Active-site structure, binding and redox activity of the heme–thiolate enzyme CYP2D6 immobilized on coated Ag electrodes: a surface-enhanced resonance Raman scattering study

Surface-enhance resonance Raman scattering spectra of the heme–thiolate enzyme cytochrome P450 2D6 (CYP2D6) adsorbed on Ag electrodes coated with 11-mercaptoundecanoic acid (MUA) were obtained in various experimental conditions. An analysis of these spectra, and a comparison between them and the RR spectra of CYP2D6 in solution, indicated that the enzyme’s active site retained its nature of six-coordinated low-spin heme upon immobilization. Moreover, the spectral changes detected in the presence of dextromethorphan (a CYP2D6 substrate) and imidazole (an exogenous heme axial ligand) indicated that the immobilized enzyme also preserved its ability to reversibly bind a substrate and form a heme–imidazole complex. The reversibility of these processes could be easily verified by flowing alternately solutions of the various compounds and the buffer through a home-built spectroelectrochemical flow cell which contained a sample of immobilized protein, without the need to disassemble the cell between consecutive spectral data acquisitions. Despite immobilized CYP2D6 being effectively reduced by a sodium dithionite solution, electrochemical reduction via the Ag electrode was not able to completely reduce the enzyme, and led to its extensive inactivation. This behavior indicated that although the enzyme’s ability to exchange electrons is not altered by immobilization per se, MUA-coated electrodes are not suited to perform direct electrochemistry of CYP2D6

Isolation, partial purification and characterization of antifungal trypsin inhibitor protease from the seed of Blighia sapida K.D. Koenig (Ackee)

Seed proteins have been evaluated for their nutritive value and biological activity. Proteases and proteinase inhibitors have been of immense benefit to both agriculture and therapeutic purposes. The seed proteins of Blighia sapida was evaluated for both structure and biological activity in this study. The matured dried seeds were pulverized and sequentially extracted using 10 mM Tris/HCl pH 7.4, 10 mM ammonium acetate and 10 mM sulphuric acid. Crude protein extracts were concentrated and the protein concentrations were estimated. Proteins were purified by 70% ammonium sulphate precipitation, Sephadex G50 reversed phase chromatography and finally by HPLC on a C18 column. Two bands were obtained from SDS-PAGE electrophoresis and they were identified by ESI/MS using in gel tryptic digestion. The seed protein from B. Sapida consists of two single polypeptide chains each with mass of about 24 to 27 KDa as established by a combination of SDS-PAGE and ESI/MS. Proteins exhibited protease activity, which was confirmed by zymography. Protease activity was characterized for effect of temperature, pH, divalent metal ions and chelating agents. The crude protein from the seed of B. sapida showed antimicrobial activity and the antifungal activity was comparable with the reference drug, Ticonazole.Keywords: Blighia sapida, chromatography, protease activity, in-gel trypsin digestion/mass spectrophotometry, antimicrobial activity.African Journal of Biotechnology, Vol 13(29) 2996-300

Inhibition of Oxidative Stress and Skin Aging-Related Enzymes by Prenylated Chalcones and Other Flavonoids from Helichrysum teretifolium

ArticleTen flavonoid-related structures viz. heliteretifolin (1), isoxanthohumol (2), 2',4',6'-trihydroxy-3'-prenylchalcone (3), isoglabranin (4), glabranin (5), 7-methoxy-isoglabranin (6), quercetin (7), 4'-methoxyquercetin (8), 4'-methoxykaempferol (9) and mosloflavone (10) were isolated from a H. teretifolium methanolic extract and identified. One of them (compound 1) is reported for the first time from a natural source, while compounds 6, 8–10 were isolated for the first time from the genus Helichrysum. The total extract of H. teretifolium showed potent antioxidant activity. When tested for total antioxidant capacity compound 3 possesses moderate biological activity compared to 2, which displayed some of the highest TEAC values (4529.01 ± 2.44; 4170.66 ± 6.72) µM TE/g, respectively. Compounds 7 and 8 demonstrated the highest inhibitory activities on Fe2+-induced lipid peroxidation (IC50 = 2.931; 6.449 µg/mL); tyrosinase (8.092; 27.573) and elastase (43.342; 86.548). Additionally, the total antioxidant capacities measured as FRAP (4816.31 ± 7.42; 3584.17 ± 0.54) µM AAE/g, and ORAC for hydroxyl radical (7.265 ± 0.71; 6.779 ± 3.40) × 106 and peroxyl radical (17.836 ± 2.90; 12.545 ± 5.07) × 103 µM TE/g were also observed for compounds 7 and 8, respectively. In conclusion, H. teretifolium total extract represents a rich source of bioactive constituents with potent antioxidant and moderate anti-tyrosinase and anti-elastase activities that can help to avert accumulation of free radicals in the body, and could therefore be good candidates for the prevention and/or treatment of skin-related conditions, such as aging. This is the first scientific report on the chemical and biological profile of H. teretifolium

Use and cultural significance of Raphia palms

The genus Raphia (Palmae / Arecaceae) contains 22 species and represents a major multiuse resource across tropical Africa and Madagascar. Raphia species provide goods that range from food to construction material and medicine. Its species play a vital cultural role in African societies. Despite its importance, the taxonomy, ecology, and ethnobotany of this genus remain poorly understood. Here, we review the multiplicity of uses, products and cultural importance of Raphia species across its distribution. We provide a near exhaustive list of all products derived from Raphia species, classified by species and major use categories. We record nearly 100 different uses, traded and commercialized at local, regional, and national levels. Most species have several uses. Raphia wine is the most important product, followed by grubs and fiber extraction. Our review improves our understanding of the uses and cultural importance of Raphia species. If Raphia resources are managed responsibly, they will contribute to alleviate poverty, fight against hunger and conserve tropical biodiversity, especially in Africa