almecillin
{{Short description|Chemical compound}}
{{Infobox drug
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| image = Penicillin O.svg
| width = 250
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| CAS_number = 87-09-2
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 6246WH0S1O
| ATCvet =
| ATC_prefix = None
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| PubChem = 71365
| DrugBank =
| ChemSpiderID = 64462
| ChEBI = 51207
| ChEMBL = 2105909
| synonyms = [(Allylthio)methyl]penicillin
| chemical_formula =
| C=13 | H=16| N=2 | O=4 | S=2
| SMILES = CC1(C)S[C@@H]2[C@H](NC(=O)CSCC=C)C(=O)N2[C@H]1C(=O)O
| StdInChI = 1S/C13H18N2O4S2/c1-4-5-20-6-7(16)14-8-10(17)15-9(12(18)19)13(2,3)21-11(8)15/h4,8-9,11H,1,5-6H2,2-3H3,(H,14,16)(H,18,19)/t8-,9+,11-/m1/s1
| StdInChIKey = QULKGELYPOJSLP-WCABBAIRSA-N
}}
Almecillin (INN),{{cite web | title = International Nonproprietary Names for Pharmaceutical Substances (INN). Recommended International Nonproprietary Names: List 40 | url =https://www.who.int/medicines/publications/druginformation/innlists/RL40.pdf | publisher = World Health Organization | page = 170}} also known as penicillin O, is a penicillin that is similar in antibiotic action to penicillin G. It is obtained by isolation from Penicillium chrysogenum.{{cite web|title=Penicillin O|url=http://www.ebi.ac.uk/chebi/searchId.do?chebiId=CHEBI:51207|website=ChEBI|publisher=EMBL-EBI|accessdate=11 June 2015}}{{cite journal | vauthors = Levitov MM, Inozemtseva II, Gotovtseva VA, Komokina ZF, Iudina OD, Kleiner GI, Ioffe RI, Nagle AM | title = [Production and basic properties of almecillin (allylmercaptomethylpenicillin)] | language = Russian | journal = Meditsinskaia Promyshlennost' SSSR | volume = 11 | issue = | pages = 12–19 | date = November 1961 | pmid = 14464705 | doi = | url = }}