Effects of rhamnose consumption on bone mineral density in healthy postmenopausal women: a randomised, placebo-controlled, double-blind, parallel-group pilot study.

Preventing the decrease in bone mineral density (BMD) is significant for postmenopausal women. We previously discovered that rhamnose, a deoxy monosaccharide used as a food additive, could suppress bone resorption; however, studies confirming this effect in postmenopausal women are lacking. Therefore, this pilot study aimed to explore whether rhamnose could help maintain BMD via bone resorption suppression in postmenopausal women. The participants consumed either 1.0 or 0.5 g/day of rhamnose or placebo for 24 weeks, and BMD (lumbar spine and femur) and bone turnover markers were measured. After 24 weeks, the group consuming rhamnose 1.0 g/day exhibited a significantly higher BMD of the lumbar spine than the placebo group. Furthermore, the levels of tartrate-resistant acid phosphatase 5b, a bone resorption marker, were significantly lower in both rhamnose groups. These results indicated that rhamnose might contribute to the maintenance of BMD by suppressing bone resorption in healthy postmenopausal women (UMIN000046570).

Purification and characterization of a serine protease from the fruit of Ficus carica cultivar Masui Dauphine.

Ficus carica produces, in addition to the cysteine protease ficin, a serine protease (FSP). Here, we purified FSP to homogeneity from the fruit of F. carica cultivar Masui Dauphine. An 81-fold enrichment in specific activity of FSP with 2.1% recovery was attained. Three protein bands (70, 62, and 60 kDa) were identified on SDS-PAGE. Each band was identified as a subtilisin-like protease (661 amino acids) by trypsin digestion, LC-MS/MS analysis, and the partial N-terminal amino acid sequence analysis. Gelatin zymography revealed that the active FSP exists as a dimer. The optimum hydrolysis pH of FSP was 7.5, and the pHs at which the enzyme retained its initial activity by 70% in 24 h were 8.0-11.0. The optimum hydrolysis temperature of FSP was 50-60 °C, and the temperature required to reduce the initial activity by 50% in 15 min was 70 °C. These results will inform the industrial use of FSP.

Insight into the collagen-degrading activity of a serine protease in the latex of Ficus carica cultivar Masui Dauphine.

Ficus carica produces, in addition to the cysteine protease ficin, a serine protease. Earlier study on a serine protease from F. carica cultivar Brown Turkey showed that it specifically degraded collagen. In this study, we characterized the collagenolytic activity of a serine protease in the latex of F. carica cultivar Masui Dauphine. The serine protease degraded denatured, but not undenatured, acid-solubilized type I collagen. It also degraded bovine serum albumin, while the collagenase from Clostridium histolyticum did not. These results indicated that the serine protease in Masui Dauphine is not collagen-specific. The protease was purified to homogeneity by two-dimensional gel electrophoresis, and its partial amino acid sequence was determined by liquid chromatography-tandem mass spectrometry. BLAST searches against the Viridiplantae (green plants) genome database revealed that the serine protease was a subtilisin-like protease. Our results contrast with the results of the earlier study stating that the serine protease from F. carica is collagen-specific.

Characterization of proteases activities in Ficus carica cultivars.

In this study, we characterized protease activities of 23 Ficus carica cultivars. Extracts of fruit, branch, and leaf of Masui Dauphine, one of the most representative F. carica cultivars in Japan, exhibited gelatin-hydrolyzing activity, both in the absence and presence of a cysteine protease-specific inhibitor, E-64, suggesting that not only ficin (classified as cysteine protease) but also collagenase (classified as serine protease) were involved in the digestion of gelatin. In the hydrolysis of (7-methoxycoumarin-4-yl)acetyl-l-Lys-l-Pro-l-Leu-Gly-l-Leu-[N3 -(2,4-dinitrophenyl)-l-2,3-diaminopropionyl]-l-Ala-l-Arg-NH2 , all branch extracts of 23 F. carica cultivars exhibited the activity both in the absence and presence of cysteine protease-specific inhibitor E-64, indicating that they contain ficin and collagenase. During digestion of acid-solubilized type I collagen by the branch extract of Masui Dauphine at 40-55 °C, collagen was completely digested in the absence of E-64, while it was partially digested in the presence of the inhibitor, indicating that the manner of digestion differed between ficin and collagenase contained in the extract. These results suggest that F. carica is attractive for industrial use to digest collagen. PRACTICAL APPLICATION: The industrial use of F. carica might be enhanced by efficiently utilizing these proteases and/or selecting the appropriate F. carica cultivar. Collagen is one of the targets to which our results might be applied. It is widely accepted today that collagen and its digestion products could be useful as functional food. F. carica is a potential candidate for use in not only complete but also partial digestion of collagen.