A novel trypsin inhibitor with immunomodulatory activity from the leaves of Cissus verticillata subsp. verticillata (L.) Nicolson & C.E.Jarvis.

Abstract

In this study, we purified and characterized a trypsin inhibitor (CvLTI) from the leaves of Cissus verticillata subsp. verticillata. CvLTI was isolated using a trypsin-agarose column and evaluated for stability towards heating (30 to 100 °C) and incubation at different pH values (2.0 to 10.0). Furthermore, CvLTI was investigated for antibacterial activity against phytopathogens, hemolytic activity as well as cytotoxicity and immunomodulatory effects on peripheral blood mononuclear cells (PBMCs). CvLTI (14.3 kDa, pI 5.3) showed sequence similarities with an endochitinase and showed a trypsin inhibitory activity thermostable and higher at acidic pH. The inhibitor exerted bacteriostatic effects on Pectobacterium isolates (minimum inhibitory concentration: 462 µg/mL). CvLTI showed hemolytic activity with an EC50 of 33 μg/mL. CvLTI (12.5 and 25.0 μg/mL) induced the release of cytokines IL-4, IL-6, IL-10 and TNF-α by PBMCs. These data will drive further studies on the toxicity, antitumor, and anti-inflammatory potentials of safe doses of CvLTI.