ペクチン

外観

白色～うすい褐色, 粉末

定義

本品は、主にリンゴなどの植物体より抽出されるコロイド状多糖類で、主としてD-ガラクトウロン酸及びそのメチルエステルである。

溶解性

水に溶け、エタノール及びアセトンにほとんど溶けない。

解説

ペクチン，ポリ(α1→4)-D-ガラクツロン酸の一部のカルボキシル基が，メチルエステル化している多糖の総称．高等植物の葉，茎，根，果実などに多く含まれ，これらの細胞の結合物質として，おもに中層に存在するが，一部は細胞膜や果汁にもある．かんきつ類の果実の皮(30％)，てん菜パルプ(25％)などにとくに多い．メチル化度は，一般に9.5～11％ であるが，3.5～50％ と多様性がある．また，少量のアセチル基をもつものもある．メチル化度の少ないものはペクチン酸とよばれる．ペクチン質を酸の希薄水溶液で加熱抽出し，抽出液を濃縮して有機溶媒で沈殿させてつくる．帯黄色の無定形粉末，またはシロップ状で，分子量は6万～8万．[α]_D約＋250°．70 ℃ 以上の熱湯に可溶，有機溶媒や冷水に不溶．水に溶けると粘性の高いコロイド溶液となる．アルカリと塩をつくり．とくに Ca2＋ とは硬いゲルをつくる．ジャム，マーマレード，ゼリーなど加工食品の天然安定増粘剤，微生物用培地，薬用消化調整剤などに用いられる．

化粧品の成分用途

結合剤、口腔衛生剤、親水性増粘剤、乳化安定剤

効能

懸濁剤, 保護剤

存在

ペクチン質は主として植物の細胞壁の中層を形成する物質で、細胞どうしを接着する糊(のり)の役目をしている。高等植物の細胞間に存在するペクチンは3種類の多糖類の混合物で、主成分のペクチン酸にアラビノース単位が分鎖状になったアラバンとガラクトースの重合体であるガラクタンが混在している。ガラクツロン酸がグリコシド結合で200以上重合したものをペクチン酸といい、ペクチン酸の一部がメチルエステル化したものがペクチンであり、ペクチンがさらにカルシウムやマグネシウムと分子間結合をして不溶性となったものがプロトペクチンである。ペクチン質は果実の成熟に伴って変化し、熟成の過程で重要な役割を果たしている。果実の成熟する初期にはプロトペクチン、ペクチン酸塩だけが蓄積しているが、成熟とともに水溶性のペクチンに変化し、ペクチン酸塩は消失して果実は柔らかくなってくる。ペクチンは熟した果実に大量に存在するので、リンゴやミカン類の果実をすりつぶしたものを酸性の水で熱抽出して得られる。

化学的特性

Pectin occurs as a coarse or fine, yellowish-white, odorless powder that has a mucilaginous taste.

天然物の起源

Pectin is found in the cell walls of all plants.

使用

In the preparation of jellies and similar food products: Owens et al., "Factors Influencing Gelation with Pectin" in Natural Plant Hydrocolloids, Advances in Chemistry Series (ACS, Washington, 1954) pp 10-15.

調製方法

Pectin is obtained from the diluted acid extract from the inner portion of the rind of citrus fruits or from apple pomace.

世界保健機関（WHO）

Pectin is a purified carbohydrate product isolated from the rinds of citrus fruits or green apples. Its major constituent is polygalacteronic acid, and it is almost completely digested and absorbed in the intestine. Pectin became popular as a simple remedy for diarrhoea in the early 1900s. It does not affect the frequency of stool or stool weight. Use of such products diverts attention away from more important aspects of treatment, such as rehydration, proper nutrition and in the case of cholera and dysentery, appropriate antibiotics.

一般的な説明

Pectin is a polysaccharide is rich in galacturonic acid and possesses a complex structure and function.

応用例（製薬）

present in multi-ingredient preparations for the management of diarrhea, constipation, and obesity;it has also been used as an emulsion stabilizer.
Experimentally, pectin has been used in gel formulations for the oral sustained delivery of ambroxol.Pectin gel beads have been shown to be an effective medium for controlling the release of a drug within the gastrointestinal (GI) tract.It has also been used in a colon-biodegradable pectin matrix with a pH-sensitive polymeric coating, which retards the onset of drug release, overcoming the problems of pectin solubility in the upper GI tract.Amidated pectin matrix patches have been investigated for the transdermal delivery of chloroquine,and gelling pectin formulations for the oral sustained delivery of paracetamol have been investigated in situ.Pectin-based matrices with varying degrees of esterification have been evaluated as oral controlled-release tablets. Lowmethoxy pectins were shown to have a release rate more sensitive to the calcium content of the formulation.Pectins have been used as a component in the preparation of mixed polymer microsphere systems with the intention of producing controlled drug release.

农业用途

Pectin is a high molecular weight polyuronide. It is related to the carbohydrate family and is present in fruits and berries.
Pectin occurs in varying amounts in fruits and plants. It contains carbon, hydrogen and oxygen, and on hydrolysis, yields glycosides and galachronic acid. It can form a gel when it absorbs water.
Commercially, the primary source of the commonly used pectin is lemon and lime peel; other citrus fruits l i e orange and grapefruit may also be used. Pectin is widely used in the food industry, principally in gel preparation.
Pectin is also used in making drugs, protective colloids, emulsifying agents, etc.

安全性プロファイル

Low toxicity by subcutaneous route. When heated to decomposition it emits acrid smoke and irritating fumes.

安全性

Pectin is used in oral pharmaceutical formulations and food products, and is generally regarded as an essentially nontoxic and nonirritant material.
Low toxicity by the subcutaneous route has been reported.
LD₅₀ (mouse, SC): 6.4 g/kg

貯蔵

Pectin is a nonreactive and stable material; it should be stored in a cool, dry place.

純化方法

Dissolve the pectin in hot water to give a 1% solution, then cool, and make it to about 0.05M in HCl by addition of conc HCl, and precipitate it by pouring it slowly, with vigorous stirring into two volumes of 95% EtOH. After standing for several hours, the pectin is filtered through a nylon cloth, then redispersed in 95% EtOH and stood overnight. The precipitate is filtered off, washed with EtOH/Et2O, then Et2O and dried in air. [Rees & Walsh Angew Chem, Int Edn 16 214 1977, Rees Adv Carbohydr Chem 24 267 1969.]

規制状況(Regulatory Status)

GRAS listed. Accepted for use as a food additive in Europe. Included in the FDA Inactive Ingredients Database (dental paste; oral powders; topical pastes). Included in the Canadian List of Acceptable Non-medicinal Ingredients. Included in nonparenteral medicines licensed in the UK.