In vitro antimicrobial activity of stokes purple and johorean blue sweet potatoes (Ipamoea Batatas (L.)) extracts

Ipomoea batatas or sweet potato is the plant that are commonly consumed by the people around the world. However, people only consume the Ipomoea batatas as their food without knowing that the Ipomoea batatas does have many benefit such as antimicrobial, anti-fungi, antioxidant and anti-inflammatory effect resulting from their phytochemical components in the plant. The aim of this study are to determine the antimicrobial activity of 2 different type of sweet potato which are Stokes purple and Johorean blue sweet potatoes. In this study, peel, flesh and tuber extract of Stokes purple and Johorean blue sweet potatoes were prepared in different polarity of solvents which were ethanol 50%, distilled water and hexane by using Soxhlet extraction method. The plant extracts were being tested by using Agar well diffusion technique in order to know the antimicrobial activity in the sweet potato. The antimicrobial activity of the plant were determine by measuring the diameter zone of inhibition that occur on the agar plate. The result from this study show that from the antimicrobial test between Stokes purple sweet potato extracts against S. aureus, ethanol 50% tuber of Stokes purple give the highest diameter zone of inhibition with the reading 15.05 mm. Then, the antimicrobial test between Stokes purple sweet potato extracts against E.coli show that distilled water flesh of Stokes purple sweet potato extracts give the highest diameter zone of inhibition with the reading 18.35 mm. After that, the antimicrobial test between Johorean blue sweet potato extracts against S. aureus resulted with the highest diameter zone of inhibition with the reading 18.5 mm is from the hexane peel of Johorean blue extracts. While the antimicrobial test between Johorean blue sweet potato extracts against E. coli show that the peel hexane of Johorean blue sweet potato extracts also give the highest diameter zone of inhibition with the reading 15.6 mm. The diameter zone of inhibition of this study is dependent to the type of solvent used to extract the extracts, type of sweet potato, concentration and the type of bacteria that was tested during the test. From the result, it can be conclude that when the concentration of the extracts were increased, the reading of the diameter zone of inhibition also increased. The data showed that the hexane peel of Johorean blue sweet potato extract has the highest diameter zone of inhibition from the other extracts, but from the overall result, the Stokes purple sweet potato extracts has more higher antimicrobial activity compare to Johorean blue sweet potato extract. While the most suitable solvent that can be used to extract the antimicrobial compound in the Stokes purple and Johorean blue sweet potato is the hexane solvent, this is because the extracts that give the highest reading of diameter zone of inhibition zone were mostly the extracts that were extracted by using the hexane solvent. Then, between the Staphylococcus aureus bacteria and Escherichia coli bacteria, the S. aureus bacteria is more easily to be inhibited by both of the sweet potatoes extracts compare to E. coli bacteria. In, overall the result obtained in this study show that both of the sweet potato contain antimicrobial activity.