, 661.0169). Bromophycolide B (2): white crystals recrystallized from aqueous methanol (6.1 mg; 0.11% plant dry mass); [α]23D −1 (c 0.044 g/100 mL, CHCl3); UV (MeOH) λmax 224 nm (log ∊ = 3.63), 265 (log ∊ = 3.68); 1H NMR (CDCl3, 500 MHz) and 13C/DEPT NMR (CDCl3, 125 MHz) data, Table 1; NOE, COSY, HMBC NMR data, Supporting Information; HRESIMS [M – H]− m/z 661.0191 (calcd for C27H36O4Br3, 661.0169). Debromophycolide A (3): white amorphous solid (1.6 mg; 0.043% plant dry mass); [α]23D −7 (c 0.012 g/100 mL, CHCl3); UV (MeOH) λmax 265 nm (log ∊ = 3.46); 1H NMR (CDCl3, 500 MHz) and 13C/DEPT NMR (CDCl3, 125 MHz) data, Table 1; NOE, COSY, HMBC NMR data, Supporting Information; HRESIMS [M – H]− m/z 439.2490 (calcd for C27H35O5, 439.2490).

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