Marco A. Mostardeiro

Cyclopeptide alkaloids from the bark of Waltheria douradinha

Abstract Two peptide alkaloids, waltherine-A and waltherine-B were isolated from Waltheria douradinha , together with two known peptide alkaloids, adouetine-Y′ and scutianine-B. Their structures were elucidated on the basis of spectroscopic analyses.

Cyclopeptide alkaloids of Scutia buxifolia

Abstract Two new peptide alkaloids, scutianines-K and -L were isolated from Scutia buxifolia, a plant growing in Brazil, Argentina and Uruguay. Their structures have been determined on the basis of spectroscopic studies. The stereochemistry of the N,N-dimethyl amino acid side-chain and the ring amino acid residues in both alkaloids have been assigned by gas chromatography employing modified cyclodextrins as chiral stationary phases.

Scutianine-J, a cyclopeptidic alkaloid isolated from Scutia buxifolia

Abstract From the methanol extract of the bark of S. buxifolia Reiss (Rhamnaceae), a new cyclopeptidic alkaloid, together with the already known alkaloids scutianines-B-E, were isolated. On the basis of elemental analysis, mass spectroscopy (EI and FAB) and 1 H NMR spectroscopy, the molecular structure of scutianine-J has been elucidated.

Diterpenoids from Humirianthera ampla.

Two diterpenoids, humirianthol and acrenol, as well as the known annonalide, were isolated from Humirianthera ampla. Humirianthol and acrenol were determined by 1D and 2D NMR spectroscopic techniques to be 3 beta,20:14 beta,16-diepoxy-3 alpha, 15 alpha-dihydroxy-7-pimaren-19,6 beta-olide and 3 beta,20-epoxy-3 alpha,15,16-trihydroxy-7-pimaren-19,6 beta-olide, respectively.

Chemical composition and evaluation of prolyl oligopeptidase and acetylcholinesterase inhibitory activities of Leonurus Sibiricus L. from Brazil

Abstract Chemical investigation of the aerial parts of Leonurus sibiricus L. used in Brazilian folk medicine led to the identification of the following constituents: the labdane-type diterpenoid leojaponin, the phytosterols β-sitosterol and β-sitosterol glucoside and the alkaloid leonurine. The crude extracts obtained from methanol and methanol/1% HCl and pure compounds isolated from L. sibirius were investigated as acetylcholinesterase (AChE) and prolyl oligopeptidase (POP) inhibitors. Extracts obtained by maceration were active against POP (53–58%), but showed weak activity against AChE. The isolated leojaponin and leonurine were evaluated as POP inhibitors.

Phytochemical analysis of bark from Helietta apiculata Benth and antimicrobial activities

Extraction and characterization of natural products from the bark of the trunk of Helietta apiculata Benth (Rutaceae) afforded nine alkaloids, eight furoquinoline and one quinolone, limonine, three cinnamic acid derivatives, three neolignans, tetracosanoic acid, six coumarins, of which apiculin A and apiculin B (neolignans), and tanizin (coumarin) are previously undescribed compounds. The structures of all compounds were determined by spectroscopic methods, and the crystal structures of two of the newly undescribed compounds, apiculin A and apiculin B, were determined by X-ray analysis. Extracts and pure compounds isolated from Helietta apiculata showed promising antimicrobial activities.

Lanostane-type triterpenes from the fungal endophyte Scleroderma UFSMSc1 (Persoon) Fries.

Two lanostane triterpenoids (sclerodols A and B) were isolated from the culture of the Eucalyptus grandis derived from the endophyte Scleroderma UFSM Sc1(Persoon) Fries together with three known compounds: one related triterpenoid lanosta-8,23-dien-3β,25-diol, the disaccharide α,β-trehalose, and the sugar alcohol mannitol. Their structures were elucidated on the basis of 2D NMR, HRME, and single-crystal X-ray diffraction data. The methanol crude extract and the isolated lanostane triterpenoids showed promising anticandidal activities.

Diterpenos isolados de Humirianthera ampla. Miers.

From Humirianthera ampla, Icacinaceae, were isolated a phthalate, lupeol, β-sitosterol, glycosyl- sitosterol, one known annonalide diterpene and two new diterpenes named Humirianthol and Acrenol. Humirianthol and Acrenol were determined by 1D and 2D NMR spectroscopic techniques to be 3 β, 20:14 β, 16-diepoxy-3 α, 15 α-dihydroxy-7-pimaren-19, 6 β-olide and 3 β, 20-epoxi-3 α, 15, 16-trihydroxy-7-pimaren-19, 6 β-olide, respectively. Acrenol has antimicrobial activity.

Cyclopeptide alkaloids: stereochemistry and synthesis of the precursors of discarines C and D and myrianthine A.

The stereochemistry of discarines C (1) and D (2) and myrianthine A (3), three cyclopeptide alkaloids isolated from Discaria febrifuga, was determined by a combination of NMR studies of 1-3, enantioselective gas chromatography, and comparison of NMR data with those of synthetic tripeptides. For the synthesis of peptides, the nonproteinogenic amino acid 3-phenylserine was also obtained in its four diastereoisomeric forms (l and d threo, obtained by recrystallization of the diastereoisomeric tripeptide, and l and d erythro, obtained by a Mitsunobu reaction with the threo-tripeptides). The general synthetic strategy described in this paper allows the tripeptide to be obtained with the free N-terminal extremity protected or dimethylated. This strategy also allows the synthesis of the corresponding peptide with an imidazolidinone ring.

Sesquiterpenoids from Nectandra megapotamica (Lauraceae)

Five sesquiterpenoid oxides, named nectandrene A, B, C, D, and E, were isolated from the essential oil of the leaves of Nectandra megapotamica. Their structures were elucidated by spectroscopic analysis, and the relative configurations were proposed by their nuclear Overhauser effect (NOESY) spectrum. Three of these isolated compounds displayed significant antimicrobial activity; the compound most active had minimal inhibitory concentration (MIC) values between 3.12 and 25.0 μg mL -1 against some tested bacteria, and antifungal activity with MIC values between 12.5 and 25.0 μg mL -1