In Vitro Antioxidant and Prooxidant Activities of Red Raspberry (Rubus idaeus L.) Stem Extracts

Leaves and stems of red raspberry (Rubus idaeus) are used in Lithuanian folk medicine. Healing properties of raspberry are related to the content of bioactive compounds, mainly polyphenols. Extracts of raspberry leaves contained higher total phenolic content (TPC) (1290 mg/L, expressed in gallic acid equivalent) compared to that in extracts of stems or peeled bark (up to 420 mg/L and 598 mg/L, respectively). To find out whether the collection time of herbal material was critical for the properties of the extracts, the stems were collected at different times of the year. TPC in the extracts depended more on extraction conditions rather than on the sampling time. Antioxidant activity of raspberry stem and bark extracts tested by spectrophotometric (DPPH^● scavenging) and electrochemical (cyclic and differential pulse voltammetry) assays correlated with TPC. DPPH radical scavenging activity values for stem, leaf, and bark extracts were as follows: ≤1.18 ± 0.07, 1.63 ± 0.10, and ≤1.90 ± 0.04 (mmol/L, TROLOX equivalent), respectively. Assessed electrochemically, hydrogen peroxide-scavenging activity of extracts was independent on TPC. The latter activity was related to the presence of some protein in the extract as revealed by gel electrophoresis. Prooxidant activity of raspberry stem extracts was dependent on solution pH and temperature.     

Drug-drug and drug-solvent interaction studies of Chloroquine phosphate,Acefylline piperazine and Gentamicin sulfate in polymeric systems

The densities of three pharmacologically significantly used drugs i.e., Chloroquine phosphate (CP), Acefylline piperazine (AP) and Gentamicin sulfate (GS) have been carried out in aqueous (aq), aqueous polyethylene glycol (aq-PEG) and aqueous polyvinyl pyrrolidone (aq-PVP) solvent systems within concentration range (0.02–0.1 ± 0.001 mol.dm⁻³) at different temperatures (293.15–318.15 K) with the interval of 5 K. Density data were used to evaluate volumetric properties of drugs (CP, AP and GS) by apparent molar volume, partial molar volumes, molar expansibilities and isothermal expansion coefficient. ${\varphi }_E^{{}^{°}}$ provides information about the absence or presence of a caging or packing effect. Partial molar transfer volume was also calculated to study the hydrophilic/hydrophobic interactions in aq-PEG and aq-PVP solvent systems. The results are interpreted in terms of drug–solvent and drug-drug interactions and structure making or breaking abilities of drugs in aq, aq-PEG and aq-PVP solvent systems.