Galangin

1 Callitris sp. 2 Glycyrrhiza sp.

Galangin is an agonist/antagonist of the arylhydrocarbon receptor, and also shows inhibition of CYP1A1 activity.

In Vitro:Galangin inhibits the catabolic breakdown of DMBA, as measured by thin-layer chromatography, in a dose-dependent manner. Galangin also inhibits the formation of DMBA-DNA adducts, and prevents DMBA-induced inhibition of cell growth. Galangin causes a potent, dose-dependent inhibition of CYP1A1 activity, as measured by ethoxyresorufin-O-deethylase activity, in intact cells and in microsomes isolated from DMBA-treated cells. Analysis of the inhibition kinetics by double-reciprocal plot demonstrates that galangin inhibits CYP1A1 activity in a noncompetitive manner. Galangin causes an increase in the level of CYP1A1 mRNA, indicating that it may be an agonist of the aryl hydrocarbon receptor, but it inhibits the induction of CYP1A1 mRNA by DMBA or by 2,3,5,7-tetrachlorodibenzo-p-dioxin (TCDD). Galangin also inhibits the DMBA- or TCDD-induced transcription of a reporter vector containing the CYP1A1 promoter[1]. Galangin treatment inhibits cell proliferation and induced autophagy (130 μM) and apoptosis (370 μM). In particular, galangin treatment in HepG2 cells causes (1) an accumulation of autophagosomes, (2) elevated levels of microtubule-associated protein light chain 3, and (3) an increased percentage of cells with vacuoles. p53 expression is also increased. The galangin-induced autophagy is attenuated by the inhibition of p53 in HepG2 cells, and overexpression of p53 in Hep3B cells restored the galangin-induced higher percentage of cells with vacuoles to normal level[2].

References:
[1]. Ciolino HP, et al. The flavonoid galangin is an inhibitor of CYP1A1 activity and an agonist/antagonist of the aryl hydrocarbon receptor. Br J Cancer. 1999 Mar;79(9-10):1340-6. [2]. Wen M, et al. Galangin induces autophagy through upregulation of p53 in HepG2 cells. Pharmacology. 2012;89(5-6):247-55.

Anti-obesity effects of galangin, a pancreatic lipase inhibitor in cafeteria diet fed female rats.[Pubmed:23363068]

Pharm Biol. 2013 May;51(5):607-13.

CONTEXT: Alpinia galanga Willd (Zingiberaceae) (AG) is a rhizomatous herb widely cultivated in shady regions of Malaysia, India, Indochina and Indonesia. It is used in southern India as a domestic remedy for the treatment of rheumatoid arthritis, cough, asthma, obesity, diabetes, etc. It was reported to have anti-obesity, hypoglycemic, hypolipidemic and antioxidant properties. OBJECTIVE: A flavonol glycoside, Galangin, was isolated from AG rhizomes. Based on its in vitro pancreatic lipase inhibitory effect, the study was further aimed to clarify whether Galangin prevented obesity induced in female rats by feeding cafeteria diet (CD) for 6 weeks. MATERIALS AND METHODS: The in vitro pancreatic lipase inhibitory effect of Galangin was determined by measuring the release of oleic acid from triolein. For in vivo experiments, female albino rats were fed CD with or without 50 mg/kg Galangin for 6 weeks. Body weight and food intake was measured at weekly intervals. On day 42, serum lipids levels were estimated and then the weight of liver and parametrial adipose tissue (PAT) was determined. The liver lipid peroxidation and triglyceride (TG) content was also estimated. RESULTS: The IC50 value of Galangin for pancreatic lipase was 48.20 mg/mL. Galangin produced inhibition of increased body weight, energy intake and PAT weight induced by CD. In addition, Galangin produced a significant decrease in serum lipids, liver weight, lipid peroxidation and accumulation of hepatic TGs. CONCLUSION: Galangin present in AG rhizomes produces anti-obesity effects in CD-fed rats; this may be mediated through its pancreatic lipase inhibitory, hypolipidemic and antioxidant activities.

Antiviral activity of galangin isolated from the aerial parts of Helichrysum aureonitens.[Pubmed:9174978]

J Ethnopharmacol. 1997 Apr;56(2):165-9.

The in vitro antiviral activity of Galangin (3,5,7-trihydroxyflavone), the major antimicrobial compound isolated from the shoots of Helichrysum aureonitens, was investigated against herpes simplex virus type 1 (HSV-1), coxsackie B virus type 1 (Cox B1), adenovirus type 31 (Ad31) and reovirus. At concentrations ranging from 12-47 micrograms/ml Galangin showed significant antiviral activity against HSV-1 and CoxB1, limited activity against reovirus, and no antiviral activity against Ad31.

Anti-genotoxicity of galangin as a cancer chemopreventive agent candidate.[Pubmed:11344041]

Mutat Res. 2001 May;488(2):135-50.

Flavonoids are polyphenolic compounds that are present in plants. They have been shown to possess a variety of biological activities at non-toxic concentrations in organisms. Galangin, a member of the flavonol class of flavonoid, is present in high concentrations in medicinal plants (e.g. Alpinia officinarum) and propolis, a natural beehive product. Results from in vitro and in vivo studies indicate that Galangin with anti-oxidative and free radical scavenging activities is capable of modulating enzyme activities and suppressing the genotoxicity of chemicals. These activities will be discussed in this review. Based on our review, Galangin may be a promising candidate for cancer chemoprevention.

Galangin attenuates mast cell-mediated allergic inflammation.[Pubmed:23535185]

Food Chem Toxicol. 2013 Jul;57:209-16.

A great number of people are suffering from allergic inflammatory disease such as asthma, atopic dermatitis, and sinusitis. Therefore discovery of drugs for the treatment of these diseases is an important subject in human health. In this study, we investigated anti-allergic inflammatory effect of Galangin and underlying mechanisms of action using in vitro and in vivo models. Galangin inhibited histamine release by the reduction of intracellular calcium in phorbol 12-mystate 13-acetate plus calcium ionophore A23187-stimulated human mast cells (HMC-1). Galangin decreased expression of pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-1beta, and IL-8. The inhibitory effect of Galangin on theses pro-inflammatory cytokines was related with c-Jun N-terminal kinases, and p38 mitogen-activated protein kinase, nuclear factor-kappaB, and caspase-1. Furthermore, Galangin attenuated IgE-mediated passive cutaneous anaphylaxis and the expression of histamine receptor 1 at the inflamed tissue. The inhibitory effects of Galangin were more potent than cromolyn, a known anti-allergic drug. Our results showed that Galangin down-regulates mast cell-derived allergic inflammatory reactions by blocking histamine release and expression of pro-inflammatory cytokines. In light of in vitro and in vivo anti-allergic inflammatory effects, Galangin could be a beneficial anti-allergic inflammatory agent.

The effects of galangin on a mouse model of vitiligo induced by hydroquinone.[Pubmed:24820380]

Phytother Res. 2014 Oct;28(10):1533-8.

Galangin, the main active component of Alpinia officinarum Hance, was tested in a mouse model of vitiligo induced in C57BL/6 mice by the topical application of 2 mL of 2.5% hydroquinone daily to shaved areas (2 x 2 cm) of dorsal skin for 60 days. Thirty days after the final application of hydroquinone, Galangin (0.425, and 4.25 mg/kg) was administered orally for 30 days. The hair colour darkened when it grew back after treatment, and histological analysis showed that the number of melanin-containing hair follicles had increased after treatment with all doses of Galangin groups and 8-methoxypsoralen (8-MOP, the positive control) compared with the untreated vitiligo group (p < 0.05). The number of skin basal layer melanocytes and melanin-containing epidermal cells had also increased significantly with the application of 4.25 mg/kg of Galangin. The concentration of tyrosinase (TYR) in serum was found to have increased, whereas the content of malondialdehyde and the activity of cholinesterase had decreased after treatment with all doses of Galangin and 8-MOP, compared with control (p < 0.05). The expression of TYR protein in treated areas of skin also increased with the application of 4.25 mg/kg Galangin and 8-MOP. In conclusion, the results showed that Galangin was able to improve vitiligo induced by hydroquinone in mice, with the activity related to concentrations of TYR, expression of TYR protein, activity of malondialdehyde and content of cholinesterase. Galangin may therefore be a potential candidate for the treatment of vitiligo, subject to further investigation.

Galangin, a flavonol derived from Rhizoma Alpiniae Officinarum, inhibits acetylcholinesterase activity in vitro.[Pubmed:20452337]

Chem Biol Interact. 2010 Sep 6;187(1-3):246-8.

Acetylcholinesterase (AChE) inhibitors are widely used for the treatment of Alzheimer's disease (AD). Several AChE inhibitors, e.g. rivastigmine, galantamine and huperzine are originating from plants, suggesting that herbs could potentially serve as sources for novel AChE inhibitors. Here, we searched potential AChE inhibitors from flavonoids, a group of naturally occurring compounds in plants or traditional Chinese medicines (TCM). Twenty-one flavonoids, covered different subclasses, were tested for their potential function in inhibiting AChE activity from the brain in vitro. Among all the tested flavonoids, Galangin, a flavonol isolated from Rhizoma Alpiniae Officinarum, the rhizomes of Alpiniae officinarum (Hance.) showed an inhibitory effect on AChE activity with the highest inhibition by over 55% and an IC(50) of 120 microM and an enzyme-flavonoid inhibition constant (K(i)) of 74 microM. The results suggest that flavonoids could be potential candidates for further development of new drugs against AD.

Galangin suppresses HepG2 cell proliferation by activating the TGF-beta receptor/Smad pathway.[Pubmed:25268046]

Toxicology. 2014 Dec 4;326:9-17.

Galangin can suppress hepatocellular carcinoma (HCC) cell proliferation. In this study, we demonstrated that Galangin induced autophagy by activating the transforming growth factor (TGF)-beta receptor/Smad pathway and increased TGF-beta receptor I (RI), TGF-betaRII, Smad1, Smad2, Smad3 and Smad4 levels but decreased Smad6 and Smad7 levels. Autophagy induced by Galangin appears to depend on the TGF-beta receptor/Smad signalling pathway because the down-regulation of Smad4 by siRNA or inhibition of TGF-beta receptor activation by LY2109761 blocked Galangin-induced autophagy. The down-regulation of Beclin1, autophagy-related gene (ATG) 16L, ATG12 and ATG3 restored HepG2 cell proliferation and prevented Galangin-induced apoptosis. Our findings indicate a novel mechanism for Galangin-induced autophagy via activation of the TGF-beta receptor/Smad pathway. The induction of autophagy thus reflects the anti-proliferation effect of Galangin on HCC cells.

Galangin, a novel dietary flavonoid, attenuates metastatic feature via PKC/ERK signaling pathway in TPA-treated liver cancer HepG2 cells.[Pubmed:25698902]

Cancer Cell Int. 2015 Feb 4;15:15.

BACKGROUND: Galangin (3,5,7-trihydroxyflavone) is a flavonoid compound found in high concentration in lesser galangal. The objective of this study was to investigate the ability of Galangin to inhibit 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced the invasion and metastasis of HepG2 liver cancer cells. RESULTS: First, using a cell-matrix adhesion assay, immunofluorescence assay, transwell-chamber invasion/migration assay, and wound healing assay, we observed that Galangin exerted an inhibitory effect on TPA-induced cell adhesion, morphology/actin cytoskeleton arrangement, invasion and migration. Furthermore, the results of gelatin zymography and reverse transcriptase polymerase chain reaction (RT-PCR) assays showed that Galangin reduced the TPA-induced enzyme activity of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) in HepG2 cells; moreover, the messenger RNA level was downregulated. We also observed through a Western blotting assay that Galangin strongly inhibited the TPA-induced protein expressions of protein kinase Calpha (PKCalpha), protein kinase Cdelta (PKCdelta), phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2), the phospho-inhibitor of kappaBalpha (phospho-IkappaBalpha), c-Fos, c-Jun, and nuclear factor kappa B (NF-kappaB). Next, Galangin dose-dependently inhibited the binding ability of NF-kappaB and activator protein 1 (AP-1) to MMP-2/MMP-9 promoters, respectively, resulting in the suppression of MMP-2/MMP-9 enzyme activity. CONCLUSIONS: The results revealed that Galangin effectively inhibited the TPA-induced invasion and migration of HepG2 cells through a protein kinase C/extracellular signal-regulated kinase (PKC/ERK) pathway. Thus, Galangin may have widespread applications in clinical therapy as an anti-metastatic medicament.

[Inhibitory effect of galangin on DNA topoisomerases in lung cancer cells].[Pubmed:26032076]

Zhong Nan Da Xue Xue Bao Yi Xue Ban. 2015 May;40(5):479-85.

OBJECTIVE: To explore the eff ect of Galangin on DNA topoisomerases in lung cancer cells A549 and H46 as well on cell growth. METHODS: The inhibitory effect of Galangin on the growth of A549 and H46 cells was analyzed by MTT method. The effect of Galangin on Topo I activity was detected by the agarose gel electrophoresis method. Furthermore, the interaction between Galangin and Topo I was evaluated by fluorescence spectroscopy. Finally, the eff ect of Galangin on the Topo I structure was discussed. RESULTS: Galangin could induce the apoptosis of A549 and H46 cells (IC50 was 0.221 mmol/L and 0.173 mmol/L, respectively). Agarose gel electrophoresis showed that Galangin exerted significant inhibitory effect on Topo I activity. Fluorescence spectrum analysis showed that Galangin was able to quench Topo I fluorescence, and hydrophobic interaction was the main driving force. Circular dichroism analysis showed that Galangin induced Topo I conformation change and increased the content of alpha-helix, which prevented the formation of active center and in turn led to the decrease in Topo I activity. Molecular simulation results showed that Galangin could bind to the active center of Topo I to form hydrogen bonds with the catalytic site at Arg364 and Asn352. CONCLUSION: Galangin is able to inhibit Topo I activity and to reduce the unwinding rate of single stranded DNNA in tumor cells, which plays an important role in induction of A549 and H46 cell apoptosis.

Vasorelaxant effect of the flavonoid galangin on isolated rat thoracic aorta.[Pubmed:16169019]

Life Sci. 2006 Jan 18;78(8):825-30.

Here we investigated the effect of the flavonoid Galangin in isolated rat thoracic aortic rings. Galangin (0.1-100 microM) induced relaxation in rings pre-contracted with phenylephrine (PE 1 microM) or with KCl (100 mM) or pre-treated with the nitric oxide synthase inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME, 100 microM), the cyclooxygenase inhibitor indomethacin (10 microM) and the adenylate cyclase inhibitor, SQ 22,536 (100 microM). In another set of experiments, rat aortic rings were incubated with Galangin (1-100 microM) and the contractile responses to PE (0.001-3 microM) or to KCl (60 mM) were evaluated. We also evaluated the effect of Galangin (100 microM) on PE (10 microM)-induced contraction in a Ca2+-free medium. Galangin relaxed aortic rings with or without endothelium. Galangin effect was significantly inhibited by L-NAME. Galangin inhibited the contractile response to PE, either in presence or in absence of external calcium, and to KCl. In the end, we also found that Galangin caused nitric oxide (NO) release from aortic rings and abolished the increase in [Ca2+]i triggered by PE or KCl in aortic smooth muscle cells, either in presence and in absence of external Ca2+. Our results suggest that Galangin reduces the contractility of rat aortic rings through an endothelium-dependent mechanism, involving NO, and also through an endothelium-independent mechanism, inhibiting calcium movements through cell membranes.

Anti-inflammatory effects of galangin on lipopolysaccharide-activated macrophages via ERK and NF-kappaB pathway regulation.[Pubmed:25270721]

Immunopharmacol Immunotoxicol. 2014 Dec;36(6):426-32.

Inflammation is the major symptom of the innate immune response to microbial infection. Macrophages, immune response-related cells, play a role in the inflammatory response. Galangin is a member of the flavonols and is found in Alpinia officinarum, galangal root and propolis. Previous studies have demonstrated that Galangin has antioxidant, anticancer, and antineoplastic activities. However, the anti-inflammatory effects of Galangin are still unknown. In this study, we investigated the anti-inflammatory effects of Galangin on RAW 264.7 murine macrophages. Galagin was not cytotoxic to RAW 264.7 cells, and nitric oxide (NO) production induced by lipopolysaccharide (LPS)-stimulated macrophages was significantly decreased by the addition of 50 muM Galangin. Moreover, Galangin treatment reduced mRNA levels of cytokines, including IL-1beta and IL-6, and proinflammatory genes, such as iNOS in LPS-activated macrophages in a dose-dependent manner. Galangin treatment also decreased the protein expression levels of iNOS in activated macrophages. Galangin was found to elicit anti-inflammatory effects by inhibiting ERK and NF-kappaB-p65 phosphorylation. In addition, Galangin-inhibited IL-1beta production in LPS-activated macrophages. These results suggest that Galangin elicits anti-inflammatory effects on LPS-activated macrophages via the inhibition of ERK, NF-kappaB-p65 and proinflammatory gene expression.

Galangin (Norizalpinin) is an agonist/antagonist of the arylhydrocarbon receptor. Galangin (Norizalpinin) also shows inhibition of CYP1A1 activity.

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