No abstract

Bioactivity-guided fractionation of an antimicrobial active extract from twigs of Baccharis retusa C. DC. (Asteraceae) yielded the flavanone 5,4'-dihydroxy-7-methoxy-flavanone (sakuranetin) as responsible for the detected activity. The structure of the bioactive compound was established on the basis of spectroscopic data analysis, including NMR and MS. Additionally, the structure of a new crystal form of sakuranetin was confirmed by X-ray diffratometry. The minimum inhibitory concentrations (MIC) of isolated compound were determined against pathogenic yeast belonging to the genus Candida (six species), Cryptococcus (two species/four serotypes) and S. cerevisiae BY 4742 (S288c background) and ranged from 0.32 to 0.63 μg/μL. Our results showed that sakuranetin, which structure was fully characterized, could be used as a tool for the design of novel and more efficacious antifungal agents.

During a polymorphism screening of hydroxybenzophenone derivatives, a monohydrate pseudopolymorph of (3,4-dihydroxyphenyl)(phenyl)methanone, C(13)H(10)O(3).H(2)O, (I), was obtained. Structural relationships and the role of water in crystal assembly were established on the basis of the known anhydrous form [Cox, Kechagias & Kelly (2008). Acta Cryst. B64, 206-216]. The crystal packing of (I) is stabilized by classical intermolecular O-H...O hydrogen bonds, generating a three-dimensional network.

A dihydrate pseudopolymorph of bis(2,4-dihydroxyphenyl)methanone, C(13)H(10)O(5)·2H(2)O, (I), was obtained during polymorphism screening of hydroxybenzophenone derivatives. This structure, in which the molecule sits on a twofold axis, was compared with the known anhydrous form of (I) [Schlemper (1982). Acta Cryst. B38, 554-559]. The role of water in the crystal assembly was established on the basis of the known monohydrate pseudopolymorph of 3,4-dihydroxybenzophenone [Landre, Souza, Corrêa, Martins & Doriguetto (2010). Acta Cryst. C66, o463-o465].

In the title compound, C14H17NO3, the piperidine ring has a chair conformation and an intra­molecular C—H⋯O inter­action stabilizes the mol­ecular conformation. In the crystal, weak inter­molecular C—H⋯O inter­actions occur.