Arboran A and B, fractionated by gel permeation, showed the following characteristics: arboran A, MW 12Kda, containing peptide moiety 2.5%; neutral sugar components Rha, Fuc, Ara, Xyl, Man, Gal, Glc; 0.3, 0.2, 0.1, 1.0, 0.2, 1.0, 0.3 in molar ratio; 16.7% of acetyl group; arboran B, MW, 57Kda, containing peptide moiety 10.4%; neutral components Man, Glc, 10.3:1.0 in molar ratio. When administered IP (inter-peritoneal) to normal mice, both arboran A and B diminished plasma glucose levels in a dose-dependent manner, and showed the marked hypoglycemic effects 24 hours after their administration IP at a concentration of 100mg/kg. In alloxan-produced hyperglycemic mice, both compounds also exerted significant blood sugar-lowering activity (Hikino etal, 1986).
Two lectins were isolated by salt precipitation, pH-dependent fractionation and gel filtration. Aloctin A has a molecular weight of c.18Kda, consists of two subunits and contains more than 18% by weight of neutral carbohydrate. The smaller subunit has a molecular weight of c.7.5Kda and the larger subunit a molecular weight of c.10.5 Kda. Aloctin B has a molecular weight of c. 24Kda, consisting of two subunits with a molecular weight of c. 12 Kda and contains more than 50% by weight of carbohydrates. The amino acid composition of aloctin A and B has a high proportion of acidic amino acids. Aloctin A showed mitogenic activity on lymphocytes precipitate-forming reactivity with serum proteins, and C3 activating activity via the alternative pathway. Aloctin B showed a strong hemagglutinating activity (Suzuki etal., 1979).
A plant lectin, ATF 1011
A plant lectin, ATF 1011, which was separable from aloctin A and B, lectins purified from the same origin on Sephadex G-100 column and characterized by the molecular weight and the lack of hemagglutination activity towards human erythrocytes, was investigated. ATF 1011 augmented tumor-specific immunity on the tumor cells surface through activation of T cells specific for the lectins (Yoshimoto etal, 1987).
Aloctin A markedly inhibited the growth of a syngenic transplantable fibrosarcoma of mice in ascites form. There is evidence that the inhibition mechanism is host-mediated and is not a direct effect on the tumor cell (Imanishi et al, 1981).
Aloelectin on DNA synthesis in baby hamster kidney cells
A homogeneous glycoprotein (MW 40 Kda) containing 34% carbohydrate was isolated from Kidachi aloe leaf. The glycoprotein was shown to stimulate deoxyribonucleic acid synthesis in baby hamster kidney cells at a concentration of 5 pg/ml and to have the properties of a lectin which reacts with sheep blood cells. The chemical and physical properties of the glycoprotein, aloelectin, are also demonstrated (Yagi et al, 1985).
Biological and pharmacological activity of aloctin A
Aloctin A prepared by Suzuki's method showed the following biological and pharmacological activities: hemagglutinating activity; cytoagglutinating activity; mitogenic activity on lymphocytes; precipitate-forming reactivity with a2-macroglobulin; complement C3-activating activity; inhibition of heat-induced haemolysis of rat erythro-cytes; antitumor effect; antiinflammatory effect; and inhibition of gastric secretion and gastric lesions (Saito, 1993).
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