Garcinol

Garcinol Blocks the Reconsolidation of Multiple Cocaine-Paired Cues after a Single Cocaine-Reactivation Session.[Pubmed:28169286]

Neuropsychopharmacology. 2017 Aug;42(9):1884-1892.

Manipulations of memory reconsolidation can interfere with the ability of a drug-paired cue to drive drug-seeking behavior. However, the typical reconsolidation paradigm that reactivates the memory through the presentation of the cue (conditioned stimulus (CS)) only interferes with the memory of the reactivated CS while leaving other drug-paired CSs intact and able to continue driving drug-seeking behavior. Here, we used a novel unconditioned-stimulus (US) reactivation paradigm to interfere with the ability of multiple cues to drive drug-seeking behavior after just one reactivation and treatment session. Rats were trained to self-administer cocaine, during which time each active lever press resulted in an i.v. cocaine infusion paired with one of two cues that alternated within each session. The drug memory was later reactivated with either i.v. or i.p. cocaine presentation in the absence of any cue. The histone acetyltransferase (HAT) inhibitor Garcinol or vehicle was injected following US reactivation to impair reconsolidation. Rats were later tested on cue-induced reinstatement to both cues. Garcinol administered after either i.v. or i.p. cocaine reactivation significantly decreased cue-induced reinstatement to both cues, indicative of reconsolidation impairment. In addition, Garcinol administered in the absence of reconsolidation or at a 6 h delay when the memory should be restabilized had no effect on reinstatement, further suggesting that Garcinol's effects on reinstatement are through reconsolidation-based mechanisms. Our results demonstrate that a US-reactivation paradigm may be preferable to traditional CS-reactivation paradigms for treating disorders that involve multiple CS-US associations and support investigations of Garcinol as a therapeutic pharmacological agent.

Protective effects of Garcinol against neuropathic pain - Evidence from in vivo and in vitro studies.[Pubmed:28302538]

Neurosci Lett. 2017 Apr 24;647:85-90.

Neuroinflammatory processes have a vital role in the pathogenesis of neuropathic pain. Garcinol, harvested from Garcinia indica, is known to exert potent anti-inflammatory properties. Recent studies have indicated that Garcinol may inhibit activation of nuclear factor-kappaB (NF-kappaB) by inhibiting NF-kappaB/p65 acetylation. These findings prompted us to evaluate the protective effects of Garcinol in the lumbar fifth spinal nerve ligation (SNL)-induced rat model of neuropathic pain and Lipopolysaccharide(LPS)-stimulated primary cultured microglia. In the present study, we found that intrathecal administration of Garcinol significantly attenuated SNL-induced nociceptive behaviors. Garcinol suppressed microglial activation as well as the expression of interleukin (IL)-1beta, IL-6, inducible nitric oxide synthase (iNOS)/nitric oxide (NO), and cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE2) in the spinal cord of SNL rats. It also reduced the nuclear translocation of NF-kappaB by decreasing acetyl-p65 protein expression. Similarly, in the in vitro study, Garcinol decreased the production of NO/iNOS, PGE2/COX-2, and proinflammatory cytokines in LPS-exposed microglia. Likewise, Garcinol inhibited the NF-kappaB signaling pathway by downregulating acetyl-p65 levels in LPS-challenged microglia. Our findings suggest that Garcinol may have protective effects against neuropathic pain that are associated with the inhibition of neuroinflammation in microglia. Therefore, Garcinol could be a promising agent in the treatment of neuropathic pain.

The C8 side chain is one of the key functional group of Garcinol for its anti-cancer effects.[Pubmed:28169002]

Bioorg Chem. 2017 Apr;71:74-80.

Garcinol from the fruit rind of Garcinia indica shows anti-carcinogenic and anti-inflammatory properties, but its mechanism and key functional groups were still need to be identified. Our previous computer modeling suggested that the C8 side chain of Garcinol is so large that it may influence the bioactivity of the compound. 8-Me Garcinol, a derivative of Garcinol in which the bulky side chain at the C8 position of Garcinol is replaced with a much smaller methyl group, was synthesized through a 12-step procedure starting from 1,3-cyclohexanedione. The antitumor activity of Garcinol and 8-Me Garcinol was evaluated in vitro by MTT, cell cycle and cell apoptosis assays. The results showed that 8-Me Garcinol had weaker inhibitory activity on cells proliferation, and little effects on cell cycle and apoptosis in oral cancer cell line SCC15 cells when compared with Garcinol. All of the results indicated 8-Me Garcinol exerts weaker antitumor activity than Garcinol, and the C8 side chain might be an important active site in Garcinol. Changing the C8 side chain will affect the inhibitory effect of Garcinol.

Garcinol loaded vitamin E TPGS emulsified PLGA nanoparticles: preparation, physicochemical characterization, in vitro and in vivo studies.[Pubmed:28373669]

Sci Rep. 2017 Apr 3;7(1):530.

Garcinol (GAR) is a naturally occurring polyisoprenylated phenolic compound. It has been recently investigated for its biological activities such as antioxidant, anti-inflammatory, anti ulcer, and antiproliferative effect on a wide range of human cancer cell lines. Though the outcomes are very promising, its extreme insolubility in water remains the main obstacle for its clinical application. Herein we report the formulation of GAR entrapped PLGA nanoparticles by nanoprecipitation method using vitamin E TPGS as an emulsifier. The nanoparticles were characterized for size, surface morphology, surface charge, encapsulation efficiency and in vitro drug release kinetics. The MTT assay depicted a high amount of cytotoxicity of GAR-NPs in B16F10, HepG2 and KB cells. A considerable amount of cell apoptosis was observed in B16f10 and KB cell lines. In vivo cellular uptake of fluorescent NPs on B16F10 cells was also investigated. Finally the GAR loaded NPs were radiolabeled with technetium-99m with >95% labeling efficiency and administered to B16F10 melanoma tumor bearing mice to investigate the in vivo deposition at the tumor site by biodistribution and scintigraphic imaging study. In vitro cellular uptake studies and biological evaluation confirm the efficacy of the formulation for cancer treatment.

Garcinol regulates EMT and Wnt signaling pathways in vitro and in vivo, leading to anticancer activity against breast cancer cells.[Pubmed:22821148]

Mol Cancer Ther. 2012 Oct;11(10):2193-201.

Anticancer properties of Garcinia indica-derived Garcinol are just beginning to be elucidated. We have earlier reported its cancer cell-specific induction of apoptosis in breast cancer cells, which was mediated through the downregulation of NF-kappaB signaling pathway. To gain further mechanistic insight, here, we show for the first time that Garcinol effectively reverses epithelial-to-mesenchymal transition (EMT), that is, it induces mesenchymal-to-epithelial transition (MET) in aggressive triple-negative MDA-MB-231 and BT-549 breast cancer cells. This was associated with upregulation of epithelial marker E-cadherin and downregulation of mesenchymal markers vimentin, ZEB-1, and ZEB-2. We also found that Garcinol upregulates the expression of miR-200 and let-7 family microRNAs (miRNAs), which provides a molecular mechanism for the observed reversal of EMT to MET. Transfection of cells with NF-kappaB p65 subunit attenuated the effect of Garcinol on apoptosis induction through reversal of MET to EMT. Forced transfection of p65 and anti-miR-200s could also reverse the inhibitory effect of Garcinol on breast cancer cell invasion. Moreover, treatment with Garcinol resulted in increased phosphorylation of beta-catenin concomitant with its reduced nuclear localization. The results were also validated in vivo in a xenograft mouse model where Garcinol was found to inhibit NF-kappaB, miRNAs, vimentin, and nuclear beta-catenin. These novel findings suggest that the anticancer activity of Garcinol against aggressive breast cancer cells is, in part, due to reversal of EMT phenotype, which is mechanistically linked with the deregulation of miR-200s, let-7s, NF-kappaB, and Wnt signaling pathways.

Ex vivo expansion of human hematopoietic stem cells by garcinol, a potent inhibitor of histone acetyltransferase.[Pubmed:21931675]

PLoS One. 2011;6(9):e24298.

BACKGROUND: Human cord blood (hCB) is the main source of hematopoietic stem and progenitor cells (HSCs/PCs) for transplantation. Efforts to overcome relative shortages of HSCs/PCs have led to technologies to expand HSCs/PCs ex vivo. However, methods suitable for clinical practice have yet to be fully established. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we screened biologically active natural products for activity to promote expansion of hCB HSCs/PCs ex vivo, and identified Garcinol, a plant-derived histone acetyltransferase (HAT) inhibitor, as a novel stimulator of hCB HSC/PC expansion. During a 7-day culture of CD34(+)CD38(-) HSCs supplemented with stem cell factor and thrombopoietin, Garcinol increased numbers of CD34(+)CD38(-) HSCs/PCs more than 4.5-fold and IsoGarcinol, a derivative of Garcinol, 7.4-fold. Furthermore, during a 7-day culture of CD34(+) HSCs/PCs, Garcinol expanded the number of SCID-repopulating cells (SRCs) 2.5-fold. We also demonstrated that the capacity of Garcinol and its derivatives to expand HSCs/PCs was closely correlated with their inhibitory effect on HAT. The Garcinol derivatives which expanded HSCs/PCs inhibited the HAT activity and acetylation of histones, while inactive derivatives did not. CONCLUSIONS/SIGNIFICANCE: Our findings identify Garcinol as the first natural product acting on HSCs/PCs and suggest the inhibition of HAT to be an alternative approach for manipulating HSCs/PCs.

Polyisoprenylated benzophenone, garcinol, a natural histone acetyltransferase inhibitor, represses chromatin transcription and alters global gene expression.[Pubmed:15155757]

J Biol Chem. 2004 Aug 6;279(32):33716-26.

Histone acetylation is a diagnostic feature of transcriptionally active genes. The proper recruitment and function of histone acetyltransferases (HATs) and deacetylases (HDACs) are key regulatory steps for gene expression and cell cycle. Functional defects of either of these enzymes may lead to several diseases, including cancer. HATs and HDACs thus are potential therapeutic targets. Here we report that Garcinol, a polyisoprenylated benzophenone derivative from Garcinia indica fruit rind, is a potent inhibitor of histone acetyltransferases p300 (IC50 approximately 7 microm) and PCAF (IC50 approximately 5 microm) both in vitro and in vivo. The kinetic analysis shows that it is a mixed type of inhibitor with an increased affinity for PCAF compared with p300. HAT activity-dependent chromatin transcription was strongly inhibited by Garcinol, whereas transcription from DNA template was not affected. Furthermore, it was found to be a potent inducer of apoptosis, and it alters (predominantly down-regulates) the global gene expression in HeLa cells.

Garcinol, a polyisoprenylated benzophenone harvested from Garcinia indica, exerts anti-cholinesterase properties towards acetyl cholinesterase (AChE) and butyrylcholinesterase (BChE) with IC50s of 0.66 µM and 7.39 µM, respectively. Garcinol also inhibits histone acetyltransferases (HATs, IC50= 7 μM) and p300/CPB-associated factor (PCAF, IC50 = 5 μM). Garcinol has anti-inflammatory and anti-cancer activity.

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