Isoeleutherin

Application of MEKC and monolithic CEC for the analysis of bioactive naphthoquinones in Eleutherine americana.[Pubmed:19862752]

Electrophoresis. 2009 Nov;30(21):3757-63.

Two microscale separation techniques for the analysis of bioactive naphthoquinones in Eleutherine americana were developed and validated. By MEKC four compounds (eleuthoside B, Isoeleutherin, eleutherol and eleutherinoside A) could be determined in plant extracts using an aqueous electrolyte solution composed of 25 mM sodium tetraborate, 50 mM sodium cholate and 20% THF. CEC on a polymeric methacrylate-based monolith with strong cationic properties showed promising results, as it additionally enabled the separation of two enantiomers, eleutherin and Isoeleutherin. The mobile phase for CEC experiments comprised 3 mM ammonium formate in a mixture of ACN and water. At an applied voltage of -25 kV, all five markers were baseline separated in less than 12 min. Both methods were successfully validated for linearity (MEKC: R(2) > or = 0.999; CEC: R(2) > or = 0.997), sensitivity (MEKC: LOD = 4-5 microg/mL; CEC: LOD=2-8 microg/mL), accuracy (MEKC: 96.5-102.7% recovery; CEC: 97.1-103.5% recovery) and precision (MEKC: sigma(rel) < or = 2.43%; CEC: sigma(rel) < or = 2.21%). The quantitative analysis of naphthoquinone derivatives in several E. americana samples showed that both methods are suitable for practical applications, because the results were well comparable to those obtained by established techniques such as HPLC.

Effects of ethanolic extract and naphthoquinones obtained from the bulbs of Cipura paludosa on short-term and long-term memory: involvement of adenosine A(1) and A(2)A receptors.[Pubmed:23057724]

Basic Clin Pharmacol Toxicol. 2013 Apr;112(4):229-35.

Previous studies from our group have indicated important biological properties of the ethanolic extract and isolated compounds from the bulbs of Cipura paludosa (Iridaceae), a native plant widely distributed in northern Brazil, including antioxidant, neuroprotective and anti-nociceptive activities. In the present study, the effects of the ethanolic extract and its two naphthoquinones (eleutherine and Isoeleutherine) on the short- and long-term memory of adult rodents were assessed in social recognition and inhibitory avoidance tasks. Acute pre-training oral administration of the ethanolic extract improved the short-term social memory in rats as well as facilitated the step-down inhibitory avoidance short- and long-term memory in mice. Moreover, the co-administration of 'non-effective' doses of the extract of Cipura paludosa and the adenosine receptor antagonists caffeine (non-selective), DPCPX (adenosine A1 receptor antagonist) and ZM241385 (adenosine A2A receptor antagonist) improved the social recognition memory of rats. In the inhibitory avoidance task, the co-administration of sub-effective doses of the extract with caffeine or ZM241385, but not with DPCPX, improved the short- and long-term memory of mice. Finally, the acute oral administration of eleutherine and Isoeleutherine facilitated the inhibitory avoidance short- and long-term memory in mice. These results demonstrate for the first time the cognitive-enhancing properties of the extract and isolated compounds from the bulbs of Cipura paludosa in rodents and suggest a possible involvement of adenosine A1 and A2A receptors in these effects.

Antifungal Activity of Pyranonaphthoquinones Obtained from Cipura paludosa Bulbs.[Pubmed:26594766]

Nat Prod Commun. 2015 Sep;10(9):1589-92.

Previous studies with the bulbs of Cipura paludosa (Iridaceae) showed the presence of pyranonaphthoquinones, including eleutherine, Isoeleutherine and eleutherol. The aim of this study was to evaluate the antifungal properties of these compounds. The activity was tested against the clinically relevant yeasts Candida albicans, C. tropicalis, Saccharomyces cerevisiae and Cryptococcus neoformans with the microbroth dilution method, following the guidelines of CLSI. Eleutherine, Isoeleutherine and eleutherol all presented significant antifungal activity, especially the first two, the major components, with MIC values between 7.8 and 250 microg/mL. In conclusion, these results demonstrate that C. paludosa bulbs produce active principles with relevant antifungal potential, contributing, at least in part, to the antimicrobial effect evidenced for this plant and justifying its popular use against infections.

Suppression of inducible nitric oxide synthase by (-)-isoeleutherin from the bulbs of Eleutherine americana through the regulation of NF-kappaB activity.[Pubmed:19135178]

Int Immunopharmacol. 2009 Mar;9(3):298-302.

Eleutherine americana Merr. et Heyne (Iridaceae) has been used as a folk medicine for the treatment of coronary disorders and wound-healing. In our previous phytochemical study, several pyranonaphthoquinoids, including (-)-Isoeleutherin, were isolated from the bulbs of E. americana. Because inhibitors of inducible nitric oxide synthase (iNOS) might be useful as anti-inflammatory agents, we investigated the potential of pyranonaphthoquinoids to inhibit iNOS activity. We found that (-)-Isoeleutherin inhibits lipopolysaccharide (LPS)-stimulated induction of nitric oxide (NO) in a dose-dependent manner (IC(50)=7.4 microM). Using western blots and reverse transcription-polymerase chain reaction, we showed that (-)-Isoeleutherin suppresses the expression of iNOS protein and mRNA. In addition, (-)-Isoeleutherin inhibited the expression of various cytokines such as interleukin-1beta and interferon-beta. Activation of the transcriptional activity of NF-kappaB by LPS was also inhibited by treatment with (-)-Isoeleutherin, suggesting that (-)-Isoeleutherin-mediated suppression of iNOS expression is associated with the regulation of transcription factor NF-kappaB. These findings suggest that (-)-Isoeleutherin might be a novel anti-inflammatory agent, and that it may work by inhibiting NFkB activation in macrophages.

Polyketides from Eleutherine bulbosa.[Pubmed:20835959]

Nat Prod Res. 2010 Oct;24(16):1578-86.

Four new polyketides, (R)-4-hydroxyeleutherin, eleuthone, eleutherinol-8-O-beta-D-glucoside and isoeleuthoside C (dihydroIsoeleutherin-5-O-beta-D-gentiobioside) were isolated from the bulbs of Eleutherine bulbosa, to join eleutherin, Isoeleutherin, eleutherinol, eleutherol, eleuthoside B (eleutherol-4-O-beta-D-gentiobioside), eleuthoside C (dihydroeleutherin-5-O-beta-D-gentiobioside), hongconin (4-oxodihydroIsoeleutherin) and elecanacin, which have already been isolated from the same plant. The structures of the new polyketides, based on oxydated cyclic systems, have been elucidated by chemical and spectroscopic methods.

Assessment of antistaphylococcal activity of partially purified fractions and pure compounds from Eleutherine americana.[Pubmed:19350980]

J Food Prot. 2009 Feb;72(2):354-9.

Ready-to-eat foods were investigated for contamination with methicillin-resistant Staphylococcus aureus (MRSA), and the partially purified fractions from the bulb of Eleutherine americana were evaluated for their anti-MRSA activity. Partially purified fractions Ea6.3 and Ea9 demonstrated good antibacterial activity with a MIC of 125 to 500 microg/ml and MBC of 250 to > or =1000 microg/ml against all the food isolates. Fraction Ea6.3 produced a MIC and MBC of 250 and 500 microg/ml, respectively, whereas fraction Ea9 yielded MIC and MBC of 125 and > or =1000 microg/ml, respectively, against the enterotoxin-producing reference strains. Growth curves in the presence of fraction Ea6.3 at 4 x MIC resulted in total elimination of all the test strains between 20 and 24 h, while fraction Ea9 reduced bacterial population by at least 6 log relative to the control. The partially purified fractions were further purified to obtain pure compounds identified as eleutherol, eleutherin, Isoeleutherin, hongconin, two anthraquinones, and elecanacin. The antibacterial activities of these compounds were also investigated; they produced MICs ranging from 31.25 to > or =1000 microg/ml. This study suggests that E. americana crude extract or its partially purified fractions have potentials for application as natural food preservatives.