Construction and co-cultivation of two mutant strains harboring key precursor genes to produce prodigiosin.

The biosynthesis of prodigiosin (PG) from Serratia marcescens involves the coupling of a bipyrrole, 4-methoxy-2,2'-bipyrrole-5-carboxaldehyde (MBC), with a monopyrrole, 2-methyl-3-n-amyl-pyrrole (MAP), and formation of a linear tripyrrole (PG). We constructed mutant strains in which either the MBC biosynthesis by S. marcescens BMJ816 or the MAP biosynthesis by S. marcescens AMJ817. S. marcescens BMJ816 and AMJ817 confirmed that they lose the ability to synthesize PG when they are cultivated alone. An experiment was also conducted in which cultures of the two mutant strains were grown to the early exponential phase in a semi-defined medium, and one suspension culture was inoculated with the other. This approach yielded 103 mg/L PG. The findings suggest that the addition of precursors may enhance PG production by microorganisms.

The influence of anti-irritants on captopril hydrophilic gel.

In this study, we compared the irritation inhibition of various types of anti-irritants such as antihistamines (cyprohetadine, diphenhydramine, and promethazine), alpha-hydroxy acids (gluconolactone and gluco-delta-lactone), corticosteroids (betamethasone and clobetasol), and ion channel modulating agents (amiloride, ethacrynic acid, nifedipine, and verapamil) on the adverse dermatological reaction caused by captopril gel using noninvasive bioengineering methods including measuring the transepidermal water loss (TEWL) and the color change of skin surface [such as change chroma (delta C) and difference in color (delta E) between the gel-treated site and the untreated site]. In addition, the influence of these anti-irritants on the penetration capacity of captopril through the rabbit skin was also investigated. The results showed that the TEWL, change chroma (delta C), and difference in color (delta E) of skin were significantly reduced via incorporating diphenhydramine and clobetasol, indicating that both substances had potent irritation inhibition activity. Moreover, these substances had no effect on the percutaneous absorption of captopril gel. However, flux of the captopril with anti-irritants was about 480 microg/cm2/h and the required minimum administration area to obtain the minimum effective concentration was about 15 cm2, indicating that this formulation could possibly be developed for a transdermal drug delivery system.

In vitro and in vivo evaluation of potassium chloride sustained release formulation prepared with saturated polyglycolyed glycerides matrices.

The aim of the present work was to evaluate the effect of sustained release of potassium chloride semi-solid matrices prepared with different kinds and added amounts of Gelucires by the in vitro dissolution test and in vivo oral absorption study, and compared with a commercial product (slow-K). The results indicating that the release rates of potassium from experimental formulations were dependent on the type of semi-solid matrices (Gelucires). The higher the melting point of the Gelucires was incorporated, the slower release rate of the active substance was observed. Moreover, the values of similarity factor of Formulae F05 and F09 versus the reference in three kinds of dissolution medium (f(2)) were higher than 50, indicating that these experimental formulations had similar sustained release effects to the reference (slow-K) in dissolution test. In vivo study, the cumulative amount (mEq) of potassium excreted curve and the excretion rate curve of F05 and F09 were found to be similar to that of slow-K, and there were no significant differences (P > 0.05) in the maximum excretion rate and the mean time to reach the maximum rate between formulations and slow-K, indicating that the potassium chloride sustained release dosage form could be prepared using the Gelucires as lipid excipients.