57
to digestion in the upper gastrointestinal tract reaching the colon and becoming vital
nutrients for the proliferation of probiotic microflora, or serving as intermediates for
microbial conversion into other bioactive compounds (Hornung et al. 2018).
Several groups of polysaccharides have been studied over the last few decades to
explore their bioactivities, especially on human health. Techniques such as centrifugation, ultrafiltration, ultrasound-assisted extraction, and pulsed electric energy has
been very useful in the extraction and purification of bioactive polysaccharides (Zhu
et al. 2016, 2017). The characterization of polysaccharide often comprise of preliminary, physical, and structural properties by glycosaminoglycans (GAG), uronic
acid, and sulfate content, Thin Layer Chromatography (TLC), High Performance
Liquid Chromatography (HPLC), Gel permeation chromatography (GPC), Fouriertransform infrared spectroscopy (FTIR), UV-Vis spectroscopy, thermal gravimetric
analysis (TGA), and X-ray powder diffraction (XRD). With the advancement of
these extraction and identification techniques, a lot of new polysaccharides are continuously discovered from various resources.
4.7 Biological Roles of Bioactive Carbohydrates
Oligosaccharides and polysaccharides are very important biomolecules with multiple functions in all living organisms. The great variations in the structure of different polysaccharides are responsible for the flexibility of the precise regulatory
mechanisms of several cell-cell interactions in higher organisms. Among macromolecules, polysaccharides have the best potential for carrying biological information because they have a high potential for structural variability (Wang et al. 2013).
It is well known that the biological functions of polysaccharides are intimately
related to their structural features (Xie et al. 2016a).
Many bioactive polysaccharides have been extracted from medicinal plants and
this has led to many research studies in the field of pharmacology and biochemistry
as a result of their potential biological activities. More importantly, polysaccharides
derived from plants are comparatively non-toxic and most of them have insignificant side effects (Xie et al. 2014).
4.7.1 Prebiotics Carbohydrates
Prebiotics are non-digestible food ingredients that selectively stimulate the growth
and activities of probiotics (i.e. the beneficial bacteria) in the colon (Elsabee and
Abdou 2013). Polysaccharides in the human diet are very good sources of prebiotics
because they usually promote the growth of probiotics and intestinal biodiversity
(Shang et al. 2018). Many polysaccharides found in foods cannot be completely
digested by the human digestive system. These indigestible polysaccharides which
include cellulose, hemicellulose, β-glucan, pectin, mucilage, gums and lignin are
4 Bioactive Carbohydrates, Biological Activities, and Sources
to digestion in the upper gastrointestinal tract reaching the colon and becoming vital
nutrients for the proliferation of probiotic microflora, or serving as intermediates for
microbial conversion into other bioactive compounds (Hornung et al. 2018).
Several groups of polysaccharides have been studied over the last few decades to
explore their bioactivities, especially on human health. Techniques such as centrifugation, ultrafiltration, ultrasound-assisted extraction, and pulsed electric energy has
been very useful in the extraction and purification of bioactive polysaccharides (Zhu
et al. 2016, 2017). The characterization of polysaccharide often comprise of preliminary, physical, and structural properties by glycosaminoglycans (GAG), uronic
acid, and sulfate content, Thin Layer Chromatography (TLC), High Performance
Liquid Chromatography (HPLC), Gel permeation chromatography (GPC), Fouriertransform infrared spectroscopy (FTIR), UV-Vis spectroscopy, thermal gravimetric
analysis (TGA), and X-ray powder diffraction (XRD). With the advancement of
these extraction and identification techniques, a lot of new polysaccharides are continuously discovered from various resources.
4.7 Biological Roles of Bioactive Carbohydrates
Oligosaccharides and polysaccharides are very important biomolecules with multiple functions in all living organisms. The great variations in the structure of different polysaccharides are responsible for the flexibility of the precise regulatory
mechanisms of several cell-cell interactions in higher organisms. Among macromolecules, polysaccharides have the best potential for carrying biological information because they have a high potential for structural variability (Wang et al. 2013).
It is well known that the biological functions of polysaccharides are intimately
related to their structural features (Xie et al. 2016a).
Many bioactive polysaccharides have been extracted from medicinal plants and
this has led to many research studies in the field of pharmacology and biochemistry
as a result of their potential biological activities. More importantly, polysaccharides
derived from plants are comparatively non-toxic and most of them have insignificant side effects (Xie et al. 2014).
4.7.1 Prebiotics Carbohydrates
Prebiotics are non-digestible food ingredients that selectively stimulate the growth
and activities of probiotics (i.e. the beneficial bacteria) in the colon (Elsabee and
Abdou 2013). Polysaccharides in the human diet are very good sources of prebiotics
because they usually promote the growth of probiotics and intestinal biodiversity
(Shang et al. 2018). Many polysaccharides found in foods cannot be completely
digested by the human digestive system. These indigestible polysaccharides which
include cellulose, hemicellulose, β-glucan, pectin, mucilage, gums and lignin are
4 Bioactive Carbohydrates, Biological Activities, and Sources