Chemical Compositions and Biological Activiities of Smoke Collected from Azadirachta Indica (Neem) and Olea Europaea (Olive) Leaves
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Date
2020-07-30
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Addis Ababa University
Abstract
This study aimed at the analysis of essential oil and smoke from neem and olive leaves for their
biological (antioxidants and insecticidal) activities. Essential oil was extracted using
hydrodistillation technique, and the smoke was collected using lab designed set of apparatus. The
chemical compositions of the oils and smoke were analyzed by Gas Chromatography Mass
Spectrometry (GC-MS). The test for antioxidant activities was performed using UV-Visible
spectroscopy. The antioxidant concentration of the sample was determined by using a calibration
curve constructed from standard ascorbic acid, and the insecticidal activity test (both repellent
and mortality) was conducted using cockroaches.
The measured average antioxidant concentrations for neem smoke trapped in methanol was
19.65% for 152.20 μg/mL, and for olive smoke trapped in methanol was 4.91% for 152.20
μg/mL. While, the antioxidant concentration test in the neem and olive smoke trapped in hexane
was found to be negligible. The time course insecticidal (insect repellent) activities were
performed at 10, 20, 30, 40, 50, and 60 minutes using 15 mg of the smoke trapped in hexane and
methanol against cockroaches.
For the neem hexane trapped smoke sample the minimum % repellent was 20 % at 10 minutes,
and the maximum was 81.24 % at 60 min, and for olive hexane trapped smoke was 14.16 % at
10 min and 77.96 % at 60 minutes. The neem methanol trapped smoke showed 42.92 % at 10
min, and 100 % at 60 min. The olive methanol trapped smoke showed 33.33 % at 10 min, and
92.10 % at 60 minutes. The time course insecticidal (insect mortality) activities were performed
at 3, 6, 9, 12, 24, and 36 hours using 1.25%, 2.5%, 5%, 10% samples concentration.
The minimum and maximum % mortality of neem hexane trapped smoke was 6.66 % at 1.25%
concentration in 3 h, and 80 % at 10 % concentration in 36 h, For olive hexane trapped smoke
the minimum rate was 6.66 % at 1.25% in 3 h, while the maximum was 60 % at 10 % over 36
h. For neem methanol trapped smoke the minimum was 20% at 1.25% concentration in 3 h and
the maximum was 100 % at 5 and 10% concentrations in 6 h, for the olive methanol trapped
smoke the minimum was 20 % at 1.25 % concentration at 3 h while, the maximum rate was
100% at 10 % concentration in 24 hours.
The major compounds detected in the neem hexane trapped smoke were Methyl Hexadecanoate
(12.11%), Methyl stearate (4.88%). The major compounds detected in olive hexane trapped
smoke were Methyl octadec-9-enoate (E)- (29.66%), Methyl (9Z,12Z) – octadeca-9,12-dienoate
(15.35%), Methyl Hexadecanoate (13.54%), The methanol trapped smoke of the neem showed
3,5-ditert butyl phenol (29.35%), Methyl Hexadecanoate (12.93%), 1,2-15,16-Diepoxy hexadecane
(7.92%) as major compounds, and the olive methanol trapped smoke showed 2,6-ditertbutyl
phenol (38.27%), Methyl Hexadecanoate (8.70%), (E) -Tetradec-2-ene (8.45%), as major
compounds. From the leaves the essential oil of neem extract showed Methyl tetracosanoate
(3.72%), 2,4-Bis (dimethyl benzyl)-6-t-butyl phenol (3.39%), Glabrol (2.79 %), as major
compounds, and the olive essential oil extract were Benzene acetaldehyde (3.24%), Ndesmethyltapentadol
(1.90%), 1-(2,6,6-trimethyl cyclohexa-1,3-dien-2-en-1-one (1.88%) as
major compounds.
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Keywords
Biological Activities, Antioxidant, Insecticidal, Bioassay, Neem, Olive Leaves