Most approved drugs with activity against hepatitis B virus (HBV) have activity against human immunodeficiency virus type 1 (HIV-1), which precludes their use in patients who are coinfected with HBV and HIV-1 and who are not receiving antiretroviral therapy due to the risk of inducing resistance. The activity of telbivudine, a highly selective HBV inhibitor, against temporally and geographically distinct wild-type and multidrug-resistant HIV-1 clinical isolates was evaluated in vitro. No inhibition was observed with up to 600 M drug, which supports further exploration of telbivudine as a therapeutic option for the treatment of HBV infections in patients coinfected with HIV-1.
ObjectivesRetinoids have been used for decades as efficacious topical agents to treat photoaged skin. The purpose of our present research is to evaluate whether the activity of the vitamin A ester retinyl propionate (RP) can be enhanced by niacinamide (Nam) and a flavonoid containing Ceratonia siliqua (CS) fruit extract in retinoid responsive in vitro models.MethodsRetinyl propionate was tested alone and in combination with Nam and CS in an RARα reporter cell line for promoter activation and compared to trans‐retinoic acid (tRA) activation. These treatments were also tested in keratinocytes for gene expression profiling by qPCR using a panel of 40 retinoid responsive genes.ResultstRA or RP elicited RARα reporter activation in a dose‐dependent manner. The combination of 0.5 μM or 2 μM RP with 10 mM Nam had a 56% and 95% signal increase compared to RP, respectively. The addition of 1% CS to 0.5 μM or 2 μM RP with 10 mM Nam elicited a further increase of 114% and 156%, respectively, over RP and Nam combinations. All retinoids elicited an increase in expression of 40 retinoid sensitive genes over control levels. Of the 40 genes, 27 were enhanced by either 0.1 μM RP or 0.5 μM RP with 10 mM Nam and 1% CS. Nam or CS had very modest activity in both models.ConclusionThe combination of RP with Nam and CS showed a higher retinoid response than RP in two separate retinoid responsive in vitro models. We hypothesize Nam and CS enhances RP activity by modulating metabolism to tRA via increasing NAD+ pools and inhibiting reduction of retinal (RAL) back to retinol, respectively. The findings provide evidence that this combination may have enhanced efficacy for treating the appearance of photoaged skin.
OBJECTIVES: Retinoids have been used for decades as efficacious topical agents to treat photoaged skin. The purpose of our present research is to evaluate whether the activity of the Vitamin A ester retinyl propionate (RP) can be enhanced by niacinamide (Nam) and a flavonoid containing Ceratonia siliqua (CS) fruit extract in retinoid responsive in vitro models. METHODS: RP was tested alone and in combination with Nam and CS in an RARalpha reporter cell line for promoter activation and compared to trans-retinoic acid (tRA) activation. These treatments were also tested in keratinocytes for gene expression profiling by qPCR using a panel of 40 retinoid responsive genes. RESULTS: tRA or RP elicited RARalpha reporter activation in a dose dependent manner. The combination of 0.5 uM or 2 uM RP with 10 mM Nam had a 56% and 95% signal increase compared to RP, respectively. The addition of 1% CS to 0.5 uM or 2 uM RP with 10 mM Nam elicited a further increase of 114% and 156%, respectively, over RP and Nam combinations. All retinoids elicited an increase in expression of 40 retinoid sensitive genes over control levels. Of the 40 genes 27 were enhanced by either 0.5 uM RP or 2 uM RP with 10 mM Nam and 1% CS. Nam or CS had very modest activity in both models. CONCLUSION: The combination of RP with Nam and CS showed a higher retinoid response than RP in two separate retinoid responsive in vitro models. We hypothesize Nam and CS enhances RP activity by modulating metabolism to tRA via increasing NAD+ pools and inhibiting reduction of retinal (RAL) back to retinol, respectively. The findings provide evidence that this combination may have enhanced efficacy for treating the appearance of photoaged skin.
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