Flavokawain B

Arch Biochem Biophys. 2014 Jul 15;554:44-54.

The chalcones cardamonin and flavokawain B inhibit the differentiation of preadipocytes to adipocytes by activating ERK.[Pubmed: 24845100]

We treated 3T3-L1 cells with a panel of 46 polyphenols and measured intracellular lipid accumulation by Sudan II staining. Four of them, including cardamonin and Flavokawain B, inhibited lipid We searched for polyphenols capable of inhibiting the lipid accumulation in 3T3-L1 cells, and investigated the mechanisms of two effective chalcones cardamonin and Flavokawain B on differentiation of preadipocytes.
METHODS AND RESULTS:
We treated 3T3-L1 cells with a panel of 46 polyphenols and measured intracellular lipid accumulation by Sudan II staining. Four of them, including cardamonin and Flavokawain B, inhibited lipid accumulation. In the further study, cardamonin and Flavokawain B inhibited lipid accumulation by downregulating the expression of CCAAT/enhancer binding protein (C/EBP)-β, C/EBPα, and peroxisome proliferator-activated receptor-γ (PPARγ) at both mRNA and protein levels. Cardamonin and Flavokawain B also increased phosphorylation of extracellular signal-regulated kinase (ERK) in the early phase of adipocyte differentiation. PD98059, an ERK inhibitor, restored C/EBPβ, PPARγ expression and intracellular lipid accumulation in adipocytes. Moreover, cardamonin and Flavokawain B also modulated the secretion of C-reactive protein, dipeptidyl peptidase IV, interleukin-6, tumor necrosis factor-α and fibroblast growth factor-21 in mature adipocytes.
CONCLUSIONS:
These results indicate that ERK activation and consequent downregulation of adipocyte-specific transcription factors are involved in the inhibitory effects of the chalcones cardamonin and Flavokawain B on adipocyte differentiation. Moreover, cardamonin and Flavokawain B are able to modulate secretion of adipokines in mature adipocytes.

Drug Des Devel Ther. 2015 Mar 6;9:1401-17.

In vivo antitumor and antimetastatic effects of flavokawain B in 4T1 breast cancer cell-challenged mice.[Pubmed: 25834398]

Flavokawain B (FKB) is a naturally occurring chalcone that can be isolated through the root extracts of the kava-kava plant (Piper methysticum). It can also be synthesized chemically to increase the yield. Flavokawain B is a promising candidate as a biological agent, as it is reported to be involved in a wide range of biological activities. Furthermore, Flavokawain B was reported to have antitumorigenic effects in several cancer cell lines in vitro. However, the in vivo antitumor effects of Flavokawain B have not been reported on yet.
METHODS AND RESULTS:
As presented in our study, Flavokawain B induced apoptosis in 4T1 tumors in vivo, as evidenced by the terminal deoxynucleotidyl transferase dUTP nick end labeling and hematoxylin and eosin staining of the tumor.Flavokawain B also regulated the immune system by increasing both helper and cytolytic T-cell and natural killer cell populations. In addition, Flavokawain B also enhanced the levels of interleukin 2 and interferon gamma but suppressed interleukin 1B. Apart from that, Flavokawain B was also found to inhibit metastasis, as evaluated by clonogenic assay, bone marrow smearing assay, real-time polymerase chain reaction, Western blot, and proteome profiler analysis.
CONCLUSIONS:
All in all, Flavokawain B may serve as a promising anticancer agent, especially in treating breast cancer.

Cell Commun Signal . 2019 Mar 18;17(1):25.

Flavokawain B targets protein neddylation for enhancing the anti-prostate cancer effect of Bortezomib via Skp2 degradation[Pubmed: 30885218]

Abstract Background: Flavokawain B (FKB) has been identified from kava root extracts as a potent apoptosis inducer for inhibiting the growth of various cancer cell lines, including prostate cancer. However, the molecular targets of FKB in prostate cancer cells remain unknown. Methods: An in vitro NEDD8 Initiation Conjugation Assay was used to evaluate the neddylation inhibitory activity of FKB. Molecular docking and a cellular thermal shift assay were performed to assess the direct interaction between FKB and the NEDD8 activating enzyme (NAE) complex. Protein neddylation, ubiqutination, stability and expression in cells were assessed with immunoprecipitation and Western blotting methods using specific antibodies. Deletion and site specific mutants and siRNAs were used to evaluate deep mechanisms by which FKB induces Skp2 degradation. Cell growth inhibition and apoptosis induction were measured by MTT, ELISA and Western blotting methods. Results: FKB inhibits NEDD8 conjugations to both Cullin1 and Ubc12 in prostate cancer cell lines and Ubc12 neddylation in an in vitro assay. Molecular docking study and a cellular thermal shift assay reveal that FKB interacts with the regulatory subunit (i.e. APP-BP1) of the NAE. In addition, FKB causes Skp2 degradation in an ubiquitin and proteasome dependent manner. Overexpression of dominant-negative cullin1 (1-452), K720R mutant (the neddylation site) Cullin1 or the F-box deleted Skp2 that losses its binding to the Skp1/Cullin1 complex causes the resistance to FKB-induced Skp2 degradation, whereas siRNA knock-down of Cdh1, a known E3 ligase of Skp2 for targeted degradation, didn't attenuate the effect of FKB on Skp2 degradation. These results suggest that degradation of Skp2 by FKB is involved in a functional Cullin1. Furthermore, proteasome inhibitors Bortezomib and MG132 transcriptionally down-regulate the expression of Skp2, and their combinations with FKB result in enhanced inhibitory effects on the growth of prostate cancer cell lines via synergistic down-regulation of Skp2 and up-regulation of p27/Kip1 and p21/WAF1 protein expression. FKB also selectively inhibits the growth of RB deficient cells with high expression of Skp2. Conclusion: These findings provide a rationale for further investigating combination of FKB and Bortezomib for treatment of RB deficient, castration-resistant prostate cancer. Keywords: And prostate cancer; Chalcone; Neddylation; Skp2.

Phytother Res . 2017 Oct;31(10):1607-1613.

The In Vitro and In Vivo Antiangiogenic Effects of Flavokawain B[Pubmed: 28816367]

Abstract Angiogenesis is implicated in the development of a variety of pathological processes, most commonly cancer. It is essential for tumor growth and metastasis, making it an important cancer therapeutic target. Naturally occurring substances have led to the discovery of anticancer agents. Flavokawain B (FKB), a chalcone isolated from the root extracts of kava-kava plant, inhibits proliferation and causes apoptosis in vitro and in vivo of various cancer cell lines. The antimetastatic potential of FKB has also been suggested. In our study, we confirm the antiangiogenic action of FKB in vitro and, for the first time, demonstrate its strong antiangiogenic activity in vivo, using a zebrafish model. Our data show that FKB inhibits human brain endothelial cell (HUVEC) migration and tube formation even at very low and non-toxic concentrations. Moreover, FKB blocks angiogenesis process in zebrafish, with a dramatic reduction of subintestinal vein formation in a dose-dependent manner. Flavokawain B at the concentration of 2.5 μg/mL did not exhibit any toxic effects in zebrafish larvae and caused a markedly or complete obliteration of subintestinal vein formation. Our findings along with previously published data confirm that FKB may form the basis for creating an additional tool in the treatment of cancer and other neovascularization-related diseases. Copyright © 2017 John Wiley & Sons, Ltd. Keywords: HUVEC; angiogenesis; Flavokawain B; kava-kava; zebrafish.

J Nutr Biochem. 2012 Apr;23(4):368-78.

Flavokawain B inhibits growth of human squamous carcinoma cells: Involvement of apoptosis and cell cycle dysregulation in vitro and in vivo.[Pubmed: 21543203 ]

Flavokawain B is a natural chalcone isolated from the rhizomes of Alpenia pricei Hayata.
METHODS AND RESULTS:
In the present study, we have investigated the antiproliferative and apoptotic effect of Flavokawain B (5-20 μg/ml; 17.6-70.4 μM) against human squamous carcinoma (KB) cells. Exposure of KB cells with Flavokawain B resulted in apoptosis, evidenced by loss of cell viability, profound morphological changes, genomic DNA fragmentation and sub-G1 phase accumulation. Apoptosis induced by Flavokawain B results in activation of caspase-9, -3 and -8, cleavage of poly ADP ribose polymerase (PARP) and Bid in KB cells. Flavokawain B also down-regulate Bcl-2 with concomitant increase in Bax level, which resulted in release of cytochrome c. Taken together, the induction of apoptosis by Flavokawain B involved in both death receptor and mitochondrial pathway. We also observed that Flavokawain B caused the G2/M phase arrest that was mediated through reductions in the levels of cyclin A, cyclin B1, Cdc2 and Cdc25C and increases in p21/WAF1, Wee1 and p53 levels. Moreover, Flavokawain B significantly inhibits matrix metalloproteinase-9 and urokinase plasminogen activator expression, whereas tissue inhibitor of matrix metalloproteinase-1 and plasminogen activator inhibitor-1 were increased, which are playing critical role in tumor metastasis. In addition, Flavokawain B treatment significantly inhibited in vivo growth of human KB cell-derived tumor xenografts in nude mice, which is evidenced by augmentation of apoptotic DNA fragmentation, as detected by in situ terminal deoxynucleotidyl transferase-meditated dUTP nick end-labeling staining.
CONCLUSIONS:
The induction of cell cycle arrest and apoptosis by Flavokawain B may provide a pivotal mechanism for its cancer chemopreventive action.

Leuk Lymphoma. 2015 Feb 23:1-10.

Flavokawain B inhibits the growth of acute lymphoblastic leukemia cells via p53 and caspase-dependent mechanisms.[Pubmed: 25641429]

The anti-leukemic effect and the potential molecular mechanisms of action of Flavokawain B on ALL were investigated.
METHODS AND RESULTS:
Flavokawain B was found to significantly inhibit the cellular proliferation of B-ALL and T-ALL cell lines in a dose-dependent manner. It also induced cellular apoptosis by increasing the expression of p53, Bax and Puma, and activating the cleavage of caspase-3 and poly ADP-ribose polymerase (PARP). Furthermore, the enhancement of p53-dependent apoptosis by Flavokawain B could be rescued by pifithrin-α, a pharmacological inhibitor of p53 transcriptional activity. Moreover, the proliferation of leukemia blast cells from 16 patients with ALL was inhibited by Flavokawain B, and tumor growth in xenograft mice was also suppressed by this drug.
CONCLUSIONS:
In conclusion, our results demonstrate the therapeutic potential of Flavokawain B for the treatment of ALL.