Screening for Antimicrobial Thai Plants by Directed TLC-Bioautography

Abstract

Medicinal plants have been discovered and used as traditional drugs since ancient years. At the present, modern drugs have killed a large number of people due to a drug of resistance, and the best solution to solve this problem was medicinal herbs. The goal of this project was to examine the antibiotic compounds from Thai herbs in our daily lives. However, Thai plants were only screened for antimicrobial activity as the time limited. In this study, 10 Thai plants were selected to screen the antimicrobial activity against methicillin-resistant Staphylococcus aureus by using directed TLC-bioautography and agar disc diffusion method. S.aureus was used to examine each crude extract as this bacteria can cause common severe illnesses. The methanol was used as the main solvent for plant extracts. However, there were 7 out of 10 crude extracts that represented the good separation of the metabolite spot on the TLC plate which were Zingiber officinale, Piper nigrum, Andrographis paniculata, Centella asiatica, Curcuma longa, Garcinia mangostana, and Lycopersicon esculentum Mill. For the other 3 plant extracts, they performed less separation on the TLC plate including Allium sativum, Allium ascalonicum, and Cymbopogon citratus. For the agar disc diffusion technique, Centella asiatica has been exhibited the highest antibacterial properties in the second trial with the amount of 700 ug crude extract. Furthermore, in the directed TLC-bioautography assay, the compounds of Andrographis paniculata and Garcinia mangostana have been performed to have clear zones on the TLC plate to represent antimicrobials.