Protective and antioxidative effect of rubropunctatin against oxidative protein damage induced by metal catalyzed reaction.

Monascus purpureus is known to produce several coloured secondary metabolites. In this study, M. purpureus CFR 410-11 mutant fermented with rice was dried and extracted in hexane for purification of pigment. The purity of the isolated pigment was confirmed by different chromatography techniques. The spectroscopic analysis revealed its structural identity as rubropunctatin. The antioxidant potencies of isolated rubropunctatin were evaluated. Rubropunctatin scavenged 16% 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical and inhibited 20% superoxide generation at 8 µg/ml concentration. The multiple antioxidant abilities of rubropunctatin were evidenced by its ferric reducing capacity also. The oxidative damage of BSA protein was induced by the metal catalyzed oxidation (MCO) by Fe2+/H2O2. The protective effects of rubropunctatin and M. purpureus (MTCC-410 and CFR 410-11) extracts were compared with glutathione and ascorbic acid. The M. purpureus extracts and rubropunctatin inhibited the formation of carbonyl content and protein oxidation assayed by SDS-PAGE. Rubropunctatin (42-169 µM) efficiently inhibited the protein oxidation compared to glutathione (48-195 µM) and ascorbic acid (85-340 µM) by scavenging the superoxide and hydroxyl radical generated in the system.

Antioxidant properties of isolated compounds from banana rhizome.

UNLABELLED: In this study, we attempted to explore banana rhizome (BR) as a source of natural bioactive compounds. Dried BR powder was subjected to sequential extraction using solvents with increasing polarity and studied for antioxidant activities. Chloroform and acetone extracts were selected for isolation and identification of bioactive compounds because of their high antioxidant properties. Antioxidant activity guided fractionation of these extracts yielded 3 compounds. The spectroscopy studies revealed the identity of isolated compounds as 4-epicyclomusalenone, cycloeucalenol acetate and chlorogenic acid. Polyphenolic compound chlorogenic acid and triterpenoid compounds, 4-cyclomusalenone and cycloeucalenol acetate displayed multifunctional antioxidant activity. PRACTICAL APPLICATION: The isolated compounds namely 4-epicyclomusalenone, cycloeucalenol acetate and chlorogenic acid have demonstrated their antioxidant properties in different in vitro assay models. The present study indicated that the vast quantity of banana rhizome which was incinerated could be a potential source of natural antioxidant compounds. This can also be used in the food, nutraceutical and pharmaceutical industries.

Activation of α-secretase by curcumin-aminoacid conjugates.

The extracellular senile plaques observed in Alzheimer's disease (AD) patients are mainly composed of amyloid peptides produced from the ß-amyloid precursor protein (ßAPP) by ß- and γ-secretases. A third non-amyloidogenic α-secretase activity performed by the disintegrins ADAM10 and ADAM17 occurs in the middle of the amyloid-ß peptide Aß and liberates the large sAPPα neuroprotective fragment. Since the activation of α-secretase recently emerged as a promising therapeutic approach to treat AD, the identification of natural compounds able to trigger this cleavage is highly required. Here we describe new curcumin-based modified compounds as α-secretase activators. We established that the aminoacid conjugates curcumin-isoleucine, curcumin-phenylalanine and curcumin-valine promote the constitutive α-secretase activity and increase ADAM10 immunoreactivity. Strickingly, experiments carried out under conditions mimicking the PKC/muscarinic receptor-regulated pathway display different patterns of activation by these compounds. Altogether, our data identified new lead natural compounds for the future development of powerful and stable α-secretase activators and established that some of these molecules are able to discriminate between the constitutive and regulated α-secretase pathways.