Antioxidant and antiinflammation capacities of some pear cultivars

Antioxidant Properties of the Native Khechechuri Pear from Western Georgia

Khechechuri is an endemic species of a pear spread over one region of Western Georgia, called Adjara. Pears are a dietary source of bioactive components such as polyphenols and triterpenic acid. In addition to highlighting its gastronomic value, the aim of the article was to examine and compare phenolic compounds, flavonoids, catechins, phenolic acids, and antioxidant activities in Khechechuri collected from various villages in the Adjara region, namely Adjaristskali, Merisi, Dandalo, Shuakhevi, and Khulo. Five parts of the fruit, the skin, edible pulp, whole pear (skin + pulp), juice, and pomace, were analyzed and the results compared. Our study indicated that the highest total phenolic content was found in the skin of West Georgian pear types (4650 mg/kg.) Moreover, the pomace showed significant amounts of total phenolic content in each of the Khechechuri samples analyzed. Flavonoids were found in each part of the Khechechuri pears, with the notable exception of the fruit juice. A positive correlation between the total phenolic content and the geographical altitude of where the fruits were collected was observed.

A Comparative Investigation on Phenolic Composition, Characterization and Antioxidant Potentials of Five Different Australian Grown Pear Varieties

Pear (Pyrus communis L.) is widely spread throughout the temperate regions of the world, such as China, America and Australia. This fruit is popular among consumers due to its excellent taste and perceived health benefits. Various bioactive compounds, which contribute to these health benefits, have been detected in the pear fruits, including a range of phenolic compounds. Five Australian grown pear varieties, which include Packham’s Triumph, Josephine de Malines, Beurre Bosc, Winter Nelis and Rico were selected for this study to examine the phenolic compounds in pears. Beurre Bosc exhibited the highest total polyphenol content (TPC) (3.14 ± 0.02 mg GAE/g), total tannin content (TTC) (1.43 ± 0.04 mg CE/g) and 2,2′-diphenyl-1-picrylhydrazyl (DPPH) (5.72 ± 0.11 mg AAE/g), while the Josephine de Malines variety was high in total flavonoid content (TFC) (1.53 ± 0.09 mg QE/g), ferric reducing antioxidant power (FRAP) (4.37 ± 0.04 mg AAE/g), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) (4.44 ± 0.01 mg AAE/g) and total antioxidant capacity (TAC) (5.29 ± 0.09 mg AAE/g). The liquid chromatography coupled with electrospray-ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS/MS) data indicate that a total of 73 phenolic compounds were detected in Beurre Bosc (37 compounds), Josephine de Malines (34), Rico (22), Packham’s Triumph (15) and Winter Nelis (9), respectively. From HPLC-PDA quantification, the Beurre Bosc pear variety showed significantly higher in phenolic acids (chlorogenic acid; 17.58 ± 0.88 mg/g) and while flavonoids were significantly higher in Josephine de Malines (catechin; 17.45 ± 1.39 mg/g), as compared to other pear varieties. The analyses suggest that the Australian grown pears might contain an ideal source of phenolic compounds which benefit human health. The information provided by the present work can serve as practical supporting data for the use of pears in the nutraceutical, pharmaceutical and food industries.

Antioxidant Properties of Western Georgia Native Khechechuri Pear

An endemic pear species spreads in one region of western Georgia, Adjara, called Khechechuri. Pears are dietary source of bioactive components such as polyphenols and triterpenic acid. In addition to its gastronomic value, the aim of the article was to examine and compare phenolic compounds, flavonoids, catechins, phenolic acids, and antioxidant activities in five species of Khechechuri collected from various regions in Adjara region: Adjaristskali, Merisi, Dandalo, Shuakhevi, and Khulo. Five fruit parts, the skin, edible pulp, the whole pear (skin + pulp), juice and the pomace were analyzed and the results were compared. Our study revealed that the amount of total phenolic content found in the skin of West Georgian pear types was as much as 4650 mg/kg. Also, the pear pomace showed significant amount of total phenolic content in all species of Khechechuri. In addition, in all species of Khechechuri pears, flavonoids were found, except in the fruit juice.

Pear Extract and Malaxinic Acid Reverse Obesity, Adipose Tissue Inflammation, and Hepatosteatosis in Mice

SCOPE

Obesity and diabetes are major public health problems and are emerging as pandemics. Considerable evidence suggests that pear fruit consumption is associated with a lower risk of obesity-related complications. Thus, the present study is conducted to investigate the therapeutic potential of pear extract (PE) for reversing obesity and associated metabolic complications in high-fat diet-induced obese mice.

METHODS AND RESULTS

Obesity is induced in male C57BL/6 mice fed a high-fat diet for 11 weeks. After the first 6 weeks on the diet, obese mice are administered vehicle or PE for 5 weeks. PE treatment decreases body weight gain, expands white adipose tissue (WAT), and causes hepatic steatosis in obese mice, as well as inhibits adipogenesis and lipogenesis. Impaired glucose tolerance and insulin resistance are improved by PE. In addition, PE reduces macrophage infiltration and expression of pro-inflammatory genes and deactivates mitogen-activated protein kinases in WAT. Finally, malaxinic acid is identified as an active component responsible for the anti-obesity effects of PE in mice.

CONCLUSION

The results demonstrate that PE supplementation ameliorates diet-induced obesity and associated metabolic complications and suggest the health-beneficial effects of both pear fruits and malaxinic acid in counteracting these diseases.

Genetic, metabolite and developmental determinism of fruit friction discolouration in pear

BACKGROUND

The unattractive appearance of the surface of pear fruit caused by the postharvest disorder friction discolouration (FD) is responsible for significant consumer dissatisfaction in markets, leading to lower returns to growers. Developing an understanding of the genetic control of FD is essential to enable the full application of genomics-informed breeding for the development of new pear cultivars. Biochemical constituents [phenolic compounds and ascorbic acid (AsA)], polyphenol oxidase (PPO) activity, as well as skin anatomy, have been proposed to play important roles in FD susceptibility in studies on a limited number of cultivars. However, to date there has been no investigation on the biochemical and genetic control of FD, employing segregating populations. In this study, we used 250 seedlings from two segregating populations (POP369 and POP356) derived from interspecific crosses between Asian (Pyrus pyrifolia Nakai and P. bretschneideri Rehd.) and European (P. communis) pears to identify genetic factors associated with susceptibility to FD.

RESULTS

Single nucleotide polymorphism (SNP)-based linkage maps suitable for QTL analysis were developed for the parents of both populations. The maps for population POP369 comprised 174 and 265 SNP markers for the male and female parent, respectively, while POP356 maps comprised 353 and 398 SNP markers for the male and female parent, respectively. Phenotypic data for 22 variables were measured over two successive years (2011 and 2012) for POP369 and one year (2011) only for POP356. A total of 221 QTLs were identified that were linked to 22 phenotyped variables, including QTLs associated with FD for both populations that were stable over the successive years. In addition, clear evidence of the influence of developmental factors (fruit maturity) on FD and other variables was also recorded.

CONCLUSIONS

The QTLs associated with fruit firmness, PPO activity, AsA concentration and concentration of polyphenol compounds as well as FD are the first reported for pear. We conclude that the postharvest disorder FD is controlled by multiple small effect QTLs and that it will be very challenging to apply marker-assisted selection based on these QTLs. However, genomic selection could be employed to select elite genotypes with lower or no susceptibility to FD early in the breeding cycle.

AraC/XylS family stress response regulators Rob, SoxS, PliA, and OpiA in the fire blight pathogen Erwinia amylovora

Transcriptional regulators of the AraC/XylS family have been associated with multidrug resistance, organic solvent tolerance, oxidative stress, and virulence in clinically relevant enterobacteria. In the present study, we identified four homologous AraC/XylS regulators, Rob, SoxS, PliA, and OpiA, from the fire blight pathogen Erwinia amylovora Ea1189. Previous studies have shown that the regulators MarA, Rob, and SoxS from Escherichia coli mediate multiple-antibiotic resistance, primarily by upregulating the AcrAB-TolC efflux system. However, none of the four AraC/XylS regulators from E. amylovora was able to induce a multidrug resistance phenotype in the plant pathogen. Overexpression of rob led to a 2-fold increased expression of the acrA gene. However, the rob-overexpressing strain showed increased resistance to only a limited number of antibiotics. Furthermore, Rob was able to induce tolerance to organic solvents in E. amylovora by mechanisms other than efflux. We demonstrated that SoxS from E. amylovora is involved in superoxide resistance. A soxS-deficient mutant of Ea1189 was not able to grow on agar plates supplemented with the superoxide-generating agent paraquat. Furthermore, expression of soxS was induced by redox cycling agents. We identified two novel members of the AraC/XylS family in E. amylovora. PliA was highly upregulated during the early infection phase in apple rootstock and immature pear fruits. Multiple compounds were able to induce the expression of pliA, including apple leaf extracts, phenolic compounds, redox cycling agents, heavy metals, and decanoate. OpiA was shown to play a role in the regulation of osmotic and alkaline pH stress responses.

Chemical composition and anti-inflammatory and antioxidant activities of eight pear cultivars

The contents of total phenolics, total flavonoids, total anthocyanins, and total triterpenes of eight pear samples were determined, and the monomeric compounds were identified and quantitated using high-performance liquid chromatography. The in vitro antioxidant and in vivo anti-inflammatory activities of the different pear cultivars were compared. Arbutin and catechin were the dominant polyphenol compounds in the eight pear varieties, followed by chlorogenic acid, quercetin, and rutin. In addition, Xuehua pear and Nanguo pear had significantly higher total phenolics and flavonoids contents, while Dangshansu pear had the largest total triterpenes value (209.2 mg/100 g). Xuehua pear and Nanguo pear also were the highest in total anthocyanins. The pears with high total phenolics and total flavonoids contents had significantly higher antioxidant and anti-inflammatory abilities than those of other species. Anthocyanins were correlated to antioxidant capacity in pears, whereas total triterpenoids were strongly correlated to anti-inflammatory activity.