RESULTS AND DISCUSSION In all, more than 30 compounds were identified for each of the six regions where samples were
taken. Three compounds (thymol, borneol, and p-cymene) in high concentrations were common in all
six regions. Although the effects of harvest time on the studied traits were not significant (except for
borneol, thymol, and acetate granules contents and essential oil yield) (Table 1), the highest average
levels of the studied traits were observed at full flowering. The studied traits in the harvest regions
were not significantly different except for the terpene content (Table 1).
Table 1: ANOVA of the effects various harvest times and different regions had on photochemical
properties of thyme.
Source
of
change
Deg
ree
of
free
-
do
m
Mean squares
Terpe
ne
p-
Cymen
e
Linalo
ol
Borneo
l
thymol
Alpha
-
terpin
yl
acetat
e
Acetate
granule
s
Caryoph
yllene
Granul
es
Essential
oil
yield
Harvest
time
1
0.84
ns
0.03 ns
9.33*
1.42
ns
The symbols ns, *, **, represent not significant, significant at 5% probability level, and significant at
1% probability level, respectively.
The antioxidant activity of the extracts are determined based on the 50% inhibitory
concentration or LC
50
in mg/g dry matter. As mentioned previously, the antioxidant activity of the
essential oil has an inverse relationship with IC
50
; i.e., the paler the DPPH solution becomes in the
presence of the essential oil, the more the antioxidant activity of the essential oil is, and the lower its
IC
50
will be. Results showed the antioxidant activity of the essential oil was at its maximum at
flowering time (Table 2). Moreover, the maximum antioxidant activity of the essential oil was
observed in region 3 of the Qaflankuh mountain range, and the minimum in region 3 of the