ARTICLE | doi:10.20944/preprints201812.0027.v1
Subject: Chemistry, Medicinal Chemistry Keywords: Rumex tunetanus; Phenolic compounds; Metabolic profiling; Antioxidant activity; RP-UHPLC-ESI-QTOF-MS
Online: 3 December 2018 (13:58:52 CET)
The present study was designed to investigate the bioactive compound in Rumextunetanus extracts (polygonaceae), a plant growing in GarâaSejnane region (NW-Tunisia). Hydro-methanol extracts of flowers and stems of Rumextunetanus were analyzed by RP-UHPLC-ESI-QTOF-MS in the negative mode to identify the maximum of bioactive compounds. Applied the aforementioned method, a total of 60 bioactive compounds were characterized for the first time in Rumextunetanus between them, 18 photochemical were firstly identified in the Polygonaceae family in negative ionization mode. Quantification of the identified compounds revealed that quercetin-3-O-glucuronide and (-)-epicatechingallate were the most abundant phenolic compounds in flowers and stems, respectively. Moreover, positive correlations were found between the antioxidant activity measured by DPPH and FRAP assays with the total phenolic compounds (r = 0.98; r = 0.99, respectively) and the abundance of some phenolic subfamilies such as hydroxycinnamic acids, hydroxybenzoic acids, flavonols and flavones with r > 0.86. The compounds displaying significant (P < 0.01) and good correlations with the antioxidant activity (r > 0.93) were hydroxybenzoic acid, rutin, quercetin-3-O-glucuronide, quercetin-3-O-glucoside, quercetin and luteolin-7-O-rutinoside. In addition, the flowers and stems of Rumex tunetanus showed different bioactive compound profiles and significant antioxidant properties of extracts. These results highlight the potential of the RP-UHPLC-ESI-QTOF-MS and MS/MS system to identify untargeted metabolic profiling of Rumex tunetanus. Overall, these results contribute to the clear explanation of the past and current usage of genus Rumex in folk medicine. Future investigations are necessary to develop purified antioxidant extracts, with the application of more selective extraction techniques.
ARTICLE | doi:10.20944/preprints201812.0024.v1
Subject: Chemistry, Food Chemistry Keywords: extra-virgin olive oil adulteration; vegetables oils; triglycerides; fatty acids; linear discriminant analysis; principal component analysis
Online: 3 December 2018 (13:38:58 CET)
Nowadays, the fingerprinting methodologies of olive oils are dominated. They consider the entire analytical signal, which is acquired and recorded by the analytical instrument, directly from olive oil or isoleted fraction, i,e chromatogram. The shape and intensity of the recorded signal the instrumental fingerprint from the whole olive oil adulteration. Therefore, the methodolygy is based on the chemical composition (Fatty acids and Triglycerides compositions). However, Fatty acids composition as an indicator of purity suggests that linolenic acid content could be used as a parameter for the detection of extra virgin olive oil fraud with 5% of soybean oil. The adulteration could also be detected by the increase of the trans-fatty acid contents with 3% of soybean oil, 2% of corn oil and 4% of sunflower oil. The use of the ∆ECN42 proved to be effective in the Chemlali extra-virgin olive oil adulteration even at low levels: 1% of sunflower oil, 3% of soybean oil and 3% of corn oil. Therefore, compared to classical methods PCA and new approach of using LDA application could represent an alternative and innovative tool for faster and cheaper evaluation of extra-virgin olive oil adulteration.