Chemical Components and Antioxidant Activity of the Peels of Commercial Apple-Shaped Pear (Fruit ofPyrus pyrifoliacv. pingguoli)

Modulatory Effect of Pyrus pyrifolia Fruit and its Phenolics on Key Enzymes against Metabolic Syndrome: Bioassay-Guided Approach, HPLC Analysis, and In Silico Study

This study aims to isolate the active constituents of Pyrus pyrifolia Nakai fruits using a bioassay-guided fractionation approach, test their activity in vitro against key enzymes for metabolic disorders, and support it with molecular docking simulations. The antioxidant potential of the methanolic extract (ME), its polar (PF), and non-polar fractions (NPF), along with the inhibitory activity against α-glucosidase, α-amylase, lipase, angiotensin I converting enzyme (ACE), renin, inducible nitric oxide synthase (iNOS), and xanthine oxidase (XO) were assessed. The PF exhibited the highest antioxidant and enzyme inhibitory activity. Purification of PF yielded rutin, isoquercitrin, isorhamnetin-3-O-β-D-glucoside, chlorogenic acid, quercetin, and cinnamic acid. HPLC-UV analysis of the PF allowed for the quantification of 15 phenolic compounds, including the isolated compounds. Cinnamic acid was the most powerful antioxidant in all assays and potent enzyme inhibitor against the tested enzymes (α-glucosidase, α-amylase, lipase, ACE, renin, iNOS, and XO). Additionally, it showed high affinity to target α-glucosidase and ACE active sites with high docking scores (calculated total binding free energy (ΔGbind) -23.11 kcal/mol and - 20.03 kcal/mol, respectively]. A 20-ns molecular dynamics simulation using MM-GBSA analysis revealed a stable conformation and binding patterns in a stimulating environment of cinnamic acid. Interestingly, the isolated compounds' dynamic investigations including RMSD, RMSF, and Rg demonstrated a stable ligand - protein complex to the active site of iNOS with ΔGbind ranging from - 68.85 kcal/mol to -13.47 kcal/mol. These findings support the notion that P. pyrifolia fruit is a functional food with multifactorial therapeutic agents against metabolic syndrome-associated diseases.

Characterization of aroma-active compounds in Dongli by quantitative descriptive analysis, gas chromatography-triple quadrupole tandem mass spectrometry, and gas chromatography-olfactometry

Dongli, or frozen pear, is a traditional Chinese snack with a unique flavor. This study identified the aroma-active volatile compounds (VOCs) in Dongli using quantitative descriptive analysis (QDA), gas chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS), and gas chromatography-olfactometry (GC-O). QDA indicated that Dongli of all cultivars presented increased sweet and wine aromas. A total of 21 VOCs were identified by GC-MS/MS. Bidirectional orthogonal partial least square (O2PLS) analysis, GC-O analysis, detection frequency analysis (DFA), and relative odor activity values (ROAV) showed that: estragole and anethole contributing "anise, green" aromas were the key aromatic VOCs of fresh pears, while ethyl butanoate, butyl acetate, heptyl acetate, benzaldehyde, and geranyl acetone contributing "sweet, fruity, green" aromas were the key aromatic VOCs of Dongli. The results revealed that the repeated freezing treatment promoted a unique aroma in pears. This study would contribute to developing new pear products.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05463-8.

Antioxidant and Hypoglycemic Activity of Sequentially Extracted Fractions from Pingguoli Pear Fermentation Broth and Identification of Bioactive Compounds

Pear fruits have been reported to contain abundant bioactive compounds and exhibit antidiabetic activity. In this study, Pingguoli pear (Pyrus pyrifolia cv.‘Pingguoli’) fermentation broth was sequentially extracted by five solvents with increasing polarity (petroleum ether, chloroform, ethyl acetate, n-butanol, and water) to evaluate its antioxidant and hypothermic activities, and then the main compounds of the fraction with the highest activity were assessed, which might be responsible for such activities. The results showed that the ethyl acetate fraction (EAF) exhibited the highest antioxidant activity according to DPPH (IC₅₀ = 0.238 mg/mL), ABTS (IC₅₀ = 0.293 mg/mL), and FRAP (IC₅₀ = 0.193 mg/mL) assays. The in vitro hypoglycemic activity assay showed that EAF exhibited the strongest inhibitory effect, with IC₅₀ values of 0.34 and 0.95 mg/mL for α-amylase and α-glucosidase, respectively. The glucose consumption in HepG2 cells treated with EAF was significantly increased to 252%, compare with control group. Liquid chromatography–mass spectrometry analysis implied that the main compounds, 3′-C-glucosylisoliquiritigenin, robustside D, caffeic acid, and chlorogenic acid may be potential candidates for the antioxidant and hypoglycemic activities of the EAF. This study suggested that EAF of Pingguoli pear fermentation broth could be utilized for development of potential functional food and antidiabetic agents.

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 Pyrus communis and Pyrus pyrifolia Peel Extracts

With the rise of global health awareness by embracing a healthy lifestyle and natural product consumption, the search for natural antioxidant sources has invited more research performed especially in fruits as a whole product or in its components, especially the ones that are usually discarded/not the mainly consumed component. Pyrus communis and Pyrus pyrifolia are two of the most popular species of pear fruits consumed in the world, and while there exist several studies about the antioxidant potential of its flesh, specific studies about the antioxidant properties of their peels are still lacking. To achieve an understanding of antioxidant properties of peel extract of P. communis and P. pyrifolia, several tests have been performed in controlled laboratory conditions to gauge phenolic and flavonoid contents through three different extraction measurements. This research has shown that peel extracts of both P. communis and P. pyrifolia contain natural antioxidants that are beneficial for health, with P. communis extracted with methanol having a higher concentration of antioxidant contents compared to P. pyrifolia.

Preparation and Characterization of Callus Extract from Pyrus pyrifolia and Investigation of Its Effects on Skin Regeneration

In the present study, an aqueous extract was prepared using calli from the in vitro-derived leaves of Pyrus pyrifolia cultured in Murashige and Skoog medium containing picloram for a plant growth regulator. The major biological components in the callus extract were identified as uridine (1), adenosine (2), and guanosine (3). In terms of the antioxidant activity, at 300 µg/mL, the extract exhibited free radical scavenging activity of 76.9% ± 2.88% in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, comparable to that of 44 µg/mL ascorbic acid (82.5% ± 3.63%). In addition, the IC50 values for inhibition of advanced glycation end product formation from collagen and elastin were 602 ± 2.72 and 3037 ± 102.5 µg/mL, respectively. The extract significantly promoted keratinocyte and fibroblast cell proliferation in a dose-dependent manner. Moreover, fibroblasts treated with 1.36 µg/mL extract exhibited a 1.60-fold increase in procollagen type I C-peptide level compared to controls. The in vitro wound recovery rates of keratinocytes and fibroblasts were also 75% and 38% greater, respectively, than those of serum-free controls at 9 and 36 h after extract treatment (1.36 µg/mL). Additionally, the extract flux across the human epidermis increased by 1598% after its incorporation into elastic nanoliposomes (NLs). Therefore, elastic NLs loaded with Pyrus pyrifolia callus extract have potential use as skin rejuvenators and antiaging ingredients in cosmetic formulations.

Hepato-protective effects and chemical constituents of a bioactive fraction of the traditional compound medicine-Gurigumu-7

BACKGROUND

Gurigumu-7 is an important traditional Mongolian medicine frequently used for liver diseases. However, the pharmacological effects and the bioactive constituents are not well understood.

METHOD

This research was to use CCl4-induced liver damage in mice to investigate the hepatoprotective effects of Gurigumu-7 and the methanol eluted fraction from a DIAION column of an extract of Gurigumu-7 (MF). The chemical constituents of MF were analyzed by UPLC-MS.

RESULTS

Pretreated orally with MF (66, 132 and 264 mg/kg) once a day for 4 days dose-dependently suppressed CCl4-induced mice liver histopathological changes and serum aminotransferase activities (alanine transaminase: 1144.0 ± 787.2 v.s. 2461.8 ± 1072.7 U/L, p < 0.05; aspartate transaminase: 1173 ± 785.3 v.s. 2506.6 ± 1140.7 U/L, p < 0.01). MF treated group demonstrated increased levels of SOD (108.19 ± 30.32 v.s. 75.75 ± 5.37 U/mg protein, p < 0.01) but decreased levels of malonyldialdehyde (7.68 ± 1.95 v.s. 44.32 ± 16.68 nmol/mg protein, p < 0.01) compared to the CCl4 control group. More than 30 chemical constituents were quantified, and MF was found to be rich in ellagic acid (297.97 mg/g), luteolin and its glucosides (35.10 mg/g), apigenin and its glucosides (>30 mg/g), ursolic acid (14.91 mg/g), bidenoside C (8.75 mg/g), and proanthocyanidins (15.64 mg/g in proanthocyanidin A2 equivalent).

CONCLUSION

The methanol eluted fraction (MF) from a DIAION column of an extract of the Mongolian medicine-Gurigumu-7 was found to be more hepatoprotective than Gurigumu-7. The results suggested that MF is a promising bioactive fraction for the development of new hepatoprotective medicine with better formulation and quality control properties.

Synthesis, Anti-HCV, Antioxidant and Reduction of Intracellular Reactive Oxygen Species Generation of a Chlorogenic Acid Analogue with an Amide Bond Replacing the Ester Bond

Chlorogenic acid is a well known natural product with important bioactivities. It contains an ester bond formed between the COOH of caffeic acid and the 3-OH of quinic acid. We synthesized a chlorogenic acid analogue, 3α-caffeoylquinic acid amide, using caffeic and quinic acids as starting materials. The caffeoylquinc acid amide was found to be much more stable than chlorogenic acid and showed anti-Hepatitis C virus (anti-HCV) activity with a potency similar to chlorogenic acid. The caffeoylquinc acid amide potently protected HepG2 cells against oxidative stress induced by tert-butyl hydroperoxide.

Chemical constituents of gold-red apple and their α-glucosidase inhibitory activities

Ten compounds were isolated and purified from the peels of gold-red apple (Malus domestica) for the 1st time. The identified compounds are 3β, 20β-dihydroxyursan-28-oic acid (1), 2α-hydroxyoleanolic acid (2), euscaphic acid (3), 3-O-p-coumaroyl tormentic acid (4), ursolic acid (5), 2α-hydroxyursolic acid (6), oleanolic acid (7), betulinic acid (8), linolic acid (9), and α-linolenic acid (10). Their structures were determined by interpreting their nuclear magnetic resonance and mass spectrometry (MS) spectra, and by comparison with literature data. Compound 1 is new, and compound 2 is herein reported for the 1st time for the genus Malus. α-Glucosidase inhibition assay revealed 6 of the triterpenoid isolates as remarkable α-glucosidase inhibitors, with betulinic acid showing the strongest inhibition (IC50 = 15.19 μM). Ultra-performance liquid chromatography-electrospray ionization MS analysis of the fruit peels, pomace, flesh, and juice revealed that the peels and pomace contained high levels of triterpenes, suggesting that wastes from the fruit juice industry could serve as rich sources of bioactive triterpenes.

Comparison of the effects of blending and juicing on the phytochemicals contents and antioxidant capacity of typical korean kernel fruit juices

Four Korean kernel fruit (apple, pear, persimmon, and mandarin orange) juices were obtained by household processing techniques (i.e., blending, juicing). Whole and flesh fractions of each fruit were extracted by a blender or a juicer and then examined for phytochemical content (i.e., organic acids, polyphenol compounds). The antioxidant capacity of each juice was determined by ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. Results revealed that juices that had been prepared by blending whole fruits had stronger antioxidant activities and contained larger amounts of phenolic compounds than juices that had been prepared by juicing the flesh fraction of the fruit. However, the concentration of ascorbic acid in apple, pear, and mandarin orange juices was significantly (P<0.05) higher in juice that had been processed by juicing, rather than blending. The juices with the highest ascorbic acid (233.9 mg/serving), total polyphenols (862.3 mg gallic acid equivalents/serving), and flavonoids (295.1 mg quercetin equivalents/serving) concentrations were blended persimmon juice, blended mandarin orange juice, and juiced apple juice, respectively. These results indicate that juice extraction techniques significantly (P<0.05) influences the phytochemical levels and antioxidant capacity of fruit juices.