Eguale, Tadesse (PhD)Hailesillassie, Tibebu2018-10-242023-11-292018-10-242023-11-292017-12http://etd.aau.edu.et/handle/123456789/13123Evaluation of the in vitro acaricidal properties of the latex and major compounds isolated from the leaves of Aloe yavellana (Reynolds) against Amblyomma variegatum (ixodidae ticks). Tibebu Hailesillassie Addis Ababa University, 2017 Aloe yavellana Reynolds is endemic to Ethiopia where its leaf latex is traditionally used for the treatment of various illnesses of humans and domestic animals in Yabelo town and other pastoralist areas of south western part of the country. The latex and isolated compounds were assessed for their acaricidal activities against Amblyomma varigatum tick larvae by using larval packet test (LPT). At a concentration of 50 mg/ml, the leaf latex showed acaricidal activity 24 h post exposure, with percentage mortality (E %) of 62.50%. Phytochemical investigation of the leaf latex led to the isolation of two anthrones, identified as microdontin A/B and aloin A/B by means of spectroscopic techniques including ESI-MS, 1H, 13C NMR and DEPT spectral data. Among the isolated compounds, microdontin A/B showed E% of 30.83 at a dose of 50 mg/ml. EC50 and EC99 values of the latex, microdontin A/B and aloin A/B were estimated to be 35.82 and 83.48 mg/ml; 89.40 and 196.49 mg/ml; 257.69 and 585.98 mg/ml, respectively. On the basis of the above results the latex was found to be more effective in killing larvae ticks than the individual isolated compounds. Dose response data of the latex, microdontin A/B and aloin A/B indicated the gradual increase in mortality pattern with slopes and R2 values of 1.047 and 0.909; 0.459 and 0.946; 0.164 and 0.988, respectively. In conclusion, the leaf latex of A. yavellana and its isolated compounds could have the potential to be used as bioacaricides against ticks and tick born disease (TBDs).en-USAloe yavellana latex; Aloaceaae; Amblyomma varigatum; anthrones; microdontin A/B; aloin A/B.Thesis