Potentiation of drug toxicity through virus latency reversal promotes preferential elimination of HIV infected cells

Eliminating latently infected cells is a highly challenging, indispensable step towards the overall cure for HIV/AIDS. We recognized that the unique HIV protease cut site (Phe-Pro) can be reconstructed using a potent toxin, monomethyl auristatin F (MMAF), which features Phe at its C-terminus. We hypothesized that this presents opportunities to design prodrugs that are specifically activated by the HIV protease. To investigate this, a series of MMAF derivatives was synthesized and evaluated in cell culture using latently HIV-infected cells. Cytotoxicity of compounds was enhanced upon latency reversal by up to 11-fold. In a mixed cell population, nanomolar concentrations of the lead compound depleted predominantly the HIV-infected cells and in doing so markedly enriched the pool with the uninfected cells. Despite expectation, mechanism of action of the synthesized toxins was not as HIV protease-specific prodrugs, but likely through the synergy of toxicities between the toxin and the reactivated virus.

Phloridzin Highly Accumulated in Malus rockii Rehder and Its Structure Revision and Hypolipidemic Activity

Phloridzin is a lead compound of the prestigious antidiabetic gliflozins. The present study found that phloridzin highly accumulated in Malus rockii Rehder. The content of phloridzin in M. rockii was the highest among wild plants, with the percentage of 15.54% in the dry leaves. The structure of phloridzin was revised by proton exchange experiments and extensive 2D NMR spectra. Phloridzin exhibited significant hypolipidemic activity in golden Syrian hamsters maybe by increasing the expression of CYP7A1, at the doses of 50 mg/kg and 200 mg/kg. The total performance of anti-hyperlipidemic effect of phloridzin may be superior to that of lovastatin, though lovastatin was more active than phloridzin. In addition, phloridzin exhibited moderate antimalarial activity with inhibition ratio of 31.3±10.9% at a dose of 25 mg/kg/day, and showed moderate analgesic activity with 28.0% inhibition at a dose of 50 mg/kg.

EVALUATION OF ANTI-MICROBIAL POTENTIAL OF STRUCTURALLY MODIFIED DERIVATIVES OF LEAD COMPOUND BERBERINE ISOLATED FROM ROOTS OF BERBERIS ARISTATA

The alkaloid berberine, the chief constituent of Berberis aristata, has been reported to have antimicrobial activity associated with it. Structural changes can be made to this lead compound to try to improve its effi cacy in terms of antimicrobial activity. In the present study, attempts have been made to evaluate anti-microbial potential of structurally modifi ed derivatives of berberine. The derivatives so synthesized were characterized on the basis of spectral techniques like 1H,13C NMR, UV, IR and MASS and by comparison with standard berberine. Structure-activity relationship studies revealed that methoxyl group is pharmacophore of berberine and is thus needed to be retained in the skeleton. Further incorporation of the electron-withdrawing group has pronounced effect on the antimicrobial activity. Further attempts could be made to extend the series with the incorporation of such electron-withdrawing groups to get potent antimicrobial agents.

Brevinin-2GHk, a Peptide Derived from the Skin of Fejervarya limnocharis, Inhibits Zika Virus Infection by Disrupting Viral Integrity

Several years have passed since the Zika virus (ZIKV) pandemic reoccurred in 2015–2016. However, there is still a lack of proved protective vaccines or effective drugs against ZIKV. The peptide brevinin-2GHk (BR2GK), pertaining to the brevinin-2 family of antimicrobial peptides, has been reported to exhibit only weak antibacterial activity, and its antiviral effects have not been investigated. Thus, we analyzed the effect of BR2GK on ZIKV infection. BR2GK showed significant inhibitory activity in the early and middle stages of ZIKV infection, with negligible cytotoxicity. Furthermore, BR2GK was suggested to bind with ZIKV E protein and disrupt the integrity of the envelope, thus directly inactivating ZIKV. In addition, BR2GK can also penetrate the cell membrane, which may contribute to inhibition of the middle stage of ZIKV infection. BR2GK blocked ZIKV E protein expression with an IC50 of 3.408 ± 0.738 μΜ. In summary, BR2GK was found to be a multi-functional candidate and a potential lead compound for further development of anti-ZIKV drugs.

Characterising the Biological Activity of a Trichlorovinyl Cysteine-Containing Mycothiol Analogue

<p>Cancer is a disease characterised by the uncontrolled growth of mutated cells, and is one of the leading causes of death worldwide, with over a third of people diagnosed with cancer in their lifetime. Despite extensive investment of both time and money in cancer research, poor patient outcomes and quality of life, and the evolution of treatment resistant cancers indicates that continued research, and more efficacious therapies are required. A recent investigation identified a mycothiol analogue which displayed significant toxicity in the promyelocytic leukemia cell line (HL60). Designed as a negative control, no biological activity was expected from this compound and its cellular target and mode of action are unknown. This thesis describes the synthesis of a toxic trichlorovinyl cysteine-containing analogue of mycothiol, and the attempted synthesis of a propynylated and fluorescent derivative of this. The research also details immunomodulatory investigations, which were undertaken to probe the mode of action of the lead compound, and to determine whether its precursor, N-Boc-S-trichlorovinyl cysteine, induced toxicity through the same mechanism. The lead compound demonstrated mild immunomodulatory activity in splenocytes isolated from euthanised C57BL/6 mice, and enzyme linked immunosorbent assays revealed a likely Th2 mediated response, induced by the production of IL-4. The precursor however appears to promote a strong pro-inflammatory response, by inducing IL-17a production, which is widely considered a deleterious immune response in cancer. Whilst further work is required to determine the cellular target of the lead compound, the research described demonstrates the potential for this compound as an anti-cancer agent, while the precursor appears inappropriate for further development.</p>

Characterising the Biological Activity of a Trichlorovinyl Cysteine-Containing Mycothiol Analogue

<p>Cancer is a disease characterised by the uncontrolled growth of mutated cells, and is one of the leading causes of death worldwide, with over a third of people diagnosed with cancer in their lifetime. Despite extensive investment of both time and money in cancer research, poor patient outcomes and quality of life, and the evolution of treatment resistant cancers indicates that continued research, and more efficacious therapies are required. A recent investigation identified a mycothiol analogue which displayed significant toxicity in the promyelocytic leukemia cell line (HL60). Designed as a negative control, no biological activity was expected from this compound and its cellular target and mode of action are unknown. This thesis describes the synthesis of a toxic trichlorovinyl cysteine-containing analogue of mycothiol, and the attempted synthesis of a propynylated and fluorescent derivative of this. The research also details immunomodulatory investigations, which were undertaken to probe the mode of action of the lead compound, and to determine whether its precursor, N-Boc-S-trichlorovinyl cysteine, induced toxicity through the same mechanism. The lead compound demonstrated mild immunomodulatory activity in splenocytes isolated from euthanised C57BL/6 mice, and enzyme linked immunosorbent assays revealed a likely Th2 mediated response, induced by the production of IL-4. The precursor however appears to promote a strong pro-inflammatory response, by inducing IL-17a production, which is widely considered a deleterious immune response in cancer. Whilst further work is required to determine the cellular target of the lead compound, the research described demonstrates the potential for this compound as an anti-cancer agent, while the precursor appears inappropriate for further development.</p>

In Silico Structure-Guided Optimization and Molecular Simulation Studies of 3-Phenoxy-4-(3-trifluoromethylphenyl)pyridazines as Potent Phytoene Desaturase Inhibitors

A series of novel 3-phenoxy-4-(3-trifluoromethylphenyl)pyridazines 2–5 were designed, based on the structure of our previous lead compound 1 through the in silico structure-guided optimization approach. The results showed that some of these new compounds showed a good herbicidal activity at the rate of 750 g ai/ha by both pre- and post-emergence applications, especially compound 2a, which displayed a comparable pre-emergence herbicidal activity to diflufenican at 300–750 g ai/ha, and a higher post-emergence herbicidal activity than diflufenican at the rates of 300–750 g ai/ha. Additionally, 2a was safe to wheat by both pre- and post-emergence applications at 300 g ai/ha, showing the compound’s potential for weed control in wheat fields. Our molecular simulation studies revealed the important factors involved in the interaction between 2a and Synechococcus PDS. This work provided a lead compound for weed control in wheat fields.