School of Biological Sciences, Universiti Sains Malaysia, USM 11800, Penang, Malaysia.
N Biotechnol. 2010 Sep 30;27(4):390-6. doi: 10.1016/j.nbt.2010.02.002. Epub 2010 Feb 17.
Methanol extract of the Gracilaria changii has been screened for antimicrobial activity against Pseudomonas aeruginosa. Antimicrobial activities were carried out using disc diffusion assay and broth dilution method against P. aeruginosa. The methanol extract of G. changii showed a good antimicrobial activity against P. aeruginosa with MIC (Minimum Inhibitory Concentration) value of 6.25mg/ml. Exposure of P. aeruginosa cells to 6.25mg/ml of methanol extract of G. changii resulted in complete inhibition of the bacterial cells. The main abnormalities noted via SEM and TEM studies were the alterations in morphology and cytology of the bacterial cells. The main reason for this deterioration was discussed. The effect of the methanol extract on the growth profile for the bacteria was also done and confirmed the bactericidal effect of the G. changii methanol extract on P. aeruginosa by changing the normal growth profile of P. aeruginosa. In an acute toxicity study using mice, the median lethal dose (LD(50)) of the extract was greater than 2000 mg/kg, and we found no pathological changes in macroscopic examination by necropsy of mice treated with extract. We conclude that G. changii might be safely used as an antimicrobial agent.
石花菜甲醇提取物对铜绿假单胞菌的抗菌活性进行了筛选。采用圆盘扩散法和肉汤稀释法对铜绿假单胞菌进行了抗菌活性试验。石花菜甲醇提取物对铜绿假单胞菌表现出良好的抗菌活性，MIC（最小抑菌浓度）值为 6.25mg/ml。暴露于 6.25mg/ml 石花菜甲醇提取物的铜绿假单胞菌细胞完全被抑制。通过扫描电子显微镜和透射电子显微镜研究观察到的主要异常是细菌细胞形态和细胞学的改变。讨论了造成这种恶化的主要原因。还对甲醇提取物对细菌生长曲线的影响进行了研究，并通过改变铜绿假单胞菌的正常生长曲线证实了石花菜甲醇提取物对铜绿假单胞菌的杀菌作用。在使用小鼠的急性毒性研究中，提取物的半数致死剂量（LD50）大于 2000mg/kg，并且我们在通过对提取物处理的小鼠进行尸检的宏观检查中未发现任何病理变化。我们得出结论，石花菜甲醇提取物可以安全地用作抗菌剂。
