RESUMO
OBJECTIVE@#To explore the effect of the composition ratio on substitution of sulfate group in sulfated exopolysaccharide (EPS) from and how sulfate modification affects the anti-tumor activity of EPS.@*METHODS@#We used a chlorosulfonic acid-pyridine method to modify EPS and analyzed the effect of esterification ratio on the degree of sulfate substitution using barium chloride turbidimetry. The sulfate groups binding with EPS were analyzed with infrared spectrum analysis. CCK-8 assay was used to evaluate the inhibitory effect of EPS sulfate (SEPS) on the proliferation of human colon cancer HCT 116 cells, and annexin V-FITC/PI double staining was used to assess the pro-apoptotic effect of SEPS in the cells.@*RESULTS@#The esterifying agent and EPS at the composition ratios of 1:1 and 2:1 resulted in sulfate substitution of 0.98% (SEPS-1) and 1.18% (SEPS-2), respectively, and the substitution was improved by increasing the ratio of the esterifying agent ( < 0.05). Infrared spectrum analysis showed that the S=O stretching vibration absorption peak of -OSO appeared near 1249 cm, indicating that the sulfate group combined with EPS to form sulfate. CCK-8 assay showed that SEPS-1 produced stronger inhibitory effects on the proliferation of HCT 116 cells than EPS within the concentration range of 0.02-0.10 mg/L ( < 0.05). At the concentrations of 0.04-0.08 mg/L, SEPS-2 showed a lower anti-tumor activity than SEPS-1 ( < 0.05). SEPS-1 also showed stronger pro-apoptotic effect than EPS, and as its concentration increased, SEPS-1 dose-dependently increased the ratio of early apoptotic cells and necrotic cells; the cells treated with 0.06, 0.08 and 0.10 mg/mL SEPS-1 showed early apoptotic rates of 6.38%, 11.8% and 12.5%, and late apoptotic and necrotic rates of 5.26%, 8.04% and 6.80%, respectively.@*CONCLUSIONS@#The composition ratio of the esterifying agent has a direct impact on the degree of substitution of EPS, which can be improved by increasing the ratio of the esterifying agent. Sulfate modification of EPS can enhance its antitumor activity, which, however, is not directly related with the degree of substitution.
RESUMO
Aim To study the inhibitory effect of ex-opolysaccharide from Rhizopus nigricans ( EPS) combined with oxaliplatin on colon cancer in rats and its mechanism. Methods Colon cancer model in rats was established by subcutaneous injection of 1,2-dime-thylhydrazine ( DMH). The experimental rats were randomly divided into five groups: Control group, model group, EPS group (150 mg • kg-1 ) , oxaliplatin group (10 mg • kg-1 ) and EPS + oxaliplatin group. The his-topathological changes of colon tissues in rats were observed by HE staining. The expression levels of Sur-vivin, caspase-3 and caspase-7 proteins in colon tissues were detected by Western blot and immunohisto-chemistry. Results HE staining results showed that the damage degree of colon tissues could be significantly improved in treatment groups. Compared with model group, the expression of Survivin protein in treatment groups decreased significantly, and the expression of caspase-3 and caspase-7 proteins increased ( P < 0. 05). Conclusions Both EPS and oxaliplatin inhibit colon cancer in rats, and the synergistic effect is more remarkable. Its mechanism may be through inhibiting the expression of Survivin protein and increasing the expression of caspase-3 and caspase-7 proteins, thereby promoting the apoptosis of tumor cells and inhibiting the occurrence and development of tumors.
RESUMO
A soft rot of fruits caused by Rhizopus nigricans occurred on peach (Prunus persica var. vulgaris ) in The Chinju City Agricultural Products Wholesale Marke during in summer season of 2000. The disease infection usually started from wounding after harvest fruits, and then moved to outside. At first, the lesions started with water soaked and rapidly softened and diseased area gradually expanded. In severely infected film house, the rate of infected fruits reached 65.2%. Numerous sporangiospores were produced on the diseased fruits. Most of the sporangiospores were appeared to be readily dispersed in the air. The mycelia grew surface of fruits and produced stolons. Colonies on potato dextrose agar at 25~30degrees C white cottony at first becoming heavily speckled by the presence of sporangia and the browinish black at maturity, spreading rapidly by means of stolons fired at various points to the substrate by rhizoids. Sporangia were 85.3~243.5x53.4~219.2microm in size and were globose or sub-globose with. somewhat flattened base. The color of sporangia was white at first and then turned black with many spores, and never over-hanging. Sporangiophores were 8.9~36.6microm in width, smooth-walled, non-septate, light brown, simple, long, arising in groups of 3~5 from stolons opposite rhizoids. Sporangiospores was 9.7~24.8x5.9~15.8microm, irregular, round, oval, elongate, angular, and browinish-black streaked. Columella was 70.2x149.7microm. brownish gray, and umberella-shaped when dehisced. The causal organism was identified as. Rhizopus nigricans Lind on the basis of the morphiogical characteristics of the fungus. Rhizopus soft rot on peach (Prunus persica ) caused by the fungi has not been reported in Korea. This is the first report of rhizopus soft rot on peach caused by Rhizopus nigricans in Korea.