Autilia Cozzolino

In vitro antioxidant, antimicrobial and anti-proliferative activities of purple potato extracts (Solanum tuberosum cv Vitelotte noire) following simulated gastro-intestinal digestion

Analyses of antioxidant and in vitro antimicrobial and anti-proliferative activities of anthocyanin-rich extracts from purple potatoes, Solanum tuberosum L. cv Vitelotte noire (Solanaceae), were performed by simulating both a domestic cooking process and human digestion. Extracts of crude and cooked purple potato did not exhibit antimicrobial activity against the tester strains: Bacillus cereus, Escherichia coli and Pseudomonas aeruginosa. The behaviour changed after the simulated gastrointestinal transit, when an inhibition halo was observed against all tester strains used, ranging from 0.53 cm against B. cereus to 0.82 cm against E. coli. In addition antioxidant activity exhibited, before and after the simulated gastrointestinal digestion (5.96 mg/mL ± 0.92; 28 mg/mL ± 0 .13, respectively) and the persistence of anti-proliferative activity against the colon cancer cells Caco-2, SW48 and MCF7, MDA-MB-231 breast cancer cells, after the simulated digestion, (EC50 = 0.21; 1.13 μg/mL), suggest that vitelotte consumption might bring tangible benefits for human health.

Biochemical and biological characterization of two Brassicaceae after their commercial expiry date.

Two Brassicaceae (Eruca sativa, Brassica oleracea var. sabauda) were stored in air and under a modified atmosphere for several days after their expiry date and then analyzed. The polyphenol content and composition, as well as the antioxidant activity of the extracts, were assessed, compared to the fresh products. Antimicrobial properties on tester strains (Bacillus cereus, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa) and in vitro anti-proliferative activity were evaluated. The cabbage extracts exhibited antimicrobial activity mainly on the ninth day after the expiry date and retained significant inhibitory effects against colon carcinoma (CaCo-2) cells. The rocket salad extract exhibited antiproliferative but not antimicrobial activity. Overall, our results indicated that they might represent a good source of natural antioxidants with antimicrobial and anti-proliferative activity, also after their expiry date, suggesting their exploitation for the recovery of important biomolecules used in the food and health industry.

Eruca sativa Might Influence the Growth, Survival under Simulated Gastrointestinal Conditions and Some Biological Features of Lactobacillus acidophilus, Lactobacillus plantarum and Lactobacillus rhamnosus Strains

The growth and viability of three Lactobacillus strains, Lactobacillus acidophilus, Lactobacillus plantarum and Lactobacillus rhamnosus, after their passage through simulated gastric and pancreatic juices were studied as a function of their presence in the growth medium of rocket salad (Eruca sativa). The presence of E. sativa affected some of the biological properties of the strains. For example, L. acidophilus and L. plantarum worked more efficiently in the presence of E. sativa, increasing not only the antioxidant activity of the medium, but also their own antioxidant power and antimicrobial activity; L. rhamnosus was not affected in the same manner. Overall, the presence of vegetables might help to boost, in specific cases, some of the characteristics of lactobacilli, including antioxidant and antimicrobial power.

Pre-cultivation with Selected Prebiotics Enhances the Survival and the Stress Response of Lactobacillus rhamnosus Strains in Simulated Gastrointestinal Transit

In our study, we dwelled upon combinations of lactobacilli/prebiotics, considering four different strains belonging to the Lactobacillus rhamnosus species, including Lactobacillus rhamnosus GG (LGG), and different prebiotics often found in commercial synbiotic products, such as inulin, lactulose and polyols mannitol and sorbitol. In the first step of the research, the survival, the growth kinetic parameters and the protein expression of Lb. rhamnosus strains cultivated in presence of the different prebiotics as a unique carbon source were evaluated. In the second step, the influence of pre-cultivation in medium added of metabolizable prebiotics on the strains survival to simulated gastrointestinal (GI) transit, assayed without prebiotics addition, was estimated. Our results showed that the presence in the medium of certain low fermented prebiotics, specific for each strain, represents a stress factor that significantly affects the growth of Lb. rhamnosus strains, inducing the up-regulation of several proteins. In detail, all added prebiotics used as unique carbon source caused a growth retard compared with glucose, as testified by increased values of the lag phase and decreased values of the μmax. Mannitol evidenced intermediate μmax values between those registered with glucose and those detected with the other assayed prebiotics. Moreover, the cultivation with prebiotics induced the over expression of 7 protein bands. Interestingly, we found a correlation between the up-regulation of two specific stress proteins, called P4 (ATP-binding subunit Clpx) and P7 (GrpE), and the death kinetic parameters (resistance and cells viability) registered during the simulated GI transit of strains pre-cultivated with specific, low fermented prebiotics. Specifically, the highest resistance and gastric-vitality scores were highlighted for the strain AT195 when pre-cultivated in presence of sorbitol. Conversely, the lowest values were found in the case of DSM20021 pre-cultivated with mannitol. Among the up-regulated stress proteins, P7 resulted involved in the response to the starvation. Finally, it is possible to conclude that the pre-cultivation with certain prebiotics as a unique carbon source represents a strain-specific, sub-lethal stress able to enhance the resistance of Lb. rhamnosus strains and consequently their viability under simulated GI transit.

Changes in visual quality, physiological and biochemical parameters assessed during the postharvest storage at chilling or non-chilling temperatures of three sweet basil (Ocimum basilicum L.) cultivars

Leaves of three different sweet basil (Ocimum basilicum L.) cultivars (Italico a foglia larga, Cammeo, and Italiano classico) packed in macro-perforated polyethylene bags were stored at chilling (4°C) or non-chilling temperature (12°C) for 9days. During storage, visual quality, physiological (respiration rate, ethylene production, ammonium content) and chemical (antioxidant activity, total polyphenols and polyphenol profile) parameters were measured. Detached leaves stored at chilling temperature showed visual symptoms related to chilling injury, while ethylene production and ammonium content resulted associated to cultivar sensibility to damage at low temperature. Storage at 4°C caused a depletion in polyphenols content and antioxidant capability, which was preserved at 12°C. Regarding the polyphenols profile, stressful storage conditions did not enhance the phenolic metabolism. However, leaves stored at 12°C did not loss a significant amount of metabolites respect to fresh leaves, suggesting the possibility to extend the storability after the expiration date, for a possible recovery of bioactive compounds.