EU/US Properties Organoleptics Cosmetics Suppliers Safety Safety in use Safety references References Other Blenders Uses Occurrence Synonyms Articles Notes

4-decen-3-one, 1-(4-hydroxy-3-methoxyphenyl)-, (4E)-

Supplier Sponsors

CAS Number: 555-66-8Picture of molecule3D/inchi
Nikkaji Web:J6.474B
Beilstein Number:2056098
XlogP3:3.70 (est)
Molecular Weight:276.37588000
Formula:C17 H24 O3
NMR Predictor:Predict (works with chrome, Edge or firefox)
Category:natural substances and extractives
US / EU / FDA / JECFA / FEMA / FLAVIS / Scholar / Patent Information:
Google Scholar:Search
Google Books:Search
Google Scholar: with word "volatile"Search
Google Scholar: with word "flavor"Search
Google Scholar: with word "odor"Search
Google Patents:Search
US Patents:Search
EU Patents:Search
Pubchem Patents:Search
Physical Properties:
Appearance:pale yellow to yellow clear oily liquid (est)
Assay: 92.00 to 100.00
Food Chemicals Codex Listed: No
Boiling Point: 427.00 to 428.00 °C. @ 760.00 mm Hg
Flash Point: 302.00 °F. TCC ( 150.00 °C. )
logP (o/w): 3.789 (est)
Soluble in:
 water, 3.378 mg/L @ 25 °C (est)
Insoluble in:
 paraffin oil
Organoleptic Properties:
Odor and/or flavor descriptions from others (if found).
Cosmetic Information:
None found
Alfa Biotechnology
For experimental / research use only.
6-Shogaol 98%
BOC Sciences
For experimental / research use only.
6-Shogaol >98%
Odor: characteristic
Use: 6-Shogaol is a pungent constituent of ginger similar in chemical structure to gingerol. It has anti-inflammatory properties. lt was reported to have antipyretic and analgesic effects in addition to inhibitory effect on lipoxygenase activity.
Dalton Pharma Services
For experimental / research use only.
6-Shogaol >95%
For experimental / research use only.
Shogaol (HPLC) ≥90%
Santa Cruz Biotechnology
For experimental / research use only.
For experimental / research use only.
analytical standard
Safety Information:
Hazards identification
Classification of the substance or mixture
GHS Classification in accordance with 29 CFR 1910 (OSHA HCS)
None found.
GHS Label elements, including precautionary statements
Hazard statement(s)
None found.
Precautionary statement(s)
None found.
Oral/Parenteral Toxicity:
oral-mouse LD50 687 mg/kg
Journal of Pharmacobio-Dynamics. Vol. 7, Pg. 836, 1984.

intraperitoneal-mouse LD50 109 mg/kg
Journal of Pharmacobio-Dynamics. Vol. 7, Pg. 836, 1984.

intravenous-mouse LD50 50900 ug/kg
Journal of Pharmacobio-Dynamics. Vol. 7, Pg. 836, 1984.

Dermal Toxicity:
Not determined
Inhalation Toxicity:
Not determined
Safety in Use Information:
natural substances and extractives
Recommendation for 6-shogaol usage levels up to:
 not for fragrance use.
Recommendation for 6-shogaol flavor usage levels up to:
 not for flavor use.
Safety References:
EPI System: View
Chemical Carcinogenesis Research Information System:Search
AIDS Citations:Search
Cancer Citations:Search
Toxicology Citations:Search
EPA ACToR:Toxicology Data
EPA Substance Registry Services (SRS):Registry
Laboratory Chemical Safety Summary :5281794
National Institute of Allergy and Infectious Diseases:Data
WGK Germany:3
NIST Chemistry WebBook:Search Inchi
Pubchem (cid):5281794
Pubchem (sid):134976704
Other Information:
(IUPAC):Atomic Weights of the Elements 2011 (pdf)
Videos:The Periodic Table of Videos
tgsc:Atomic Weights use for this web site
(IUPAC):Periodic Table of the Elements
KEGG (GenomeNet):C10494
HMDB (The Human Metabolome Database):HMDB31463
Typical G.C.
VCF-Online:VCF Volatile Compounds in Food
Potential Blenders and core components note
None Found
Potential Uses:
None Found
Occurrence (nature, food, other):note
 ginger oil
Search Trop Picture
 ginger rhizome
Search Trop Picture
 ginger rhizome oil
Search Trop Picture
 ginger root
Search Trop Picture
 ginger root oil
Search Trop Picture
 ginger root oil CO2 extract @ 12.22%
Data GC Search Trop Picture
 ginger root oil CO2 extract australia @ 0.31%
Data GC Search Trop Picture
 grains of paradise
Search Trop Picture
4-decen-3-one, 1-(4-hydroxy-3-methoxyphenyl)-, (4E)-


PubMed:Cytotoxic activity against small cell lung cancer cell line and chromatographic fingerprinting of six isolated compounds from the ethanolic extract of Benjakul.
PubMed:Anti-inflammatory activity of grains of paradise (Aframomum melegueta Schum) extract.
PubMed:Modulation of cytochrome P450 metabolism and transport across intestinal epithelial barrier by ginger biophenolics.
PubMed:Ginger compound [6]-shogaol and its cysteine-conjugated metabolite (M2) activate Nrf2 in colon epithelial cells in vitro and in vivo.
PubMed:Anthelmintic constituents from ginger (Zingiber officinale) against Hymenolepis nana.
PubMed:[6]-Shogaol inhibits α-MSH-induced melanogenesis through the acceleration of ERK and PI3K/Akt-mediated MITF degradation.
PubMed:Influence of side chain structure changes on antioxidant potency of the [6]-gingerol related compounds.
PubMed:6-Shogaol exerts anti-proliferative and pro-apoptotic effects through the modulation of STAT3 and MAPKs signaling pathways.
PubMed:6-shogaol, a major compound in ginger, induces aryl hydrocarbon receptor-mediated transcriptional activity and gene expression.
PubMed:6-Shogaol, an active constituent of ginger, attenuates neuroinflammation and cognitive deficits in animal models of dementia.
PubMed:Cysteine-conjugated metabolites of ginger components, shogaols, induce apoptosis through oxidative stress-mediated p53 pathway in human colon cancer cells.
PubMed:Synthesis and quorum sensing inhibitory activity of key phenolic compounds of ginger and their derivatives.
PubMed:Ginger and its pungent constituents non-competitively inhibit serotonin currents on visceral afferent neurons.
PubMed:6-Shogaol from dried ginger inhibits growth of prostate cancer cells both in vitro and in vivo through inhibition of STAT3 and NF-κB signaling.
PubMed:Variations in the contents of gingerols and chromatographic fingerprints of ginger root extracts prepared by different preparation methods.
PubMed:Role of 6-shogaol in tert -butyl hydroperoxide-induced apoptosis of HepG2 cells.
PubMed:Reply to Comments on the article "[6]-Shogaol induced calcium signal in rat insulinoma cells".
PubMed:Comments on the article "[6]-Shogaol induced calcium signal in rat insulinoma cells".
PubMed:Multitargeted effects of hangeshashinto for treatment of chemotherapy-induced oral mucositis on inducible prostaglandin E2 production in human oral keratinocytes.
PubMed:Induction of lung cancer cell apoptosis through a p53 pathway by [6]-shogaol and its cysteine-conjugated metabolite M2.
PubMed:Enterohepatic recirculation of bioactive ginger phytochemicals is associated with enhanced tumor growth-inhibitory activity of ginger extract.
PubMed:Antitumor activity of gemcitabine can be potentiated in pancreatic cancer through modulation of TLR4/NF-κB signaling by 6-shogaol.
PubMed:[6]-shogaol induces Ca²⁺ signals by activating the TRPV1 channels in the rat insulinoma INS-1E cells.
PubMed:Inhibition of human low-density lipoprotein oxidation in vitro by ginger extracts.
PubMed:Preventive Effect of TU-100 on a Type-2 Model of Colitis in Mice: Possible Involvement of Enhancing Adrenomedullin in Intestinal Epithelial Cells.
PubMed:[6]-shogaol inhibits growth and induces apoptosis of non-small cell lung cancer cells by directly regulating Akt1/2.
PubMed:6-Shogaol induces apoptosis in human leukemia cells through a process involving caspase-mediated cleavage of eIF2α.
PubMed:6-Shogaol inhibits chondrocytes' innate immune responses and cathepsin-K activity.
PubMed:Active components of ginger potentiate β-agonist-induced relaxation of airway smooth muscle by modulating cytoskeletal regulatory proteins.
PubMed:A novel shogaol analog suppresses cancer cell invasion and inflammation, and displays cytoprotective effects through modulation of NF-κB and Nrf2-Keap1 signaling pathways.
PubMed:6-Shogaol, an active compound of ginger, protects dopaminergic neurons in Parkinson's disease models via anti-neuroinflammation.
PubMed:Cysteine-conjugated metabolite of ginger component [6]-shogaol serves as a carrier of [6]-shogaol in cancer cells and in mice.
PubMed:6-Shogaol inhibits breast and colon cancer cell proliferation through activation of peroxisomal proliferator activated receptor γ (PPARγ).
PubMed:[6]-Shogaol inhibits the production of proinflammatory cytokines via regulation of NF-κB and phosphorylation of JNK in HMC-1 cells.
PubMed:Glutathione conjugation attenuates biological activities of 6-dehydroshogaol from ginger.
PubMed:Population pharmacokinetic analysis of daikenchuto, a traditional Japanese medicine (Kampo) in Japanese and US health volunteers.
PubMed:6-Shogaol Protects against Oxidized LDL-Induced Endothelial Injruries by Inhibiting Oxidized LDL-Evoked LOX-1 Signaling.
PubMed:Ginger and its pungent constituents non-competitively inhibit activation of human recombinant and native 5-HT3 receptors of enteric neurons.
PubMed:Highly efficient sample preparation and quantification of constituents from traditional Chinese herbal medicines using matrix solid-phase dispersion extraction and UPLC-MS/MS.
PubMed:Role of the Toll Like receptor (TLR) radical cycle in chronic inflammation: possible treatments targeting the TLR4 pathway.
PubMed:A new phenanthrene derivative and two diarylheptanoids from the roots of Brassica rapa ssp. campestris inhibit the growth of cancer cell lines and LDL-oxidation.
PubMed:Invadopodia-associated proteins blockade as a novel mechanism for 6-shogaol and pterostilbene to reduce breast cancer cell motility and invasion.
PubMed:[6]-shogaol attenuates neuronal apoptosis in hydrogen peroxide-treated astrocytes through the up-regulation of neurotrophic factors.
PubMed:Metabolites of ginger component [6]-shogaol remain bioactive in cancer cells and have low toxicity in normal cells: chemical synthesis and biological evaluation.
PubMed:Metabolism of ginger component [6]-shogaol in liver microsomes from mouse, rat, dog, monkey, and human.
PubMed:Characterization of thiol-conjugated metabolites of ginger components shogaols in mouse and human urine and modulation of the glutathione levels in cancer cells by [6]-shogaol.
PubMed:Grains of paradise (Aframomum melegueta) extract activates brown adipose tissue and increases whole-body energy expenditure in men.
PubMed:Epithelial transient receptor potential ankyrin 1 (TRPA1)-dependent adrenomedullin upregulates blood flow in rat small intestine.
PubMed:The Cytotoxicity Mechanism of 6-Shogaol-Treated HeLa Human Cervical Cancer Cells Revealed by Label-Free Shotgun Proteomics and Bioinformatics Analysis.
PubMed:Simultaneous determination of gingerols and shogaol using capillary liquid chromatography and its application in discrimination of three ginger varieties from Indonesia.
PubMed:[Effect of Zingiber offiicinale and Aconitum cainichaeli before and after compatibility on contents of four gingerols].
PubMed:[6]-Shogaol inhibits melanogenesis in B16 mouse melanoma cells through activation of the ERK pathway.
PubMed:Effects of ginger and its constituents on airway smooth muscle relaxation and calcium regulation.
PubMed:Identification of phase II metabolites of thiol-conjugated [6]-shogaol in mouse urine using high-performance liquid chromatography tandem mass spectrometry.
PubMed:In vitro antioxidant and anti-inflammatory activities of 1-dehydro-[6]-gingerdione, 6-shogaol, 6-dehydroshogaol and hexahydrocurcumin.
PubMed:Anti-platelet aggregation and vasorelaxing effects of the constituents of the rhizomes of Zingiber officinale.
PubMed:6-Shogaol induces apoptosis in human hepatocellular carcinoma cells and exhibits anti-tumor activity in vivo through endoplasmic reticulum stress.
PubMed:6-shogaol-rich extract from ginger up-regulates the antioxidant defense systems in cells and mice.
PubMed:Molecular mechanism inhibiting human hepatocarcinoma cell invasion by 6-shogaol and 6-gingerol.
PubMed:Optimization of Extraction Conditions for the 6-Shogaol-rich Extract from Ginger (Zingiber officinale Roscoe).
PubMed:Zingiber officinale (ginger) as an anti-emetic in cancer chemotherapy: a review.
PubMed:Anti-Candida and radical scavenging activities of essential oils and oleoresins of Zingiber officinale Roscoe and essential oils of other plants belonging to the family Zingiberaceae.
PubMed:6-Shogaol, a ginger product, modulates neuroinflammation: a new approach to neuroprotection.
PubMed:Effects of [6]-shogaol on cholinergic signaling in HT22 cells following neuronal damage induced by hydrogen peroxide.
PubMed:Phenylpropanoid ester from Zingiber officinale and their inhibitory effects on the production of nitric oxide.
PubMed:[Phenolic and amide constituents from Lycianthes marlipoensis].
PubMed:Cytotoxic, cytoprotective and antioxidant effects of isolated phenolic compounds from fresh ginger.
PubMed:Metabolism of [6]-shogaol in mice and in cancer cells.
PubMed:Protection by [6]-shogaol against lipopolysaccharide-induced toxicity in murine astrocytes is related to production of brain-derived neurotrophic factor.
PubMed:Anti-inflammatory effects of [6]-shogaol: potential roles of HDAC inhibition and HSP70 induction.
PubMed:Pharmacokinetics of daikenchuto, a traditional Japanese medicine (kampo) after single oral administration to healthy Japanese volunteers.
PubMed:Antiinflammatory effects of ginger and some of its components in human bronchial epithelial (BEAS-2B) cells.
PubMed:Examination of the pharmacokinetics of active ingredients of ginger in humans.
PubMed:Shogaols at proapoptotic concentrations induce G(2)/M arrest and aberrant mitotic cell death associated with tubulin aggregation.
PubMed:Chemopreventive effects of dietary phytochemicals against cancer invasion and metastasis: phenolic acids, monophenol, polyphenol, and their derivatives.
PubMed:Ginger suppresses phthalate ester-induced airway remodeling.
PubMed:Protective Effects of Ginger against Aspirin-Induced Gastric Ulcers in Rats.
PubMed:Effects of ginger constituents on the gastrointestinal tract: role of cholinergic M3 and serotonergic 5-HT3 and 5-HT4 receptors.
PubMed:Preparation of the monomers of gingerols and 6-shogaol by flash high speed counter-current chromatography.
PubMed:Quantitation of 6-, 8- and 10-Gingerols and 6-Shogaol in Human Plasma by High-Performance Liquid Chromatography with Electrochemical Detection.
PubMed:6-Shogaol, an active constituent of ginger, inhibits breast cancer cell invasion by reducing matrix metalloproteinase-9 expression via blockade of nuclear factor-κB activation.
PubMed:Profiling of the compounds absorbed in human plasma and urine after oral administration of a traditional Japanese (kampo) medicine, daikenchuto.
PubMed:Effect of [6]-shogaol on cytosolic Ca2+ levels and proliferation in human oral cancer cells (OC2).
PubMed:Zingiber officinale (ginger) compounds have tetracycline-resistance modifying effects against clinical extensively drug-resistant Acinetobacter baumannii.
PubMed:Larvicidal constituents of Zingiber officinale (ginger) against Anisakis simplex.
PubMed:Anti-invasion effects of 6-shogaol and 6-gingerol, two active components in ginger, on human hepatocarcinoma cells.
PubMed:[Chemical constituents of rhizomes of Zingiber officinale].
PubMed:6-Shogaol is more effective than 6-gingerol and curcumin in inhibiting 12-O-tetradecanoylphorbol 13-acetate-induced tumor promotion in mice.
PubMed:Pharmacokinetics of [6]-shogaol, a pungent ingredient of Zingiber officinale Roscoe (Part I).
PubMed:Anti-inflammatory properties of red ginger (Zingiber officinale var. Rubra) extract and suppression of nitric oxide production by its constituents.
PubMed:Six-shogaol inhibits production of tumour necrosis factor alpha, interleukin-1 beta and nitric oxide from lipopolysaccharide-stimulated RAW 264.7 macrophages.
PubMed:Larvicidal activities of ginger (Zingiber officinale) against Angiostrongylus cantonensis.
PubMed:Increased growth inhibitory effects on human cancer cells and anti-inflammatory potency of shogaols from Zingiber officinale relative to gingerols.
PubMed:Comparative antioxidant and anti-inflammatory effects of [6]-gingerol, [8]-gingerol, [10]-gingerol and [6]-shogaol.
PubMed:6-Shogaol inhibits monosodium urate crystal-induced inflammation--an in vivo and in vitro study.
PubMed:Identification and quantification of gingerols and related compounds in ginger dietary supplements using high-performance liquid chromatography-tandem mass spectrometry.
PubMed:6-Shogaol, an active constituent of dietary ginger, induces autophagy by inhibiting the AKT/mTOR pathway in human non-small cell lung cancer A549 cells.
PubMed:Compounds from Sichuan and Melegueta peppers activate, covalently and non-covalently, TRPA1 and TRPV1 channels.
PubMed:TBK1-targeted suppression of TRIF-dependent signaling pathway of Toll-like receptors by 6-shogaol, an active component of ginger.
PubMed:Inhibition of homodimerization of toll-like receptor 4 by 6-shogaol.
PubMed:[Analysis of volatile and non-volatile compositions in ginger oleoresin by gas chromatography-mass spectrometry].
PubMed:Simultaneous determination of 6-gingerol, 8-gingerol, 10-gingerol and 6-shogaol in rat plasma by liquid chromatography-mass spectrometry: Application to pharmacokinetics.
PubMed:Modulation of macrophage functions by compounds isolated from Zingiber officinale.
PubMed:Specific reaction of alpha,beta-unsaturated carbonyl compounds such as 6-shogaol with sulfhydryl groups in tubulin leading to microtubule damage.
PubMed:Goshuyuto, a traditional Japanese medicine for migraine, inhibits platelet aggregation in guinea-pig whole blood.
PubMed:Analysis of anti-platelet aggregation components of Rhizoma Zingiberis using chicken thrombocyte extract and high performance liquid chromatography.
PubMed:Pharmacokinetics of 6-gingerol, 8-gingerol, 10-gingerol, and 6-shogaol and conjugate metabolites in healthy human subjects.
PubMed:6-Shogaol suppressed lipopolysaccharide-induced up-expression of iNOS and COX-2 in murine macrophages.
PubMed:[RP-HPLC fingerprint evaluating different ginger juice as processing material].
PubMed:6-Shogaol and 6-gingerol, the pungent of ginger, inhibit TNF-alpha mediated downregulation of adiponectin expression via different mechanisms in 3T3-L1 adipocytes.
PubMed:Changes in the contents of oleoresin and pungent bioactive principles of Jamaican ginger (Zingiber officinale Roscoe.) during maturation.
PubMed:Cytotoxic components from the dried rhizomes of Zingiber officinale Roscoe.
PubMed:6-Shogaol induces apoptosis in human colorectal carcinoma cells via ROS production, caspase activation, and GADD 153 expression.
PubMed:Ginger inhibits cell growth and modulates angiogenic factors in ovarian cancer cells.
PubMed:Liquid chromatographic determination of 6-, 8-, 10-gingerol, and 6-shogaol in ginger (Zingiber officinale) as the raw herb and dried aqueous extract.
PubMed:Stability of [6]-gingerol and [6]-shogaol in simulated gastric and intestinal fluids.
PubMed:Ginger ingredients reduce viability of gastric cancer cells via distinct mechanisms.
PubMed:High-performance liquid chromatographic analysis of 6-gingerol, 8-gingerol, 10-gingerol, and 6-shogaol in ginger-containing dietary supplements, spices, teas, and beverages.
PubMed:6-shogaol (alkanone from ginger) induces apoptotic cell death of human hepatoma p53 mutant Mahlavu subline via an oxidative stress-mediated caspase-dependent mechanism.
PubMed:A nonpungent component of steamed ginger--[10]-shogaol--increases adrenaline secretion via the activation of TRPV1.
PubMed:6-Shogaol reduced chronic inflammatory response in the knees of rats treated with complete Freund's adjuvant.
PubMed:6-Shogaol, a natural product, reduces cell death and restores motor function in rat spinal cord injury.
PubMed:Species differences in the prokinetic effects of ginger.
PubMed:Variation in concentration and labeling of ginger root dietary supplements.
PubMed:The effect of extracts from ginger rhizome on inflammatory mediator production.
PubMed:Mode of action of gingerols and shogaols on 5-HT3 receptors: binding studies, cation uptake by the receptor channel and contraction of isolated guinea-pig ileum.
PubMed:Cardiovascular effects of ginger aqueous extract and its phenolic constituents are mediated through multiple pathways.
PubMed:5-HT3 receptor blocking activity of arylalkanes isolated from the rhizome of Zingiber officinale.
PubMed:Commercially processed dry ginger (Zingiber officinale): composition and effects on LPS-stimulated PGE2 production.
PubMed:Separation and isolation methods for analysis of the active principles of Sho-saiko-to (SST) oriental medicine.
PubMed:Component of Zingiber officinale that improves the enhancement of small intestinal transport.
PubMed:The herbal medicine Dai-kenchu-to and one of its active components [6]-shogaol increase intestinal blood flow in rats.
PubMed:The stability of gingerol and shogaol in aqueous solutions.
PubMed:Stomachic principles in ginger. III. An anti-ulcer principle, 6-gingesulfonic acid, and three monoacyldigalactosylglycerols, gingerglycolipids A, B, and C, from Zingiberis Rhizoma originating in Taiwan.
PubMed:Capsaicin-like effect of (6)-shogaol on substance P-containing primary afferents of rats: a possible mechanism of its analgesic action.
PubMed:[Stomachic principles in ginger. II. Pungent and anti-ulcer effects of low polar constituents isolated from ginger, the dried rhizoma of Zingiber officinale Roscoe cultivated in Taiwan. The absolute stereostructure of a new diarylheptanoid].
PubMed:6-Gingesulfonic acid, a new anti-ulcer principle, and gingerglycolipids A, B, and C, three new monoacyldigalactosylglycerols, from zingiberis rhizoma originating in Taiwan.
PubMed:[The study of Chinese herbal medicinal prescription with enzyme inhibitory activity. V. The study of hange-shashin-to, kanzo-shashin-to, shokyo-shashin-to with adenosine 3',5'-cyclic monophosphate phosphodiesterase].
PubMed:[The effect of ginger on serotonin induced hypothermia and diarrhea].
PubMed:Gastrointestinal motility enhancing effect of ginger and its active constituents.
PubMed:Lethal efficacy of extract from Zingiber officinale (traditional Chinese medicine) or [6]-shogaol and [6]-gingerol in Anisakis larvae in vitro.
PubMed:Reversed effects between crude and processed ginger extracts on PGF2 alpha-induced contraction in mouse mesenteric veins.
PubMed:Chemical structural requirement in gingerol derivatives for potentiation of prostaglandin F2 alpha-induced contraction in isolated mesenteric veins of mice.
PubMed:[Pharmacological studies on ginger. V. Pharmacological comparison between (6)-shogaol and capsaicin].
PubMed:Pharmacological studies on ginger. II. Pressor action of (6)-shogaol in anesthetized rats, or hindquarters, tail and mesenteric vascular beds of rats.
PubMed:[Pharmacological studies on ginger. IV. Effect of (6)-shogaol on the arachidonic cascade].
PubMed:Pharmacological studies on ginger. III. Effect of the spinal destruction on (6)-shogaol-induced pressor response in rats.
PubMed:Pharmacological studies on ginger. I. Pharmacological actions of pungent constitutents, (6)-gingerol and (6)-shogaol.
PubMed:The active part of the [6]-gingerol molecule in mutagenesis.
from ginger, zingiber officinale; less mutagenic than gingerol. Constit. of grains of paradise (Amomum melegueta) and Zingiber officinale (ginger) [DFC] Shogaol, also known as (6)-shogaol, is a pungent constituent of ginger similar in chemical structure to gingerol. Like zingerone, it is produced when ginger is dried or cooked. Constit. of ginger (Zingiber officinale) [DFC]
Please share your Comments.
Email Address:
Top of Page Home
Copyright © 1980-2021 The Good Scents Company (tgsc) ™ Disclaimer Privacy Policy