A Computational Study of Famciclovir Derivatives Against Thymidine Kinase as a Molecular Target for the Development of Novel Anticancer Drugs via Suicide Gene Therapy Concepts

BACKGROUND

The viral thymidine kinase (TK) phosphorylates the antiviral medication famciclovir (FCV), which treats herpes simplex virus (HSV-TK). The phosphorylated FCV destroys the infected cells by preventing cellular DNA synthesis.

OBJECTIVE

We hypothesize that FCV impurity, which is a related substance to FCV, should be efficient in killing cells independent of HSV-TK and is currently the most widely used suicide agent for gene therapy of cancer.

METHODS

This study proposes the binding affinity of these derivatives for the active site of TK through molecular docking to a protein (PDB ID: 1W4R). The derivatives' reliability was ensured through the in-silico preliminary drug designing model by screening their Lipinski rule of five violations, if any, ADMET prediction for their profile using online tools. Using MOE 2009.10 computational software, we performed molecular docking of approximately 22 famciclovir derivatives alongside the famciclovir drug.

RESULTS

Our results suggest that these derivatives are indicative of possible chemical stability irrespective of all the parameters used to evaluate the selected derivatives as a possible drug candidates for their cytotoxicity. FC20 (i.e., 2-(2-(2-((1-(9-(4-Acetoxy-3-(acetoxymethyl)butyl)-2-amino-9Hpurin- 8-yl)ethyl)amino)-9H-purin-9-yl)ethyl)propane-1,3-diyl diacetate) and FC21 (i.e., 2-Amino-1,9- dihydro-9-(4-hydroxybutyl)-6H-purin-6-one), showed maximum and minimum scores of -26.95 and - 7.21 kcal/mol, respectively when compared to famciclovir (-15.4122 kcal/mol).

CONCLUSION

Considering that there might be a cytotoxicity effect due to competition between protein TK and the suicidal gene of famciclovir derivatives. The outcome of the study proved that the FCV impurity could successfully modify an HSV-TK-dependent antiviral drug into an anti-tumor drug. Further, it can be used for the design and development of novel compounds of FCV impurity that could be cytotoxic agents if properly delivered to cancer cells.

Favorable Aspects of Silymarin in Linezolid Treatment Against Diabetic Methicillin-Resistant Staphylococcus aureus (MRSA) Infected Rats

Background:

Linezolid used for diabetic methicillin-resistant Staphylococcus aureus (MRSA) infections is limited due to hepatotoxicity, lactic acidosis, anemia, and oxidative stress induced by diabetes and linezolid therapy. Silymarin is a hepatoprotective, antioxidant, antibacterial, and antidiabetic.

Objective:

The research investigated the role of silymarin in linezolid treatment against MRSA-infected diabetic rats.

Methods:

Type 2 diabetes mellitus (T2DM) was induced by a high-fat diet (58% calories fat) for 2 weeks, followed by a single intraperitoneal injection of streptozotocin (STZ) 35 mg/kg into Wistar rats. The diabetic rats were rendered neutropenic and subcutaneously injected with 106 CFU/ml of MRSA. Linezolid and silymarin were administered orally at a dose of 50 mg/kg twice daily for 14 days. The bacterial load/abscess, hematological, biochemical, enzymatic parameters, antioxidants, and histopathological studies were performed on the 42nd day.

Results:

The MRSA was confirmed by PCR assay. The minimum inhibitory concentration of linezolid was found to be 0.5-2 μg/ml. The linezolid treated MRSA infected diabetic rats showed 9.69 x 103 CFU / abscess bacterial count, decreased intestinal alkaline phosphatase (IAP), RBC, antioxidants, elevated lactate, and liver markers than diabetic rats. The silymarin treatment showed a decrease in the bacterial count (2.98 x 103 CFU / abscess), serum lactate, liver markers, increased IAP levels, and antioxidants in linezolid treated diabetic infected rats.

Conclusion:

The research concluded that silymarin could be a better herbal therapeutic agent that attenuated diabetic and linezolid induced complications in MRSA-infected diabetic rats.

Ameliorative effect of silymarin against linezolid-induced hepatotoxicity in methicillin-resistant Staphylococcus aureus (MRSA) infected Wistar rats

Linezolid has a better choice for eradication of methicillin-resistant Staphylococcus aureus (MRSA) infections, but its use is limited because of linezolid-induced hepatotoxicity, myelosuppression, and lactic acidosis. This research elucidated the role of silymarin against hepatoxicity of linezolid therapy in MRSA infected Wistar rats. The rats were rendered neutropenic by an intraperitoneal injection of cyclophosphamide injection. The neutropenic rats were injected subcutaneously with 10⁶ CFU/ml of MRSA. The rats were divided into 6 groups. Normal control, Infected, Infected animals treated with linezolid 50 mg/kg/twice/day and Infected animals treated with linezolid and different dose of silymarin 25, 50, and 100 mg/kg/twice/day for 14 days. On the 15th day, the blood, liver, kidney, and bone marrow were collected for biochemical and histopathological examination. The MRSA was confirmed by PCR assay. The minimum inhibitory concentration of linezolid was 0.5-2 μg/ml. The linezolid induced liver damage was confirmed by elevation of marker enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), Lactate dehydrogenase (LDH) levels, serum bilirubin, lactate, and histopathological studies of the liver. The linezolid treated rats also showed myelosuppression, lactic acidosis, oxidative stress and decreased intestinal alkaline phosphatase (IAP). The silymarin administration exhibited marked hepatoprotective effect by significantly lowering the liver marker enzymes, serum parameters, and cytological findings reflect the hepatoprotection. Additionally, Silymarin showed protection against myelosuppression and lactic acidosis evidenced by bone marrow smear and serum lactate estimation. Antioxidant effect of silymarin was confirmed by decreased levels of lipid peroxidation, restored the enzymatic and non-enzymatic antioxidants of the liver nearer to normal. The present study indicates that the silymarin could be a better herbal therapeutic agent which protects against the linezolid induced hepatotoxicity in MRSA infected rats.

Anti-nociceptive effect in mice of thillai flavonoid rutin

We investigated the anti-nociceptive effect of Excoecaria agallocha (E.agallocha) against chemically and thermally induced nociception, Albino mice received a dose of 10, 15, 20, or 25 mg/kg of alkaline chloroform fraction (Alk-CF) of E.agallocha by oral administration. Compared with controls, Alk-CF decreased the writhing numbers (P<0.01) in a dose dependent manner. Further we determined that, Alk-CF contained, a potent compared to control, also potent anti-nociceptive agent that acted via opioid receptors and using HPLC, identified this compound as Rutin. Docking simulation demonstrated that Rutin interacted strongly with cyclooxygenase, forming a number of specific hydrogen bonds. In conclusion we have identified peripheral and central anti-nociceptive activities of E.agallocha that involve opioid receptor, and in which the active compound is Rutin.