Evaluation of scopadulciol-related molecules for their stimulatory effect on the cytotoxicity of acyclovir and ganciclovir against Herpes simplex virus type 1 thymidine kinase gene-transfected HeLa cells

Anti-Herpes Simplex Virus Type 1 Activity Evaluation of Natural Derived Phloroglucinol Derivatives and Their Molecular Mechanisms Study

HSV-1 is a common infection that can cause cold sores. In this study, the anti-HSV-1 virus activity of three series compounds A1-A9, B1-B12, C1-C22 was screened by MTT assay, qRT-PCR assay, Western blot assay and viruses' plaque assays. The results of MTT assay disclosed that phloroglucinol derivatives C2 and C3 effectively inhibited the death of HSV-1 infected vero cells with the CC50 values of C2 and C3 were 72.64 μmol/L and 32.62 μmol/L in HaCaT cells, 137.6 μmol/L and 48.55 μmol/L in Hela cells. The IC50 values of C3 in vero cells and Hela cells were 19.26 μmol/L and 22.98 μmol/L, respectively. In the qRT-PCR experiments, it showed that C2 and C3 effectively reduced the synthesis of HSV-1 early viral gene VP16 and late viral gene gD. The Western blot results showed that both C2 and C3 inhibited the expression of HSV-1 gD protein in a concentration-dependent manner. Lastly, viruses' plaque assay results showed that C2 and C3 inhibited the production of HSV-1 progeny virus in Hela cells and HaCaT cells in a concentration-dependent manner. Taken together, these results suggest that C2 and C3 are promising candidate that warrants further attention in the development of anti-HSV-1 drugs.

Antimicrobial Diterpenes: Recent Development From Natural Sources

Antimicrobial resistance has been posing an alarming threat to the treatment of infectious diseases over the years. Ineffectiveness of the currently available synthetic and semisynthetic antibiotics has led the researchers to discover new molecules with potent antimicrobial activities. To overcome the emerging antimicrobial resistance, new antimicrobial compounds from natural sources might be appropriate. Secondary metabolites from natural sources could be prospective candidates in the development of new antimicrobial agents with high efficacy and less side effects. Among the natural secondary metabolites, diterpenoids are of crucial importance because of their broad spectrum of antimicrobial activity, which has put it in the center of research interest in recent years. The present work is aimed at reviewing recent literature regarding different classes of natural diterpenes and diterpenoids with significant antibacterial, antifungal, antiviral, and antiprotozoal activities along with their reported structure–activity relationships. This review has been carried out with a focus on relevant literature published in the last 5 years following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 229 diterpenoids from various sources like plants, marine species, and fungi are summarized in this systematic review, including their chemical structures, classification, and significant antimicrobial activities together with their reported mechanism of action and structure–activity relationships. The outcomes herein would provide researchers with new insights to find new credible leads and to work on their synthetic and semisynthetic derivatives to develop new antimicrobial agents.

Turning an antiviral into an anticancer drug: nanoparticle delivery of acyclovir monophosphate

Anti-herpes simplex virus (HSV) drug acyclovir (ACV) is phosphorylated by the viral thymidine kinase (TK), but not the cellular TK. Phosphorylated ACV inhibits cellular DNA synthesis and kills the infected cells. We hypothesize that ACV monophosphate (ACVP), which is an activated metabolite of ACV, should be efficient in killing cells independent of HSV-TK. If so, ACVP should be a cytotoxic agent if properly delivered to the cancer cells. The Lipid/Calcium/Phosphate (LCP) nanoparticles (NPs) with a membrane/core structure were used to encapsulate ACVP to facilitate the targeted delivery of ACVP to the tumor. The LCP NPs showed entrapment efficiency of ~70%, the nano-scaled particle size and positive zeta potential. Moreover, ACVP-loaded LCP NPs (A-LCP NPs) exhibited concentration-dependent cytotoxicity against H460 cells and increased S-phase arrest. More importantly, a significant reduction of the tumor volume over 4 days following administration (p<0.05-0.005) of A-LCP NPs, suggests excellent in vivo efficacy. Whereas, two free drugs (ACV and ACVP) and blank LCP NPs showed little or no therapeutic effect. It was also found that the high efficacy of A-LCP NPs was associated with the ability to induce dramatic apoptosis of the tumor cells, as well as significantly inhibit tumor cell proliferation and cell cycle progression. In conclusion, with the help of LCP NPs, monophosphorylation modification of ACV can successfully modify an HSV-TK-dependent antiviral drug into an anti-tumor drug.