Methanolic extract of white asparagus shoots activates TRAIL apoptotic death pathway in human cancer cells and inhibits colon carcinogenesis in a preclinical model

Shoots of white asparagus are a popular vegetable dish, known to be rich in many bioactive phytochemicals reported to possess antioxidant, and anti-inflammatory and antitumor activities. We evaluated the anticancer mechanisms of a methanolic extract of Asparagus officinalis L. shoots (Asp) on human colon carcinoma cells (SW480) and their derived metastatic cells (SW620), and Asp chemopreventive properties were also assessed in a model of colon carcinogenesis. SW480 and SW620 cell proliferation was inhibited by 80% after exposure to Asp (80 μg/ml). We demonstrated that Asp induced cell death through the activation of TRAIL DR4/DR5 death receptors leading to the activation of caspase-8 and caspase-3 and to cell apoptosis. By specific blocking agents of DR4/DR5 receptors we were able to prevent Asp-triggered cell death confirming the key role of DR4/DR5 receptors. We found also that Asp (80 μg/ml) was able to potentiate the effects of the cytokine TRAIL on cell death even in the TRAIL-resistant metastatic SW620 cells. Colon carcinogenesis was initiated in Wistar rats by intraperitoneal injections of azoxymethane (AOM), once a week for two weeks. One week after (post-initiation) rats received daily Asp (0.01%, 14 mg/kg body weight) in drinking water. After 7 weeks of Asp-treatment the colon of rats exhibited a 50% reduction of the number of preneoplastic lesions (aberrant crypt foci). In addition Asp induced inhibition of several pro-inflammatory mediators, in association with an increased expression of host-defense mediators. In the colonic mucosa of Asp-treated rats we also confirmed the pro-apoptotic effects observed in vitro including the activation of the TRAIL death-receptor signaling pathway. Taken together, our data highlight the chemopreventive effects of Asp on colon carcinogenesis and its ability to promote normal cellular homeostasis.

Improvement of total lipid and glycerophospholipid recoveries from various food matrices using pressurized liquid extraction

The extraction of three major phospholipid (PL) classes contained in soybean, egg yolk, calf brain, and ox liver was investigated by means of two methods. The PL amounts were evaluated. A new method, based on pressurized liquid extraction (PLE), was applied for total lipids (TL), including PL, extraction and compared with a standard liquid extraction method, a modified Folch method. The three PL classes (phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidylcholine (PC)) that were recovered in the obtained TL extracts were quantified using HPLC with an evaporative light-scattering detector (ELSD). Using the PLE method, a single extraction allowed a recovery of more than 94% of TL and 96% of each PL class. Two successive extractions could achieve a total recovery of the three studied PL classes. With the modified Folch method, 77-83% of TL, 80-91% of PE, 82-94% of PC, and no more than 78% of PI could be achieved from various food matrices after one extraction. Four successive extractions were necessary to recover the whole TL content and each PL class. Results indicate that PLE is a rapid and efficient lipid extraction system for the broad range of plant and animal tissues.

Oxidative stability at high temperatures of oleyol and linoleoyl residues in the forms of phosphatidylcholines and triacylglycerols

An investigation was carried out into the stability of fatty acyl groups to heat-induced oxidative changes as affected by their chemical environment. The behavior of oleic and linoleic acyl groups when esterified in triacylglycerols (TAGs) and phosphatidylcholines (PCs) was evaluated. The monitoring of the oxidative degradation using liquid chromatography-mass spectrometry (LC-MS) showed that fatty acyl groups are less likely to be oxidized when in the form of PCs than when in the form of TAGs. In addition, oxidation products from PCs were more stable than those from TAGs. This finding strengthens the idea that the choline group in PCs increases the stability of fatty acyl groups to oxidation in comparison to TAGs.

Investigation of natural phosphatidylcholine sources: separation and identification by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS2) of molecular species

This study is a contribution to the exploration of natural phospholipid (PL) sources rich in long-chain polyunsaturated fatty acids (LC-PUFAs) with nutritional interest. Phosphatidylcholines (PCs) were purified from total lipid extracts of different food matrices, and their molecular species were separated and identified by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS(2)). Fragmentation of lithiated adducts allowed for the identification of fatty acids linked to the glycerol backbone. Soy PC was particularly rich in species containing essential fatty acids, such as (18:2-18:2)PC (34.0%), (16:0-18:2)PC (20.8%), and (18:1-18:2)PC (16.3%). PC from animal sources (ox liver and egg yolk) contained major molecular species, such as (16:0-18:2)PC, (16:0-18:1)PC, (18:0-18:2)PC, or (18:0-18:1)PC. Finally, marine source (krill oil), which was particularly rich in (16:0-20:5)PC and (16:0-22:6)PC, appeared to be an interesting potential source for food supplementation with LC-PUFA-PLs, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).