Ursolic acid is a triterpenoid compound present in many plants. This study examined the antimicrobial activity of ursolic acid against mutans streptococci (MS) isolated from the Korean population. The antimicrobial activity was evaluated by the minimum inhibitory concentration (MIC) and time kill curves of MS. The cytotoxicity of ursolic acid against KB cells was tested using an MTT assay. The MIC90 values of ursolic acid for Streptococcus mutans and Streptococcus sobrinus isolated from the Korean population were 2 μg/ml and 4 μg/ml, respectively. Ursolic acid had a bactericidal effect on S. mutans ATCC 25175 T and S. sobrinus ATCC 33478 T at > 2 × MIC (4 μg/ml) and 4 × MIC (8 μg/ml), respectively. Ursolic acid had no cytotoxic effect on KB cells at concentrations at which it exerted antimicrobial effects. The results suggest that ursolic acid can be used in the development of oral hygiene products for the prevention of dental caries.

This study aimed to determine the elemental compositions of selected edible wild plant species, Hemerocallis fulva, Allium victorialis, Syneilesis palmata and Ligularia fischeri. The samples were dried, crushed, and subjected to microwave-assisted digestion. The macro and micro elements were analyzed by inductively coupled plasma-optical emission spectrometery (ICP-OES), and ICP-mass spectrometry (ICP-MS), respectively. The macro elements in the analyzed species decreased in the order K Ca P Mg S Fe Zn Na, and the micro elements ˃ ˃ ˃ ˃ ˃ ˃ ˃ followed the order Mn˃Ba˃Rb˃Cu˃Ni˃Ga˃Li˃Cr˃V˃Co˃Be˃Se. The percentage ratio of calcium content for potassium in the samples was 42.9% (A. victorialis) > 42.4% (S. palmata) > 33.8% (L. fischeri) > 25.3% (H. fulva). The calcium content was 13.7, 10.9, 6.4, and 2.9 times higher than the phosphorus content in S. palmata, L. fischeri, A. victorialis, and H. fulva, respectively (p<0.05). Manganese was the most predominant among the trace minerals, and it followed the order of A. victorialis > H. fulva > L. fischeri > S. palmata. In general, these wild plants are richer in calcium as compared to other common vegetables, and hence can be considered a good source for calcium that is lacking in Korean food products.

This study was conducted to confirm the usefulness of essential oil components in yuzu and kumquat cultivated in Korea for comparison with those in lemon and lime. The volatile flavor compounds in citrus fruits (yuzu, kumquat, lemon and lime) were extracted for 3 h with 100 mL redistilled n-pentane/diethylether (1:1, v/v) mixture, using a simultaneous steam distillation and extraction apparatus (SDE). The volatile flavor compositions of the samples were analyzed by gas chromatography-mass spectrometry (GC-MS). The aroma compounds analyzed were 104 (3,713.02 mg/kg) in yuzu, 87 (621.71 mg/kg) in kumquat 103 (3,024.69 mg/kg) in lemon and 106 (2,209.16 mg/kg) in lime. Limonene was a major volatile flavor compound in four citrus fruits. The peak area of limonene was 35.03% in yuzu, 63.82% in kumquat, 40.35% in lemon, and 25.06% in lime. In addition to limonene, the major volatile flavor compounds were γ-terpinene, linalool, β-myrcene, (E)-β-farnesene, α-pinene and β-pinene in yuzu, and β-myrcene, α-pinene, (Z)-limonene oxide, (E)-limonene oxide, geranyl acetate and limonen-10-yl acetate in kumquat. Furthermore, γ-terpinene, β-pinene, β-myrcene, geranyl acetate, neryl acetate and (Z)-β-bisabolene in lemon and γ-terpinene, β-pinene, (Z)-β-bisabolene, neral, geranial and neryl acetate in lime were also detected. As a result, it was confirmed that the composition of volatile flavor compounds in four citrus fruits was different. Also, yuzu and kumquat are judged to be worthy of use alternatives for lemon and lime widely used in the fragrance industry.

The volatile flavor components of the fruit pulp and peel of orange (Citrus sinensis) and grapefruit (Citrus paradisi) were extracted by simultaneous distillation-extraction (SDE) using a solvent mixture of n-pentane and diethyl ether (1:1, v/v) and analyzed by gas chromatography-mass spectrometry (GC-MS). The total volatile flavor contents in the pulp and peel of orange were 120.55 and 4,510.81 mg/kg, respectively, while those in the pulp and peel of grapefruit were 195.60 and 4,223.68 mg/kg, respectively. The monoterpene limonene was identified as the major voltile flavor compound in both orange and grapefruit, exhibiting contents of 65.32 and 3,008.10 mg/kg in the pulp and peel of orange, respectively, and 105.00 and 1,870.24 mg/kg in the pulp and peel of grapefruit, respectively. Limonene, sabinene, α-pinene, β-myrcene, linalool, (Z)-limonene oxide, and (E)-limonene oxide were the main volatile flavor components of both orange and grapefruit. The distinctive component of orange was valencene, while grapefruit contained (E)-caryophyllene and nootkatone. δ-3-Carene, α-terpinolene, borneol, citronellyl acetate, piperitone, and β-copaene were detected in orange but not in grapefruit. Conversely, grapefruit contained β-pinene, α-terpinyl acetate, bicyclogermacrene, nootkatol, β-cubebene, and sesquisabinene, while orange did not. Phenylacetaldehyde, camphor, limona ketone and (Z)-caryophyllene were identified in the pulp of both fruits, while α-thujene, citronellal, citronellol, α-sinensal, γ-muurolene and germacrene D were detected in the peel of both fresh fruit samples.

Effector-triggered immunity (ETI) is an active immune response triggered by interactions between host resistance proteins and their cognate effectors. Although ETI is often associated with the hypersensitive response (HR), various R genes mediate an HR-independent process known as extreme resistance (ER). In the soybean-Soybean mosaic virus (SMV) pathosystem, the strain-specific CI protein of SMV functions as an effector of Rsv3-mediated ER. In this study, we used the soybean (Rsv3)-SMV (CI) pathosystem to gain insight into the molecular signaling pathway involved in ER. We used genome-wide transcriptome analysis to identify a subset of the type 2C protein phophatase (PP2C) genes that are specifically up-regulated in Rsv3-mediated ER. Gain-of-function analysis of the most significantly expressed soybean PP2C gene, GmPP2C3a, showed that ABA-induced GmPP2C3a functions as a key regulator of Rsv3-mediated ER. Our results further suggest that the primary mechanism of ER against viruses is the inhibition of viral cell-to-cell movement by callose deposition in an ABA signaling-dependent manner.