Owing to their high content of flavonoids and saponins, plantlets of Avena sativa L. (Poaceae) are likely to possess anti-inflammatory and immunoregulatory properties of value in the treatment of atopic dermatitis (AD). With a view to its potential use in atopic subjects at risk of developing sensitisation to dietary proteins, we prepared a plantlet extract without proteins and isolated 2 flavonoids, isoorientin-2''- O-arabinoside (1) and isovitexin-2''- O-arabinoside (2), and two saponins, avenacosides A (3) and B (4). The absence of protein in this extract was evidenced by electrophoresis and Western immunoblotting. Furthermore, Western immunoblotting demonstrated the absence of cross-reaction between grain and plantlet proteins. We evaluated the anti-inflammatory activity of the plantlet extract and its compounds IN VITRO in a model of keratinocyte inflammation: 6-keto prostaglandin F1 α production was inhibited by the plantlet extract (- 35 % and - 57 % at 10 and 30 µg/mL, respectively; p < 0.001) and isoorientin-2''- O-arabinoside (- 31 %, - 51 %, and - 56 % at 3, 10, and 30 µg/mL, respectively; p < 0.001). Intracellular interleukin-2 production in activated T lymphocytes was also inhibited by 16 %, 27 %, and 31 % with 3, 10, and 30 µg/mL plantlet extract, respectively, and by 23 % and 32 % with 3 and 10 µg/mL avenacoside A, respectively, (p < 0.001), demonstrating their immunoregulatory activity IN VITRO. The plantlet extract was also effective on the phenotype and function of dendritic cells (DC) differentiated from monocytes. It decreased the expression of major histocompatibility complex class II molecules on DC and significantly impaired their stimulatory activity on autologous T-cell proliferation (-25 %, p < 0.05). In conclusion, this protein-free oat plantlet extract exhibits anti-inflammatory and immunoregulatory activities in vitro.

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This study aimed to investigate the biochemical content and antioxidant activity of methanol extracts prepared from Synsepalum dulcificum dried fruits. The results obtained by phytochemical screening of the extracts revealed the presence of some pharmacologically active chemical compounds such as: alkaloids, flavonoids, phenolic compounds and tannins. Quantitative analysis showed that the seeds had phenols in greater amounts (157.88 ± 2.09 mg GAE / g dry matter) than dried fruit pulp (54.09 ± 2.24 mg GAE / g dry matter). Contrariwise, flavonoid content was found to be low in seed (0.013 ± 0.02 mg EQ / g) and high in fruit pulp (0.13 ± 0.05 mg EQ / g). Correlated with the high amount of total phenol, in the seed extracts was found a good antioxidant activity – measured by both DPPH and ferric reducing antioxidant power (FRAP) assays. This antioxidant capacity may be also correlated with the amount of alkaloids, flavonoids, tannins and phenolic compounds, and as well as with their synergistic interactions. Synsepalum dulcificum fruits can be used as a healthy source of additives for the food industry or as natural antioxidants for the pharmaceutical industry.

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