Leaf extracts of eight selected southern African medicinal plants modulate pro-inflammatory cytokine secretion in LPS-stimulated RAW 264.7 macrophages.

This study investigates the anti-inflammatory properties of extracts prepared from the leaves of eight southern African medicinal plants used traditionally to treat inflammation and pain. The inhibitory effect of aqueous and ethanol extracts on the release of pro-inflammatory cytokines was determined in lipopolysaccharide (LPS) stimulated and unstimulated RAW 264.7 murine macrophage cells. The levels of interleukin (IL)-1ß, IL-6, tumour necrosis factor-α (TNF-α), interferon-gamma (IFN-γ), monocyte chemoattractant protein 1 (MCP-1) and macrophage inflammatory protein (MIP)-2 release were determined using cytokine multiplex-bead assays. The ethanol extracts of Melianthus comosus Vahl (commonly known as honey flower), Tetradenia riparia (Hochst.) Codd (misty plume bush) and Warburgia salutaris (G. Bertol.) Chiov. (pepper-bark tree), demonstrated the most significant inhibitory activity, with over 50-fold inhibition of IL-1ß, IL-6 and TNF-α levels in LPS-stimulated RAW 264.7 macrophages. The aqueous extract of M. comosus also significantly inhibited the secretion of all the tested cytokines and chemokines. Phytochemical investigation of M. comosus ethanol leaf extract using ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS) led to the detection of crassolide, deoxylimonoic acid D-ring-lactone, 2-hydroxynonanoic acid and 5-noniloxytryptamine. To the best of our knowledge, the cytokine inhibition properties of most of the medicinal plants screened in this study are reported for the first time. Our results support the use of southern African medicinal plants as anti-inflammatory remedies and provide an insight into the immunomodulatory mechanisms of action.

Identification of a New α-Synuclein Aggregation Inhibitor via Mass Spectrometry Based Screening.

The aggregation of disordered α-synuclein protein is pathogenically connected with Parkinson's disease. Therefore, discovering molecules that can inhibit the misfolding and aggregation of α-synuclein is an active research area in PD drug development. A key property of such required therapeutic agents is specific binding to the target protein. Mass spectrometry allows rapid detection of direct interactions between molecules and proteins and is an ideal technique for discovering specific α-synuclein binders. Here, by setting up an automated mass spectrometry-based screening system, we were able to screen over 2500 compounds and identify a new α-synuclein inhibitor, 3-[(3-methoxyphenyl)carbamoyl]-7-[( E)-2-phenylethenyl]-4,7-dihydropyrazolo [1,5- a]pyrimidine-5-carboxylic acid (compound 2). This compound not only significantly inhibits the misfolding and aggregation of α-synuclein and protects neuroblastoma cells from α-synuclein toxicity, but also has a more specific binding site compared with positive controls. Our work for the first time reports the inhibition of compound 2 on α-synuclein aggregation and also consolidates the capability of mass spectrometry to discover α-synuclein aggregation inhibitors.

Epicocconone-Hemicyanine Hybrids: Near Infrared Fluorophores for Protein Staining and Cell Imaging.

The development of new near infrared (NIR) dyes is crucial for diverse applications and especially bioimaging, as they absorb and emit light in the "therapeutic window" (650-950 nm). We report here a new family of NIR fluorophores that has been obtained by hybridising hemicyanines with epicocconone. Emission wavelengths of these hybrid dyes is in the range 715-795 nm and is combined with large Stokes' shifts (75-95 nm). The absorption and emission wavelength can be modulated according to the hemicyanine moiety and adding sulfonic acid moieties enhances water solubility. We demonstrate their application in the sensitive detection of proteins in gel electrophoresis and the staining of specific cellular organelles in confocal microscopy. These results are particularly encouraging and bring forward a new fluorescent skeleton for chemical biology.

Antimicrobial and antioxidant activity and chemical characterisation of Erythrina stricta Roxb. (Fabaceae).

ETHNOPHARMACOLOGICAL RELEVANCE: The bark of Erythrina stricta Roxb. (Fabaceae) has been used in Indian indigenous systems as a remedy for rheumatism, stomach-ache, asthma, dysentery, contact dermatitis, eczema and skin infections. However, there have been limited phytochemical or biological studies on the bark of E. stricta and there are no studies that align with its traditional medicinal uses. AIM OF THE STUDY: The aim of this study was to assess the antimicrobial and antioxidant activity of the stem bark of E. stricta to support its topical use in the treatment of contact dermatitis, eczema and skin infections and to isolate and identify any bioactive compounds. MATERIALS AND METHODS: MTT microdilution and disc diffusion assays were used to determine the antimicrobial activities of n-hexane, dichloromethane, ethyl acetate, methanol and water extracts of the bark of E. stricta. Column and preparative thin layer chromatography were used for the purification of the dichloromethane extract. The structures of the compounds isolated were elucidated by extensive 1D and 2D NMR spectroscopic techniques and comparison with published data. The antioxidant activities of the extracts were determined by DPPH free radical scavenging and FRAP assays and the antioxidant activity of the pure compounds by dot-blot and DPPH staining methods. RESULTS: The dichloromethane, ethyl acetate, and n-hexane extracts showed the most significant activity with MIC values of 7.8µg/mL, 125µg/mL, and 125µg/mL against a sensitive strain of Staphylococcus aureus. The dichloromethane and ethyl acetate extracts also showed significant activity against Candida albicans with MIC values of 125µg/mL and 1mg/mL respectively. GC-MS analysis of the n-hexane extract showed the presence of the antibacterial and antifungal compounds ß-caryophyllene, caryophyllene oxide, α-selinene, ß-selinene, selin-11-en-4-α-ol, α-copaene and δ-cadenine. Phytochemical studies of the dichloromethane extract led to the isolation of the novel compound erynone (1), together with six known compounds; wighteone (2), alpinum isoflavone (3), luteone (4), obovatin (5), erythrinassinate B (6) and isovanillin (7). Luteone (4) exhibited the most significant antibacterial activity with minimum inhibitory quantity (MIQ) values of 1.88µg, 1.88µg and 3.75µg, respectively, against sensitive (MSSA) and resistant strains (MRSA and MDRSA) of S. aureus using a TLC bioautography assay. Erynone (1) exhibited the greatest DPPH free radical scavenging activity. CONCLUSIONS: Seven compounds, including a new chromanone, were isolated from the antimicrobial dichloromethane extract of the stem bark of E. stricta. Six of the seven compounds showed antibacterial and/or antioxidant activities. These findings provide support for the customary (traditional and contemporary) use of E. stricta bark for the treatment of skin and wound infections.

A one-pot synthesis and biological activity of ageladine A and analogues.

A one-pot synthesis of ageladine A and analogues is reported. The key Pictet-Spengler reaction between 2-aminohistamine and aryl aldehydes has been successfully utilized for the synthesis of the natural product and 14 analogues. These compounds were screened for their matrix metalloprotease (MMP) and kinase inhibition to develop the first structure-activity relationship of ageladine A analogues. One compound, which showed significant kinase activity but little MMP inhibitory activity, was found to be highly active in an antiangiogenic screen, suggesting that the angiogenic activity of ageladine A is not associated with MMP inhibition but rather kinase inhibitory activity. Cytotoxicity was excluded as a mode of action by the assay of ageladine A and an analogue against 60 human cell lines.