| The current researches showed that plant polyphenols have preventive effects against chronic diseases including heart disease, diabetes, neurodegenerative disease, and cancer. As a natural product, plant polyphenols has attracted much attention in current researches. Rose rogusa is one of the plant flowers with high value in food and medicine. The main utility of Rose rogusa is for rose oil production, but the yield of oil in R. rogusa was just 0.025%～0.03%, so, massive R. rogusa dregs was produced and wasted in this process. R. rogusa dregs rich in polyphenols and flavonoids, is one of the natural ingredients with great application prospects. To put R. rogusa dregs into use is an important way to improve the economic benefits of R. rogusa. The research and application of R. rogusa was extensive but very little in R. rogusa dregs. In this text, we produced R. rogusa polyphenols from the R. rogusa drags through the ultrasonic assisted extraction and macroporous resin adsorption methods, and obtained the fingerprint of the polyphenols by HPLC/MS/MS analysis. And then, we performed the further study on the biological activities of Rose rogusa polyphenols in order to exploit a new kind of polyfunctional food additive from R. rogusa dregs, and collected all the main results as following:1. Optimization of the extraction process of total polyphenols from R. rogusa gregs using response surface methodA response surface methodology (RSM) was launched to investigate the influence of process variables on the ultrasound-assisted extraction followed by a central composite design (CCD) approach. The statistical analysis revealed that the optimised conditions were 50%(v/v) ethanol, a ultrasound time of 45 min, a ultrasound power of 150 W, and a liquid-to-solid ratio of 24:1. Under the optimised conditions, total polyphenol yield was determined as 116.68±1.61 mg/g DW, and it is closely related with the predicted average yield of 109.30±1.30 mg/g DW.2. Purification and ingredient identification of R.rogusa polyphenolAdsorption on macroporous resins was tested as a means of purifying the polyphenols from crude R. rogusa extracts. Macroporous resin HPD600 was verified to offer the best adsorption capacity and desorption ratio for total polyphenols from crude R. rogusa extracts among the five macroporous resins investigated. Influential factors, such as pH value and flow speed of feeding solution, strippant, and adsorption isotherm to the separation of total polyphenols, were successively investigated on HPD600 resin. The optimal conditions for the dynamic experiments can be summarized as follows:feading flow rate was 1 mL/min, processing volume was 300 mL, desorption solvent was 60% ethanol solution, a eluted flow of 1 mL/min, a eluent volume of 250 mL. After purification, the polyphenol content increased to 875.2±8.6 mg GAE/g DW, about 3.64 times of the crude extracts.The component contents of the R. rogusa polyphenol were identified by HPLC-HESI-MS/MS. These identifications confirmed that R. rogusa polyphenol was composed mainly by hydrolyzed tannins and flavonoid glycosides. There are 23 kinds of compounds in total, including six kinds of gallic acid glycoside, six kinds of HHDP glycoside, seven kinds of quercetin glycoside and two resurrectionlily phenolic glycoside, the other two were quercetin and Eriodictyol.3. Anti-QS activities of R. rogusa polyphenolThe R. rogusa polyphenol specifically inhibited QS-controlled violacein production in Chromobacterium violaceum 026 with 87.56% reduction without affecting its growth. It was also exhibited inhibition in swarming motility of Escherichia coli K-12 and Pseudomonas aeruginosa PAO1 in a concentration dependent manner. At the concentration of R. rogusa polyphenol were 80,160,320 and 640 μg/mL, the inhibition rates for swarming motility of E. coli K-12 were 32.73%,56.03%,67.11% and 84.90%, respectively. And at the same conditions, the inhibition rates for swarming motility of P. aeruginosa PAO1 were 46.54%,52.12%,57.25% and 78.03%, respectively.4. Anti-biofilm activities of R. rogusa polyphenolThe R. rogusa polyphenol exhibited stronger inhibition in biofilm formation of E. coli K-12 and P. aeruginosa PAO1 in a concentration dependent manner, too. At the concentration of R. rogusa polyphenol was 640 μg/mL, the inhibition rates for biofilm formation of E. coli K-12 and P. aeruginosa PAO1 were 67.02% and 72.90% reduction, respectively. The confocal stack images showed that, in the negative control group, the thicknesses of biofilms formatted by E. coli K-12 and P. aeruginosa PAO1 were respectively 21.606±1.029 μm and 27.924±1.105 μm. While E. coli K-12 and P. aeruginosa PAO1 were incubated together with 640 μg/ml of RTP, the biofilms thicknesses dropped to 8.231± 1.019 μm and 9.318±1.074μm, respectively. In addition, when the R. rogusa polyphenol was used with s-polylysine or potassium sorbate in combination, it significantly enhanced the inhibitory effects of the preservative on the biomass of E. coli K-12 and P. aeruginosa PAO1.5. Antioxidant and Anti-aging activities of R. rogusa polyphenolPotent antioxidant activities of R. rogusa polyphenol were observed through several antioxidant assays including FRAP approach, hydroxyl radical, DPPH radical and ABTS radical scavenging assays. Our current findings revealed that R. rogusa polyphenol showed remarkable antioxidant effects. For another, the R. rogusa polyphenol significantly protected the DNA damage induced by the hydroxyl radicals generated by Fenton’s reagent. At the final concentration of 25,50,100 and 200 μg/ml of R. rogusa polyphenol, the inhibition rate of DNA damage were 7.3%,18.0%,26.3%, and 26.4%, respectively, compared to the control group. A well established model organism Caenorhabditis elegans was utilized to elucidate the anti-aging activities of R. rogusa polyphenol in vivo. On the incubated plate with the final concentration of 200 μg/ml R. rogusa polyphenol, the mean lifespan of wild-type adult C. elegans increased 26.4%, compared to the control group. In addition, R. rogusa polyphenol also enhanced the thermotolerance and resistance to oxidative stress of C. elegans. At a concentration of 25 μg/ml, R. rogusa polyphenol elicited a T-SOD level of C. elegant 2.12 times higher than the control group. And the T-AOC level of R. rogusa polyphenol treated C. elegant increased to 3.58 times higher than the control group at the concentration of 50 μg/ml. And the increased rate of T-AOC level in wild C. elegant was accordance to their survival rate at the oxidative stress.6. Anti-cancer activities of R. rogusa polyphenol in vitroUsing the tumor cell model in vitro, we could find that R. rogusa polyphenol possessed of siglilfieantly inhibited effects on the proliferation of human gastric cancer cells BGC-823, hepatoma carcinoma cells HepG-2, and colorectal cancer cells HT-29, with the maximum inhibition rates were 81.10%,72.69%和82.33%, repectively. But the colorectal cancer Caco-2 cells was weakly inhibited by R. rogusa polyphenol, with a inhibition rate of 61.39%.In conclusion, polyphenols extracted from R. rogusa gregs possessed QS inhibitory activity thus could be utilized as food preservative or antibacterial adjuvant. In addition, they could also be utilized as antioxidant in food or protective agent for certain nutrients (such as Vc). Meanwhile, R. rogusa polyphenols had good neutraceutical properties, which capable of prolonging the life span of C. elegans, retarding the aging process, and inhibiting cancer cell proliferation. The preparation of R. rogusa polyphenols was absent of toxic solvents, and there was no organic residues thus would have broad application prospects in the food industry. |
