Parkia platycephala Lectin (PPL) Inhibits Orofacial Nociception Responses via TRPV1 Modulation.

Lectins are a heterogeneous group of proteins that reversibly bind to simple sugars or complex carbohydrates. The plant lectin purified from the seed of Parkia platycephala (PPL) was studied. This study aimed to investigate the possible orofacial antinociceptive of PPL lectin in adult zebrafish and rodents. Acute nociception was induced by cinnamaldehyde (0.66 µg/mL), 0.1% acidified saline, glutamate (12.5 µM) or hypertonic saline (5 M NaCl) applied into the upper lip (5.0 µL) of adult wild zebrafish. Zebrafish were pretreated by intraperitoneal injection (20 µL) with vehicle (Control) or PPL (0.025; 0.05 or 0.1 mg/mL) 30 min before induction. The effect of PPL on zebrafish locomotor behaviour was evaluated in the open field test. Naive groups were included in all tests. In one experiment, animals were pre-treated with capsazepine to investigate the mechanism of antinociception. The involvement of central afferent C-fibres was also investigated. In another experiment, rats pre-treated with PPL or saline were submitted to the temporomandibular joint formalin test. Other groups of rats were submitted to infraorbital nerve transection to induce chronic pain, followed by induction of mechanical sensitivity using von Frey. PPL reduced nociceptive behaviour in adult zebrafish, and this is related to the activation of the TRPV1 channels since antinociception was effectively inhibited by capsazepine and by capsaicin-induced desensitization. PPL reduced nociceptive behaviour associated with temporomandibular joint and neuropathic pain. The results confirm the potential pharmacological relevance of PPL as an inhibitor of orofacial nociception in acute and chronic pain.

Lectins ConA and ConM extracted from Canavalia ensiformis (L.) DC and Canavalia rosea (Sw.) DC inhibit planktonic Candida albicans and Candida tropicalis.

Lectins participate in the defense against microorganisms and in signaling the damage caused by pathogens to the cell surface and/or intracellular in plants. This study aims to analyze the antifungal potential of lectins extracted from seeds of Canavalia ensiformis (L.) DC and Canavalia rosea (Sw.) DC, against Candida albicans and Candida tropicalis. The antimicrobial tests were performed by microdilution against Candida spp. The test to verify the combined lectin/fluconazole effect was performed using subinhibitory concentrations of lectins and with antifungal ranging from 0.5 to 512 µg/mL. The ability to inhibit the morphological transition of Candida spp. was evaluated by microcultivation in a moist chamber. The results of the minimum inhibitory concentration revealed no antifungal activity against the tested strains. However, lectins modified the action of fluconazole, reducing the IC50 of the drug against C. albicans. Lectins were also able to discretely modulate the morphological transition of the tested strains.

Lactose-binding lectin from Vatairea macrocarpa seeds induces in vivo angiogenesis via VEGF and TNF-ɑ expression and modulates in vitro doxorubicin-induced genotoxicity.

Lactose-binding lectin from Vatairea macrocarpa seeds (VML) has attracted great attention due to its interesting biological activities, such as pro-inflammatory effects and macrophage activation. This study evaluated the cytotoxicity and genotoxicity/antigenotoxicity of VML in human lymphocytes using the CometChip assay, and angiogenic activity by the chick embryo chorioallantoic membrane (CAM) assay. In genotoxicity, lymphocytes were treated with different concentrations of VML (0.5, 2 and 8 µM). In antigenotoxicity, lymphocytes were treated with the same concentrations of VML concomitant doxorubicin (90 µM DXR). To evaluate angiogenesis, all CAM were treated with different concentrations of VML (0.5, 2 and 8 µM) alone or co-treated with lactose (0.1 M). Furthermore, the levels of vascular endothelial growth factor (VEGF) and tumor necrosis factor-alpha (TNF-α) in CAM were assessed by immunohistochemistry. The results showed that VML was cytotoxic to lymphocytes, genotoxic at the highest concentration (8 µM) and antigenotoxic at low concentrations (0.5, and 2 µM). Regarding the CAM assay and immunohistochemistry, VML was angiogenic and significantly increased VEGF and TNF-α levels. In contrast, co-treatment with lactose significantly reduced the angiogenic effect and VEGF levels. We propose that protein-carbohydrate interactions between VML and glycans in the cell membrane are probably the major events involved in these activities. It seems likely that VML elicits a pro-inflammatory response through VEGF and TNF-α expression, resulting in increased vascularization at the site of inflammation. Therefore, our results show novel information on the effects of VML on DNA, as well as provide data regarded the neovascularization process involving this lectin.