Antibacterial activity of indole alkaloids from Aspidosperma ramiflorum

Abstract

We evaluated the antibacterial activities of the crude methanol extract, fractions (I-V) obtained after acid-base extraction and pure compounds from the stem bark of Aspidosperma ramiflorum. The minimum inhibitory concentration (MIC) was determined by the microdilution technique in Mueller-Hinton broth. Inoculates were prepared in this medium from 24-h broth cultures of bacteria (10 7 CFU/mL). Microtiter plates were incubated at 37ºC and the MICs were recorded after 24 h of incubation. Two susceptibility endpoints were recorded for each isolate. The crude methanol extract presented moderate activity against the Gram-positive bacteria B. subtilis (MIC = 250 µg/ mL) and S. aureus (MIC = 500 µg/mL), and was inactive against the Gram-negative bacteria E. coli and P. aeruginosa (MIC > 1000 µg/ mL). Fractions I and II were inactive against standard strains at concentrations of ≤1000 µg/mL and fraction III displayed moderate antibacterial activity against B. subtilis (MIC = 500 µg/mL) and S. aureus (MIC = 250 µg/mL). Fraction IV showed high activity against B. subtilis and S. aureus (MIC = 15.6 µg/mL) and moderate activity against E. coli and P. aeruginosa (MIC = 250 µg/mL). Fraction V presented high activity against B. subtilis (MIC = 15.6 µg/mL) and S. aureus (MIC = 31.3 µg/mL) and was inactive against Gram-negative bacteria (MIC > 1000 µg/mL). Fractions III, IV and V were then submitted to bioassay-guided fractionation by silica gel column chromatography, yielding individual purified ramiflorines A and B. Both ramiflorines showed significant activity against S. aureus (MIC = 25 µg/mL) and E. faecalis (MIC = 50 µg/mL), with EC 50 of 8 and 2.5 µg/ mL for ramiflorines A and B, respectively, against S. aureus. These results are promising, showing that these compounds are biologically active against Gram-positive bacteria.

In vitro inhibition of Plasmodium falciparum by substances isolated from Amazonian antimalarial plants

“…In general, indole alkaloids are a class of compound having a range of biological activities, including antibacterial, trypanocidal, leishmanicidal and anticancer (Sakamoto-Hojo et al 1988, Delorenzi et al 2001, Ferreira et al 2006, Tanaka et al 2006). The antiplasmodial activity of monoterpene indole alkaloids has been investigated (Wright et al 1994, Iwu et al 1994).…”

Relaxant effects of an alkaloid-rich fraction from Aspidosperma ulei root bark on isolated rabbit corpus cavernosum

“…[17][18][19] This in vitro system was utilized for the present study to verify the underlying mechanism in the proerectile activity of A. ulei fraction (F 3-5 ) observed A. ulei on rabbit corpus cavernosum AR Campos et al in vivo. 23 The initial objective of our study was to verify a possible relaxant effect of F 3-5 on PHE or high potassium-precontracted RbCC and then to elucidate the likely involvement of adrenergic, cholinergic and nitrergic neuroeffector systems as well as the role of potassium and calcium channel activation in its relaxant mechanism.…”

“…[11][12][13][14] Aspidiosperma species commonly grown in tropical America have proven to be a rich source of indole alkaloids and several of them exhibit important pharmacological properties that include antimalarial, antileishmania, antidiabetic and anti-inflammatory effects. [15][16][17][18] The use of bark extract from Aspı´dosperma quebracho blanco has been a common traditional practice in many parts of South America to treat impotence, benign prostatic hypertrophy and to obtain relief from cardiac-or asthmarelated dyspnea. 19 An a-adrenoceptor blocking activity of it has been described in literature.…”

Atividade biológica e alcalóides indólicos do gênero Aspidosperma (Apocynaceae): uma revisão

“…Assim a atividade antileishmaniose do extrato alcaloidal das cascas do caule e substâncias puras de A. ramiflorum contra Leishmania brasiliensis e L. amazonensis foram avaliados e constatou-se uma maior efetividade contra L. amazonensis do que contra a L. brasiliensis, tanto para o extrato (DL 50 <47 µg mL -1 ) quanto para as substâncias puras, ramiflorina A (DL 50 = 16,3 + 1,6 µg mL -1 ) e ramiflorina B (DL 50 = 4,9 + 0,9 µg mL -1 ) (6) (Tanaka et al, 2007;Ferreira et al, 2004). O mesmo grupo de trabalho avaliou a atividade antibacteriana, e neste foram constatados resultados de inibição de crescimento de Bacilus subtilis e Staphylococcus aureus do extrato básico e das substâncias ramiflorinas A e B (6) (Oliveira, 1999;Tanaka et al, 2006), e antifúngica do extrato bruto metanólico e ramiflorinas A e B (6) contra Cryptococcus neoformans (Souza et al, 2006). Data de 1988 o primeiro trabalho de isolamento e identificação de alcalóides de A. ramiflorum, onde foram descritos os alcalóides β-ioimbina (OH-17 em β) (2), 10-metoxigeissoschizol (7) presentes nas cascas do caule e sementes com estruturas já relatadas em outras espécies, e ramiflorinas A e B (6), presentes nas cascas do caule (Marques, 1988;Marques et al, 1996).…”