PMC

General derivatization of polygodial

Synthesis of cyclic bis-acetals 10a,b-16a,b

Structures of selected α,β-unsaturated 1,4-dialdehyde terpenoids and a proposed pyrrole adduct of 1 with methylamine (4)

Chemical mechanism of the modified Paal-Knorr pyrrole condensation of 1 with primary amines

(a) Paal-Knorr pyrrole formation implicated in the neurotoxicity of hexane and (b) proposed lysine pyrrolylation by 1 and chemical demonstration of its feasibility

(A) Lack of an effect of 9-epipolygodial (2) on [Ca²⁺]_i despite (B) a pronounced effect of cell viability of MDA-MB-231 breast cancer cells at 4 μM. (C) Effect of polygodiol 6 on [Ca²⁺]_i into TRPV1-expressing MDA-MB-231 breast cancer cells, which is blocked with capsazepine. (E) Lack of an effect of polygodiol 6 on cell viability at these concentrations.

(A) Elimination of all cells in all 5 cultures tested with analogue 2 and contrasting effects on viability of all cells between 2 and standard chemotherapeutic agents paclitaxel and podophyllotoxin in (B) U87 GBM and (C) A549 NSCLC cell cultures

Effect of polygodial on TRPV1 activity in MDA-MB-231 breast cancer cells. (A) Effect of capsaicin on MDA-MB-231 [Ca²⁺]_i. (B) Effect of polygodial on MDA-MB-231 [Ca²⁺]_i. (C) TRPV1-like current activation. (D) Effect of capsazepine on polygodial-mediated [Ca²⁺]_i response. (E) Effect of co-treatment with polygodial and capsazepine on the 24 h cell viability (*** p<0.001; Two-way ANOVA following by Holm-Sidak tests).

Molecular modeling showing the capsaicin binding region of TRPV1 with a solvent interpolated charge surface containing docked polygodial (1) and the close proximity of Lys571 (Left). Hydrogen bonding interactions to Tyr511 and Thr550 are observed for docked 1 (middle). Polygodiol 6 (right) docked within the pocket assumes a similar pose; however, the ability to act as a hydrogen bond donor to Thr550 means that this residue can maintain its structural hydrogen bonding interaction to Ala546.

Evaluation of selected polygodial analogues in a [³H]-RTX TRPV1 displacement assay. Effect of a single concentration (10 μM) of the selected analogues in the specific binding of [³H]-RTX to the vanilloid site of TRPV1 receptor from rats spinal cord membranes. Results are expressed as mean ± S.E.M from 3 independent experiments, analyzed by one way analysis of variance (ANOVA), followed by Dunnett’s multiple comparison test (***p<0.05 and ****p<0.001).

Activity of 2 against neurosphere glioma cell cultures with clinically relevant mutations. Transgenic mouse gliomas of defined molecular subtypes were generated by forced expression of EGFRvIII (classical GBM subtype) or PDGFB (proneural GBM subtype) in cdkn2a-deficient subventricular neural precursors (NPC). These 2 different mouse gliomas and cdkn2a-deficient NPC were treated for 24 hours either with 10 μM CBD versus a corresponding vehicle-control (containing 0.01% DMSO) or 4 μM of 2 versus vehicle control (0,004% DMSO). Cytotoxicity was measured 24 h after incubation and base-line cytotoxicity levels in the controls were arbitrarily defined as 1. Read-outs from treated cells were normalized to their respective vehicle controls and the fold change of relative cytotoxicity was calculated. Each bar represents the mean ± SD; satistical significance, as determined by unpaired t-tests, is indicated: *** represents p < 0,001; ** p < 0,005).