Five fl avonoids (rutin, asebotin, 3-hydroxyasebotin, quercetin-3-O-β-D-xylopyranoside, and a racemic mixture of catechin) and caffeic acid were isolated and identifi ed for the fi rst time from seagrass, Thalassodendron ciliatum, collected from the Hurghada region in Egypt. The crude extract and the isolated pure compounds were evaluated for their cytotoxic activities against HCT-116, HEPG, MCF-7, and HeLa human cancer cell lines, for their antiviral activity against Herpes Simplex and hepatitis A viruses, and for their antioxidant activity.

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The present paper deals with gelatin nanofibres functionalized with silver nanoparticles, prepared by electrospinning using solutions of gelatin mixed with silver nitrate (AgNO 3 ). As a common solvent for gelatin and silver nitrate (AgNO 3 ), a mixture of acetic acid and water (70:30 v/v) was selected. In this system, acetic acid was used as a solvent for gelatin, and at the same time reducing agent for silver ions in solution. Silver nanoparticles (nAg) were stabilized through a mechanism that involves an interaction of the oxygen atoms of the carbonyl groups of gelatin. The viscosity and the conductivity of the gelatinous solutions were found to increase with the solution concentration. There is an observed decrease in the viscosity of the nAg containing gelatin solutions with the aging time increasing, whereas the conductivity of the AgNO 3 -containing gelatin solutions was greater than that of the base gelatin solution. The gelatin nanofibres functionalized with silver nanoparticles were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and antimicrobial test. The results of investigations by TEM and XRD confirmed the presence of silver nanoparticles with diameters in the range of (2 -10 nm), uniformly distributed over the surface of smooth nanofibres with an average diameter of 70 nm. The release of silver ions from both the 2-and 4-hrs crosslinked nAg containing gelatin fiber mats by a total immersion method in buffer and distilled water occurred rapidly during the first 60 minutes, and increased gradually afterwards. Lastly, the tests demonstrated that gelatin/Ag nanofibers have a good antimicrobial activity against some common bacteria found on burned wounds. The antibacterial activity of these materials was greatest against Staphylococcus aureus, followed by Escherichia coli, and Pseudomonas aeroginosa ≈ Candida albicans.

Three strains of Streptomyces rimosus were grown on four different media. The one suitable for the production of oxytetracycline by Streptomyces rimosus 12907 was modified by black strap molasses, fodder yeast (40% total protein) and rice bran. The volume of the fermentation medium was sealed up in a 1200-litre fermentor aerated with sterile air obtained from a system used in the purification of air. 850 g crude oxytetracycline was obtained when the fermented medium (700 litres) was extracted with 1-butanol.

Two strains of Streptomyces alboniger NRRL B‐1832 and 2403 were used for the biosynthesis and production of puromycin using different media. Streptomyces alboniger NRRL B‐2403 produced more puromycin than NRRL B‐1832 on medium composed of (amounts in g/1), soybean meal 10.0; corn steep 20.0; dextrin 10.0; NaCl 5.0; CaCO3 2.0, and K2HPO4 2.0. When the carbon and nitrogen sources of the basal medium were replaced by different carbon and nitrogen sources it was found that dextrin, sucrose, starch and maltose favoured the production of higher titres of puromycin, while generally organic nitrogen sources such as soybean meal and fodder yeast (40.0 and 50.0% total nitrogen) stimulated puromycin yield. On the evidence of their chemical compositions and because they are cheap and produced locally Egyptian black, strap molasses and fodder yeast are preferably used in medium for the production of puromycin. The other conditions favouring and controlling the production and biosynthesis of puromycin by fermentation were investigated.