Goniothalamin

Goniothalamin enhances the ATPase activity of the molecular chaperone Hsp90 but inhibits its chaperone activity.[Pubmed:25294885]

J Biochem. 2015 Mar;157(3):161-8.

Hsp90 is an ATP-dependent molecular chaperone that is involved in important cellular pathways such as signal transduction pathways. It is a potential cancer drug target because it plays a critical role for stabilization and activation of oncoproteins. Thus, small molecule compounds that control the Hsp90 function are useful to elucidate potential lead compounds against cancer. We studied effect of a naturally occurring styryl-lactone Goniothalamin on the activity of Hsp90. Although many drugs targeting Hsp90 inhibit the ATPase activity of Hsp90, Goniothalamin enhanced rather than inhibited the ATPase activity of a cyanobacterial Hsp90 (HtpG) and a yeast Hsp90. It increased both K(m) and k(cat) of the Hsp90s. Domain competition assays and tryptophan fluorescence measurements with various truncated derivatives of HtpG indicated that Goniothalamin binds to the N-terminal domain of HtpG. Goniothalamin did not influence on the interaction of HtpG with a non-native protein or the anti-aggregation activity of HtpG significantly. However, it inhibited the activity of HtpG that assists refolding of a non-native protein in cooperation with the Hsp70 chaperone system. This is the first report to show that a small molecule that binds to the N-terminal domain of Hsp90 activates its ATPase activity, while inhibiting the chaperone function of Hsp90.

Involvement of Seladin-1 in goniothalamin-induced apoptosis in urinary bladder cancer cells.[Pubmed:25107315]

BMC Complement Altern Med. 2014 Aug 9;14:295.

BACKGROUND: Selective Alzheimer Disease Indicator-1 (or Seladin-1) is a multifunctional protein first discovered by downregulation of its expression in Alzheimer's disease. Interestingly, the expression of this protein is upregulated in several cancers, including primary bladder cancer. However, its role in cancer formation has yet to be discovered. Goniothalamin is a natural product that has been demonstrated to induce apoptosis in various cancer cell lines. In this study, we have elucidated the role of Seladin-1 in Goniothalamin-induced cytotoxicity towards human urinary bladder cancer cell line RT4. METHODS: The cytotoxicity of Goniothalamin in human urinary bladder cancer cell line RT4 was assessed using MTT assay and the mode of cell death was determined by Annexin V-FITC/PI labeling assay. Finally, the expression of Seladin-1 protein in Goniothalamin-treated RT4 cells was determined by Western blot. RESULTS: MTT assay showed that the cytotoxicity of Goniothalamin on RT4 cells was concentration and time dependent with IC50 values of 61 muM (24 hr), 38 muM (48 hr) and 31 muM for 72 hr, respectively. Cell death induced was confirmed through apoptosis; as assessed using the Annexin V-FITC/PI labeling assay. Furthermore, the involvement of Seladin-1 in Goniothalamin-induced apoptosis was evidenced through the cleavage of 60 kDa protein to 40 kDa and 20 kDa. This was followed by a gradual increase of 20 kDa fragment suggesting the involvement of Seladin-1 in Goniothalamin-induced apoptosis on RT4 cells. CONCLUSION: This study demonstrates that Goniothalamin induce cytotoxicity and apoptosis on RT4 cells. The involvement of Seladin-1 in Goniothalamin-induced apoptosis further suggested that Seladin-1 may play a role in the formation of primary bladder cancer.

Goniothalamin selectively induces apoptosis on human hepatoblastoma cells through caspase-3 activation.[Pubmed:23767409]

Nat Prod Res. 2013;27(23):2216-8.

Goniothalamin is a biologically active styrylpyrone derivative isolated from various Goniothalamus species. The ability of Goniothalamin to induce apoptosis via caspase-3 activation against hepatoblastoma (HepG2) and normal liver cells (Chang cells) was studied using morphological and biochemical evaluations. HepG2 and Chang cells were treated with Goniothalamin for 72 h and analysed by TUNEL and Annexin-V/PI staining. Furthermore, the post-mitochondrial caspase-3 was quantified using ELISA. In view of our results, Goniothalamin induced apoptosis on treated cells via alteration of cellular membrane integrity and cleavage of DNA. On the other hand, post-mitochondrial caspase-3 activity was significantly elevated in HepG2 cells treated with Goniothalamin after 72 h. These findings suggest that Goniothalamin induced apoptosis on HepG2 liver cancer cells via induction of caspase-3 with less sensitivity on the cell line of Chang cells.

Gastroprotective effects of goniothalamin against ethanol and indomethacin-induced gastric lesions in rats: Role of prostaglandins, nitric oxide and sulfhydryl compounds.[Pubmed:25451594]

Chem Biol Interact. 2014 Dec 5;224:206-12.

Goniothalamin (GTN), a styryl-lactone, is a secondary metabolite naturally found in its enantiomeric form (R) in plants of the genus Goniothalamus (Annonaceae). The antiproliferative activity against human tumor cell lines reported in several studies suggest that the alpha,beta-unsaturated delta-lactone moiety emerges as a key Michael acceptor for cysteine residues or other nucleophilic biological molecules. Our group reported on the in vivo activity of (R)- and (S)-GTN as well as its racemic form (rac-GTN) in both Ehrlich solid tumor and carrageenan-induced paw edema in mice, without side effects in the effective doses. Despite the rich body of data on the in vitro GTN biological activity, much less is known about its in vivo pharmacological action. Herein we describe the gastroprotective activity of rac-GTN on chemical-induced gastric ulcers models in rats. GTN has a potent gastroprotective effect on ethanol-induced ulcers (effective dose50=18mg/kg) and this activity is dependent on sulfhydryl compounds and prostaglandins generation, but independent of nitric oxide (NO), gastric secretion and mucus production. We hypothesize that Goniothalamin may act as a mild irritant, inducing the production of sulfhydryl compounds and prostaglandins, in a process known as adaptive cytoprotection. This hypothesis is supported by the fact that Michael acceptors are the most potent inducers of antioxidant response (as activation of Nrf2 pathway) through generation of mild oxidative stress and that gastroprotective activity of Goniothalamin is inhibited after pre-treatment with NEM (N-ethylmaleimide) and NSAID (non-steroidal anti-inflammatory drugs), highlighting the importance of sulfhydryl compounds and prostaglandins on GTN activity.

Transcriptomic evaluation of plant growth inhibitory activity of goniothalamin from the Malaysian medicinal plant Goniothalamus andersonii.[Pubmed:26058144]

Nat Prod Commun. 2015 May;10(5):725-7.

Goniothalamin produced by the Malaysian medicinal plant, Goniothalamus andersonii J. Sinclair, strongly inhibits plant growth. However, its mode of action has not been characterized at the gene expression level. We conducted DNA microarray assay to analyze the changes in early gene responses of Arabidopsis thaliana seedlings. After a 6-h exposure to Goniothalamin, we observed an upregulation of genes highly associated with heat response, and 22 heat shock protein (AtHSP) genes were upregulated more than 50 fold. Together with these genes, we observed upregulation of the genes related to oxidative stress and protein folding. Also, the genes related to cell wall modification and cell growth, expansin (AtEXPA) genes, were significantly downregulated. The results suggested that Goniothalamin induces oxidative stresses and inhibits the expression of cell wall-associated proteins resulting in growth inhibition of Arabidopsis seedlings.