Antibacterial and antioxidative properties of different parts of garden rhubarb, blackcurrant, chokeberry and blue honeysuckle.

BACKGROUND: It is important to find plant materials that can inhibit the growth of Listeria monocytogenes and other food-spoiling bacteria both in vitro and in situ. The aim of the study was to compare antibacterial and antioxidative activity of selected plant-ethanol infusions: leaves and berries of blackcurrant (Ribes nigrum L.), berries of chokeberry (Aronia melanocarpa (Michx.) Elliott) and blue honeysuckle (Lonicera caerulea L. var. edulis); petioles and dark and light roots of garden rhubarb (Rheum rhaponticum L.) for potential use in food matrices as antibacterial and antioxidative additives. RESULTS: The strongest bacterial growth inhibition was observed in 96% ethanol infusions of the dark roots of rhubarbs. In 96% ethanol, nine out of ten studied plant infusions had antibacterial effect against L. monocytogenes, but in 20% ethanol only the infusions of dark rhubarb roots had a similar effect. Chokeberry and other berries had the highest antioxidative activity, both in 20% and 96% ethanol infusions. CONCLUSION: The combination of dark rhubarb roots or petioles and berries of black chokeberry, blackcurrant or some other anthocyanin-rich berries would have potential as both antibacterial and antioxidative additives in food. © 2018 Society of Chemical Industry.

In Vitro Antibacterial and Antioxidative Activity and Polyphenolic Profile of the Extracts of Chokeberry, Blackcurrant, and Rowan Berries and Their Pomaces.

The chemical composition of berries and berry pomaces is diverse, containing polyphenolic components that may have both antibacterial and antioxidative properties. In the present study, in vitro antibacterial effect of the extracts of chokeberry, blackcurrant, and rowan berries and berry pomaces against L. monocytogenes, S. aureus, E. coli, and C. jejuni was studied. In addition, the polyphenolic profile and antioxidant activity of these extracts were investigated. The polyphenolic profiles in the aqueous and 30% ethanolic extracts were determined chromatographically by HPLC-MS, and the total polyphenol content was estimated spectrophotometrically by HPLC-DAD-UV. The minimal inhibition concentrations (MICs) of the extracts against tested bacteria were determined by the broth microdilution method. The content of total polyphenols was highest and good antioxidative properties of the extracts were determined for chokeberry and blackcurrant berries and their pomaces. The highest proportions of total quercetin derivatives and anthocyanins were found in the extracts of chokeberry berry/pomace and blackcurrant berry/pomace, respectively. The sensitivity of tested microbes to the extracts of berries and berry pomaces was as follows: S. aureus > L. monocytogenes > E. coli and C. jejuni. In vitro antibacterial activity of tested extracts depended on the extraction solvent, mainly for the ethanolic extracts. Findings suggest that chokeberry and blackcurrant berries and their pomaces can be used as a good source of polyphenols with antioxidative properties, and they also have antibacterial activity against some foodborne pathogenic bacteria. It is important that the valuable compounds are extracted from juice press residues before their disposal.

Phytochemical characterization of oil and protein fractions isolated from Japanese quince (Chaenomeles japonica) wine by-product.

The wine industry generates large quantities of by-products each year. Therefore, this work aimed to isolate and evaluate the oil and protein fractions of Japanese quince (Chaenomeles japonica, JQ) press residue, offering a partial utilization of valuable bioactive compounds of wine industry by-products. To study the JQ oil extract yield, composition and oxidation stability, we modified the co-solvent composition during the supercritical CO2 (SC-CO2) extraction of oil by adding different ethanol content. The remaining defatted material was used for the isolation of proteins. The SC-CO2 extraction yielded oil rich in polyunsaturated fatty acids, tocopherols, and phytosterols. The use of ethanol as a co-solvent increased the oil yield but did not enhance its oxidative stability or content of antioxidants. We recovered protein isolate after removing tannins with 70% ethanol extraction in the next step. The JQ protein isolate contained all essential amino acids. In addition to its balanced amino acid composition, the protein isolate exhibited excellent emulsifying properties highlighting its potential as a food additive. In conclusion, JQ wine by-products can be utilized for the extraction of oil and protein fractions which can be used in food or cosmetic product formulation.

Comparative Analyses of Bioactive Compounds in Inonotus obliquus Conks Growing on Alnus and Betula.

Inonotus obliquus grows in the Northern Hemisphere on some living broadleaved tree species as a pathogen, causing stem rot. In Estonia, the fungus is well known in the Betula species but can also be found on Alnus. Sterile conks of I. obliquus contain different bioactive compounds, but the quantitative and comparative research of these compounds in conks on different host species is limited. In the current work, I. obliquus was isolated and, evidently, determined from Alnus incana (L.) Moench., Alnus glutinosa (L.) Gaertn., and Betula pendula Roth, and the content of bioactive compounds in conks on these hosts were analysed. All the analysed conks sampled from A. incana and B. pendula contained betulin that varied from 111 to 159 µg/g. A significantly (p < 0.05) higher betulinic acid content was found in conks sampled from A. incana when compared with B. pendula: 474−635 and 20−132 µg/g, respectively. However, the conks from Betula were richer in total polyphenols, flavonols, and glucans. The content of inotodiol was quite similar in the conks from A. incana (7455−8961 µg/g) and B. pendula (7881−9057 µg/g). Also, no significant differences in the lanosterol content were found between the samples from these two tree species. To the best of our knowledge, this study is the first investigation of the chemical composition of I. obliquus parasitizing on Alnus. The results demonstrate that the bioactive compounds are promising in conks of I. obliquus growing not only on Betula but also on the Alnus species. It supports the opportunity to cultivate I. obliquus, also on the Alnus species, thus increasing the economic value of growing this tree species in forestry.

Enzyme-assisted extraction of anthocyanins and other phenolic compounds from blackcurrant (Ribes nigrum L.) press cake: From processing to bioactivities.

The effects of commercial enzymes (pectinases, cellulases, beta-1-3-glucanases, and pectin lyases) on the recovery of anthocyanins and polyphenols from blackcurrant press cake were studied considering two solid:solvent ratios (1:10 and 1:4 w/v). ß-glucanase enabled the recovery of the highest total phenolic content - 1142 mg/100 g, and the extraction of anthocyanins was similar using all enzymes (∼400 mg/100 g). The use of cellulases and pectinases enhanced the extraction of antioxidants (DPPH - 1080 mg/100 g; CUPRAC - 3697 mg/100 g). The freeze-dried extracts presented antioxidant potential (CUPRAC, DPPH), which was associated with their biological effects in different systems: antiviral activity against both non-enveloped viruses (enterovirus coxsackievirus A-9) and enveloped coronaviruses (HCoV-OC43), and cytotoxicity towards cancer cells (A549 and HCT8). No cytotoxic effects on normal human lung fibroblast (IMR90) were observed, and no anti-inflammatory activity was detected in lipopolysaccharides-treated murine immortalised microglial cells.

Optimization of Ultrasound-Assisted Extraction of Phloretin and Other Phenolic Compounds from Apple Tree Leaves (Malus domestica Borkh.) and Comparison of Different Cultivars from Estonia.

Polyphenolic compounds, plant secondary metabolites essential for plant survival, are known for their high antioxidant and anti-inflammatory activity. In addition, several polyphenols, such as phloretin, also have potential antiviral effects, making these compounds potential ingredients of biofunctional foods. A promising source for the extraction of phloretin is a by-product of apple production-apple tree leaves. Focusing on green technologies, the first aim of the present study was to optimize the direct ultrasound-assisted extraction conditions to gain the maximum yield of phloretin from air-dried apple leaves. For the optimization of process parameters, we applied the response surface method with Box-Behnken design. The optimal extraction conditions were extraction time 14.4 min, sonication amplitude 10% and 10 g of sample per 100 mL solvent (70% ethanol, w/w). Using these conditions, we assessed the content of individual and total polyphenolic compounds along with antioxidant activity in the leaves of different autumn and winter apple cultivars grown in Estonia. The analyses were carried out with chromatographic (HPLC-DAD-MS/MS)and spectrophotometric methods. The phloretin concentration ranged from 292 to 726 µg/g and antioxidant activity from 6.06 to 11.42 mg GA eq./g, these being the highest in the local winter cultivars 'Paide taliõun' and 'Tellissaare', respectively.

Lipid oxidation inhibition capacity of plant extracts and powders in a processed meat model system.

A meat model system was used for screening lipid oxidation inhibiting capacity of diverse horticultural plant materials. In the model, heme-containing sarcoplasmic proteins from the meat water-phase were homogenized with linoleic acid and thiobarbituric reactive substances (TBARS) were measured. 23 Plant materials were investigated at three high (50, 100, and 200 ppm) concentrations and five plant extracts were tested at three low (5, 10, and 20 ppm) concentrations over time. In the high concentration sets, summer savory freeze-dried powder, beetroot leaves extracted with 50% ethanol, and an olive polyphenol powder extracted from wastewater, inhibited oxidation the most effectively. After two weeks and at 200 ppm concentration, oxidation was reduced to 17.2%, 16.6% and 13.5% of the blank sample with no added antioxidants respectively. In the low concentration set, spray dried rhubarb juice inhibited oxidation the most after two weeks at 5 ppm where oxidation was reduced to 68.3% of the blank sample with no added antioxidants.