Isocratic high-performance liquid chromatography (HPLC) for simultaneous quantification of curcumin and piperine in a microparticle formulation containing Curcuma longa and Piper nigrum.

Poor bioavailability has been reported as a major challenge in the development of curcumin as a pharmaceutical agent. However, co-administration of curcumin with piperine has been shown to improve curcumin bioavailability. Therefore, to assure product control quality, an analytical method needs to be developed for the determination of curcumin and piperine content in a dosage form formulation. The objective of this study was to develop a simple isocratic reversed-phase HPLC (RP-HPLC) method to simultaneously quantify curcumin and piperine content in solid dispersion based microparticle formulation containing Curcuma longa and Piper nigrum extracts. The method was validated according to the International Council for Harmonization (ICH) guideline. Chromatographic separation of three curcuminoids and piperine could be achieved using acetonitrile-methanol-water of 65:5:35 %, at a flow rate of 1 mL/min and a wavelength of 353 nm for detection. Resolution (Rs) of 3.57 and 1.68 for piperine and curcumin, respectively, a theoretical plate number (N) > 8000 and a tailing factor (T) < 1.5 indicate a satisfactory separation of the compounds. The calibration curve was linear from 1.25-15 µg/mL and 2.5-30 µg/mL for piperine and curcumin, respectively, with the correlation coefficient of >0.999. The intra-day/inter-day accuracy and precision demonstrated a recovery of 99.54-101.50%/99.38-99.89% and 100.78-102.51%/101.15-102.47% with a Relative Standard Deviation (RSD) of 0.53-0.95%/0.13-1.44 % and 0.28-1.62%/0.46-1.14% for piperine/curcumin. The limit of detection (LOD) were 0.27 and 0.42 µg/mL, for piperine and curcumin, which reveals an adequate sensitivity. A solid dispersion based microparticle formulation containing C. longa and P. nigrum extracts confirmed the validity of the developed method as a recovery of 91.14% and 99.14% for piperine and curcumin, respectively. In conclusion, all the tested parameters confirm the precision, accuracy, and reliability of the method for the simultaneous analysis of curcumin and piperine within a microparticle formulation containing C. longa and P. nigrum extracts.

Biflavonoid as potential 3-chymotrypsin-like protease (3CLpro) inhibitor of SARS-Coronavirus.

3CL protease is one of the key proteins expressed by SARS-Coronavirus-2 cell, the potential to be targeted in the discovery of antivirus during this COVID-19 pandemic. This protein regulates the proteolysis of viral polypeptide essential in forming RNA virus. 3CL protease (3CLpro) was commonly targeted in the previous SARS-Coronavirus including bat and MERS, hence, by blocking this protein activity, the coronavirus should be eradicated. This study aims to review the potency of biflavonoid as the SARS-Coronavirus-2 3CLpro inhibitor. The review was initiated by describing the chemical structure of biflavonoid and followed by listing its natural source. Instead, the synthetic pathway of biflavonoid was also elaborated. The 3CLpro structure and its function were also illustrated followed by the list of its 3D-crystal structure available in a protein data bank. Lastly, the pharmacophores of biflavonoid have been identified as a protease inhibitor, was also discussed. This review hopefully will help researchers to obtain packed information about biflavonoid which could lead to the study in designing and discovering a novel SARS-Coronavirus-2 drug by targetting the 3CLpro enzyme.