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https://ptsldigital.ukm.my/jspui/handle/123456789/485630| Title: | Mosquitocidal properties of selected seaweeds against aedes aegypti and aedes albopictus (diptera: culicidae) |
| Authors: | Yu Ke Xin (P56284) |
| Supervisor: | Ibrahim Jantan, Prof. Dr. |
| Keywords: | Seaweed Mosquito Aedes aegypti Aedes albopictus Dissertations, Academic -- Malaysia Universiti Kebangsaan Malaysia -- Dissertations |
| Issue Date: | 5-Oct-2016 |
| Description: | The ever-increasing threat from infectious diseases and the development of insecticide resistance in mosquito population urge the international community to search for new naturally derived insecticides. The long history of seaweed products in food and pharmaceutical industries supports insecticide research on discovering new active agents in seaweeds. In the present study, seaweeds collected in Malaysia, namely Bryopsis pennata, Padina australis and Sargassum binderi were proven to have active larvicidal activity against Aedes aegypti and Ae. albopictus. These seaweeds were subjected to further investigation, in order to determine their other mosquitocidal potentials, characterize their chemical constituents, and assess their toxicity against brine shrimp nauplii. The proximate composition and mineral contents of the three seaweeds were determined. In addition, methanol extracts of the seaweeds were analysed by using high performance liquid chromatography (HPLC) and liquid chromatography-mass spectroscopy (LC-MS). Among all the extracts and fractions tested, A7 fraction of chloroform extract of green seaweed B. pennata exhibited the strongest larvicidal activity against Ae. aegypti (LC50 value: 4.65 μg/mL) and Ae. albopictus (LC50 value: 5.32 μg/mL). The results of LC-MS analysis suggested that bis-(3-oxoundecyl) tetrasulfide was the major component in A7 fraction. The strong larvicidal activity of this compound may be linked to its aliphatic chemical structure with long hydrocarbon chain. The morphology study done by using light and scanning electron microscopes showed that the extract-treated larvae had deformed anal papillae and damaged stigma plate of terminal spiracle. These aberrations were suggested to affect the function of osmo-regulatory and spiracle respiratory of larvae. In the histopathology study, the midgut epithelial cells of treated larvae were identified as the most susceptible region to the extract treatment. Methanol extract of B. pennata exhibited in vitro acetylcholinesterase (AChE) inhibition by using homogenates of Ae. aegypti (IC50 value: 0.84 mg/mL) and Ae. albopictus (IC50 value: 0.91 mg/mL) as enzyme source. Furthermore, AChE kinetic assay revealed that methanol extract of B. pennata displayed mixed type inhibition. In the adulticidal assay, methanol extract of brown seaweed P. australis exhibited the strongest lethal effect among the three seaweeds, against females of Ae. aegypti (LC50 value: 30.80μg/mL) and Ae. albopictus (LC50 value: 36.21 μg/mL). The most effective repellent towards oviposition of Ae. aegypti and Ae. albopictus females was methanol extract of B. pennata with RC50 values of 44.36 and 51.60μg/mL, respectively. In the ovicidal assay, methanol extract of B. pennata exhibited the strongest lethal effect against eggs of Ae. aegypti (LC50 value: 315.30μg/mL) and Ae. albopictus (LC50 value: 396.60μg/mL). In the sublethal assay, B. pennata was noted to induce higher mortality in eggs and larvae, while S. binderi and P. australis were observed to prolong larval period and to induce higher delay mortality. Extracts of these seaweeds exhibited relative low toxicity against brine shrimp nauplii. Future investigation is to necessitate the isolation and elucidation of the potential larvicidal compounds in A7 fraction, as well as to determine their mosquitocidal activity. In conclusion, among the three seaweeds, B. pennata offers potential biological advantages in the development of target-specific mosquito larvicide.,Ph.D. |
| Pages: | 257 |
| Call Number: | QV20.5.Y94m 2016 9 Tesis |
| Publisher: | UKM, Kuala Lumpur |
| Appears in Collections: | Faculty of Pharmacy / Fakulti Farmasi |
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| ukmvital_98535+Source01+Source010.PDF Restricted Access | 437.59 kB | Adobe PDF |  View/Open |
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