Correction for Irrelevant Absorption in Multicomponent Spectrophotometric Assay of Riboflavin, Formylmethylflavin, and Degradation Products: Kinetic Applications.

Correction for Irrelevant Absorption in Multicomponent Spectrophotometric Assay of Riboflavin, Formylmethylflavin, and Degradation Products: Kinetic Applications.

AAPS PharmSciTech. 2013 Jul 3;
Ahmad I, Qadeer K, Iqbal K, Ahmed S, Sheraz MA, Ali SA, Mirza T, Hafeez A

In the spectrophotometric assay of multicomponent systems involved in drug degradation studies, some minor or unknown degradation products may be present. These products may interfere in the assay and thus invalidate the results due to their absorption in the range of analytical wavelengths. This interference may be eliminated by the application of an appropriate correction procedure to obtain reliable data for kinetic treatment. The present study is based on the application of linear and non-linear irrelevant absorption corrections in the multicomponent spectrophotometric assay of riboflavin and formylmethylflavin during the photolysis and hydrolysis studies. The correction procedures take into account the interference caused by minor or unknown products and have shown considerable improvement in the assay data in terms of the molar balance. The treatment of the corrected data has led to more accurate kinetic results in degradation studies. HubMed – drug

 

Hypericum hircinum L. components as new single-molecule inhibitors of both HIV-1 reverse transcriptase-associated DNA polymerase and ribonuclease H activities.

Pathog Dis. 2013 Jun 12;
Esposito F, Sanna C, Del Vecchio C, Cannas V, Venditti A, Corona A, Bianco A, Serrilli AM, Guarcini L, Parolin C, Ballero M, Tramontano E

Among HIV-1 reverse transcriptase (RT)-associated functions, DNA polymerase and Ribonuclease H (RNase H) are both essential for HIV replication and excellent targets for drug development. While all RT inhibitors approved for therapy target the DNA polymerase activity, there is the pressing need for new RT inhibitors possibly targeting the RNase H function. In the last 20¬†years, many natural substances have shown antiviral activity against HIV-1, but only a few against the RNase H function. In this study, we have tested the ethanolic extracts obtained by the Hypericum hircinum L. (Hypericaceae) growing in Sardinia (Italy) on the HIV-1 RT-associated RNase H function and found that they have inhibitory effects. Active extracts were fractionated up to obtain the main components that have been isolated, tested, and identified to be betulinic acid, shikimic acid, chlorogenic acid, quercetin, 5,7,3′,5′-tetrahydroxyflavanone, and 5,7,3′,5′-tetrahydroxyflavanone 7-O-glucoside. Betulinic acid and 5,7,3′,5′-tetrahydroxyflavanone 7-O-glucoside were active on both RT-associated activities, and betulinic acid was also active on HIV-1 mutant RTs resistant to efavirenz. Overall, our results suggest that some of these compounds inhibit the HIV-1 RT binding to an allosteric site previously described for other natural compounds and are potential leads for further drug development of a single molecules having dual inhibitory activity. HubMed – drug