Phytochemical Investigation of Essential Oil and Organic Extracts of <i>Vitex trifolia</i> L. and their Larvicidal Activities Against <i>Aedes aegypti</i> Larvae In Penang, Malaysia

Aedes aegypti is one of the major species of mosquitoes considered to be highly dangerous, as it transmits diseases such as dengue fever and dengue haemorrhagic fever, which are major public health problems in Malaysia. The use of botanicals in the control of Aedes aegyptiis essential because of the development of mosquito resistance against most synthetic insecticides employed for vector control. This study was conducted to investigate the phytochemical effects of the essential oil and organic extracts of Vitex trifolia L. and their larvicidal activities against Aedes aegyptilarvae in Penang, Malaysia. The stems, leaves, fruits, and flower buds of V. trifolia plants were collected, air-dried, and extracted using hydrodistillation and maceration methods. The phytochemical constituents were investigated using gas chromatography-mass spectrometry (GC-MS). The larvicidal activity of V. trifolia was evaluated against third-instar larvae of Aedes aegypti after 24 h of treatment. The results revealed that the highest larvicidal activity was observed with the methanolic flower bud extract and the chloroform flower bud extract which resulted in 100% larval mortality at the lowest concentration of 17.5 ppm. Moreover, the methanol flower bud extract of V. trifolia showed relatively high larvicidal activity against the third instar larvae of Ae. aegypti with a relatively low LC and LC of 9.59 ppm and 16.03 ppm, respectively. However, methanol stem 50 90 extract showed the highest LC and LC of 615.41 ppm and 763.56 ppm, 50 90 respectively, leading to the lowest larvicidal activities. In addition to the essential oils obtained, the results revealed the presence of phytochemicals, including flavonoids, saponins, tannins, glycosides, and steroids in the plant extract. In conclusion, the larvicidal activity profile of the essential oil from the sample depends on its concentration and extraction techniques. Therefore, additional quantitative research on these phytochemicals should be conducted to investigate their biomedical functions.