WordNet

send a message from one computer to another to check whether it is reachable and active; "ping your machine in the office"
a sharp high-pitched resonant sound (as of a sonar echo or a bullet striking metal)
contact, usually in order to remind of something; "Ill ping my accountant--April 15 is nearing"
hit with a pinging noise; "The bugs pinged the lamp shade"
make a short high-pitched sound; "the bullet pinged when they struck the car"
street name for lysergic acid diethylamide (同)back breaker, battery-acid, dose, dot, Elvis, loony toons, Lucy in the sky with diamonds, pane, superman, window pane, Zen
any of various water-soluble compounds having a sour taste and capable of turning litmus red and reacting with a base to form a salt
having the characteristics of an acid; "an acid reaction"
the 16th letter of the Roman alphabet (同)p

PrepTutorEJDIC

(小銃弾などの)ピュー(ブーン)という音 / ピュー(ブーン)と音がする
酸性の / 酸味のある,すっぱい(sour) / (言葉・態度などが)厳しい,しんらつな / 酸 / すっぱいもの / 《俗》=LSD
parking
phosphorusの化学記号

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/06/19 21:59:33」(JST)

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4-Aminobenzoic acid (also known as para-aminobenzoic acid or PABA because the number 4 carbon in the benzene ring is also known as the para position) is an organic compound with the formula H₂NC₆H₄CO₂H. PABA, a white-grey crystalline substance, is only slightly soluble in water. It consists of a benzene ring substituted with an amino group and a carboxyl group.

Production and occurrence

In industry, PABA is prepared mainly by two routes:

Reduction of 4-nitrobenzoic acid
Hoffman degradation of the monoamide derived from terephthalic acid.^[1]

Food sources of PABA include liver, brewer's yeast (and unfiltered beer), kidney, molasses, mushrooms, and whole grains.^[2]

Biology

Biochemistry

Tetrahydrofolate synthesis pathway

PABA is an intermediate in the synthesis of folate by bacteria, plants, and fungi.^[3] Many bacteria, including those found in the human intestinal tract such as E. coli, generate PABA from chorismate by the combined action of the enzymes 4-amino-4-deoxychorismate synthase and 4-amino-4-deoxychorismate lyase.^[4] Plants produce PABA in their chloroplasts, and store it as a glucose ester (pABA-Glc) in their tissues. Humans lack the enzymes to convert PABA to folate, so require folate from dietary sources such as green leafy vegetables. In humans, PABA is considered nonessential and, although it has been referred to historically as "vitamin B_x", is no longer recognized as a vitamin,^[3] because most people have colon bacteria that generate PABA.

Sulfonamide drugs are structurally similar to PABA, and their antibacterial activity is due to their ability to interfere with the conversion of PABA to folate by the enzyme dihydropteroate synthetase. Thus, bacterial growth is limited through folate deficiency.^[5]

Medical use

The potassium salt is used as a drug against fibrotic skin disorders, such as Peyronie's disease, under the trade name Potaba.^[6] PABA is also occasionally used in pill form by sufferers of irritable bowel syndrome to treat its associated gastrointestinal symptoms, and in nutritional epidemiological studies to assess the completeness of 24-hour urine collection for the determination of urinary sodium, potassium, or nitrogen levels.

Nutritional supplement

Despite the lack of any recognized syndromes of PABA deficiency in humans, except for a few people who lack the bacteria that generate PABA in their colons, many claims of benefit are made by commercial suppliers of PABA as a nutritional supplement. Benefit is claimed for fatigue, irritability, depression, weeping eczema (moist eczema), scleroderma (premature hardening of skin), patchy pigment loss in skin (vitiligo), and premature grey hair.^[7]

Commercial and industrial use

PABA finds use mainly in the biomedical sector. Other uses include its conversion to specialty azo dyes and crosslinking agents.

In the past, PABA was widely used in sunscreens as a UV filter. It is a UVB absorber, meaning it can absorb wavelengths between 290 and 320 nm.^[8] Patented in 1943, PABA was one of the first active ingredients to be used in sunscreen.^[9] The first in vivo studies on mice showed that PABA reduced UV damage. In addition, it was shown to protect against skin tumors in rodents.^[10] Animal and in vitro studies in the early 1980s suggested PABA might increase the risk of cellular UV damage.^[11] On the basis of these studies, as well as problems with allergies and clothing discoloration, PABA fell out of favor as a sunscreen. However, water-insoluble PABA derivatives such as padimate O are currently used in some products.

Safety considerations

PABA is largely nontoxic; the median lethal dose of PABA in dogs (oral) is 2 g/kg.^[1] Allergic reactions to PABA can occur. It is formed in the metabolism of certain ester local anesthetics, and many allergic reactions to local anesthetics are the result of reactions to PABA.^[12]

References

^ ^a ^b Maki, T.; Takeda, K. (2000). "Benzoic Acid and Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH. doi:10.1002/14356007.a03_555.
^ Nutritional Health Resource
^ ^a ^b "Para-aminobenzoic acid". Medline Plus Medical Encyclopedia. United States National Institutes of Health. Retrieved 24 January 2014.
^ Folate Synthesis (Abstract)
^ Brown GM (1962). "The biosynthesis of folic acid. II. Inhibition by sulfonamides". J. Biol. Chem. 237 (2): 536–40. PMID 13873645.
^ "Compound Summary on PubChem". PubChem. National Institute of Health: National Library of Medicine. 2006. Retrieved 2006-04-05.
^ Health Library (Supplements) PABA
^ Melanoma Madness The scientific flap over sunscreens and skin cancer -- Chemical studies, Science News Online, 6/6/98 (accessed 10/1/2009, 2009)
^ F. P.; Mitchnick, M.; Nash, J. F. A Review of Sunscreen Safety and Efficacy Photochem. Photobiol. 1998, 68, 243 <last_page> 256.
^ H.; Thune, P.; Eeg Larsen, T. The inhibiting effect of PABA on photocarcinogenesis Arch. Dermatol. Res. 1990, 282, 38 <last_page> 41
^ Osgood, Pauline J.; Moss, Stephen H.; Davies, David J. G. (1982). "The Sensitization of Near-Ultraviolet Radiation Killing of Mammalian Cells by the Sunscreen Agent Para-aminobenzoic Acid". Journal of Investigative Dermatology 79 (6): 354–7. doi:10.1111/1523-1747.ep12529409. PMID 6982950.
^ Toxicity, Local Anesthetics: eMedicine Emergency Medicine

External links

Para-Aminobenzoic acid MS Spectrum
PABA Cancer link

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. アレルギー性接触皮膚炎の一般的なアレルゲン common allergens in allergic contact dermatitis
2. トリメトプリムスルファメトキサゾール：概要 trimethoprim sulfamethoxazole an overview
3. 日焼け止めおよび太陽光線からの保護法の選択 selection of sunscreen and sun protective measures
4. ハンセン病の治療および予防 treatment and prevention of leprosy
5. フルオロキノロン類、ドキシサイクリン、およびトリメトプリムスルファメトキサゾールに対する肺炎レンサ球菌の耐性 resistance of streptococcus pneumoniae to the fluoroquinolones doxycycline and trimethoprim sulfamethoxazole

English Journal

Farnesyltransferase inhibitors: CAAX mimetics based on different biaryl scaffolds.

Straniero V1, Pallavicini M1, Chiodini G1, Ruggeri P1, Fumagalli L1, Bolchi C1, Corsini A2, Ferri N3, Ricci C2, Valoti E4.
Bioorganic & medicinal chemistry letters.Bioorg Med Chem Lett.2014 Jul 1;24(13):2924-7. doi: 10.1016/j.bmcl.2014.04.078. Epub 2014 Apr 30.
Mimetics of the C-terminal CAAX tetrapeptide of Ras protein were designed as farnesyltransferase (FTase) inhibitors (FTIs) by replacing AA with o-aryl or o-heteroaryl substituted p-hydroxy- or p-aminobenzoic acid, while maintaining the replacement of C with 1,4-benzodioxan-2-ylmethyl or 2-amino-4-th
PMID 24821376

Structural enzymology and inhibition of the bifunctional folate pathway enzyme HPPK-DHPS from the biowarfare agent Francisella tularensis.

Shaw GX1, Li Y, Shi G, Wu Y, Cherry S, Needle D, Zhang D, Tropea JE, Waugh DS, Yan H, Ji X.
The FEBS journal.FEBS J.2014 Jun 27. doi: 10.1111/febs.12896. [Epub ahead of print]
Two valid targets for antibiotic development, 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) and dihydropteroate synthase (DHPS), catalyze consecutive reactions in folate biosynthesis. In Francisella tularensis (Ft), these two activities are contained in a single protein, FtHPPK-DHPS. Wh
PMID 24975935

Characterization of the N-oxygenase AurF from Streptomyces thioletus.

Chanco E1, Choi YS2, Sun N3, Vu M2, Zhao H4.
Bioorganic & medicinal chemistry.Bioorg Med Chem.2014 Jun 12. pii: S0968-0896(14)00434-9. doi: 10.1016/j.bmc.2014.06.002. [Epub ahead of print]
AurF catalyzes the N-oxidation of p-aminobenzoic acid to p-nitrobenzoic acid in the biosynthesis of the antibiotic aureothin. Here we report the characterization of AurF under optimized conditions to explore its potential use in biocatalysis. The pH optimum of the enzyme was established to be 5.5 us
PMID 24973817

Japanese Journal

酸不溶性カルボン酸モノマーを含むヒドロゲル粒子の作製とpH応答性

高分子論文集 72(10), 642-647, 2015
NAID 130005104179

酸不溶性カルボン酸モノマーを含むヒドロゲル粒子の作製とpH応答性

高分子論文集 advpub(0), 2015
NAID 130005093822

Development of a new high-throughput method to determine the composition of ten monosaccharides including 4-O-methyl glucuronic acid from plant cell walls using ultra-performance liquid chromatography

Plant Biotechnology 32(1), 55-63, 2015
NAID 130005061608

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★リンクテーブル★

リンク元	「パラアミノ安息香酸」「aminobenzoic acid」「paraben」
関連記事	「aminobenzoic acid」「P」「ps」「p」

「パラアミノ安息香酸」

4-Aminobenzoic acid
Names
	IUPAC name 4-Aminobenzoic acid
	Other names para-Aminobenzoic acid; p-Aminobenzoic acid; PABA; Vitamin B10; Vitamin Bx; Bacterial vitamin H1
Identifiers
CAS Number	150-13-0
ChEBI	CHEBI:30753
ChEMBL	ChEMBL542
ChemSpider	953
DrugBank	DB02362
Jmol 3D model	Interactive image
KEGG	D02456
PubChem	978
UNII	TL2TJE8QTX
	InChI InChI=1S/C7H7NO2/c8-6-3-1-5(2-4-6)7(9)10/h1-4H,8H2,(H,9,10) Key: ALYNCZNDIQEVRV-UHFFFAOYSA-N ; InChI=1/C7H7NO2/c8-6-3-1-5(2-4-6)7(9)10/h1-4H,8H2,(H,9,10) Key: ALYNCZNDIQEVRV-UHFFFAOYAH ;
	SMILES O=C(O)c1ccc(N)cc1 ;
Properties
Chemical formula	C7H7NO2
Molar mass	137.14 g·mol−1
Appearance	White-grey crystals
Density	1.374 g/mL
Melting point	187 to 189 °C (369 to 372 °F; 460 to 462 K)
Boiling point	340 °C (644 °F; 613 K)
Solubility in water	1 g/170 mL (25 °C); 1 g/90 mL (90 °C)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
	verify (what is ?)
	Infobox references