Alpha-mannosidase activity in goats fed with Sida carpinifolia

Human α-mannosidosis results from α-mannosidase deficiency and progressive accumulation of mannose-rich oligosaccharides in lysosomes. Two days before Saanen goats were fed with Sida carpinifolia, α-mannosidase activity in leukocytes was 128±28 nmoles 4-MU/h/mg protein (first trial) and 104±6 nmoles 4-MU/h/mg protein (second trial). At day 5, after the introduction of S. carpinifolia diet, the α-mannosidase activity in leukocytes was significantly increased, both in the first (288±13 nmoles 4-MU/h/mg protein) and in the second trial (303±45 nmoles 4-MU/h/mg protein), and it returned to normal levels 2 days after the withdrawal of the plant from the diet (114±7 nmoles 4-MU/h/mg protein in first trial, and 108±25 nmoles 4-MU/h/mg protein in the second one). Plasma α-mannosidase activity decreased significantly 4 days after animal exposure to the S. carpinifolia diet (769±167 nmoles 4-MU/h/ml) and returned to normal values 10 days after the withdrawal of the plant from the diet (1289±163 nmoles 4-MU/h/ml). Thin-layer chromatography showed an abnormal excretion of oligosaccharides in urine as of day 2 after diet exposure, which persisted until one day after the withdrawal of the plant. Animals presented neurological clinical signs beginning at day 37 (in the first trial) and at day 25 (in the second trial) after being fed with the plant. The results obtained herein suggest that oligosaccharides observed in urine are a result of a decrease in α-mannosidase activity in plasma. S. carpinifolia seems to have other compounds that act on α-mannosidase enzyme in leukocytes in a competitive manner with swainsonine. The increase in α-mannosidase enzyme in leukocytes could be attributed to one of these compounds present in S. carpinifolia.