Chemical composition
Carob leaves exhibited the highest concentrations of CP and ADF (P<0.05) than pods (Table 1). For carob leaves,
Silanikove et al., (1996) reported higher DM, ash and NDF contents; however, the CP level was similar (9%). Concerning carob fruits, the CP, NDF and ADF contents were slightly lower than those founded by
Obeidat et al., (2010).
The contents of chemical constituents (ash, CP, ADL) of
P. angustifolia leaves were higher than pods (P<0.05).
For
M. arborea,
Ventura et al., (1999) founded similar ash value, lower NDF content and higher ADF rate. This chemical composition variation’s can be due to several parameters such as: soil and air moisture, species and plant organ harvested
(Jarrige et al., 1995).
Polyphenolic compounds and biological activity
C. siliqua leaves showed the highest polyphenolic compounds and BA (P<0.05) than
C. siliqua pods (Table 2). In comparison to values reported by
Manolaraki et al., (2010), TP and TT values of carob were higher for leaves and lower for pods, CT rates of carob leaves and pods were lower and the carob leaves BA was similar.
P. angustifolia pods presented highest TP and TT contents than
P. angustifolia leaves (P<0.05). For CT and BA values, the tendency was reversed (P<0.05). This difference may be due to assay methods that do not measure all the same entities
(Aufrere et al., 2012). It should be noted that the highest values in CT and BA were recorded for leaves. Indeed,
Aufrere et al., (2012) reported that the majority of tannins were accumulated in young leaves and the secondary compounds rates varied according pedoclimatic conditions (water stress, light intensity), species, locality and the plant exploited organ’s of the plant.
Shrub’s effect on larval exsheathement assay
The effect of shrub was demonstrated without PVPP (P<0.001) and with PVPP, a tannin inhibitor (P=0.004) (Table 3). The highest % L3 exsheathed was recorded for
M. arborea (55.01%) and the lowest value was founded for
C. siliqua and
P. angustifolia leaves (16.26%). The % L3 exsheathed values for carob pods were higher than carob leaves. The leaves and pods of
P. angustifolia showed close values for %L3 exsheathed and also inhibition.
The % L3 exsheathed values founded for carob pods were higher than for leaves.
P. angustifolia leaves and pods showed close values for the % L3 exsheathed. The recorded value was equivalent to 39.20% for
M. arborea.
The highest inhibition was recorded for
C. siliqua leaves and
P. angustifolia leaves and pods. This strong inhibition could be due to their high content of secondary compounds and mainly to their high BA content. Indeed,
C. siliqua leaves and
P. angustifolia leaves and pods showed an inhibition higher than 50% so it may be considered as a bioactive plant with an interesting anthelmintic power.
Dose extract effect on larval exsheathement assay
Our results were concentration-dependent (P<0.001). As the doses increased, the % of exsheathment decreased to 29.74, 24.28, 18.80 and 16.39 for the doses 150, 300, 600 and 1200 µg/ml, respectively (Table 4). After addition of PVPP, the exsheathment trend reversed and was closer to that of PBS. Previous studies showed the same trend
(Alonzo-Diaz et al., 2008; Manolaraki et al., 2010; Oliveira et al., 2011).
The restoration of L3 exsheathment to values similar to PBS, after PVPP addition, indicates that tannins of these shrubs are involved in the AH effects against
H.contortus.
Incubation time effect on larval exsheathement assay
The result of incubation time effect on the % of exsheathment without and with PVPP was reported in Table 5. The % of exsheathment increased as the time of incubation increased (P<0.001) as reported by
Aïssa
et_al(2015).
Interaction effects
Table 6 summarized data from the LEA. The interaction (shrub×time×dose) was significant (P<0.001). For PBS, the %L3 exsheathed of
H.contortus ranged from 91.51% for
C.siliqua leaves to 96.43% for
P. angustifolia pods at 60 min. At the highest concentration, the % L3 exsheathed at 60min ranged from 0.00% to 93.75% for
C. siliqua leaves and
M. arborea, respectively. Indeed, AH was important for
C.silique and
P. angustifolia (leaves and pods). These results are in agreement with other studies that reported shrub’s AH activity
(Alonso-Diaz et al., 2008; Oliveira et al., 2011). The variability of the AH effect is mainly due to variability in their phenolic compounds at the quantitative and qualitative level
(Manolaraki et al., 2010).
After PVPP addition, all the extracts of the studied shrubs showed a restoration of the L3 exsheathment values similar to the control values (P<0.001) (Table 7).
Alonso-Diaz et al., (2008) and
Oliveira et al., (2011) also noted that the % of exsheathment was completely reversed. This suggests a major role of tannins, especially CT.
Molan et al., (2003) mentioned that CT have the property of forming complexes with macromolecules including proteins and in our case the proteins of parasites
(Manolaraki et al., 2010).
Effective concentration for 50% inhibition
EC50 was different (p<0.05) for plant extract (Table 8).
C. siliqua leaves showed a lower EC50 than pods. However, the EC50 of
P. angustifolia pods and leaves were similar.
M. arborea had an EC50 around 954.08 μg/ml. More EC50 was lowest and the shrub sample’s was more effective against the exsheathment of L3 larvae, helping to prevent animal infestation.