Hang Yeon Jeong

Change in chemical constituents and free radical-scavenging activity during Pear (Pyrus pyrifolia) cultivar fruit development

Changes in chemical constituent contents and DPPH radical-scavenging activity in fruits of pear (Pyrus pyrifolia) cultivars during the development were investigated. The fruits of seven cultivars (cv. Niitaka, Chuhwangbae, Wonhwang, Hwangkeumbae, Hwasan, Manpungbae, and Imamuraaki) were collected at 15-day intervals after day 20 of florescence. Vitamins (ascorbic acid and α-tocopherol), arbutin, chlorogenic acid, malaxinic acid, total caffeic acid, total flavonoids, and total phenolics were the highest in immature pear fruit on day 20 after florescence among samples at different growth stages. All of these compounds decreased gradually in the fruit during the development. Immature pear fruit on day 35 or 50 after florescence exhibited higher free radical-scavenging activity than that at other times, although activities were slightly different among cultivars. The chemical constituent contents and free radical-scavenging activity were largely different among immature fruits of the pear cultivars, but small differences were observed when they matured. Graphical Abstract The contents of total phenolics and main phenolic compounds gradually decreased during the development of pear fruit.

Protocatechuic Acid from Pear Inhibits Melanogenesis in Melanoma Cells

Despite the critical role of melanin in the protection of skin against UV radiation, excess production of melanin can lead to hyperpigmentation and skin cancer. Pear fruits are often used in traditional medicine for the treatment of melasma; therefore, we investigated the effects of pear extract (PE) and its component, protocatechuic acid (PCA), on melanogenesis in mouse melanoma cells. We found that PE and PCA significantly suppressed melanin content and cellular tyrosinase activity through a decrease in the expression of melanogenic enzymes and microphthalmia-associated transcription factor (Mitf) in α-melanocyte stimulating hormone-stimulated mouse melanoma cells. Moreover, PCA decreased cyclic adenosine monophosphate (cAMP) levels and cAMP-responsive element-binding protein phosphorylation, which downregulated Mitf promoter activation and subsequently mediated the inhibition of melanogenesis. These results suggested that pear may be an effective skin lightening agent that targets either a tyrosinase activity or a melanogenic pathway.

Comparison of bioactive compound contents and in vitro and ex vivo antioxidative activities between peel and flesh of pear (Pyrus pyrifolia Nakai)

We compared chemical constituents and antioxidative activities between the flesh and peel of two Asian pears (Pyrus pyrifolia Nakai cv. Niitaka and Chuhwangbae). Total phenolic, flavonoid, and ascorbic acid contents in the peels were higher than those in the flesh. However, total tocopherol content between peels and flesh was not different. The peels exhibited higher free radical scavenging activities in the in vitro models of DPPH, ABTS+, nitrite radicals, and reducing capabilities than those of the flesh. Pear fruit extracts significantly prevented 3T3-L1 cells from undergoing H2O2-induced oxidation and the effect was higher by the peel extract than by the flesh extract. In addition, blood plasma of rats administered the peel extract showed higher antioxidative activity than that of rats administered the flesh extract. These results suggest that consumption of unpeeled Asian pear fruit may effectively increase antioxidant activity in the body.

A phenyl lipid alkaloid and flavone C-diglucosides from Spergularia marina

A phenyl lipid alkaloid and seven phenolic compounds were isolated from the aerial part of Spergularia marina, a halophyte that grows on salt marshes and tidal flat. These compounds were identified as 2,4-di-tert-butylphenol, N-hexacosanoylanthranilic acid, tryptophan, 4-hydroxybenzyol glucopyranoside, luteolin 6-C-β-D-glucopyranoside 8-C-β-D-(2-O-feruloyl)glucopyranoside, luteolin 6-C-β-D-(2-O-feruloyl)glucopyranoside 8-C-β-D-glucopyranoside, apigenin 6-C-β-D-glucopyranoside 8-C-β-D-(2-O-feruloyl)glucopyranoside, and apigenin 6-C-β-D-(2-O-feruloyl)glucopyranoside 8-C-β-D-glucopyranoside. The structures were determined by nuclear magnetic resonance and electrospray ionization-mass spectroscopy.

Comparison of the content of bioactive substances and antioxidative activity between conventionally and organically cultivated brown rice (Oryza sativa L.)

The content of bioactive substances and antioxidative activity in conventionally grown brown rice (CGBR) and organically grown brown rice (OGBR) were compared. Minerals (mg/100 g) such as magnesium (OGBR, 168.59±2.62; CGBR, 121.43±2.22), copper (OGBR, 0.50±0.06; CGBR, 0.41±0.05), and manganese (OGBR, 4.70±0.04; CGBR, 2.49±0.02) were higher in OGBR than in CGBR (p<0.05). In addition, levels of (μg/100 g) vitamins B2 (OGBR, 27.22±2.56; CGBR, 22.12±2.24) and B6 (OGBR, 46.32±2.66; CGBR, 39.91±3.32) were higher in OGBR than in CGBR (p<0.05). The contents (mg/100 g) of β-sitosterol (OGBR, 27.40±2.79; CGBR, 24.75±1.06), total phenolic (OGBR, 6.72±0.02; CGBR, 6.64±0.02), and ferulic acid (OGBR, 1.75±0.45; CGBR, 1.11±0.14) as well as the antioxidative activity (OGBR, 53.09±1.90%; CGBR, 48.29±3.38%) evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay were higher in OGBR than in CGBR, although no significant differences between samples were observed. In comparison to the control group, brown rice samples significantly inhibited cholesteryl ester hydroperoxide formation in rat plasma subjected to copper ion-induced lipid peroxidation. The inhibitory effect of OGBR was higher than that of CGBR. These results indicate that OGBR showed higher levels of bioactive substances and enhanced antioxidative activity than CGBR, although the differences were not statistically significant.

Metabolism and antioxidant effect of malaxinic acid and its corresponding aglycone in rat blood plasma

Abstract Malaxinic acid (MA) is a phenolic acid compound, found mainly in pear fruits (Pyrus pyrifolia N.), that is isoprenylated on the C‐3 position of benzoic acid. Recently, the effects of prenylated phenolics on health have received much interest owing to their reported potent beneficial biological effects. We conducted a comparative study in rats to determine the metabolism, pharmacokinetics, and antioxidative activities of MA and its corresponding aglycone (MAA). MA and MAA were orally administered to rats (Sprague‐Dawley, male, 6 weeks old) and their metabolites in plasma were analyzed. In addition, the MA metabolites in plasma were separated and the structures were confirmed via NMR and HR‐MS analyses. The antioxidative activities of MA and MAA were evaluated by measuring their inhibitory effects on the 2,2′‐azobis(2‐amidinopropane)dihydrochloride‐ or copper ion‐induced lipid peroxidation of rat plasma. MA was not absorbed in the intact form (the glucoside); both MA and MAA were absorbed as MAA and its metabolite form (glucuronide or sulfate). Moreover, the observed metabolite was the glucuronate of MAA rather than the glucuronide or sulfate. Concentrations of the free form of aglycone (MA administration, 4.6 ± 2.2 &mgr;M; MAA administration, 7.2 ± 2.3 &mgr;M) and total MAA (MA administration, 19.6 ± 4.4 &mgr;M; MAA administration, 21.7 ± 3.3 &mgr;M) in plasma reached a maximum at 15 min after the oral administration of MA and MAA, respectively. The relative inhibitory effects on the formation of cholesteryl ester hydroperoxides in plasma collected at 15 min after the oral administration of MA, MAA, and p‐hydroxybenzoic acid (p‐HBA) were as follows: MAA > MA ≥ p‐HBA > control. Although the majority of MA and MAA is metabolized to conjugates, the compounds may contribute to the antioxidant defenses in the blood circulation owing to the presence of a phenolic hydroxyl group in the free form. Graphical abstract Figure. No caption available. HighlightsMalaxinic acid (MA) is a glucoside of isoprenylated phenolic acid in fruits.MA and MA aglycone (MAA) were chemically synthesized.MA and MAA were absorbed as MAA and its metabolite.Metabolite of MA and MAA was a MAA glucuronate rather than the glucuronide.MA and MAA showed antioxidant activity in blood plasma after oral administration.

Phenolics and eudesmanolide from aged common sage exudate with sugar

Nineteen compounds including one new flavanone were isolated from the juice of aged common sage exudate with sugar (ACSE). The isolated compounds were identified by NMR and MS analyses as levodopa methyl ester (1), 3,4-dihydroxybenzoic acid (2), (S)-8-hydroxy-4-hydroxy-phenylpropanoic acid (3), 4-hydroxybenzoic acid ethyl ester (4), cis-caffeic acid (5), trans-caffeic acid (6), esculetin (7), (S)-8-hydroxy-3,4-dihydroxy-phenylpropanoic acid ethyl ester (8), cis-rosmarinic acid (9), trans-rosmarinic acid (10), trans-rosmarinic acid methyl ester (11), 6-methoxy-7,8,3′,5′-tetrahydroxyflavanone (12), nepetin (13), trans-caffeic acid ethyl ester (14), luteolin (15), cis-caffeic acid ethyl ester (16), 6-methoxynaringenin (17), 1α-acetoxy-2-oxo-eudesman-3,7(11)-dien-8β,12-olide (18), and hispidulin (19). Compound 12 was isolated for the first time from nature and seven compounds (1, 3, 4, 7, 8, 14, and 18) were newly identified from common sage. Of them, 15 isolated phenolic compounds (1–3, 5–8, 10–15, 17, and 19) were detected in ACSE juice, while only 10 was detected in the fresh common sage.

Enhancement of antioxidative and antimicrobial activities of immature pear (Pyrus pyrifolia cv. Niitaka) fruits by fermentation with Leuconostoc mesenteroides

Immature pear (Pyrus pyrifolia cv. Niitaka) fruits were fermented with Leuconostoc mesenteroides and Aspergillus oryzae, which are commonly used as starters for manufacturing fermented foods. Fermented immature pear fruit extracts (FIPF) by L. mesenteroides showed significantly higher radical-scavenging activity using DPPH, ABTS, superoxide anion, and hydroxyl radicals and reducing power capacity than unfermented immature pear fruit extracts. L. mesenteroides-FIPF more effectively inhibited the formation of cholesteryl ester hydroperoxide in copper ion-induced rat blood plasma. In addition, the L. mesenteroides-FIPF strongly inhibited tyrosinase activity and the growth of pathogenic skin bacteria. In contrast, enhanced antioxidative and antibacterial activities were not apparent in A. oryzae-FIPF. The antioxidative and antimicrobial activities of the fermented and unfermented immature pear fruits were correlated with the flavonoid contents. These results indicate that fermentation enhances antioxidative and antimicrobial activities of immature pear fruits.