Antimicrobial, antioxidant, anti-inflammatory activities and phytoconstituents of extracts from the roots of Dissotis thollonii Cogn. (Melastomataceae)

Abstract Background Dissotis thollonii Cogn. belonging to the Malastomataceae family is used in the West Region of Cameroon for the treatment of inflammation, kidney diseases, pregnancy control and sinusitis. Despite the traditional use of this plant, no scientific report or information was found in the literature regarding neither its biological activity nor its chemical constituents. Aim of the study The present work was designed to determine the antimicrobial, antioxidant and anti-inflammatory activities of different extracts of the roots of D. thollonii Cogn. as well as the isolation and identification of the chemical constituents of this plant. Materials and methods The tests for antimicrobial, antioxidant and anti-inflammatory activities were performed over the MeOH, EtOAc, n-BuOH and aqueous extracts. Compounds were isolated from EtOAc and n-BuOH extracts of the roots of D. thollonii Cogn. through column chromatography and their structures were determined by means of NMR and MS analysis, and published data. Results According to the antimicrobial and antioxidant assays, the EtOAc and n-BuOH extracts were submitted to further separation and purification. This led to the isolation of twelve compounds identified as 3,3′-di- O -methylellagic acid 4′- O-β -D-xylopyranoside 1 , 3- O -methylellagic acid 4′- O-β -D-arabinopyranoside 2 , casuarinin 3 , betulinic acid 4 , β -sitosterol-3- O -D-glucopyranosyl-6′-mirystate 5 , cellobiosylsterol 6 , β -sitosterol 7 , β -sitosterol-3- O-β -D-glucopyranoside 8, arjunolic acid 9 , 3,3′-di- O -methylellagic acid 10 , ellagic acid 11 , and 3,3′-di- O -methylellagic acid 4′- O - β -D-glucopyranoside 12 . The EtOAc extract was the only antimicrobial active sample [diameter of the zone of inhibition (DZI) of 10 mm against Staphyloccocus aureus ] among all the tested extracts. The analysis of fractions of this extract revealed the presence of bioactive compounds with a described antimicrobial activity such as β -sitosterol, β -sitosterol-3- O-β -D-glucopyranoside and arjunolic acid. By using Trolox as the standard drug, all extracts showed antioxidant activity against DPPH in the following order of scavenging ability: Trolox > nBuOH > EtOAc > MeOH > WE (water extract). The ABTS •+ scavenging ability was similar to that found for the DPPH assay, being Trolox > n-BuOH > MeOH > EtOAc > WE. Along with the DPPH and ABTS assays, the FRAP assay showed the scale n-BuOH > MeOH > WE > EtOAc. The phytochemical study of the EtOAc and n-BuOH extracts revealed the presence of important known antioxidant compounds such as ellagic acid derivatives, arjunolic acid, betulinic acid and β -sitosterol. The anti-inflammatory properties of D. thollonii extracts were investigated using RAW 264.7 murine macrophage cells. The MeOH extract reduced the stimulated NO production in a concentration-dependent manner. 86% reduction was observed at the highest tested concentration of 100 μg/ml (IC 50 = 5.9 μg/ml). The n-BuOH extract showed higher dose dependent reduction of NO formation (IC 50 = 6.5 μg/ml) than the EtOAc extract (IC 50 = 18.1 μg/ml), whereas the water extract had no significant influence on the NO production. All the extracts did not have any influence on the macrophage viability. The phytochemical investigation of the EtOAc and n-BuOH extracts revealed that the main compounds identified do have potent anti-inflammatory properties. Conclusion The biological and phytochemical characterization of the root extracts of D. thollonii validates the use of this plant for the treatment of inflammation and sinusitis, thus providing evidence that this plant extracts, as well as some of the isolated compounds, might be potential sources of antioxidant and anti-inflammatory drugs

ANTIMICROBIAL DITERPENOID ALKALOIDS FROM ERYTHROPHLEUM SUAVEOLENS (GUILL. & PERR.) BRENAN

An investigation of the stem bark of Erythrophleum suaveolens (Guill. & Perr.) Brenan yielded the known amide norcassaide (1) and a new diterpenoid alkaloid named norerythrosuaveolide (2) which was characterized as 7β-hydroxy-7-deoxo-6-oxonorcassaide. The structures were established on the basis of one and two-dimensional 1H and 13C NMR spectral data. The compounds showed potent antimicrobial activities against bacteria and yeasts. KEY WORDS: Erythrophleum suaveolens (Guill. & Perr.) Brenan, Norcassaide, Diterpenoid alkaloid, Norerythrosuaveolide, Antimicrobial activities, Bacteria, Yeasts Bull. Chem. Soc. Ethiop. 2005, 19(2), 221-226

Toxicological and pharmacological evaluation of Discaria americana Gillies & Hook (Rhamnaceae) in mice

Medicinal plants (e.g. Discaria americana) have been used by populations for centuries. However, popular use is not enough to validate these plants as safe and effective medicinal products. The present study sought to evaluate the acute and subacute toxicity as well as the anxiolytic and antinociceptive effects of D. americana root bark and aerial parts extracts in mice. In acute toxicity studies, mice were treated with single intraperitoneal doses of the aforementioned extracts. Subacute toxicity studies were performed by oral administration of the extracts over 14 days. Anxiolytic studies consisted of the elevated plus maze method, and antinociceptive studies were based on the hot plate test. The LD50 value for D. americana aerial parts extract was established at >500 mg/kg, and for the root bark extract, 400 mg/kg. D. americana aerial parts extract produced anxiolytic (250 mg/kg) and antinociceptive effects (125, 200 and 250 mg/kg). Conversely, D. americana root bark extract showed neither anxiolytic nor antinociceptive effects in mice.As plantas medicinais (i. e. Discaria americana) têm sido utilizadas pela população por séculos, entretanto, o conhecimento popular não é suficiente para validá-las como medicamentos seguros e/ou efetivos. Assim, o presente estudo teve por objetivo avaliar a toxicidade aguda e subaguda, bem como o efeito ansiolítico e antinociceptivo dos extratos da casca da raiz e das partes aéreas da D. americana em camundongos. A toxicidade aguda foi avaliada pela administração dos extratos, via intraperitoneal. Para o estudo da toxicidade subaguda os animais foram tratados oralmente com os extratos por 14 dias. O efeito ansiolítico dos extratos foi determinado através do modelo do labirinto em cruz elevado e o efeito antinociceptivo, mediante o teste da placa quente. O valor da DL50 para o extrato das partes aéreas da D. americana foi definido como > 500 mg/kg, enquanto que para o extrato da casca da raiz foi estabelecido em 400 mg/kg. O extrato das partes aéreas da D. americana apresentou atividade ansiolítica (250 mg/kg) e antinociceptiva (125, 200 e 250 mg/kg). O extrato da casca da raiz da D. americana não apresentou efeito ansiolítico nem antinociceptivo

Bafoudiosbulbin H, a new clerodane diterpene from the flowers of Dioscorea bulbifera L. var sativa

A new clerodane diterpenoid, bafoudiosbulbin H (1), was isolated from the flowers of Dioscorea bulbifera L. var sativa. Its acetylation using acetic anhydride-pyridine and catalytic amount of 4-DMAP at 60 8C yielded bafoudiosbulbin H acetate (2) together with a clerodane with an unprecedented acylation pattern (bafoudiosbulbin H1, 3). The reaction of the known bafoudiosbulbin G (4) in the same conditions yielded demethylbafoudiosbulbin G (5). Structural elucidation of 5 led to the revision of the stereochemistry previously assigned to 4. Structures were elucidated using spectroscopic techniques, including 1D and 2D NMR (1H, 13C, HSQC, COSY, HMBC, ROESY, NOESY) and mass spectrometry (HRESIMS)

Two new tryptophan derivatives from the seed kernels of Entada rheedei: Effects on cell viability and HIV infectivity

Two new tryptophan derivatives, N-sulfonyl-L-tryptophan (tryptorheedei A) (1) and 3-(Nsulfonylindolyl)- D-lactic acid (tryptorheedei B) (2) together with the known 5-O-β-Dglucopyranosyl- 2-hydroxyphenylacetic acid (3), 1-O-methylglucopyranoside, entadamide A, homogentisic acid and 3-O-β-D-glucopyranosyl-β-sitosterol, were isolated from the seed kernels of Entada rheedei (Mimosaceae). Their structures were established using 1D and 2D NMR spectroscopy, mass spectrometry and by comparison with spectroscopic data reported in the literature. Compounds 1 and 2 showed no toxicity to TZM and Human PBMC cells. Both compounds 1 and 2 were found to promote early infection events in HIV, likely by inhibiting the enzyme indolamine 2,3-dioxygenase (IDO) and preventing tryptophan depletion. Inhibition of IDO acutely in HIV infection inhibits viral replication, but chronic activation of IDO leads to immune impairment in AIDS. IDO is also the gatekeeper enzyme for kynurenine metabolism, a pathway involved in serotonin and melatonin biosynthesis and the regulation of glutamate and dopamine levels in the brain. Therefore inhibition of IDO might explain both the reported medicinal and neuropsychiatric effects of E. rheede

<b>Antimicrobial diterpenoid alkaloids from <i>Erythrophleum suaveolens</i> (Guill. & perr.) Brenan</b>

An investigation of the stem bark of Erythrophleum suaveolens (Guill. & Perr.) Brenan yielded the known amide norcassaide (1) and a new diterpenoid alkaloid named norerythrosuaveolide (2) which was characterized as 7&beta;-hydroxy-7-deoxo-6-oxonorcassaide. The structures were established on the basis of one and two-dimensional 1H and 13C NMR spectral data. The compounds showed potent antimicrobial activities against bacteria and yeasts

Evaluation of (arene)Ru(II) complexes of curcumin as inhibitors of dipeptidyl peptidase IV

Curcumin, the main component of Curcuma longa, shows an anti-hyperglycemic effect and improved insulin sensitivity. This action may be attributed at least in part to its anti-inflammatory properties and also to its possible interaction with dipeptidyl peptidase-4 (DPPIV), the enzyme that the conversion of glucagon-like peptide-1 (GLP-1), responsible for glucose tolerance into inactive GLP-1. In this work we evaluated the inhibitory activities of a series of different arene-Ru(II)-curcumin complexes on bovine kidney dipeptidyl peptidase-4 (DPPIV).We studied also the interaction of these inhibitors on the enzyme with fluorescence studies displaying the binding poses with molecular docking studies. Specifically organometallic ruthenium(II) complexes of general formula [(h6-arene)Ru(curcuminato)Cl], with arene being p-iPrC6H4Me (1), C6H6 (2), and C6Me6 (3), were evaluated for their inhibition activity toward the mammalian enzyme. Among them, 2 suppressed DPPIV activities more potently (Ki 1⁄4 20.2(0.8) mM) than 1, 3, or free curcumin, and all complexes showed an antioxidant activity as free curcumin. As shown from our docking simulations a putative binding site of the compound 2 was found on subdomains S1 and S2 of DPP-IV, where S1 hydrophobic pocket includes catalytic residues and is the primary determinant of substrate specificity for the enzyme. Collectively, our results demonstrate that the complexation of curcumin with ruthenium(II) could be a promising starting point for the development of curcumin-based DPPIV inhibitors