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The proteins Neo-11 and Neo-18 encoded in the neomycin gene cluster (neo) of Streptomyces fradiae NCIMB 8233 have been characterized as glucosaminyl-6'-oxidase and 6'-oxoglucosaminyl:L-glutamate aminotransferase, respectively. The joint activity of Neo-11 and Neo-18 is responsible for the conversion of paromamine to neamine in the biosynthetic pathway of neomycin through a mechanism of FAD-dependent dehydrogenation followed by a pyridoxal-5'-phosphate-mediated transamination. Neo-18 is also shown to catalyze deamination at C-6''' of neomycin, thus suggesting bifunctional roles of the two enzymes in the formation of both neosamine rings of neomycin. The product of the btrB gene, a homologue of neo-18 in the butirosin biosynthetic gene cluster (btr) in Bacillus circulans, exhibits the same activity as Neo-18; this indicates that there is a similar reaction sequence in both butirosin and neomycin biosynthesis.

Antioxidative activity and inhibition of key enzymes linked to type-2 diabetes (a-glucosidase and a-amylase)by Khaya senegalensis , respectively. Enzyme kinetic studies indicated that the butanol fraction is a non-competitive inhibitor for a-glucosidase with an inhibition binding constant K i of 1.30 µg mL -1 and a competitive inhibitor of a-amylase with a K i of 7.50 µg mL -1 . GC-MS analysis revealed that the butanol fraction contained two chromones, p-anilinophenol and 3-ethyl-5-(3-ethyl-(3H)-benzothiazol-2-ylidene)-2-(p-tolylvinylamino)-4-thiazolidinone. Data obtained in the study suggest that the butanol fraction derived from the ethanolic extract of K. senegalensis root possessed excellent antioxidative as well as a-glucosidase and a-amylase inhibitory activities while chromones and/or p-anilinophenol could be the main bioactive compounds responsible for the observed activities.

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The present study aimed to investigate the effects of the various parts of Ficus carica L. (figs) on antioxidant, antidiabetic, and antiobesogenic effects in vitro. Fruit, leaves, and stembark of the F. carica plant were sequentially extracted using organic and inorganic solvents and their total polyphenol and flavonoid contents were estimated. The effects of the extracts on antioxidative, antidiabetic (inhibition of α-amylase and α-glucosidase enzymes), and antiobesogenic (antilipase) activities were measured using several experimental models. The fruit ethanolic extract contained a high quantity of polyphenols and flavonoids (104.67±5.51 μg/mL and 81.67±4.00 μg/mL) compared with all other extracts. The activity of the ethanolic extract of F. carica fruit was significantly (p<0.05) higher than all other extracts and parts of the plant in terms of antioxidative, antidiabetic, and antiobesogenic effects. The IC values of the fruit ethanolic extract in terms of antioxidative (134.44±18.43 μg/mL), and inhibition of α-glucosidase (255.57±36.46 μg/mL), α-amylase (315.89±3.83 μg/mL), and pancreatic lipase (230.475±9.65 μg/mL) activity indicate that the activity of fruit ethanolic extract is better than all other extracts of the plant. The gas chromatography-mass spectroscopy analysis of the fruit ethanolic extract showed the presence of a number of bioactive compounds such as butyl butyrate, 5-hydroxymethyl furfural, 1-butoxy-1-isobutoxy butane, malic acid, tetradecanoic acid, phytol acetate, trans phytol, n-hexadecanoic acid, 9Z,12Z-octadecadienoic acid, stearic acid, sitosterol, 3,5-dihydroxy-6-methyl-2,3-dihydro-4H-pyran-4-one, and 2,4,5-trimethyl-2,4-dihydro-3H-pyrazol-3-one. The results of this study suggest that the ethanolic extract of the fruit of F. carica may have potential antidiabetic and antiobesogenic agents.