Today, an ethnobotanical approach makes sense for identifying new active bioactive chemicals from uses of indigenous plants. Two water-soluble enriched polysaccharide fractions (L-PSPN and S-PSPN) were extracted by hot water extraction from the leaves and seeds of Plantago ciliata Desf. (1798), a Mzab indigenous herb currently used in Algeria by traditional healers. Primary investigation was performed for describing the main structural features of these polysaccharides (pectin- and heteroxylan-like compositions) by using colorimetric assays, FTIR spectroscopy, HPAEC/PAD and GC/MS-EI analyses. Some biological activities were also monitored, such as anticomplement, anti-inflammatory (phagocytic ability, NOX2 and MPO inhibitions) and anti-diabetic (α-amylase and α-glucosidase inhibitions). L-PSPC seems able to moderately modulate innate immune system (IC₅₀ around 100 µg/mL) and contribute to wound-healing processes (IC₅₀ close to 217 vs. 443 µg/mL for sodium heparin). S-PSPC shows some potential as an anti-hyperglycemic (IC₅₀ around 4.7 mg/mL) and anti-inflammatory (IC₅₀ ranging from 111 to 203 µg/mL) agent, as well as other (fiber) psyllium-like polysaccharides extracted from Plantago species.

Polysaccharides are highly variable and complex biomolecules whose inventory of structures is still very incomplete, as nature still preserves unexplored biotopes. Plants, macroalgae and microalgae are an integral part of the daily life of human being regardless of culture, time, or knowledge development of a country. Natural medicine is an ancestral knowledge widely distributed throughout the world, handed down for centuries from generation to generation by those commonly referred to as “nganga” healers or shamans. It is also called alternative medicine or traditional medicine, and has been associated for millennia to legends. This review gives an emphasis regarding the ethnobotanic approach associated to the structural variability of poly- and oligosaccharides for designing the new polysaccharide-based drugs and hydrocolloids of tomorrow. The guiding thread is to survey the potential of plants (and some macroalgae) from Africa as a source of polysaccharides with original structures and, secondly, to correlate these structures with biological and/or functional properties in particular to address and advance the sustainable development and economic growth of mankind.