2.1.2 Allelophatic Effects of P. juliflora Carbohydrates and Phenolic
Compounds
In addition to the presence of alkaloids in its chemical constitution, polysaccharides
and several secondary metabolites such as flavonoids, phenolic derivatives, tannins,
saponins, terpenoids, and coumarin were detected from different parts of Prosopis
juliflora [30, 58, 59]. Many secondary metabolites produced by plants and also
microorganism can act as a potential allelochemicals, but just having the presence of
these compounds does not establish the allelopathic process [60, 61].
Regarding the P. juliflora polysaccharides, the presence mainly of
galactomannans with different proportions of mannose and galactose has been
reported, as well as compounds formed by arabinose and glucose [58, 62–68].
However, although the presence of carbohydrates in P. juliflora is well reported,
along with its many activities, probably the allelopathic activity reported in the
species cannot be attributed to these primary metabolites. Therefore, additional
efforts to better comprehend this issue are necessary.
Only one paper that related the presence of carbohydrates in vegetal growth has
been found so far. Hedin, McCarty, and Dollar [69] evaluated the effect of commercial formulations on the yield of cotton (Gossypium hirsutum) lint. According to the
authors, bioregulators have an important role in plant growth and may induce the
biosynthesis of allelochemicals. This way, the commercial product tested presents a
carbohydrate fraction composed of xylose, mannose, galactose, and glucose that
when applied as a foliar spray tends to increase the yield of cotton lint. Although the
results were not statistically significant, they did show consistently small increases
which have not been reported so far for carbohydrates [69].
Historically, the literature reports several studies using different concentrations of
aqueous extracts of the leaves, barks, and roots of P. juliflora in the search for
allelochemical compounds. Thus, it is well reported that in areas adjacent to species
and especially beneath the tree canopy, there is a decrease in seed germination and
growth of other competing species caused by the action of allelochemical compounds of P. juliflora [70–73].
This way, the allelopathy exercised by P. juliflora described in the literature is
related to the secondary metabolites of the species, which may act as the main
allelochemical compounds [70–73]. According to Getachew, Demissew, and
Woldemariam [73], P. juliflora presents its allelochemical compounds in different
parts of the plant and in different amounts and the leaves are responsible for the
greater inhibitory effects, whereas the barks and roots present less activity.
Phenolics are a common class of secondary metabolites which depending on the
nature and availability in the soil and could play an important role in allelopathy. The
term “phenolic compounds” also could be related to aromatic phenols, benzoic acids
and aldehyde, cinnamic acids, coumarins, tannins, and flavonoids [2, 60, 61, 74].
The phenolic compounds can act through several mechanisms such as (1) changing the membrane permeability leading to increased permeability, contents spill
and increased lipid peroxidation and inhibiting plants from absorbing nutrients;
(2) inhibiting root elongation, cell division and changes in cell structure; (3) weakening
oxygen absorption capacity and reducing chlorophyll content and photosynthetic
530
G. A. de Brito Damasceno et al.
Compounds
In addition to the presence of alkaloids in its chemical constitution, polysaccharides
and several secondary metabolites such as flavonoids, phenolic derivatives, tannins,
saponins, terpenoids, and coumarin were detected from different parts of Prosopis
juliflora [30, 58, 59]. Many secondary metabolites produced by plants and also
microorganism can act as a potential allelochemicals, but just having the presence of
these compounds does not establish the allelopathic process [60, 61].
Regarding the P. juliflora polysaccharides, the presence mainly of
galactomannans with different proportions of mannose and galactose has been
reported, as well as compounds formed by arabinose and glucose [58, 62–68].
However, although the presence of carbohydrates in P. juliflora is well reported,
along with its many activities, probably the allelopathic activity reported in the
species cannot be attributed to these primary metabolites. Therefore, additional
efforts to better comprehend this issue are necessary.
Only one paper that related the presence of carbohydrates in vegetal growth has
been found so far. Hedin, McCarty, and Dollar [69] evaluated the effect of commercial formulations on the yield of cotton (Gossypium hirsutum) lint. According to the
authors, bioregulators have an important role in plant growth and may induce the
biosynthesis of allelochemicals. This way, the commercial product tested presents a
carbohydrate fraction composed of xylose, mannose, galactose, and glucose that
when applied as a foliar spray tends to increase the yield of cotton lint. Although the
results were not statistically significant, they did show consistently small increases
which have not been reported so far for carbohydrates [69].
Historically, the literature reports several studies using different concentrations of
aqueous extracts of the leaves, barks, and roots of P. juliflora in the search for
allelochemical compounds. Thus, it is well reported that in areas adjacent to species
and especially beneath the tree canopy, there is a decrease in seed germination and
growth of other competing species caused by the action of allelochemical compounds of P. juliflora [70–73].
This way, the allelopathy exercised by P. juliflora described in the literature is
related to the secondary metabolites of the species, which may act as the main
allelochemical compounds [70–73]. According to Getachew, Demissew, and
Woldemariam [73], P. juliflora presents its allelochemical compounds in different
parts of the plant and in different amounts and the leaves are responsible for the
greater inhibitory effects, whereas the barks and roots present less activity.
Phenolics are a common class of secondary metabolites which depending on the
nature and availability in the soil and could play an important role in allelopathy. The
term “phenolic compounds” also could be related to aromatic phenols, benzoic acids
and aldehyde, cinnamic acids, coumarins, tannins, and flavonoids [2, 60, 61, 74].
The phenolic compounds can act through several mechanisms such as (1) changing the membrane permeability leading to increased permeability, contents spill
and increased lipid peroxidation and inhibiting plants from absorbing nutrients;
(2) inhibiting root elongation, cell division and changes in cell structure; (3) weakening
oxygen absorption capacity and reducing chlorophyll content and photosynthetic
530
G. A. de Brito Damasceno et al.