Xanthophyll esters are hydrolysed in the presence of recombinant human pancreatic lipase

Screening of critical factors influencing the efficient hydrolysis of zeaxanthin dipalmitate in an adapted in vitro- digestion model

As hydrolysis of carotenoid esters is believed to be highly efficient in vivo, their insufficient hydrolysis in in vitro-digestion models, particularly, regarding zeaxanthin diesters, is a current issue. Therefore, in this study, several factors related to the enzymatic hydrolysis were investigated in an adapted version of the standardized INFOGEST in vitro-digestion model, using zeaxanthin dipalmitate (ZDP) as a substrate. The results showed that pancreatic lipase was able to hydrolyze ZDP, whereas carboxyl ester lipase (CEL) substantially contributed to ZDP cleavage. Replacement of commonly used porcine with bovine bile extracts and the substitution of coffee creamer for soybean oil at identical fat contents both significantly improved hydrolysis efficiency and bioaccessibility of total zeaxanthin to better mimic in vivo conditions. Thus, bile and lipids selection for in vitro digestion of carotenoid esters was crucial. The combined use of coffee creamer, pancreatin, CEL, and bovine bile led to the highest hydrolysis efficiency of 29.5%.

Porcine Pancreatic Lipase Inhibitory Agent Isolated from Medicinal Herb and Inhibition Kinetics of Extracts from Eleusine indica (L.) Gaertner

Eleusine indica (Linnaeus) Gaertner is a traditional herb known to be depurative, febrifuge, and diuretic and has been reported with the highest inhibitory activity against porcine pancreatic lipase (PPL) among thirty two plants screened in an earlier study. This study aims to isolate and identify the active components that may possess high potential as an antiobesity agent. Of the screened solvent fractions of E. indica, hexane fraction showed the highest inhibitory activity of 27.01 ± 5.68% at 100 μg/mL. Bioactivity-guided isolation afforded three compounds from the hexane fraction of E. indica, namely, β-sitosterol, stigmasterol, and lutein. The structures of these compounds were elucidated using spectral techniques. Lutein showed an outstanding inhibitory activity against PPL (55.98 ± 1.04%), with activity 60% higher than that of the reference drug Orlistat. The other compounds isolated and identified were β-sitosterol (2.99 ± 0.80%) and stigmasterol (2.68 ± 0.38%). The enzyme kinetics of E. indica crude methanolic extract on PPL showed mixed inhibition mechanism.

Bioaccessibility of bioactive compounds after non-thermal processing of an exotic fruit juice blend sweetened with Stevia rebaudiana

A comparative study of the bioaccessibility of bioactive compounds and antioxidant capacity in a fruit juice-Stevia rebaudiana mixture processed by pulsed electric fields (PEF), high voltage electrical discharges (HVED) and ultrasound (USN) technology at two equivalent energy inputs (32-256kJ/kg) was made using an in vitro model. Ascorbic acid was not detected following intestinal digestion, while HVED, PEF and USN treatments increased total carotenoid bioaccessibility. HVED at an energy input of 32kJ/kg improved bioaccessibility of phenolic compounds (34.2%), anthocyanins (31.0%) and antioxidant capacity (35.8%, 29.1%, 31.9%, for TEAC, ORAC and DPPH assay, respectively) compared to untreated sample. This was also observed for PEF treated samples at an energy input of 256kJ/kg (37.0%, 15.6%, 29.4%, 26.5%, 23.5% for phenolics, anthocyanins, and antioxidant capacity using TEAC, ORAC and DPPH method, respectively). Consequently, pulsed electric technologies (HVED and PEF) show good prospects for enhanced bioaccessibility of compounds with putative health benefit.

Isolation, identification and characterization of a new lipolytic pseudomonas sp., strain AHD-1, from Tunisian soil

A novel, lipid-degrading bacterium (strain AHD-1) was isolated from soil regularly contaminated with washing-machine wastewater in Sfax, Tunisia. When this strain was grown in a medium containing 2% triacylglycerol, the hydrolysis products were found to be diacylglycerols, monoacylglycerols and free fatty acids. This strain was an aerobic, mesophilic, Gram-negative, motile, non-sporulating bacterium, capable of growing optimally at pH 7 and 27 degrees C. The predominant fatty acids were found to be C16:1omega7c (31%), C16:0 (28.1%), C18:1 omega7c (16.3%) and C17:0 (5.8%). Phylogenetic analysis of the 16S rRNA gene showed that this isolate is a new strain belonging to the genus Pseudomonas. Strain AHD-1 was found to be closely related to Pseudomonas azotoformans IAM 1603T, Pseudomonas gessardii CIP 105469T and Pseudomonas libanensis CIP 105460T with 99.7%, 99.56% and 99.54% of similarity, respectively.