In vitro Inhibition Kinetics of Crocodylus mindorensis (Philippine crocodile) Serum against Human Immunodeficiency Virus Type I Reverse Transcriptase

The study aimed to determine the inhibition kinetics of Crocodylus mindorensis (Philippine crocodile) serum against recombinant HIV-1 Reverse Transcriptase (RT) using Enzyme-linked Immunosorbent Assay. The study utilized an experimental design where different concentrations of Philippine crocodile serum were used to determine its quantitative inhibitory effect and mechanism of inhibition against the HIV-1 reverse transcriptase activity. A colorimetric enzyme immunoassay that incorporates digoxigenin and biotin-labeled dUTP onto DNA were used for the assay (Roche Version 13.0, 2010). In addition, the kinetic activity of HIV-1 Reverse transcriptase was studied to determine the mechanism of enzyme inhibition by Philippine crocodile serum. A minimum of 2 mL serum sample from each of the seven (7) purposively selected Crocodylus mendoremsis were collected at the Animal clinic of the Davao Crocodile Park facility. The results showed that the HIV-1 Reverse transcriptase activity was inhibited by high as 92.93±0.72% (CM-07) at 0.5 vol/vol % and as low as 4.66±20.76 at 4 vol/vol % (CM-04) of Philippine crocodile serum. The average half maximal inhibitory concentration (IC50) of the seven crocodile serum samples was 1.47% vol/vol.The 92.93±0.72% inhibition of 0.5% vol/vol of Philippine crocodile serum has almost the same inhibition as the positive control Nevirapine (92.64±0.20%). The inhibition kinetics of the Philippine crocodile suggests a potential novel HIV-1 Reverse Transcriptase inhibitor.