Production of a biopesticide on host and Non-Host serine protease inhibitors for red palm weevil in palm trees.

Serine proteases are essential metabolic enzymes in the midgut of many pests, including the red palm weevil (RPW), Rhynchophorus ferrugineus Olivier, which has a significant impact economically, environmentally and socially worldwide especially in the middle east. Some methods have been used to manage this pest such as trapping of RPW with pheromones, chemicals, and X-rays. However, these methods are costly, not effective and negatively impact the human. The main objective of this study is to contribute to the discovery of an eco-friendly pesticide to eradicate this infection by using serine protease inhibitors (SPIs) extracted from different parts of plant resources. In this research, both in vitro and in vivo effects of SPIs activity against RPW were examined. The protease inhibitors (PIs) activity was recorded in the crude extract that was isolated from the date's kernel (DKE), host and Calotropis latex (CLE), non-host. These PIs were partially purified by ammonium sulfate precipitation. The midgut tissue of RPW was extracted and analyzed for protases activity assay. PIs assays were consistent with the increased in the inhibitory activity against the midgut proteases after treatment with a DKE and CLE. The reduction of gut proteases by DKE solution and CLE was 39%, 18%, respectively. Partially purified DKE showed the most prominent inhibition pattern of protease activity of the gut extract. While, latex exhibited acute toxicity, imparting the least LC50 (5.132 mg/mL) against RPW larvae. Taken together, these findings provide evidence for the hypothesis that SPIs activity may play an important role in enhancing the mortality of RPW and relieving the toxicity of insecticide in palm trees.

An efficient methodology for the purification of date palm peroxidase: Stability comparison with horseradish peroxidase (HRP).

In the present study, Peroxidase from date palm (Phoenix dactylifera) leaves was purified to homogeneity by three-step procedure including aqueous two-phase system, hydrophobic and Ion-exchange chromatography. The enzyme migrated as single band on SDS-PAGE giving molecular weight of 68 ±â€¯3 kDa. The purification factor for purified date palm peroxidase was 68 with high 41% yield. Enzymatic assays together with far-UV circular dichroism (CD), intrinsic and extrinsic fluorescence studies were carried out to monitor the structural stability of date palm and horseradish peroxidase (HRP) against various pH and temperatures. Activity measurements illustrated different pH stability for date palm and HRP. Both peroxidases are more susceptible to extreme acidic conditions as suggested by 4 & 15 nm red shift in date palm and HRP, respectively. Secondary structure analysis using far UV-CD exhibited predominance of α-helical (43.8%) structure. Also, pH induces loss in the secondary structure of date palm peroxidase. Thermal stability analysis revealed date palm peroxidase is more stable in comparison to HRP. In summary, date palm peroxidases could be promising enzymes for various applications where extreme pH and temperature is required.