Browsing by Author "Rodríguez, Benjamín"
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- An easy and stereoselective rearrangement of an abietane diterpenoid into a bioactive microstegiol derivativePublication . Simões, Maria de Fátima; Rijo, Patrícia; Duarte, Aida; Matias, Diogo; Rodríguez, BenjamínParvifloron D was isolated from Plectranthus ecklonii together with sugiol and mixtures of β-sitosterol and stigmasterol and ursolic and oleanolic acids. Treatment of parvifloron D [2α-(4-hydroxy)benzoyloxy-11-hydroxy-5,7,9(11),13-abietatetraen-12-one] with acid-washed molecular sieves gave the microstegiol derivative 2β-(4-hydroxy)benzoyloxy-11β-hydroxy-4(5 → 11),20(10 → 5)diabeo-5(10),6,8,13-abietatetraen-12-one in a moderate yield (26%). The new microstegiol derivative inhibited the growth of some Staphylococcus and Enterococcus species with significant MIC values ranging from 3.91 to 7.81 μg/ml.
- Antimicrobial properties of Plectranthus ornatus extracts, 11-acetoxyhalima-5,13-dien-15-oic acid metabolite and its derivativesPublication . Rijo, Patrícia; Rodríguez, Benjamín; Duarte, Aida; Simões, Maria de FátimaAn antimicrobial screening of six different extracts of Plectranthus ornatus, revealed anti-Gram positive bacteria activity for the acetone and methanol-water extracts. 11R*-Acetoxyhalima-5,13E-dien-15-oic acid (1), isolated from the acetone extract of P. ornatus, exhibited growth inhibitory activity against five Staphylococcus and five Enterococcus strains. [MIC values 15.62 μg/mL (43.15 μM) – 62.50 μg/mL (172.65 μM)]. Diterpenes with a halimane skeleton are rarely isolated and their pharmacologic properties remain unknown. To study the potential of 1 as antibacterial prototype some derivatives (2-10) were obtained from 1 and the majority were tested against the same ten Gram positive bacteria. The more active was the (11R*,13E)-halima-5,13-diene-11,15-diol (4) with MIC values of 15.62 μg/mL (51.05 μM) to 31.25 μg/mL (102.12 μM). The preparation and spectroscopic data of 2 – 10 are also reported.
- Antimycobacterial metabolites from Plectranthus. Royleanone derivatives against Mycobacterium tuberculosis strainsPublication . Rijo, Patrícia; Simões, Maria de Fátima; Francisco, Ana Paula; Rojas, Rosário; Gilman, Robert H.; Vaisberg, Abraham J.; Rodríguez, Benjamín; Moiteiro, CristinaThe antimycobacterial activities of eight diterpenes, 1–8, isolated previously from Plectranthus and eleven esters, 9–19, of 7α-acetoxy-6β,12-dihydroxyabieta-8,12-diene-11,14-dione (5) were evaluated against the MTB strains H37Rv and MDR. Only diterpenoids with a quinone framework revealed anti-MTB activity. Abietane 5 and its 6,12-dibenzoyl, 12-methoxybenzoyl, 12-chlorobenzoyl, and 12-nitrobenzoyl esters, 9, 11, 12, and 13, respectively, showed potent activities against the MDR strain with MIC values between 3.12 and 0.39 μg/ml. Cytotoxic activities towards 3T3 and Vero cells were also evaluated. Compound 11, with the best selectivity index, may be a suitable lead for further chemical modifications. The complete structural elucidation of the new esters, 9–14, 16, 18, and 19, as well as the NMR data of known derivatives 15 and 17 are reported.
- Two new diterpenoids from Plectranthus speciesPublication . Simões, Maria de Fátima; Rijo, Patrícia; Duarte, Aida; Barbosa, Diana; Matias, Diogo; Delgado, Joana; Cirilo, Nádia; Rodríguez, BenjamínTwo new diterpenoids, ent-7α-acetoxy-15-beyeren-18-oic acid and (13S,15S)-6β,7α,12α,19-tetrahydroxy-13β,16-cyclo-8-abietene-11,14-dione, have been isolated from Plectranthus saccatus and Plectranthus porcatus, respectively, and their structures were established by 1D and 2D NMR spectroscopic studies. The new diterpenes showed no activity against Gram-negative bacteria and Candida albicans (yeast strain). Among Gram-positive bacteria, the lower MIC value was 62.50 μg/ml for the abietane derivative against Staphylococcus aureus ATCC 6538.