Drying Kinetics and Optimization of Quercetrin Extraction from Melastoma malabathricum Leaves.

Researchers employ different wavelengths and times of the reaction for the absorbance measurements with FCR. For example, such wavelengths are used in the Folin-Ciocalteu method: 760 or 765 nm (European Pharmacopoeia 2016), 760 nm (Blainski et al. 2013), 750 nm (Abdelkader et al. 2014). The European Pharmacopeia provides a wavelength of 760 nm for the measurement of absorbance, 30 min as the reaction time and pyrogallol as a reference substance (European Pharmacopoeia 2016). For polyphenols assay in different species of Salvia the following conditions were used: 765 nm, incubation for 30 min, gallic acid as a reference substance (Jafari et al. 2017); a wavelength of 750 nm, 120 min as the reaction time, gallic acid as a reference substance for aqueous-alcoholic extracts of Salvia officinalis leaves (Abdelkader et al. 2014); a wavelength of 760 nm, 120 min as the reaction time, gallic acid as a reference substance for methanolic extracts of Salvia officinalis leaves (Jasicka-Misiak et al. 2018). Stankovič et al. (2011) employed a wavelength of 765 nm, incubation at a temperature of 45 °C for 45 min, and gallic acid as a reference substance for the determination of TPC in methanolic extracts of Marrubium peregrinum (Stanković 2011). A wavelength of 650 nm, incubation in a boiling water for 1 min, catechol as a reference substance are used for TPC determination in ethanolic extracts of eight species of Lamiaceae (Khomdram and Singh 2011). The authors of the published papers with exception of Blainski et al. (2013) did not explain why they selected the proper marker, a wavelength or reaction time for the evaluation of TPC in the tested extracts.

Article Application of the Folin-Ciocalteu method to the evaluation ...

Dear all, the following documents deals with the case you are working on. Usually, it is recommanded to use at least two different techniques to evaluate the TPC. My Regards

https://doi.org/10.1016/j.foodchem.2007.04.008

https://www.researchgate.net/publication/308419778_Ginkgo_biloba_Ginkgoaceae_as_a_Source_of_Phenolic_Compounds_with_Antioxidant_Activity

https://www.researchgate.net/publication/296686929_Total_phenolic_content_and_antioxidant_capacity_of_ginkgo_teas

Many thanks for all the responses.

Have a look at these articles:

Article Evaluation of chemical constituents and biological propertie...

and

M.A. Yoon, et al.

Antioxidant effects of quinoline alkaloids and 2,4-Di-tert-butylphenol isolated from Scolopendra subspinipes

Biological and Pharmaceutical Bulletin, 29 (2006), pp. 735-739

and

C. Proestos, I.S. Boziaris, G.-J.E. Nychas, M. Komaitis

Analysis of flavonoids and phenolic acids in Greek aromatic plants: Investigation of their antioxidant capacity and antimicrobial activity

Food Chemistry, 95 (2006), pp. 664-671

Thank you professor Mozafari