Effect of probiotication on antioxidant and antibacterial activities of pomegranate juices from sour and sweet cultivars

Punicalagin, a pomegranate polyphenol sensitizes the activity of antibiotics against three MDR pathogens of the Enterobacteriaceae

BACKGROUND

Multidrug resistance (MDR) in the family Enterobacteriaceae is a perniciously increasing threat to global health security. The discovery of new antimicrobials having the reversing drug resistance potential may contribute to augment and revive the antibiotic arsenal in hand. This study aimed to explore the anti-Enterobacteriaceae capability of bioactive polyphenols from Punica granatum (P. granatum) and their co-action with antibiotics against clinical isolates of Enterobacteriaceae predominantly prevalent in South Asian countries.

METHODS

The Kandhari P. granatum (Pakistani origin) extracts were tested for anti-Enterobacteriaceae activity by agar well diffusion assay against MDR Salmonella enterica serovar Typhi, serovar Typhimurium and Escherichia coli. Predominant compounds of active extract were determined by mass spectrometry and screened for bioactivity by agar well diffusion and minimum inhibitory concentration (MIC) assay. The active punicalagin was further evaluated at sub-inhibitory concentrations (SICs) for coactivity with nine conventional antimicrobials using a disc diffusion assay followed by time-kill experiments that proceeded with SICs of punicalagin and antimicrobials.

RESULTS

Among all P. granatum crude extracts, pomegranate peel methanol extract showed the largest inhibition zones of 25, 22 and 19 mm, and the MICs as 3.9, 7.8 and 7.8 mg/mL for S. typhi, S. typhimurium and E. coli, respectively. Punicalagin and ellagic acid were determined as predominant compounds by mass spectrometry. In plate assay, punicalagin (10 mg/mL) was active with hazy inhibition zones of 17, 14, and 13 mm against S. typhi, S. typhimurium and E. coli, respectively. However, in broth dilution assay punicalagin showed no MIC up to 10 mg/mL. The SICs 30 μg, 100 μg, and 500 μg of punicalagin combined with antimicrobials i.e., aminoglycoside, β-lactam, and fluoroquinolone act in synergy against MDR strains with % increase in inhibition zone values varying from 3.4 ± 2.7% to 73.8 ± 8.4%. In time-kill curves, a significant decrease in cell density was observed with the SICs of antimicrobials/punicalagin (0.03-60 μg/mL/30, 100, 500 μg/mL of punicalagin) combinations.

CONCLUSIONS

The P. granatum peel methanol extract exhibited antimicrobial activity against MDR Enterobacteriaceae pathogens. Punicalagin, the bacteriostatic flavonoid act as a concentration-dependent sensitizing agent for antimicrobials against Enterobacteriaceae. Our findings for the therapeutic punicalagin-antimicrobial combination prompt further evaluation of punicalagin as a potent activator for drugs, which otherwise remain less or inactive against MDR strains.

Probiotics in anthocyanin-rich fruit beverages: research and development for novel synbiotic products

Anthocyanin-rich fruit beverages are of special interest as functional products due to their antioxidant activity, antimicrobial properties against pathogens, and, more recently, evidence of prebiotic potential. The stability and bioactivity of anthocyanins, probiotics, prebiotics, and synbiotics have been extensively documented in beverage models and reviewed separately. This review summarizes the most recent works and methodologies used for the development of probiotic and synbiotic beverages based on anthocyanin-rich fruits with a synergistic perspective. Emphasis is made on key optimization factors and strategies that have allowed probiotic cultures to reach the minimum recommended doses to obtain health benefits at the end of the shelf life. The development of these beverages is limited by the high acidity and high content of phenolic compounds in anthocyanin-rich fruits. However, a proper selection of probiotic strains and strategies for their media adaptation may improve their viability in the beverages. Fermentation increases the viability of the probiotic cultures, improves the safety and stability of the product, and may increase its antioxidant capacity. Moreover, fermentation metabolites may synergistically enhance probiotic health benefits. On the other hand, the inoculation of probiotics without fermentation allows for synbiotic beverages with milder changes in terms of physicochemical and sensory attributes.

Development and screening of byproduct for its secondary metabolites, antioxidant and anti-diabetic potential from anthracnose-infected fruits of pomegranate: a sustainable approach

The main focus of the present study was to analyze the antioxidant and anti-diabetic potential of fermentative byproduct, developed from anthracnose-infected pomegranate fruits. The analysis of fermented juice showed a reduction in total phenolic content, total flavanoid content, anthocyanins, and antioxidant potential over the time in 6 months as compared to fresh juice, while total protein and alcohol percent (11%) were increased. Measurements of antioxidant activity by DPPH, ABTS, superoxide radical scavenging activity, and reducing power assays were highly correlated to total phenolic content, with corresponding R ² values as r _DPPH = 0.88, r _ABTS = 0.90, r _SRS = 0.67, r _RPA = 0.80. High-performance liquid chromatography clearly revealed that the increment of antioxidant activity is associated with the release of gallic acid, vanillin, and ferulic acid. LC-MS analysis identified 1263 metabolites in fresh juice, 1580 metabolites after 1 month of fermentation, and 1063 metabolites after 6 months of fermentation. Most of the detected metabolites are linked with antioxidant, anti-diabetic, phenolics, flavanoids, cardiac glycosides, anticancer, and anti-vomiting activity. Mainly, naphthofluorescein, CAY10599, CAY10506, aminofluoropropionic acid, and 8-azaadenosine anti-diabetic compounds were found in fresh juice and fermented juice. Administration of fresh juice and fermented juice for 1 month helped in the reduction of blood plasma glucose level from 112.6 to 94.73 mg/dL before food and 142.43 to 133.20 mg/dL after food as compared to prescribed medicine. The sensory attributes of fermented juice were well appreciated for taste, after taste, and flavor. Further research is necessary to improve the quality and stability of metabolites during storage.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-020-02629-z.

Pomegranate variety and pomegranate plant part, relevance from bioactive point of view: a review

Pomegranate (Punica granatum L.) belongs to the Punicaceae plant family. It is an important fruit due to its nutritional and medicinal properties. Pomegranates are widely distributed around the world and, therefore, have a broad genetic diversity, resulting in differences in their phytochemical composition. The scientific community has focused on the positive health effects of pomegranate as a whole, but the different varieties have rarely been compared according to their bioactive compounds and bioactivity. This review aims to provide a holistic overview of the current knowledge on the bioactivity of pomegranate trees, with an emphasis on differentiating both the varieties and the different plant parts. This review intends to provide a general and organized overview of the accumulated knowledge on pomegranates, the identification of the most bioactive varieties, their potential consumption pathways and seeks to provide knowledge on the present gaps to guide future research.

Production of Vitamin D3 Enriched Biomass of Saccharomyces Cerevisiae as A Potential Food Supplement: Evaluation and Optimization of Culture Conditions Using Plackett-Burman and Response Surface Methodological Approaches

Vitamin D deficiency causes osteoporosis, osteopenia, fractures, rickets, and more recently is linked with some chronic illnesses such as cancer. Because of the safety and probiotic properties of the yeast Saccharomyces cerevisiae, we hypothesized that yeast cells enriched with cholecalciferol (vitamin D₃) could represent a solution for prevention or treatment of vitamin D deficiency. In this study S. cerevisiae was used as a vitamin D₃ accumulator for the first time and the optimal conditions for enrichment of S. cerevisiae were determined. The Plackett-Burman screening studies were used for selection of the most important factors affecting cholecalciferol entrapment. Response surface methodology was employed for optimization of cholecalciferol accumulation in S. cerevisiae cells by using Box-Behnken design. A modified quadratic polynomial model fit the data appropriately. The optimal points of variables to maximize the response were cholecalciferol initial concentration of 358021.16 IU/mL, tryptone concentration of 1.82 g/L, sucrose concentration of 7.13 % (w/v), and shaking speed of 140.46 rpm. The maximum amount of cholecalciferol in dry cell weight of S. cerevisiae was 4428.11 IU/g. The cholecalciferol entrapment in yeast biomass increased about two-folds in optimized condition which indicates efficiency of optimization.

Effects of Agitation Speed and Kinetic Studies on Probiotication of Pomegranate Juice with Lactobacillus casei

The issues of lactose intolerance and vegetarianism have encouraged the introduction of non-dairy fermented food into the market. Therefore, this study aims to evaluate the effect of agitation speed on the bioactive compounds and functional characteristics of probioticated pomegranate juice. Pomegranate juice was fermented with Lactobacillus casei at different agitation speeds ranging from 0 (microaerophilic) to 150 rpm at 37 °C. The functional properties of probioticated pomegranate juice were evaluated in terms of growth (biomass), lactic acid production, antioxidant activity, total phenolic content, and key metabolites using LC-MS/MS. The growth kinetics of fermentation was monitored at the optimal condition using one factor at a time method. High cell growth (3.58 × 1010 cfu/mL or 7.9 gL-1) was observed for L. casei probioticated pomegranate juice agitated at 0 rpm. The findings of this study reveal the potential of pomegranate juice as a medium for L. casei cultivation without nutrient supplementation. The improvement of antioxidant activity in the probioticated juice could be due to the increment of quercetin-3-glucoside. Therefore, L. casei grew well in pomegranate juice with a high cell viability and antioxidant activity at a non-agitated condition. Probioticated pomegranate juice is a potentially functional drink.

Partial identification of antifungal compounds from Punica granatum peel extracts

Aqueous extracts of pomegranate peels were assayed in vitro for their antifungal activity against six rot fungi that cause fruit and vegetable decay during storage. The growth rates of Alternaria alternata , Stemphylium botryosum , and Fusarium spp. were significantly inhibited by the extracts. The growth rates were negatively correlated with the levels of total polyphenolic compounds in the extract and particularly with punicalagins, the major ellagitannins in pomegranate peels. Ellagitannins were also found to be the main compounds in the bioactive fractions using bioautograms, and punicalagins were identified as the main bioactive compounds using chromatographic separation. These results suggest that ellagitannins, and more specifically punicalagins, which are the dominant compounds in pomegranate peels, may be used as a control agent of storage diseases and to reduce the use of synthetic fungicides.