Considering the relevance of natural products to the development of new drugs, this study focuses on the species Sida rhombifolia (L.), Malvaceae, widely used as a traditional remedy in several countries. The species is used to treat several diseases such as fevers, skin diseases, stomach pain, diarrhea, gum infection, conjunctivitis, urinary infections and inflammation. Many researchers around the word have investigated its pharmacological potential, and many uses have been confirmed. In spite of that, the phytochemical composition of its extracts is still poorly investigated. This research aims to make advances on the understanding of the constituents of S. rhombifolia identifying its alkaloidal compounds using ultra-high performance liquid chromatography coupled to mass spectrometry (UPLC-QTOF-MS/MS). By analyzing its alkaloidal fraction, it was possible to identify: 11-cryptolepine carboxylic acid (1), cryptolepine (2), quindoline (3), 11 methoxyquidoline (4), quindolinone (5), cryptolepinone (6), and 11-quindoline methyl ester (7). The alkaloids 1 and 7 are being reported for the first time from Sida genus. Based on the antimicrobial potential of cryptolepinone-type alkaloids, we prepared by semi-synthesis two cryptolepinone derivatives: 10-methylcryptolepinone (8) and the unreported compound 10-ethylcryptolepinone (9). Both derivatives were tested against fungal and bacterial strains and 10-methylcryptolepinone (8) showed strong activity against Cryptococcus neoformans, Candida albicans, Candida tropicalis, Aspergillus fumigatus and Aspergillus flavus.

Previous researches showed that fatty acids analysis might be a useful tool to support the taxonomic investigation. In this approach the fatty acids content of ten Malvoideae species was analyzed and its chemotaxonomic significance has been investigated. The aerial parts of the species were collected in the Northeast of Brazil and their fatty acid methyl esters were analyzed by gas chromatography with flame ionization detector. The chemometric analysis consisted of principal component analysis (PCA) and hierarchical clustering analysis (HCA) with the euclidean distance between the samples given by the Ward.D2 algorithm. This is the first report of fatty acids from Wissadula peripocifolia, Herissantia crispa, Bakeridesia pickelii, Sidastrum micranthum, Pavonia cancellata and Pavonia malacophylla. The results showed the predominance of palmitic (C16:0), oleic (C18:1) and linoleic (C18:2) acids in the studied species. By the PCA and HCA analysis, the fatty acid composition was able to distinguish the species Herissantia crispa and Pavonia malacophylla. Our findings showed a chemotaxonomic proximity among species from different genera reflecting the taxonomic and phylogenetic closeness previously demonstrated by molecular investigations on Malvoidae species. Furthermore, our results demonstrated that the fatty acid analysis may be an interesting tool to support the taxonomic investigations on Malvoideae species.

A phytochemical investigation from aerial parts of Casearia arborea (Rich.) Urb. (Salicaceae) led to isolation and identification of: sitosterol, 4-en-stigmast-3-one, 13-hydroxy-trans-ent-cleroda-3,14-diene,3-hydroxy-2-oxo-trans-ent-cleroda-3,14-diene (kolavelone), a mixture of 13-hydroxy-trans-ent-cleroda-3,14-diene and an ester ethyl hexadecanoate, kaempferol-3-O-a-L-arabinofuranoside and 4',5,7-trihydroxy-3',5'-dimethoxyflavone (tricin). The compounds have been described for the first time in this species. Five trihydroxy-flavone-hexoside derivatives have been identified by LC-ESI-HR-MS. The antimicrobial activity of kolavelone was evaluated against strains of Staphylococcus, Bacillus, Pseudomonas, Shigella and Candida spores, and its minimum inhibitory concentration (MIC) was determined. The results showed the antimicrobial activity of kolavelone against several bacteria and Candida tropicalis indicating its potential use as antimicrobial agent.

AbstractSidastrum paniculatum (L.) Fryxell, Malvaceae, is popularly known in Brazil as “malva-roxa” or “malvavisco”. The species is found mainly in Northeast region where it is used by locals to treat spider bites and bee stings. Aiming to identify the chemical compounds from S. paniculatum secondary metabolism and to contribute to the chemotaxonomic knowledge of Malvaceae family, a phytochemical study of S. paniculatum was carried out. Besides that, the isolated compounds were evaluated for antileishmanial activity against promastigotes of Leishmania braziliensis. By using chromatographic techniques the study resulted the isolation of eight compounds: 3-oxo-21β-H-hop-22(29)-ene; sebiferic acid; sitosterol 3-O-β-d-glucopyranoside/stigmasterol 3-O-β-d-glucopyranoside; phaeophytin a; 132(S)-hydroxyphaeophytin a; 132(S)-hydroxy-(173)-ethoxyphaeophorbide a and 7,4′-di-O-methylisoescutellarein. The structure of all isolated compounds was elucidated by spectroscopic analysis, including two-dimensional NMR techniques. In addition, the isolated compounds phaeophytin a; 132(S)-hydroxyphaeophytin a; 132(S)-hydroxy-(173)-ethoxyphaeophorbide a and 7,4′-di-O-methylisoescutellarein exhibited antileishmanial activity against promastigotes of L. braziliensis.