Paulo M. Imamura

Clerodane-type diterpenes from the seed pods of Hymenaea courbaril var. stilbocarpa

Three known and two new diterpenes were isolated from the ethyl acetate extract of Hymenaea courbaril var. stilbocarpa seed pods. One of the compounds was elucidated as (5R*,8S*,9S*,10R*)-cleroda-3,13E-dien-15-oic acid and the other was elucidated, after treatment with diazomethane, as methyl (5S*,8S*,9S*,10R*)-cleroda-3,13E-dien-15-oate. The known diterpenes were identified as (-)-ozic acid, (-)-isoozic acid and (-)-kovalenic acid which were characterized as their methyl ester derivatives.

13C NMR spectral analysis of eperuane diterpenes

Abstract The 13 C NMR spectra of some eperuane diterpenes have been recorded and the signals assigned. The substituent shielding effects in these compounds, in comparison with those observed in other series of diterpenes, are also presented.

Isolation and synthesis of a new clerodane from Echinodorus grandiflorus

Abstract A new clerodane derivative, (−)-16-hydroxycleroda-3,13-dien-16,15-olide-18-oic acid, (4a α ,6 α ,8a α )1-carboxy-5( S )-[2(2,5-dihydro-5-hydroxy-2-oxo-4-furanyl)ethyl-5,6,8a-trimethyl-3,4,4a,5,6,7,8,8a-octahydro-naphthalene was isolated as a minor component of the polar fractions of the leaves of E. grandiflorus . The structure was determined by spectroscopy (IR, MS, 1D and 2D 1 H and 13 C NMR). The absolute configuration was determined by a hemisynthesis using (+)-hardwickiic acid methyl ester, from commercial copaiba oil, as starting material.

Synthesis of (−)- and (+)-hyrtiosal and their C-16 epimers

Abstract A total synthesis of the marine sponge metabolite (−)-hyrtiosal along with its enantiomer (+)-hyrtiosal and their C-16 epimers were achieved starting from 30% ee copalic acid.

Stereoselective synthesis of the noval marine diterpene (+)-isoagatholactone

The synthesis of (+)-isoagatholactone (1) from (+)-manool (4)via the key intermediate ent-methyl isocopalate (2) is described.

Quantification of chlorpheniramine maleate enantiomers by ultraviolet spectroscopy and chemometric methods

Chlorpheniramine maleate (CLOR) enantiomers were quantified by ultraviolet spectroscopy and partial least squares regression. The CLOR enantiomers were prepared as inclusion complexes with β-cyclodextrin and 1-butanol with mole fractions in the range from 50 to 100%. For the multivariate calibration the outliers were detected and excluded and variable selection was performed by interval partial least squares and a genetic algorithm. Figures of merit showed results for accuracy of 3.63 and 2.83% (S)-CLOR for root mean square errors of calibration and prediction, respectively. The ellipse confidence region included the point for the intercept and the slope of 1 and 0, respectively. Precision and analytical sensitivity were 0.57 and 0.50% (S)-CLOR, respectively. The sensitivity, selectivity, adjustment, and signal-to-noise ratio were also determined. The model was validated by a paired t test with the results obtained by high-performance liquid chromatography proposed by the European pharmacopoeia and circular dichroism spectroscopy. The results showed there was no significant difference between the methods at the 95% confidence level, indicating that the proposed method can be used as an alternative to standard procedures for chiral analysis.

Synthetic studies with Pinus elliottiis rosin derivatives. Oxidation of maleopimaric anhydride methyl ester and trimethyl fumaropimarate

Ozonolysis of maleopimaric anhydride methyl ester in the presence of tetracyanoethylene led to an epoxide and an ozonide. Ozonolysis of the trimethyl fumaropimarate, followed by treatment with Me2S, led to an epoxide, a diene, a keto-acid and an allylic oxidation product. Some of the compounds obtained were active against Staphylococcus aureus, Bacillus subtilis and Micrococcus luteus.

A New ent-Clerodane Diterpene from Hymenaea courbaril var. altissima

A new ent-clerodane and two known ent-labdanes were isolated from the barks of Hymenaea courbaril var. altissima (Ducke). The new diterpene was identified, after esterification with diazomethane, as methyl (-)-(5R,8S,9S,10R)-clerod-3-en-15-oate and known diterpenes were identified as methyl (-)-copalate and methyl (-)-eperuate. From the EtOAc extract of seed pods a known methyl (-)-zanzibarate was isolated. The structures of isolated compounds were elucidated based on spectroscopic studies.

Isolation, structural identification and cytotoxic activity of hexanic extract, cyperenoic acid, and jatrophone terpenes from Jatropha ribifolia roots

The cytotoxicity of a hexanic fraction produced from the ethanolic crude extract, obtained from Jatropha ribifolia (Pohl) Baill, Euphorbiaceae, roots was evaluated against ten human cancer cell lines (MCF-7, NCI-ADR/RES, OVCAR-3, PC-3, HT-29, NCI-H460,786-O, UACC-62, K-562, U251) compared with doxorrubicine as positive control. Compounds jatrophone and cyperenoic acid were isolated from the hexanic extract and characterized by spectroscopic techniques (NMR of 1H, 13C and IR). The in vitro antiproliferative activity of jatrophone showed selectivity in a concentration dependent way with Total Inhibition growth of: glioma 0.57 µg mL-1 (U251), breast cancer 9.2 µg mL-1 (MCF-7), adriamycin-resistant ovarian cancer 0.96 µg mL-1 (NCI-ADR/RES), kidney 4.2 µg mL-1 (786-0), prostate cancer 8.4 µg mL-1 (PC-3), colon cancer 16.1 µg mL-1 (HT29) and leukemia 0.21 µg mL-1 (K-562).

Antinociceptive activity of Ipomoea imperati (Vahl) Griseb., Convolvulaceae

Ipomoea imperati (Vahl) Griseb., Convolvulaceae, is used in folk medicine for the treatment of inflammation, swelling and wounds, as well as to treat pains after childbirth and for stomach problems. Administration of ethanol extract, lipid and aqueous fraction of I. imperati(300, 100 and 200 mg/kg) significantly inhibited the abdominal constriction in mice induced by acetic acid; increased the sleeping time evoked by pentobarbital sodium and showed a significant activity by inhibiting formalin-induced paw edema in mice. The same dose of I. imperatialso raised the pain of mice in the hot-plate test and increased the latency at all observation times. The pre-treatment of the animals with naloxone (5 mg/kg, i.p.) suggested the participation of the opioid system in the antinociceptive effect of Ipomoea imperati.