アカシア(アラビアゴム)

外観

白色～わずかにうすい褐色, 粉末

定義

本品は、Acacia senegal から得られる樹脂である。

溶解性

水に溶け、エタノール(95)にほとんど溶けない。

解説

アフリカ産のマメ科（APG分類：マメ科）アカシア属の植物アラビアゴムノキ（学名はAcacia senegal）、またはその同属や近縁の植物の幹に傷をつけて採取した樹液を日照で乾燥した天然樹脂のこと。アラビアガムともいわれ、かつてアラビア半島を経由して輸出されたのでこの名がある。無色ないし淡黄色のガラス状樹脂である。主成分はアラビン酸とよばれる複雑な多糖であり、L-アラビノース、D-ガラクトース、L-ラムノースおよびD-グルクロン酸からなる。通常、カルシウム、マグネシウムおよびカリウム塩として存在し、加水分解酵素および酸化酵素が含まれている。用途は、水彩絵の具の展色剤（バインダー）、医療用の粘滑剤、錠剤の結合剤、乳化剤、糊(のり)および接着剤、ガムシロップなどである。かつてその水溶液はアラビア糊とよばれて用いられた。現在市販されているアラビックヤマト糊は、ポリビニルアルコール水溶液が主成分である。

解説

アラビアゴムは，アフリカ産のマメ科Acacia senegal，またはその同属植物の枝幹から得た分泌物の乾燥品．往時，アラビアを経て輸出されたのでその名がある．無色ないし淡黄褐色の透明または多少乳濁した球状塊あるいは破片で，砕面はガラス状で光沢があり堅い．またこの樹脂を出す植物を単にこの名で呼ぶこともある。木は高さ 10m足らずの低木状で，2回羽状の複葉をつけ，葉のつけ根に鋭いとげをもつ。花は白色で，径 1cmほどの球状に密集してつく。樹脂の採取は 12月から4月頃にかけて行う。主要な栽培，生産はセネガルを中心にアフリカ西部で行われ，現在でも重要な輸出品となっている。成分となっている糖およびその誘導体は，アラビノース，ガラクトース，グルクロン酸など。こはく色ないし褐色の固形樹脂状のものとして産する。

主成分はアラビン酸79～81％ で，Ca，MgおよびK塩として存在する．アラビン酸はL-アラビノース．D-ガラクトース，L-ラムノースおよびD-グルクロン酸からなる．加水分解酵素および酸化酵素が含まれている．水溶性であり粘滑剤として胃腸カタルなどに対する医療用として用いられるほか，錠剤などの結合剤，乳化剤，あるいは糊料，接着剤などとしても用いられる．森北出版「化学辞典（第2版）

用途

比色分析におけるコロイドの保護、増粘剤、乳化剤、分散剤。

化粧品の成分用途

香料、粘着剤

化学的特性

white to yellow-white powder

使用

As mucilage, excipient for tablets, size, emulsifier, thickener, also in candy, other foods; as colloidal stabilizer. In the manufacture of spray-dried "fixed" flavorsstable, powdered flavors used in packaged dry-mix products (puddings, desserts, cake mixes) where flavor stability and long shelf life are important.

定義

The dried, water-soluble exudate from the stems of Acacia senegal or related species.

調製方法

Acacia is the dried gummy exudate obtained from the stems and branches of Acacia senegal (Linné ) Willdenow or other related species of Acacia (Fam. Leguminosae) that grow mainly in the Sudan and Senegal regions of Africa.
The bark of the tree is incised and the exudate allowed to dry on the bark. The dried exudate is then collected, processed to remove bark, sand, and other particulate matter, and graded. Various acacia grades differing in particle size and other physical properties are thus obtained. A spray-dried powder is also commercially available.

一般的な説明

White powder.

空気と水の反応

Water soluble. Aqueous solution is acid to litmus.

反応プロフィール

Arabic gum reacts with strong oxidizing agents. Arabic gum precipitates out of solution or jellies upon addition of solutions of ferric salts, borax, basic lead acetate, alcohol, sodium silicate, gelatin or ammoniated tincture of guaiac.

健康ハザード

Exposures to gum arabica dust produce a weak allergen reaction. Prolonged periods of dust inhalation may cause allergic respiratory reaction, headache, coughing, dizziness, dyspnea, respiratory symptoms such as asthma, watery nose and eyes, cough, wheezing, nausea, vomiting, dyspnea, and urticaria. Hives, eczema, and swelling may also occur. Ingestion and inhalation of gum acacia is considered non-toxic, but sensitive individuals may develop symptoms of mild toxicity.

火災危険

Flash point data for Arabic gum are not available; however, Arabic gum is probably combustible.

応用例（製薬）

Acacia is mainly used in oral and topical pharmaceutical formulations as a suspending and emulsifying agent, often in combination with tragacanth. It is also used in the preparation of pastilles and lozenges, and as a tablet binder, although if used incautiously it can produce tablets with a prolonged disintegration time. Acacia has also been evaluated as a bioadhesive; and has been used in novel tablet formulations,and modified release tablets.
Acacia is also used in cosmetics, confectionery, food products, and spray-dried flavors.

安全性プロファイル

Very low toxicity by ingestion.Inhalation or ingestion has produced hives, eczema, andangiodema. Experimental reproductive effects. A severeeye irritant. A weak allergen. Mutation data reported.Combustible. When heated to decomposition it emitsacrid

安全性

Acacia is used in cosmetics, foods, and oral and topical pharmaceutical formulations. Although it is generally regarded as an essentially nontoxic material, there have been a limited number of reports of hypersensitivity to acacia after inhalation or ingestion.Severe anaphylactic reactions have occurred following the parenteral administration of acacia and it is now no longer used for this purpose.
The WHO has not set an acceptable daily intake for acacia as a food additive because the levels necessary to achieve a desired effect were not considered to represent a hazard to health.
LD₅₀ (hamster, oral): >18 g/kg
LD₅₀ (mouse, oral): >16 g/kg
LD₅₀ (rabbit, oral): 8.0 g/kg
LD₅₀ (rat, oral): >16 g/kg

貯蔵

Aqueous solutions are subject to bacterial or enzymatic degradation but may be preserved by initially boiling the solution for a short time to inactivate any enzymes present; microwave irradiation can also be used. Aqueous solutions may also be preserved by the addition of an antimicrobial preservative such as 0.1% w/v benzoic acid, 0.1% w/v sodium benzoate, or a mixture of 0.17% w/v methylparaben and 0.03% propylparaben. Powdered acacia should be stored in an airtight container in a cool, dry place.

不和合性

amidopyrine, apomorphine, cresol, ethanol (95%), ferric salts, morphine, phenol, physostigmine, tannins, thymol, and vanillin.
An oxidizing enzyme present in acacia may affect preparations containing easily oxidizable substances. However, the enzyme may be inactivated by heating at 100℃ for a short time.
Many salts reduce the viscosity of aqueous acacia solutions, while trivalent salts may initiate coagulation. Aqueous solutions carry a negative charge and will form coacervates with gelatin and other substances. In the preparation of emulsions, solutions of acacia are incompatible with soaps.

規制状況(Regulatory Status)

GRAS listed. Accepted for use in Europe as a food additive. Included in the FDA Inactive Ingredients Database (oral preparations and buccal or sublingual tablets). Included in the Canadian List of Acceptable Non-medicinal Ingredients. Included in nonparenteral medicines licensed in the UK.