A new angiotensin-converting enzyme inhibitor from Peperomia pellucida(L.) Kunth

Objective:To isolate,identify,and evaluate a new angiotensin-converting enzyme inhibitor from Peperomia pellucida(L.)Kunth herbs.Methods:A dried sample of Peperomia pellucida herb was successively macerated with n-hexane and ethyl acetate.The ethyl acetate extract solution was evaporated to obtain the crude extract.Vacuum liquid column chromatography and thin layer chromatography were performed to obtain two pure compounds.Then,both compounds were elucidated and identified using the spectroscopic method.Angiotensin-converting enzyme inhibitory activity studies of both compounds were determined using angiotensin-converting enzyme kit WST-1 with spectrophotometer microplate reader 96-well at 450 nm wavelength.Results:Two bioactive compounds were successfully isolated from Peperomia pellucida herb,including a new compound of 2,3,5-trimethoxy-9-(12,14,15-trimethoxybenzyl)-1 H-indene and pellucidin A.Both compounds demonstrated angiotensin-converting enzyme inhibitory activity,with IC50 values of 72 μM(27.95 μg/mL)and 1 1μM(4.4 μg/mL),respectively.Conclusions:In the present study,two active angiotensin-converting enzyme inhibitors were successfully isolated and purified from Peperomia pellucida which is used as an antihypertensive in traditional medicine,and support its use as an angiotensin-converting enzyme-inhibiting drug.

Effects of Mg^(2+) interstitial ion on the properties of Mg_(0.5+x/2)Si_(2-x)Al_(x)(PO_(4))_(3) ceramic electrolytes

Nasicon type,Mg_(0.5+x/2)Si_(2-x)Al_(x)(PO_(4))_(3) was synthesized using citric acid assisted sol-gel method.The X-ray diffraction was applied to investigate the effect of extra Mg^(2+)interstitial ion on the phase,unit cell parameters and structure of the samples.The Mg_(0.625)Si_(1.75)Al_(0.25)(PO_(4))_(3) sample exhibited highest bulk conductivity value of 1.54×10^(−4)S cm^(−1)at ambient temperature.The frequency dependence of theσac of these ceramic electrolytes follows the universal power law variation,σac(ω)=σo+Aωα.The conductivity parameters such as hopping frequencies,charge carrier concentration and mobile ion concentration proved that the increase in conductivity with x was due to the existence of Mg^(2+) interstitial ions.The experiment results also revealed that the dielectric constant and dielectric loss decreased with frequency.The Mg_(0.625)Si_(1.75)Al_(0.25)(PO_(4))_(3) was found to be electrochemically stable up to 2.51 V at ambient temperature.

Electrochemical performance of overlithiated Li1＋xNi0.8Co0.2O2： structural and oxidation state studies

Pure, layered compounds of overlithiated Li1＋xNi0.8Co0.2O2（x = 0.05 and 0.1） were successfully prepared by a modified combustion method. XRD studies showed that cell parameters of the material decreased with increasing the lithium content. SEM revealed that the morphology of particles changed from rounded polyhedral-like crystallites to sharp-edged polyhedral crystals with more doped lithium. EDX showed that the stoichiometries of Ni and Co agrees with calculated synthesized values. Electrochemical studies revealed the overlithiated samples have improved capacities as well as cycling behavior. The sample with x = 0.05 shows the best performance with a specific capacity of 113.29 mA.h.g-1 and the best capacity retention of 92.2% over 10 cycles. XPS results showed that the binding energy of Li ls is decreased for the Li doped samples with the smallest value for the x = 0.05 sample, implying that Li＋ ions can be extracted more easily from Li1.05Ni0.8Co0.2O2 than the other stoichiometries accounting for the improved performance of the material. Considerations of core level XPS peaks for transition metals reveal the existence in several oxidation states. However, the percentage of the＋3 oxidation state of transition metals for the when x = 0.1 is the highest and the availability for charge transition from the ＋3 to＋4 state of the transition metal during deintercalation is more readily available.