Anti-inflammatory and antinociceptive effects of racemic goniothalamin, a styryl lactone

AIMS

The present study aimed to further investigate the anti-inflammatory activity of goniothalamin (GTN), a styryl lactone, as well as its antinociceptive effects.

MAIN METHODS

The anti-inflammatory activity was evaluated in models of paw edema induced by different mediators in mice and carrageenan-induced peritonitis. Evaluation of the antinociceptive effect was performed through acetic acid-induced writhing test and formalin test. Activity of GTN on gene expression levels of interleukin-1beta (IL-1β), induced nitric oxidase synthase (iNOS) and cyclooxygenase-2 (COX-2) were evaluated in vitro in lipopolysaccharide (LPS)-stimulated macrophage (RAW 264.7), as well as gene expression and protein levels of tumor necrosis factor-alpha (TNF-α).

KEY FINDINGS

Pretreatment with GTN (300 mg/kg) significantly reduced paw edema induced by compound 48/80, prostaglandin E2, phospholipase A2 and bradykinin. GTN (10, 30 and 100mg/kg) inhibited leukocyte migration in the peritonitis model and gene expression levels of IL-1β, iNOS and TNF-α, as well as TNF-α protein levels, in LPS-stimulated macrophages, without affecting COX-2 gene expression levels. GTN inhibited nociception induced by acetic acid in the writhing model and in the formalin test, when both neurogenic and inflammatory phases were inhibited.

SIGNIFICANCE

For the first time the acute anti-inflammatory profile of GTN is characterized and its antinociceptive activity reported. The current study shows that GTN inhibits both vascular and cellular phases of inflammation, with bradykinin and PLA2 induced inflammation being the most affected by GTN. Its anti-inflammatory effects also involved the in vitro inhibition of gene expression of alarm cytokines and mediators as IL-1β, iNOS and TNF-α.

A comparative study of chromatographic behavior and lipophilicity of selected natural styryl lactones, their derivatives and analogues

This study is based on the analyses of the retention behavior of selected natural styryl lactones and their synthetic analogues in reversed-phase high-performance liquid chromatography. Chromatographic separations were achieved applying ZORBAX SB-C18 column and two different mobile phases: methanol-water and acetonitrile-water. Chromatographic lipophilicity of the analyzed compounds was defined by logk₀ constant and correlated with in silico molecular descriptors. According to the statistical validation parameters, obtained results indicate that the presented linear and multiple quantitative structure-retention relationship models can successfully predict the chromatographic lipophilicity of structurally similar compounds. Hierarchical cluster analyses (HCA) was applied in order to group similar compounds according to their chromatographic and in silico lipophilicity. It can be concluded that chromatographic systems with methanol-water were better for modelling of logk₀. Modelling was performed in order to characterize compounds regarding their lipophilicity profiles as future drug candidates.

In vitro antiplasmodial and cytotoxicity activities of crude extracts and major compounds from Goniothalamus lanceolatus

ETHNOPHARMACOLOGICAL RELEVANCE

Malaria, a devastating infectious disease which was initially recognized as episodic fever, is caused by parasitic protozoan of the genus Plasmodium. Medicinal plants with ethnobotanical information to treat fever and/or malaria has been the key element in identifying potential plant candidates for antimalarial screening. Goniothalamus lanceolatus Miq. (Annonaceae) is used as a folk remedy, particularly to treat fever and skin diseases.

AIM OF THE STUDY

In this context, supported with previous preliminary data of its antiplasmodial activity, this study was undertaken to determine the in vitro antiplasmodial and cytotoxicity activities of G. lanceolatus crude extracts and its major compounds.

MATERIALS AND METHODS

The in vitro antiplasmodial activity was determined by parasite lactate dehydrogenase (pLDH) assay on chloroquine-sensitive (3D7) and chloroquine-resistant (K1) strains of Plasmodium falciparum. The cytotoxicity activity was evaluated using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on hepatocellular carcinoma (HepG2) and normal liver (WRL-68) cell lines.

RESULTS

The root methanol extract possessed potent antiplasmodial activity against both P. falciparum 3D7 and K1 strains (IC₅₀ = 2.7 μg/ml, SI = 140; IC₅₀ = 1.7 μg/ml, SI = 236). Apart from the DCM extract of stem bark and root that were found to be inactive (IC₅₀ > 50 μg/ml) against 3D7 strain, all other tested crude extracts exhibited promising (5< IC₅₀ < 15 μg/ml) to moderate (15< IC₅₀ < 50 μg/ml) antiplasmodial activity against both strain. Additionally, only compound C (Parvistone D) exerted promising antiplasmodial activity against 3D7 strain (IC₅₀ = 7.5 μM, SI = 51) whereas compound A, B and D showed moderate antiplasmodial activity against the same strain (20 < IC₅₀ < 100 μM). Interestingly, when tested on K1 strain, compound A, C and D exhibited promising antiplasmodial activity (2 < IC₅₀ < 20 μM) while compound B exhibited moderate activity (IC₅₀ = 26.9 μM). Cytotoxicity study showed that all tested crude extracts and compounds were non-toxic on WRL-68 and HepG2 cell lines (CC₅₀ > 30 µg/ml, CC₅₀ > 10 µM, respectively), except for the hexane and DCM extracts of root, which exerted mild cytotoxicity on HepG2 cell line (IC₅₀ < 30 μg/ml).

CONCLUSIONS

This study suggests that the root methanol extract and compound C (Parvistone D) obtained from G. lanceolatus are highly potential for exploitation as source of antimalarial agents. Parvistone D is identified as one of the bioactive styryl lactones found in the plant extract. It is also noteworthy, that the extract and compound were more active against chloroquine-resistant (K1) strain of P. falciparum. Further studies are being carried out to assess their toxicity profile and antimalarial efficacy in animal model.

Synthesis and antiproliferative activity of thiazole bioisosteres of goniofufurone and 7-epi-goniofufurone

Several new goniofufurone (1) and 7-epi-goniofufurone (2) mimics in which the benzene ring has been replaced with a thiazole residue have been designed, synthesized and evaluated for their antiproliferative activity against a panel of human tumour cell lines. The key steps of the synthesis represent the initial condensation of suitably protected furanose urononitriles with cysteine ethyl ester hydrochloride, followed by the subsequent oxidation of resulting C-4' epimeric thiazolines with BrCCl3 and DBU, to build up the thiazole ring. Biological studies have shown that the HeLa cell line is most sensitive to the action of synthesized analogues with IC50 values in the range of 0.01-7.67 μM. The most active compound in this cell culture was 7-epi-goniofufurone mimic 28, with a thiazole-carboxamide function at C-7 and a benzyloxy group at the C-5 position. Compound 28 exhibited 89-fold higher antiproliferative potency in this cell line than lead 2 and was 7-fold more active than the commercial antitumour agent doxorubicin. A SAR study identified structural features responsible for the antiproliferative activity of synthesized analogues. The analogues 3-28 are completely inactive toward the normal MRC-5 cell line. Their selectivity indexes (SI) range from 4.1 to 17,470.7.