Deciphering the biotransformation mechanism of dialkylresorcinols by CYP4F11.

Cytochrome P450 enzymes (CYPs) are one of the most important classes of oxidative enzymes in the human body, carrying out metabolism of various exogenous and endogenous substrates. In order to expand the knowledge of these enzymes' specificity and to obtain new natural product derivatives, CYP4F11, a cytochrome P450 monooxygenase, was used in the biotransformation of dialkylresorcinols 1 and 2, a pair of antibiotic microbial natural products. This investigation resulted in four biotransformation products including two oxidative products: a hydroxylated derivative (3) and a carboxylic acid derivative (4). In addition, acetylated (5) and esterified products (6) were isolated, formed by further metabolism by endogenous yeast enzymes. Oxidative transformations were highly regioselective, and took place exclusively at the ω-position of the C-5 alkyl chain. Homology modeling studies revealed that optimal hydrogen bonding between 2 and the enzyme can only be established with the C-5 alkyl chain pointing towards the heme. The closely-related CYP4F12 was not capable of oxidizing the dialkylresorcinol 2. Modeling experiments rationalize these differences by the different shapes of the binding pockets with respect to the non-oxidized alkyl chain. Antimicrobial testing indicated that the presence of polar groups on the side-chains reduces the antibiotic activity of the dialkylresorcinols.

Experimental and Computational Studies on the Biotransformation of Pseudopyronines with Human Cytochrome P450 CYP4F2.

The secondary metabolite pseudopyronine B, isolated from Pseudomonas mosselii P33, was biotransformed by human P450 enzymes, heterologously expressed in the fission yeast Schizosaccharomyces pombe. Small-scale studies confirmed that both CYP4F2 and CYP4F3A were capable of oxidizing the substrate, with the former achieving a higher yield. In larger-scale studies using CYP4F2, three new oxidation products were obtained, the structures of which were elucidated by UV-vis, 1D and 2D NMR, and HR-MS spectroscopy. These corresponded to hydroxylated, carboxylated, and ester derivatives (1-3) of pseudopyronine B, all of which had been oxidized exclusively at the ω-position of the C-6 alkyl chain. In silico homology modeling experiments highlighted key interactions between oxygen atoms of the pyrone ring and two serine residues and a histidine residue of CYP4F2, which hold the substrate in a suitable orientation for oxidation at the terminus of the C-6 alkyl chain. Additional modeling studies with all three pseudopyronines revealed that the seven-carbon alkyl chain of pseudopyronine B was the perfect length for oxidation, with the terminal carbon lying close to the heme iron. The antibacterial activity of the substrates and three oxidation products was also assessed, revealing that oxidation at the ω-position removes all antimicrobial activity. This study both increases the range of known substrates for human CYF4F2 and CYP4F3A enzymes and demonstrates their utility in producing additional natural product derivatives.

Eritrean pharmacists' job satisfaction and their attitude to re-professionalize pharmacy in to pharmaceutical care.

OBJECTIVE: Job satisfaction is a very important contributing factor for a person's productivity and motivation. Naturally, if people are not satisfied with what they practice, they will probably need to change or reshape their way of practice at a certain period in time. Pharmacists are not exception to this principle and have been observed to re-professionalize pharmacy in to clinical and/or pharmaceutical care in many parts of the world. Thus, this survey aims to investigate the Eritrean pharmacists' current level of job satisfaction and their views on re-professionalization of pharmacy. METHOD: A cross-sectional survey was conducted among all Eritrean pharmacists who reside inside Eritrea. MAIN OUTCOME MEASURES: Opinion of pharmacists about job satisfaction and re-professionalization of pharmacy into pharmaceutical care. RESULTS: Out of the 95 questionnaires distributed 86 were completed and returned giving a response rate of 90.5 %. Nearly three fourth of the respondents (71 %) have chosen pharmacy as their ever profession and they want to encourage their children or their close relatives to pursue it as a career. Sixty four percent of the pharmacists are either partially or fully unsatisfied to spend the remainder of their working life in a job like their current one and this has a strong statistical association with less years of experience (p = 0.007) and place of work of the younger pharmacists (p = 0.008). Majority of the study participants (86 %) believe there is a great mismatch between pharmacists' level of education and level of practice in the work area. This was significant with lower age (p = 0.002), less years of experience (p = 0.006) and later year of admission to university (p = 0.000). Ninety five percent of the pharmacists perceive that the current role of the Eritrean pharmacists needs to be redefined and re-oriented. CONCLUSION: Although the Eritrean pharmacists are proud to be pharmacy professionals, they want to redefine and reorient their current role into pharmaceutical care.