title: Final Demonstration of the Co-Identity of Lipiarmycin A3 and Tiacumicin B (Fidaxomicin) through Single Crystal X-ray Analysis.
abstract: Lipiarmycin A3 and tiacumicin B possess the same chemical structure and have been considered identical till recently, when some authors have suggested the possibility of a minor difference between the chemical structures of the two antibiotics. In this work we performed a comparative X-ray analysis of lipiarmycin A3 and tiacumicin B. Although the commercial samples of the aforementioned compounds crystallize into two different crystal systems-evidently due to the different crystallization conditions-their chemical structures are identical. These results confirmed the previous assigned chemical structure of lipiarmycin A3 and its absolute configuration as well as its co-identity with the chemical structure of tiacumicin B, providing the definitive proof that these pharmaceutical compounds are identical in all respects.
authors.affiliation: Consiglio Nazionale delle Ricerche (C.N.R.), Istituto di Chimica del Riconoscimento Molecolare; Via L. Mancinelli 7, I-20131 Milano, Italy. stefano.serra@cnr.it.
authors.forename: Stefano
authors.initials: S
authors.lastname: Serra
authors.affiliation: Dipartimento di Chimica, Materiali ed Ingegneria Chimica del Politecnico, Via Mancinelli 7, I-20131 Milano, Italy. luciana.malpezzi@polimi.it.
authors.forename: Luciana
authors.initials: L
authors.lastname: Malpezzi
authors.affiliation: OLON S.p.A, Strada Rivoltana 6/7, 20090 Rodano, Italy. abedeschi@olonspa.it.
authors.forename: Angelo
authors.initials: A
authors.lastname: Bedeschi
authors.affiliation: Consiglio Nazionale delle Ricerche (C.N.R.), Istituto di Chimica del Riconoscimento Molecolare; Via L. Mancinelli 7, I-20131 Milano, Italy. antibiotics@mdpi.com.
authors.forename: Claudio
authors.initials: C
authors.lastname: Fuganti
authors.affiliation: OLON S.p.A, Strada Rivoltana 6/7, 20090 Rodano, Italy. pfonte@olonspa.it.
authors.forename: Piera
authors.initials: P
authors.lastname: Fonte
keywords: X-ray analysis; actinomycetes; antibiotic; fidaxomicin; lipiarmycin A3; tiacumicin B