Biology Reference
In-Depth Information
but inhibited ecdysis, whereas oral injection of
25 mg/ml of
n-
hexane resulted only in a delay of
the normal moult to the fifth instar. Doubling
the oral dose of verbascoside, ethyl acetate and
methanol extracts to 50 mg/ml, after 48 and 72 h
induced prothetely the appearance of preco-
cious pupal structures in the larvae, in some
(30%) of the treated fourth instar larvae. These
larvae moulted directly to pupae. Prothetely
can sometimes be elicited experimentally in
larvae by the application of juvenile hormone
or juvenile hormone mimics (Truman and
Riddiford, 2002). Extract-induced prothetely
resulted in precociousness and browning of
pupae in roughly half of the controls.
concentration. The aqueous extract, however,
showed a percentage reduction of 97.74% to
47.46% at concentrations from 300 ppm to
50 ppm. The ethyl acetate extract showed
the highest antioxidant capacity at the
same concentrations, being the maximum of
97.58% at 300 ppm and 64.87% at 50 ppm.
15.5.10
Condalia mycrophylla
Cav.
The milled sample from the aerial parts of
C. microphylla
was macerated with methanol
and further partitioned with
n-
hexane, ethyl
acetate and water. These extracts were used
in a preliminary bioassay trial. Subsequently,
in order to obtain more satisfactory data for
insecticidal activity, some bioassays were
carried out at lower concentrations. Gedunin
and methanol extract from
Cedrela salvado-
rensis
(Me-Ced) were used as patterns and
positive controls (Céspedes
et al.
, 2000,
2004, 2005; Torres
et al.
, 2003).
15.5.9
Antioxidant activity of
C. talcana
The antioxidant activity of extracts of
C. tal-
cana
was evaluated using DPPH. All extracts
showed some ability to sequester free
radicals (Table 15.7, Fig. 15.3). The hexane
extract showed a lower antioxidant capa-
city, reaching a percentage reduction of only
8.1% at concentrations as high as 300 ppm.
The methanolic extract had an intermediate
value of 41.35% activity at the same
15.5.11
Phytochemical analysis
Table 15.8 shows the
n-
alkane composition
(%) of
C. microphylla
. In the present work,
Table 15.7.
Antioxidant activity of extracts from
Calceolaria talcana.
Extracts
Concentration (ppm)
DPPH Reduction (%)*
n
-Hexane
300
8.10 ± 0.72
200
5.09 ± 0.45
100
3.90 ± 0.34
50
2.63 ± 0.23
300
41.35 ± 3.67
Methanol
200
31.97 ± 2.83
100
18.31 ± 1.62
50
12.21 ± 1.08
300
97.74 ± 8.67
Aqueous
200
97.11 ± 8.62
100
59.45 ± 5.27
50
47.46 ± 4.21
300
97.58 ± 8.66
Ethyl acetate
200
97.05 ± 8.62
100
69.27 ± 6.15
50
64.87 ± 5.76
*DPPH Reduction %: (Blank absorbance - extract absorbance / blank absorbance) × 100. Each
value corresponds to the average of the three different experiments ± SD. The significance level
is
p
<95%.
Search WWH ::
Custom Search