Flour made from Passiflora edulis fruit peel has been used in Brazil to treat diabetes. This study evaluated the effects of pectin from P. edulis on rats with alloxan-induced diabetes, on myeloperoxidase release from human neutrophils, and on carrageenan-induced paw edema. In the experiments on carrageenan-induced paw edema, paws were dissected for hematoxylin-eosin staining and immunohistochemistry determinations of tumor necrosis factor-α and inducible nitric oxide synthase. Male Wistar rats were divided into the following groups: diabetic controls and diabetic treated with pectin daily for 5 days (0.5-25 mg/kg orally). Glibenclamide and metformin were used as reference drugs. Forty-eight hours after alloxan administration, blood measures were determined (before treatment) and again 5 days later (after treatment). Pectin decreased blood glucose and triglyceride levels in diabetic rats. Pectin also decreased edema volume and release of myeloperoxidase (0.1-100 μg/mL). It also significantly decreased neutrophil infiltration and partially decreased immunostaining for tumor necrosis factor-α and inducible nitric oxide synthase. In conclusion, these data indicated that pectin, a bioactive compound present in P. edulis, has potential as a useful alternative treatment for type 2 diabetes. Its anti-inflammatory properties are probably involved in its antidiabetic action.

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Seaweeds are sources of biomolecules with biological activities and pharmacological potential - for example, lectins, a group of proteins that can bind reversibly to carbohydrates or compounds containing them. The aim of this study was to elucidate the structural properties of a lectin extracted from the red seaweed Bryothamnion triquetrum (BtL) and to investigate its anti-inflammatory activity in mice. The lectin was purified by precipitation with ammonium sulfate and ion-exchange chromatography. Its secondary structure and tryptophan (Trp) microenvironment were analyzed by circular dichroism spectroscopy and steady-state fluorescence spectroscopy, respectively. The anti-inflammatory effect was evaluated by means of paw edema induced by carrageenan or dextran, myeloperoxidase activity in paw tissue, and by measurement of leukocyte and neutrophil migration and cytokine quantification in a peritonitis model. The secondary structure of BtL is mostly composed of β-strands and unordered conformation, and it is quite resistant to extremes of pH and temperature, preserving the exposure of Trp residues under these conditions. In an assessment of biological activities, groups of mice were subjected to pretreatment with BtL before the inflammatory stimulus. BtL had anti-inflammatory effects in the models tested, and hence may be considered a molecule with potential to be used in the pharmaceutical industry.

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Sulfated polysaccharides derived from seaweeds have important biological activities. The aim of this work was to demonstrate the anti-inflammatory effect of a sulfated polysaccharide extracted from the seaweed Digenea simplex (Wulfen) C. Agardh 1822 on 2,4,6-trinitrobenzene sulfonic acid-induced colitis in rats. After inducing colitis, rats were euthanized, and the colon was excised to determine macroscopic lesion scores and wet weight and to histologically evaluate and quantify glutathione, malondialdehyde, myeloperoxidase, nitrate/nitrite, and cytokines. The polysaccharide, composed of β-D-galactose and 3,6-α-L-anhydrogalactose residues, reduced wet weight as well as macroscopic and microscopic lesion scores. It also reduced myeloperoxidase activity; reduced proinflammatory cytokines, malondialdehyde, and nitrate/nitrite levels; and preserved glutathione consumption in the colon. According to these results, we can infer that the sulfated polysaccharide derived from D. simplex has an anti-inflammatory effect on induced colitis in vivo.