Antimicrobial, anti-inflammatory and anti-arthritic activity of hemolymph lectin (NagLec) isolated from the freshwater crab, Oziotelphusanaga.

Lectins are non-immune glycoproteins or proteins having a unique capacity to interact with carbohydrate ligands found on the surface of their host cells. In the present investigation, the lectin was purified from the hemolymph of freshwater crab, Oziotelphusa naga and its antimicrobial, anti-inflammatory and anti-arthritic activity was analysed. The preliminary characterization of the hemagglutinin was carried out to identify the erythrocyte and sugar specificity, optimum pH and temperature and cation dependency. The agglutinin was found to be highly specific to rabbit erythrocyte and inhibited by fetuin and α-lactose. Maximum hemagglutination activity was noted at pH 7.5-8 and temperature 20-40 °C. An O-acetyl sialic acid specific 75 kDa hemolymph lectin, designated as NagLec was isolated from the freshwater crab, Oziotelphusa naga by affinity chromatography on fetuin coupled Sepharose 4 B, with a purification fold of 185. The bacteria Staphylococcus aureus, Proteus mirabilis and fungus Candida albicans had the greatest zone of inhibition when treated with NagLec. The results of the Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) assays showed that the purified lectin inhibited the growth of Staphylococcus aureus at 0.031 and 0.065 μg/ml, which proved the bactericidal property of NagLec. NagLec generated alterations on the bacterial cells and led to protein leakage, which was dosage (24 and 48 μg/ml) and time dependent (10-40 min). COX and LOX enzyme was inhibited to 49.43% and 61.81% with 100 μg/ml concentration of NagLec respectively, demonstrating NagLec's ability to reduce inflammation. Furthermore, NagLec (500 μg) suppressed protein denaturation up to 77.12% whereas diclofenac sodium (a standard drug) was inhibited by 89.36%. The results indicate that NagLec, a sialic acid specific lectin isolated from the freshwater crab O. naga could be formulated as a nano drug in future owing to its antimicrobial, anti-inflammatory and anti-arthritic potential that could be targeted to specific pathogenic microbes and treat arthritis.