1.Superheated liquid extraction of oleuropein and related biophenols from olive leaves.
Japón-Luján R;Luque de Castro MD J Chromatogr A. 2006 Dec 15;1136(2):185-91. Epub 2006 Oct 11.
Oleuropein and other healthy olive biophenols (OBPs) such as verbacoside, apigenin-7-glucoside and luteolin-7-glucoside have been extracted from olive leaves by using superheated liquids and a static-dynamic approach. Multivariate methodology has been used to carry out a detailed optimisation of the extraction. Under the optimal working conditions, complete removal without degradation of the target analytes was achieved in 13 min. The extract was injected into a chromatograph-photodiode array detector assembly for individual separation-quantification. The proposed approach - which provides more concentrated extracts than previous alternatives - is very useful to study matrix-extractant analytes partition. In addition, the efficacy of superheated liquids to extract OBPs, the simplicity of the experimental setup, its easy automation and low acquisition and maintenance costs make the industrial implementation of the proposed method advisable.
2.Dietary Exposure Risk Assessment of Flonicamid and Its Effect on Constituents after Application in Lonicerae Japonicae Flos.
Li J;Wang Y;Xue J;Wang P;Shi S Chem Pharm Bull (Tokyo). 2018 Jun 1;66(6):608-611. doi: 10.1248/cpb.c17-00985. Epub 2018 Mar 14.
To investigate the dietary exposure risk of flonicamid application on Lonicerae Japonicae Flos and the effect of flonicamid on constituents of Lonicerae Japonicae Flos, field experiments were conducted in Fengqiu, Henan province, and flonicamid residue in samples collected was detected by gas chromatography equipped with electron capture detector (GC-ECD). And chlorogenic acid and luteoloside were determined by HPLC. Dietary exposure risk assessment was conducted through comparing the estimated daily intake (EDI) which was calculated by using the consumed residual level along with the acceptable daily intake (ADI). The effect of flonicamid on chlorogenic acid and luteoloside were obtained by ANOVA statistical analysis and least significant difference (LSD)-t test. The results showed that the terminal-residue contents of flonicamid were under 1.6 mg kg;-1;. And risk quotient ranged from 0.0011 to 0.0028, indicating the long-term exposure to flonicamid residual through consumption of Lonicerae Japonicae Flos in consumers was relatively low. Flonicamid could suppress the generation of luteoloside, so it was not advised to be used in L. japonica flowering phase. The study aims at providing the useful suggestion on the reasonable flonicamid usage and the reference for the establishment of maximum residue limits (MRLs) of flonicamid in Lonicerae Japonicae Flos.
3.Free radical scavenging abilities of flavonoids as mechanism of protection against mutagenicity induced by tert-butyl hydroperoxide or cumene hydroperoxide in Salmonella typhimurium TA102.
Edenharder R;Grünhage D Mutat Res. 2003 Sep 9;540(1):1-18.
Mutagenicity induced by tert-butyl hydroperoxide (BHP) or cumene hydroperoxide (CHP) in Salmonella typhimurium TA102 was effectively reduced by flavonols with 3',4'-hydroxyl groups such as fisetin, quercetin, rutin, isoquercitrin, hyperoxide, myricetin, myricitrin, robinetin, and to a lesser extent also by morin and kaempferol (ID50=0.25-1.05 micromol per plate). With the exception of isorhamnetin, rhamnetin, morin, and kaempferol, closely similar results were obtained with both peroxides. Hydrogenation of the double bond between carbons 2 and 3 (dihydroquercetin, dihydrorobinetin) as well as the additional elimination of the carbonyl function at carbon 4 (catechins) resulted in a loss of antimutagenicity with the notable exception of catechin itself. Again, all flavones and flavanones tested were inactive except luteolin, luteolin-7-glucoside, diosmetin, and naringenin. The typical radical scavenger butylated hydroxytoluene also showed strong antimutagenicity against CHP (ID50=5.4 micromol per plate) and BHP (ID50=11.4 micromol per plate). Other lipophilic scavengers such as alpha-tocopherol and N,N'-diphenyl-1,4-phenylenediamine exerted only moderate effects, the hydrophilic scavenger trolox was inactive.
