130
J. Pospíšil et al.
administered drugs on human health. In the case of leishmaniasis, it has been established that the impact of nutrition and coinfection on drug treatment is high. Thus,
lignan and neolignan structures that may have a positive value in the search for new
biologically active antileishmanial compounds are indicated.
3.3 Bioactive Lignans and Neolignans
Lignans and neolignans, as phenylpropanoid dimers, may have a beneficial effect
on human health, in terms of both potential drug therapy and disease prevention
[98–100]. The term “beneficial to human health” includes not only direct biological activities related to specific compounds or drugs but also to the ability of such
molecules in helping prolong human life by direct or indirect interaction with additional compounds or receptors in the body [101]. The great potential of phenylpropanoid dimers results from their capacity, alone or in a synergistic way with
several other phenolics, to interact with enzymes, receptors, or even directly with
DNA (or other so-far-unknown targets) [90, 102, 103]. Up to the present, more than
8,000 phenylpropanoids have been detected and characterized. However, only a few
have been fully characterized with respect to their biological activity profiles. Most
importantly, their effects (short- or longer-term) on human health are mostly unknown
[104].
In this part of the chapter will be mentioned numerous lignans and neolignans with
various biological activities that potentially are beneficial to human health. These will
be dealt with according to the system or organ that may benefit from the presence
of such molecules. The effects of various structurally rather similar compounds are
wide. From the literature, this range of biological activities is referred to in terms
of the “scavenger theory” [105, 106]. This theory assumes that phenolic compounds
in general are capable of “disabling” free radicals via the formation of stabilized
chemical complexes [107]. Some other studies have suggested that plant phenols
may interfere with the way that peroxo/nitro radicals are formed and thus diminish
the impact of oxidative stress on the organism [107]. Another theory indicates that the
previously observed interference of phenolics (lignans and neolignans) with oxidative
stress or radical generation/scavenging has an impact on the immune response of the
organism and serves as an endogenous modulator [108].
Unfortunately, a clear mode of action is still unknown for many phenolic
compounds of plant origin [101]. What is interesting is that all currently used models
suggest that the mode of action of these phenols, inclusive of lignans and neolignans,
starts with immune response modulation. Depending on the model, this modulation
is either direct (lignan receptor) or indirect (interaction with radicals or peroxides,
for example) [105–108]. This is thought to constitute the mechanism of most of the
currently used antileishmanial compounds, so that in some way they all enhance or
regulate the immune system of a patient [61].
J. Pospíšil et al.
administered drugs on human health. In the case of leishmaniasis, it has been established that the impact of nutrition and coinfection on drug treatment is high. Thus,
lignan and neolignan structures that may have a positive value in the search for new
biologically active antileishmanial compounds are indicated.
3.3 Bioactive Lignans and Neolignans
Lignans and neolignans, as phenylpropanoid dimers, may have a beneficial effect
on human health, in terms of both potential drug therapy and disease prevention
[98–100]. The term “beneficial to human health” includes not only direct biological activities related to specific compounds or drugs but also to the ability of such
molecules in helping prolong human life by direct or indirect interaction with additional compounds or receptors in the body [101]. The great potential of phenylpropanoid dimers results from their capacity, alone or in a synergistic way with
several other phenolics, to interact with enzymes, receptors, or even directly with
DNA (or other so-far-unknown targets) [90, 102, 103]. Up to the present, more than
8,000 phenylpropanoids have been detected and characterized. However, only a few
have been fully characterized with respect to their biological activity profiles. Most
importantly, their effects (short- or longer-term) on human health are mostly unknown
[104].
In this part of the chapter will be mentioned numerous lignans and neolignans with
various biological activities that potentially are beneficial to human health. These will
be dealt with according to the system or organ that may benefit from the presence
of such molecules. The effects of various structurally rather similar compounds are
wide. From the literature, this range of biological activities is referred to in terms
of the “scavenger theory” [105, 106]. This theory assumes that phenolic compounds
in general are capable of “disabling” free radicals via the formation of stabilized
chemical complexes [107]. Some other studies have suggested that plant phenols
may interfere with the way that peroxo/nitro radicals are formed and thus diminish
the impact of oxidative stress on the organism [107]. Another theory indicates that the
previously observed interference of phenolics (lignans and neolignans) with oxidative
stress or radical generation/scavenging has an impact on the immune response of the
organism and serves as an endogenous modulator [108].
Unfortunately, a clear mode of action is still unknown for many phenolic
compounds of plant origin [101]. What is interesting is that all currently used models
suggest that the mode of action of these phenols, inclusive of lignans and neolignans,
starts with immune response modulation. Depending on the model, this modulation
is either direct (lignan receptor) or indirect (interaction with radicals or peroxides,
for example) [105–108]. This is thought to constitute the mechanism of most of the
currently used antileishmanial compounds, so that in some way they all enhance or
regulate the immune system of a patient [61].