La thérapie par les plantes en Afrique: activités immunostimulantes des polysaccharides de la paroi végétale

Abstract

Dans cette revue, nous mettons en avant le potentiel thérapeutique des polysaccharides isolés à partir des parois végé tales des plantes médicinales africaines. In vivo, la paroi végétale joue un rôle important dans le contrôle de la physiologie de la plante (croissance cellulaire, mécanismes de défense de la plante, morphologie de la plante). Principalement composée de polysac charides comme la cellulose, les hémicelluloses ou de pectines, la relation entre la structure chimique de ces polysaccharides et leurs fonctions biologiques a fait l'objet de très nombreuses études. Des extraits de ces parois, principalement polysaccharidi ques, isolés à partir de plantes sont également couramment utili sés comme « remède traditionnel » en Afrique. Dans cette revue, nous présentons quelques plantes médicinales africaines pour lesquelles la structure chimique de certains extraits polysaccha ridiques, présentant souvent une activité immunomodulatoire, a été déterminée. Ce type d'étude et d'approche, encore margi nale, gagnerait à être généralisé aux autres plantes médicinales africaines jusqu'alors peu étudiées. Cette propriété immunomo dulatoire de certains extraits polysaccharidiques pourrait consti tuer un complément thérapeutique de choix chez des patients immunodéprimés ou immunodéficients.Abstract: This review article aims to draw attention to thera peutic potential of plant cell wall polysaccharides isolated from African medicinal plants. Plant cell wall, or plant cell extracel lular compartment, consists on various polysaccharides having different chemical structures. Among these polysaccharides, cellulose, hemicelluloses and pectin polysaccharides are the predominant ones, and play an important role in controlling several biological processes like cell growth and morpho genesis, or defense mechanisms. The structurefunction rela tionship of plant cell wall polysaccharides have been extensively studied, regarding their in vivo biological functions. Here, we have partially described the chemical structure of several biologically active hemicelluloses or pectin polysaccharides extracts, isolated from different African medicinal plants. It appears that these polysaccharides taken individually are able to modulate the activity of the mammal immune system in different manner, providing an interesting complementary therapy to immune deficient patients for instance. Further investigations on cell wall polysaccharide structurebiological activity relationship of the numerous unexplored medicinal plants are therefore strongly suggested.

Screening of immunomodulatory activity of total and protein extracts of some Moroccan medicinal plants

“…In contrast to the PE of U. dioica , which has no mitogenic activity in contrary to the other studies, the existence of lectin was indicated in the U. dioica with specific T cell mitogenic action (Galelli and Truffa-Bachi, 1993). The PE of C. colocynthis , D. stramonium and L. sativum have immunomodulatory activity due to the presence of lectins (Hajto et al, 1989), proteins, peptides (Kuttan and Kuttan, 1992) and polysaccharides (Angone et al, 2010).…”

In Vitro Proliferation and Production of Cytokine and IgG by Human PBMCs Stimulated with Polysaccharide Extract from Plants Endemic to Gabon

“…Other studies have shown the immunomodulating activity of polysaccharides [8,14,15,16]. However, this study is the first with plants endemic to Gabon, although polysaccharides from fragments rich in xylan acid extract from Fleurya aestuans (Linnaeus) in Gabon have shown increased proliferation of B-cells after stimulation with Staphylococcus aureus Cowan A [10].…”

“…Plants have been used for many centuries [5,6,7], and the efficacy of plant decoctions has been shown in several reports. However, most of the studies on plants are based on their secondary metabolites, although a few studies have investigated the immunostimulant activities of plant polysaccharides [8,9,10]. However, because of their vast structural diversity, which suggests variability in their biological activities, further studies are needed to fully understand their biological properties.…”

Polysaccharides and Derivatives from Africa to Address and Advance Sustainable Development and Economic Growth in the Next Decade

“…The global biopharmaceuticals mar-ket accounted for USD 186,470 million in 2017, and is projected to reach USD 526,008 million by 2025, registering a CAGR (Compound Annual Growth Rate) of 13.8% from 2018 to 2025 [176]. As seen previously, the absence of polysaccharide toxicity (or very low) is an important aspect for their medical use [177]. Toxicity testing is an important step in the drug development process evaluating the potential of a medicinal plant before it can be considered for clinical trials [73].…”

“…Polysaccharides can be used as adsorbents for various pollutants such as heavy metals from different environmental and food samples [188]. Their functionalities such as hydroxyl, carboxyl and amine groups along their chains give them a high affinity for heavy metals [177,188]. The advantages of sugars (biodegradability, non-toxicity, environmental friendliness) make them promising, ecological, and economical.…”