Absolute Structure Determination and Kv1.5 Ion Channel Inhibition Activities of New Debromoaplysiatoxin Analogues

Figures

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  Figure 1. Structures of identified debromoaplysiatoxin analogues in this study: new compounds 1–4 and reported Compound 5.

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  Figure 2. Key 2D correlations and X-ray structure of 1.

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  Figure 3. (A) Key 2D correlations of 2. (B) Key NOESY correlations of 2 (solid lines: α-orientation; dashed lines: β-orientation). (C) DP4 analysis results for 2.

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  Figure 4. Newman projection analysis of the energy equivalent isomer.

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  Figure 5. (A) Key 2D correlations of 3. (B) Key NOESY correlations of 3 (solid lines: α-orientation; dashed lines: β-orientation). (C) DP4 analysis results for 3.

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  Figure 6. (A) Key 2D correlations of 4. (B) Key NOESY correlations of 4 (solid lines: α-orientation; dashed lines: β-orientation). (C) DP4 analysis results for 4.

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  Figure 7. (A) Kv1.5 currents were evoked by a 300 ms depolarizing pulse from –50 mV to 50 mV in 20 mV increments from a holding potential of –70 mV in the absence and presence of 0.3 μM, 1 μM, 3 μM and 10 μM oscillatoxin J (1). The current amplitudes were measured at the end of the 300 ms pulse at 50 mV. (B) Concentration–inhibition curve expressed in %. The abscissa represents the concentration, and the ordinate represents the percentage of Kv1.5 current that is blocked at different concentrations of oscillatoxin J (1). Data points represent mean ± SEM of 3 to 5 measurements, and the inhibitory effect showed an IC50 value of 2.61 ± 0.91 µM.

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  Figure 8. (A) Kv1.5 currents were evoked by a 300 ms depolarizing pulse from –50 mV to 50 mV in 20 mV increments from a holding potential of –70 mV in the absence and presence of 0.3 μM, 1 μM, 3 μM and 10 μM oscillatoxin K (2). The current amplitudes were measured at the end of the 300 ms pulse at 50 mV. (B) Concentration–inhibition curve expressed in %. The abscissa represents the concentration, and the ordinate represents the percentage of Kv1.5 current that is blocked at different concentrations of oscillatoxin K (2). Data points represent mean ± SEM of 3 to 5 measurements, and the inhibitory effect showed an IC50 value of 3.86 ± 1.03 µM.

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  Figure 9. Kv1.5 currents were evoked by a 300 ms depolarizing pulse from –50 mV to 50 mV in 20 mV increments from a holding potential of –70 mV in the absence and presence of 0.3 μM, 1 μM, 3 μM and 10 μM oscillatoxin M (4). The current amplitudes were measured at the end of the 300 ms pulse at 50 mV. (B) Concentration–inhibition curve expressed in %. The abscissa represents the concentration, and the ordinate represents the percentage of Kv1.5 current that is blocked at different concentrations of oscillatoxin M (4). Data points represent mean ± SEM of 3 to 5 measurements, and the inhibitory effect showed an IC50 value of 3.79 ± 1.01 µM.

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  Figure 10. Dose effect of compounds 1–4 to Artemia salina (A. salina). A. salina was treated with indicated concentration (1 µM and 30 µM) of dichloromethane (DCM), debromoaplysiatoxin (DAT) and compounds 1–4 for 24 h. (A) The percentage of A. salina compounds 1–4 in 1 µM; (B) the percentage of A. salina with compounds 1–4 in 30 µM. N.D: the life of brine shrimp not detected. Data were analyzed by GraphPad prism (Table S1.3.2.1).