Allium sativum L

Fiorito, Serena, Epifano, Francesco, Preziuso, Francesca, Taddeo, Vito Alessandro & Genovese, Salvatore, 2018, Selenylated plant polysaccharides: A survey of their chemical and pharmacological properties, Phytochemistry 153, pp. 1-10 : 3

5.1.1. Allium sativum L

Garlic is well known for its properties both as a medicinal and a food plant. Polysaccharides from different parts of this species are endowed for their capacity to positively modulate the immune response to microbial and viral infections ( Sabater Molina et al., 2009) and as a powerful natural remedy for the cure of metabolic syndrome ( Wang and Ng, 1999). The effect of the introduction of Se into the carbohydrate skeleton of garlic polysaccharides have been investigated for the first time in 2014 by Qiu and coworkers. These authors obtained a library of 9 Se-P samples in low yield (18.1%–37.6%) but good Se content (6.2 mg /g - 12.5 mg /g). All polymers were preliminarily tested for their effects in vitro on bioavailability and proliferation rate in chicken peripheral lymphocytes by the MTT test in the concentration range 0.195 –3.125 μg/mL. The 3 Se-Ps with the highest content in Se (12.5 mg /g, 11.3 mg /g, and 10.4 mg /g) displayed at all doses assayed the best effects being able to increase lymphocytes proliferation by 43.9%, 52.2%, and 57.9% respectively. It is noteworthy that all polymers of the synthesized library provided better results than the native polysaccharide. The most effective Se-Ps were subsequently tested in vivo in chickens previously vaccinated with ND vaccine. Se-Ps were administered i.m. for 3 days and the overall duration of the experiment was 4 weeks. Key parameters like lymphocyte proliferation, serum antibody titer, IFN-γ, and IL-2 concentrations were measured. The Se-P with a content of Se of 11.3 mg /g in all cases gave the best results. Lymphocyte proliferation increased by 45.2% respect to untreated vaccinated control animals, the antibody titer increased in a dose-dependent manner until day 21 and remain virtually equal until the end of the experiment (day 28). For what concerns IFN-γ and IL-2, concentrations values for the 3 Se-Ps were higher respect to controls and native polysaccharide but practically the same between them. Two years later the same research group applied an alternative method for the selenylation of garlic polysaccharides, using acetic acid instead of nitric acid as the promoter of the in-situ formation of H 2 SeO 3, as well as SeOCl 2, but obtaining no appreciable increases either in yields or Se contents. These last compounds were tested in a similar way as in 2014 confirming the results obtained in the first investigations.