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Context Global studies on Argemone mexicana L. (Papaveraceae) traditionally used against malaria in Mali are limited to its low-mass compounds activities, and little information on its bioactive polysaccharides is available.Objective This study determines the structure and the immunomodulatory activity of polysaccharides from aerial parts of A. mexicana.Materials and methods Acidic polysaccharides from this plant material named HMAmA1 and HMAmA2 were isolated from water extracts. Their monosaccharide composition was determined by gas chromatography. Glycosidic linkages were determined using GC-MS. NMR was also applied. The polymers were tested for effects on the human complement system in vitro at different doses.Results The monosaccharide composition showed that the two polysaccharides contained in different amounts the following monomers: arabinose, rhamnose, galactose, and galacturonic acid. Overall structural analysis showed the presence of a low ratio of 1,2-linked rhamnose compared to 1,4-linked galacturonic acid with arabinogalactans substituted on position 4 of rhamnose. NMR data showed the presence of galacturonans alternated by rhamnogalacturonans bearing arabinose and galactose units. α-Linkages were found for l-arabinose, l-rhamnose and d-galacturonic acid, while β-linkages were found for d-galactose. The two polysaccharides exhibited strong complement fixation activities, with HMAmA1 being the highest potent fraction. ICH50 value of HMAmA1 was 5 µg/mL, compared to the control BPII being 15.9 µg/mL.Discussion and conclusions Polysaccharides form A. mexicana presented a complement fixation effect. The complement system is an important part of the immune defense, and compounds acting on the cascade are of interest. Therefore, these polymers may be useful as immunodulatory agents.

Background and objectives: In India, Argemone mexicana is traditionally used against fever, wounds, worms and malaria. In Mali the efficacy and safety of “Sumafura Tiemoko Bengaly” an herbal tea based on A. mexicana aerial parts against malaria have been demonstrated. This study was aimed to investigate the pharmacognostic, physicochemical and phytochemical parameters of its aerial parts. Methods: Macroscopy, microscopy, chemo-microscopy, phytochemical, mineral and physicochemical analyses were performed using standard methods. Results: The macroscopy showed that A. mexicana is an herbal plant with prickly both on its greenish stem and the pinnatelobed leaves; the flower is terminal and yellow and the fruit is a capsule with thorns. The microscopy revealed the presence of epidermal cells with actinocytic stomata, calcium oxalate prism, lacticifers, palisade cells, vascular bundle, fibers and collenchyma cells in the fresh leaf and the dry aerial parts. The chemo-microscopy revealed the presence of lignins, tannins, starch, calcium oxalate, oils and proteins. Phytochemical screening revealed the presence of carbohydrates, alkaloids, tannins, flavonoids, saponins, sterols and triterpenoids. The physicochemical parameters as observed included moisture content (8.2 %); total ash value (16.7 %); acid-insoluble ash value (2.9 %); water-soluble ash value (4.8 %); ethanol - soluble extractive value (17.2 %) and water- soluble extractive value (34.3 %). Six minerals (Fe, Cu, Mn, Mg, Pb, and Cd) have been also measured. Conclusion: These parameters help to establish the correct identity of A. mexicana and check the occurrence of adulterations. Further, they are useful for the standardization and pharmacopoeia development.