Discovery and Characterization of Cyclotides from Rinorea Species.

Cyclotides are macrocyclic cystine-knotted peptides most commonly found in the Violaceae plant family. Although Rinorea is the second-largest genera within the Violaceae family, few studies have examined whether or not they contain cyclotides. To further our understanding of cyclotide diversity and evolution, we examined the cyclotide content of two Rinorea species found in Southeast Asia: R. virgata and R. bengalensis. Seven cyclotides were isolated from R. virgata (named Rivi1-7), and a known cyclotide (cT10) was found in R. bengalensis. Loops 2, 5, and 6 of Rivi1-4 contained sequences not previously seen in corresponding loops of known cyclotides, thereby expanding our understanding of the diversity of cyclotides. In addition, the sequence of loop 2 of Rivi3 and Rivi4 were identical to some related noncyclic "acyclotides" from the Poaceae plant family. As only acyclotides, but not cyclotides, have been reported in monocotyledons thus far, our findings support an evolutionary link between monocotyledon-derived ancestral cyclotide precursors and dicotyledon-derived cyclotides. Furthermore, Rivi2 and Rivi3 had comparable cytotoxic activities to the most cytotoxic cyclotide known to date: cycloviolacin O2 from Viola odorata; yet, unlike cycloviolacin O2, they did not show hemolytic activity. Therefore, these cyclotides represent novel scaffolds for use in future anticancer drug design.

Cell proliferative effect of polyxyloses extracted from the rhizomes of wild turmeric, Curcuma aromatica.

Hot water-soluble crude polysaccharides were extracted from the rhizomes of wild turmeric, Curcuma aromatica Salisb. (Zingiberaceae), using dry grinding, boiling water extraction, and then ethanol precipitation. The crude polysaccharide extract was then fractionated by DEAE-cellulose ion exchange column chromatography, and subsequently further purified by Superdex G-200 gel filtration column chromatography, giving two relatively abundant polysaccharide fractions, called P11 and P21, and a much less common fraction P22 obtained in insufficient amounts for further analysis. The two main polysaccharide fractions were evaluated for monosaccharide composition by acid hydrolysis and high performance liquid chromatography (HPLC), whilst the molecular weight and functional groups were determined by gel permeable chromatography (GPC) and FT-IR, respectively. Fractions P11 and P21 were found to be polyxyloses with molecular weight-averages of 469,171 and 157,665 Da, respectively. P11 (100 microg/mL) could significantly induce human gingival fibroblast cells proliferation by 30%, while P21 (100 microg/mL) could significantly inhibit gingival fibroblast cells proliferation by 92%. The in vitro human primary gingival fibroblast cell proliferation in cell culture at a concentration of 100 microg/mL.