Analysis Of Active Constituents And Researches On Polysaccharides Of Aloe Barbadensis Miller Irrigated With Sea Water

The deterioration of environment, serious scarcity of fresh water and continued reducing arable land in the world has threatened the survival and development of human society. Therefore, it is of great significance to make use of saline and sea resource to cultivate economic crops. Aloe barbadensis Miller is a perennial tropical/subtropical plant with succulent and elongate leaves. The plant is a member of the lily family (Liliaceae). At present, it is the widest species used as food, medicine and cosmetic for its therapeutic properties. Since 1980s', many states have been paid more attention to Aloe barbadensis Miller for its curative effect and supernatural virtue.Field experiments were conducted over a period of 3 years to evaluate long-term different concentration of sea water irrigation (0% (CK), 10%, 25%, 50%, 75% and 100%) on yield of Aloe barbaadensis Miller and biochemical constituents of its whole leaf juice. Results indicated that no differences were found among the yield of aloe irrigated with 10%, 25% sea water and fresh water. However, the yield exhibited reductions with the increase of sea water concentration when it exceeded 50%. Increase of sea water concentration caused a considerable increase in absorbance and the contents of soluble protein, Mg²⁺ and Na⁺. A slight increase in contents of Fe^2+,3+ and Zn²⁺ in whole leaf juice irrigated with sea water compared with that irrigated with fresh water was found. The contents of Ca²⁺ and Mn²⁺ increased sharply with the increase of sea water concentration and reached the highest in 50%, which increased 100% and 70% than that irrigated with fresh water, respectively. However, aloin and K⁺ contents reduced consistently with the progressive increase of sea water concentration. The results of 3-year consecutive field experiments indicated that the contents of soluble saccharides, total flavones and total solids of aloe whole leaf juice had no significant difference when the concentration of sea water was less than 25%, but when sea water concentration exceeded 50%, they all increased sharply. Moreover, the contents of polysaccharides in whole leaf juice of aloe irrigated with 10%, 25% and 50% increased distinctly, while other levels were no significant changes compared with that irrigated with fresh water. Vitamin C content in whole leaf juice of aloe only irrigated with 25% and 50% sea water increased distinctly compared with that irrigated with fresh water. In addition, no significant changes were found in the pH, relative density and the contents of Ni²⁺, Pb²⁺, Cu²⁺ and Cd²⁺ of whole leaf juice in all levels. Two new polysaccharides, GAPS-1 and SAPS-1, were isolated from the gel and the skin of Aloe barbadensis Miller irrigated with 100% sea water through a combination of anion-exchange column chromatography and repeated gel chromatography. GAPS-1 and SAPS-1 was composed of Mannose: Glucose: Galactose in a ratio of 120:2:3 and 296:36:1 with their molecular weight 174 kDa and 39.7 kDa, respectively. IR and NMR study of GAPS-1 and SAPS-1 demonstrated that the main skeletons of GAPS-1 wasβ- (1→4) -D linkaged mannose with acetylation at C-3 and C-6 of manopyranosyl and SAPS-1 wasβ- (1→4)-D linkaged galactoglucomannan with acetylation at C-6 of pyranosyl. The degree of acetylation of GAPS-1 and SAPS-1 was 0.53 and 0.40, respectively.In order to study bioactivities of GAPS-1and SAPS-1, the in vitro antioxidant activities, antitumor, immunomodulating acitivies of GAPS-1 and SAPS-1 were investigated. In a concentration-dependent manner, GAPS-1 and SAPS-1 were demonstrated to have antioxidant activities, especially high scavenging activities against superoxide radical. The in vitro growth-inhibition of Hela, MCF-7, BGC, 3T3-L1 cells were evaluated with MTT tetrazolium assay. The results indicated that GAPS-1 and SAPS-1 had antitumor activities, but were nontoxic and did not cause significant side effects to normal cells. With the same methods, the immunomodulating activities of GAPS-1 and SAPS-1 were studied. GAPS-1 and SAPS-1 could enhance lymphocyte proliferation spontaneously and induced by ConA. They could repair the injured spleen cells by ultraviolet ray. The functions may be relevant to their significant antioxidant activities. They also could activate RAW264.7 cells function and increase RAW264.7 cytotoxic activity against Hela cells.The antioxidant mechanism of GAPS-1 and SAPS-1 may be directly scavenging free radicals, chelating the metal ions required in ROS reaction and their anomeric carbon donating hydrogen atom to terminate radical chain reactions. Their antitumor mechanism were directly hurting tumor cells and strengthening immunocompetence of the body. The latter may be relevant to their antioxidant activities and their activation to macrophages cells.