Department of Chemistry, School of Advanced Sciences, VIT University, Vellore 632014, India.
Department of Biomedical Sciences, VIT University, Vellore 632014, India.
J Photochem Photobiol B. 2017 Apr;169:148-160. doi: 10.1016/j.jphotobiol.2017.03.007. Epub 2017 Mar 9.
The investigation was conducted to analyse the bioactive compounds from the leaf extracts of L. speciosa by GC-MS. The extracts were screened for antibacterial and antibiofilm activities against potential clinical strains. The bioactive compounds from the leaves of L. speciosa were extracted by soxhlet continuous extraction method and their chemical composition was analysed by Gas Chromatography-Mass Spectroscopy (GC-MS). The antibacterial activity was evaluated against clinical strain like Staphylococcus aureus, Escherichia coli, P. aeruginosa and Salmonella typhi by well diffusion technique. We also screened for antibacterial property against common food borne pathogens namely Listeria monocytogenes and Bacillus cereus at varied concentration 250μml to 1000μml. Thereafter antibiofilm assay was carried out at from 250 to 1000μg/ml against P. aeruginosa (high biofilm forming pathogen) clinical strain by cover slip technique and the morphology of the pathogen was observed using Scanning Electron Microscopy-(SEM). It was observed that diverse class of secondary metabolites were found by GC-MS analysis for all the extracts upon the continuous extraction. It was found that only minimum inhibition was seen in alcoholic extract for antibacterial activity, whereas all other extracts showed negligible activity. P. aeruginosa biofilm inhibited to 93.0±2% and 91±2% at higher concentration (1000μg/ml) for methanolic and ethanolic extract respectively. Absence of extracellular matrix structure and the surface cracking of biofilm were viewed by SEM, which confirmed the antibiofilm activity. Hence this study reveals that L. speciosa showed significant antibiofilm activity against P. aeruginosa due to the phytoconstituents present in the leaf extracts which was well documented in the alcoholic extracts by GC-MS analysis. The methanolic and ethanolic extract showed good photocatalytic activity of 77.44% and 96.66% against azo dye degradation respectively. Further, isolating the novel phyto-compounds would yield better promising biological activities.
本研究通过 GC-MS 分析了大花紫玉盘叶提取物中的生物活性化合物。提取物被筛选出具有针对潜在临床菌株的抗菌和抗生物膜活性。采用索氏连续提取法从大花紫玉盘叶中提取生物活性化合物，并通过气相色谱-质谱联用技术（GC-MS）分析其化学成分。采用平板扩散法评估其对金黄色葡萄球菌、大肠杆菌、铜绿假单胞菌和伤寒沙门氏菌等临床菌株的抗菌活性。我们还筛选了不同浓度（250μml 至 1000μml）的常见食源性病原体李斯特菌和蜡样芽孢杆菌的抗菌特性。然后，通过盖玻片技术在 250 至 1000μg/ml 浓度下对铜绿假单胞菌（高生物膜形成病原体）临床株进行抗生物膜测定，并通过扫描电子显微镜（SEM）观察病原体的形态。GC-MS 分析表明，所有提取物在连续提取过程中都发现了不同类别的次生代谢产物。结果发现，只有酒精提取物在抗菌活性方面表现出最小的抑制作用，而其他提取物则表现出可忽略的活性。甲醇和乙醇提取物在较高浓度（1000μg/ml）下对铜绿假单胞菌生物膜的抑制率分别为 93.0±2%和 91±2%。SEM 观察到无细胞外基质结构和生物膜表面破裂，证实了其抗生物膜活性。因此，本研究表明，大花紫玉盘由于叶提取物中存在的植物成分，对铜绿假单胞菌表现出显著的抗生物膜活性，这在 GC-MS 分析的酒精提取物中得到了很好的证明。甲醇和乙醇提取物对偶氮染料降解的光催化活性分别为 77.44%和 96.66%。进一步分离新型植物化合物将产生更好的有前途的生物活性。
