Department of Microbiology, JIPMER, Pondicherry, India.
Department of Microbiology, JIPMER, Pondicherry, India.
J Ethnopharmacol. 2021 Oct 28;279:113930. doi: 10.1016/j.jep.2021.113930. Epub 2021 Feb 15.
Centella asiatica (L.) Urb or Indian pennywort is a plant of ethnopharmacological relevance, commonly called as Brahmi in South India known for its antimicrobial property in gut and for the treatment of other gut ailments. Natural anti-virulence drugs that disarm pathogens by directly targeting virulence factors or the cell viability and are thus preferred over antibiotics as these drugs impose limited selection pressure for resistance development. In this regard, an in-vitro experimental study was conducted to know the effect of extract of Centella asiatica(L.) Urb. on cholera toxin, gene expression and its vibriocidal effect on five standard strains of Vibrio cholerae; IDH03097 (El Tor variant), N16961 (El Tor), O395 (Classical) as well as five clinical strains (Haitian variant).
To study the effect of extract of Centella asiatica on Vibrio cholerae.
Crude extract was prepared from the leaves and stem part of the plant. The vibriocidal concentration was tested at different concentrations of the extract. The amount of cholera toxin released from the strains before and after exposure to the extract of Centella asiatica to Vibrio cholerae was measured using Bead ELISA. ctxA gene expression in the strains before and after exposure to extract of Centella asiatica was measured using quantitative real time PCR. All the above assays were performed with commercially obtained asiaticoside as well.
The vibriocidal activity was tested at the different concentration of the extract, where 1g/mL of crude extract and 12.5mg/mL of asiaticoside was found to be vibriocidal. The amount of cholera toxin released before and after the exposure to extract of C. asiatica was measured using Bead ELISA, showing a reduction of 70%, 89% and 93% toxin produced by classical, El Tor and variant respectively. ctxA gene expression before and after exposure to extract of Centella asiatica as well as asiaticoside was measured using qRT-PCR. We found a decrease in expression of ctxA gene transcription by 6.19 fold in classical strain, 4.29 fold in El Tor, 1.133 fold in variant strains and about 10.13-10.20 fold for the clinical strains of V. cholerae using the extract of C.asiatica while, the reduction with the exposure to the asiaticoside were 2.762 fold in classical strain, 4.809 in El Tor, 24.1 in variant strain and 34.77 - 34.8 for the clinical strains.
Centella asiatica extract inhibited the CT production in Vibrio cholerae as well as decreased the transcription of ctxA gene expression.
积雪草（L.）城市或印度金钱草是一种具有民族药理学相关性的植物，在南印度通常被称为 Brahmi，因其在肠道中的抗菌特性以及治疗其他肠道疾病而闻名。天然抗毒药物通过直接针对毒力因子或细胞活力来削弱病原体，因此优于抗生素，因为这些药物对耐药性发展的选择压力有限。在这方面，进行了一项体外实验研究，以了解积雪草提取物（L.）城市。对霍乱毒素、基因表达及其对五种标准霍乱弧菌菌株（埃尔托变种 IDH03097、埃尔托 N16961、古典 O395 以及五种临床菌株（海地变种）的杀菌效果的影响。
研究积雪草提取物对霍乱弧菌的影响。
从植物的叶子和茎部分制备粗提取物。以不同浓度的提取物测试杀菌浓度。使用 Bead ELISA 测量菌株在暴露于积雪草酸提取物前后释放的霍乱毒素量。使用定量实时 PCR 测量菌株在暴露于积雪草酸提取物前后 ctxA 基因的表达。所有上述测定均使用商业获得的积雪草酸进行。
在不同浓度的提取物中测试了杀菌活性，其中 1g/mL 的粗提取物和 12.5mg/mL 的积雪草酸被发现具有杀菌活性。使用 Bead ELISA 测量暴露于积雪草提取物前后释放的霍乱毒素量，结果显示经典、埃尔托和变体分别产生的毒素减少了 70%、89%和 93%。使用 qRT-PCR 测量暴露于积雪草提取物和积雪草酸前后 ctxA 基因的表达。我们发现经典菌株 ctxA 基因转录表达降低了 6.19 倍，埃尔托菌株降低了 4.29 倍，变异菌株降低了 1.133 倍，而临床菌株降低了约 10.13-10.20 倍。使用积雪草酸提取物时，而暴露于积雪草酸的减少量分别为经典菌株 2.762 倍、埃尔托菌株 4.809 倍、变异菌株 24.1 倍和临床菌株 34.77-34.8 倍。
积雪草提取物抑制霍乱弧菌 CT 的产生，并降低 ctxA 基因表达的转录。
