• Journal of Life Science
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• v.31 no.2
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• pp.126-136
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• 2021

Oxidative stress causes injury to and degeneration of retinal pigment epithelial (RPE) cells. It is involved in several retinal disorders and leads to vision loss. In the present study, we investigated the effect of 14 kinds of natural compounds and two kinds of synthetic compounds on oxidative stress-induced cellular damage in human PRE cell lines (ARPE-19). From among them, we selected five kinds of compounds, including auranofin, FK-509, hemistepsin A, honokiol, and spermidine, which have inhibitory effects against hydrogen peroxide (H2O2)-mediated cytotoxicity. In addition, we found that four kinds of compounds (excluding auranofin) have protective effects on H2O2-induced mitochondrial dysfunction. Furthermore, the expression of phosphorylation of histone H2AX, a sensitive marker of DNA damage, was markedly up-regulated by H2O2, whereas it was notably down-regulated by FK-506, honokiol, and spermidine treatment. Meanwhile, five kinds of candidate compounds had no effect on H2O2-induced intracellular reactive oxygen species (ROS) levels, suggesting that the five candidate compounds have protective effects on oxidative stress-induced cellular damage through the ROS-independent pathway. Taken together, according to the results of H2O2-mediated cellular damage―such as cytotoxicity, apoptosis, mitochondrial dysfunction, and DNA damage―spermidine and FK-506 are the natural and synthetic compounds with the most protective effects against oxidative stress in RPE. Although further studies on the identification of the mechanism responsible are required, the results of the present study suggest the possibility of using spermidine and FK-506 to suppress the risk of retinal disorders.

• Journal of Life Science
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• v.30 no.12
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• pp.1078-1084
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• 2020

Protaetia brevitarsis seulensis is an insect belonging to the order Coleoptera. This insect is reported to contain large amounts of physiologically active substances useful for liver protective effect and improvements in blood circulation as well as a broad source of edible protein. Antimicrobial peptides (AMPs) are found in a variety of species, from microorganisms to mammals, and play an important role in the innate immune systems of living things. Microglia are the main source of proinflammatory cytokines and nitric oxide (NO) in the central nervous system. Activated microglia secrete large amounts of neuroinflammatory mediators (e.g., TNF-α, NO, and ROS), which are the main cause of neuronal cell death. In the present study, we investigated the inhibitory effect of Protaetiamycine 6 (PKARKLQKLSAYKTTLRN-NH2), an AMP derived from Protaetia brevitarsis seulensis, on LPS-induced neuroinflammation in BV-2 microglia. Protaetiamycine 6 significantly inhibited NO production without cytotoxicity and decreased the expression levels of inducible NO synthase and cyclooxygenase-2. In addition, Protaetiamycine 6 also reduced the production of neuroinflammatory cytokines on activated BV-2 microglia. These results suggest that Protaetiamycine 6 could be a good source of functional substance to prevent neuroinflammation and neurodegenerative diseases.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.178-184
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• 2011

In this study, the antibacterial, antioxidative and inhibitory effects of Allium cepa peel extracts on tyrosinase and elastase were investigated. MIC values of the ethyl acetate fraction of Allium cepa peel on especially, S. aureus among the skin resident flora (Staphylococcus aureus, S. aureus; Propionibacterium acnes, P. acnes; Pityrosporum ovale, P. ovale; Escherichia coli, E. coli) were 0.06%. The aglycone fraction showed more excellent free radical (1,1-diphenyl-2-picrylhydrazyl radical, DPPH) scavenging activity ($FSC_{50}=5.05{\mu}g/mL$). Reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) of the ethyl acetate fraction and aglycone fraction in the luminol-dependent $Fe^{3+}-EDTA/H_2O_2$ system were 0.05 and $0.03{\mu}g/mL$, respectively. The cellular protective effect of the aglycone fraction on the rose-bengal sensitized photohemolysis of human erythrocytes exhibited more prominent (${\tau}_{50}$, 480 min at $25{\mu}g/mL$). The inhibitory effects ($IC_{50}$) of the ethyl acetate fraction and aglycone fraction on tyrosinase were 9.16 and $8.68{\mu}g/mL$, the inhibitory effect ($IC_{50}$) of the aglycone fraction on elastase was $14.12{\mu}g/mL$ The transepidermal water loss of the cream containing 0.1% ethyl acetate fraction was decreased from $8.3g/m^2h$ in control to $6.8g/m^2h$ in the subjects applied with cream containing the ethyl acetate fraction. These results indicate that extract/fractions of Allium cepa peel can function as antioxidant in biological systems, particularly skin exposed to UV radiation by scavenging $^1O_2$ and other ROS, and protect cellular membranes against ROS, and possibly as antiaging agents. Allium cepa peel extract could be used as a new cosmeceutical for whitening and anti-wrinkle products.

• Korean Journal of Food Science and Technology
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• v.53 no.3
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• pp.267-277
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• 2021

To evaluate hepatoprotective effects, the antioxidant capacities of matcha green tea extract (Camellia sinenesis) were compared to those of green leaf tea and the anti-inflammatory activities in HepG2 cells were investigated. Evaluation of the total phenolic and total flavonoid content, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, and inhibitory effect on lipid peroxidation indicated that the aqueous extract of matcha green tea presented significant catechin content and antioxidant capacity compared to those of green leaf tea. In addition, the extract had considerable inhibitory effects on α-glucosidase, α-amylase, and advanced glycation end-products. The matcha green tea extract significantly increased cell viability and reduced reactive oxygen species in H₂O₂- and high-glucose-treated HepG2 cells. Furthermore, in response to oleic acid-induced HepG2 cell injury, treatment with matcha green tea aqueous extract inhibited lipid accumulation and regulated the expression of inflammatory proteins such as p-JNK, p-Akt, p-GSK-3β, caspase-3, COX-2, iNOS, and TNF-α. Matcha green tea could be used as a functional material to ameliorate hepatic lipid accumulation and inflammation.

• Journal of Nutrition and Health
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• v.54 no.6
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• pp.618-630
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• 2021

Purpose: The ginger rhizome (Zingiber officinale) is widely cultivated as a spice for its aromatic and pungent components. One of its constituents, 6-hydroxydopamine (6-OHDA) is usually thought to cross the cell membrane through dopamine uptake transporters, and induce inhibition of mitochondrial respiration and the generation of intracellular reactive oxygen species (ROS). This study examines the neuroprotective effect and acetylcholinesterase (AChE) inhibitory activity of fermented ginger extracts (FGEs) on 6-OHDA induced toxicity in SH-SY5Y human neuroblastoma cells. Methods: Ginger was fermented using 2 species of Bacillus subtilis, with or without enzyme pretreatment. Each sample was extracted with 70% ethanol. Neurotoxicity was assessed by applying the EZ-Cytox cell viability assay and by measuring lactic dehydrogenase (LDH) release. Morphological changes of apoptotic cell nuclei were observed by Hoechst staining. Cell growth and apoptosis of SH-SY5Y cells were determined by Western blotting and enzyme activity analysis of caspase-3, and AChE enzymatic activity was determined by the colorimetric assay. Results: In terms of cell viability and LDH release, exposure to FGE showed neuroprotective activities against 6-OHDA stimulated stress in SH-SY5Y cells. Furthermore, FGE reduced the 6-OHDA-induced apoptosis, as determined by Hoechst staining. The occurrence of apoptosis in 6-OHDA treated cells was confirmed by determining the caspase-3 activity. Exposure to 6-OHDA resulted in increased caspase-3 activity of SH-SY5Y cells, as compared to the unexposed group. However, pre-treatment with FGE inhibited the activity of caspase-3. The neuroprotective effects of FGE were also found to be caspase-dependent, based on reduction of caspase-3 activity. Exposure to FGE also inhibited the activity of AChE induced by 6-OHDA, in a dose-dependent manner. Conclusion: Taken together, our results show that FGE exhibits a neuroprotective effect in 6-OHDA treated SH-SY5Y cells, thereby making it a potential novel agent for the prevention or treatment of neurodegenerative disease.

• Journal of Food Hygiene and Safety
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• v.36 no.6
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• pp.528-536
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• 2021

The purpose of the study was to investigate the content of sinigrin, an index component, in Brassica juncea extract and to evaluate the differentiation of lipocytes, inhibition of production of reactive oxygen species (ROS) and reduction of protein production by lipogenic factors (PPARγ, C/EBPα, aP2) in the processing of Brassica juncea extract and sinigrin in 3T3-L1 preadipocytes which induces Bisphenol A (BPA), an endocrine disrupting environmental hormone. From the investigation, the content of sinigrin in Brassica juncea extract, measured by HPLC, is found to be 21.27±0.2 mg/g. The XTT assay result on BPA-derived 3T3-L1 adipocytes shows there is no cytotoxicity found from 180 µM of sinigrin and 300 ㎍/mL of Brassica juncea extract. Moreover, both intracellular lipid accumulation and ROS production during differentiation of lipocyte are significantly reduced in cells processed with Brassica juncea extract and sinigrin. Lastly, it was also found that the production of transcription factors of lipocyte differentiation, PPARγ, C/EBPα and aP2, were found to be suppressed by the application of Brassica juncea extract and sinigrin. Such results reveals that Brassica juncea is effective in not only suppressing lipid accumulation in the environmental hormone bisphenol A-derived lipocyte, but also in reducing the ROS. The sinigrin-containing Brassica juncea is highly expected to be used in natural functional supplements that prevents the lipid metabolism disorders caused by BPA. There are necessities for additional clinical research and follow-up studies on the in vivo model to verify the relevant mechanisms.

• Korean journal of applied entomology
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• v.61 no.1
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• pp.155-163
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• 2022

The application of fungicides is indispensable to global food security, and their use has increased in recent times. Fungicides, directly or indirectly, have impacted insects, leading to genetic and molecular-level changes. Various detoxification mechanisms allow insects to eliminate reactive oxygen species (ROS) toxicity induced by agrochemicals including fungicides. In the present study, we analyzed the mRNA expression levels of detoxifying enzymes in Tenebrio molitor larvae following exposure to non-lethal doses (0.2, 2, and 20 ㎍/µL) of a fungicide captan. Transcripts of peroxidases (POXs), catalases (CATs), superoxide dismutases (SODs), and glutathione-s-transferases (GSTs) were screened from the T. molitor transcriptome database. RT-qPCR analysis showed that TmPOX5 mRNA increased significantly 24 h post-captan exposure. A similar increase was noticed for TmSOD4 mRNA 3 h post-captan exposure. Moreover, the expression of TmCAT2 mRNA increased significantly 24 h post-treatment with 2 ㎍/µL captan. TmGST1 and TmGST3 mRNA expression also increased noticeably after captan exposure. Taken together, these results suggest that TmPOX5 and TmSOD4 mRNA can be used as biomarkers or xenobiotics sensors for captan exposure in T. molitor, while other detoxifying enzymes showed differential expression.

• Journal of Life Science
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• v.31 no.12
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• pp.1110-1119
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• 2021

The purpose of this study was to investigate whether the inflammatory response in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages could be promoted by particulate matter 2.5 (PM_2.5) stimulation. To this end, the levels of inflammatory parameters, reactive oxygen species (ROS) and inflammation-regulating genes were investigated in RAW 264.7 cells treated with PM_2.5 in the presence or absence of LPS. Our results showed that the production levels of pro-inflammatory mediators (nitric oxide and prostaglandin E₂) and cytokines (interleukin-6 and -1β) were significantly increased by PM_2.5 stimulation in LPS-treated RAW 264.7 cells, which was correlated with increased expression genes involved in their production. In addition, when LPS-treated RAW 264.7 cells were exposed to PM_2.5, nuclear factor-kappaB (NF-κB) expression was further increased in the nucleus, and the expression of inhibitor of NF-κB as well as NF-κB in the cytoplasm was decreased. These results suggest that the co-treatment of PM_2.5 and LPS further increases the activation of the NF-κB signaling pathway compared to each treatment alone, thereby contributing to the promotion of transcriptional activity of inflammatory genes. Furthermore, although the generation of ROS was greatly increased by PM_2.5 in LPS-treated RAW 264.7 cells, the NF-κB inhibitor did not reduce the generation of ROS. In addition, when the generation of ROS was artificially suppressed, the production of inflammatory mediators and the activation of NF-κB were both abolished. Therefore, our results suggest that the increase in the NF-κB-mediated inflammatory response induced by PM_2.5 in LPS-treated RAW 264.7 macrophages was a ROS generation-dependent phenomenon.

• Journal of Life Science
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• v.32 no.4
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• pp.310-317
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• 2022

Recently, interest in the harmful factors of particulate matter (PM), a major component of air pollution, has been increasing. In particular, PM_2.5 with a diameter of less than 2.5 ㎛ is well known to induce oxidative stress accompanied by autophagy in human lung epithelial cells. However, studies on whether PM_2.5 increases autophagy under oxidative stress and whether this process is reactive oxygen species (ROS)-dependent are insufficient. Therefore, in this study, we investigated whether PM_2.5 promotes autophagy through the generation of ROS in human alveolar epithelial A594 cells. According to our results, cells co-treated with PM_2.5 and hydrogen peroxide (H₂O₂) showed a lower cell viability than cells treated with each alone, which was associated with increased total and mitochondrial ROS production. The co-treatment of PM_2.5 and H₂O₂ also increased autophagy induction, which was confirmed through Cyto-ID staining, and the expression of autophagy biomarker proteins increased. However, when ROS generation was artificially blocked by N-acetyl-L-cysteine pretreatment, the reduction in cell viability and induction of autophagy by PM_2.5 and H₂O₂ co-treatment were markedly attenuated. Therefore, the present results suggest that PM_2.5-induced ROS generation may play a critical role in autophagy induction in A549 cells.

• Korean Journal of Plant Resources
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• v.37 no.2
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• pp.120-129
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• 2024

Alcoholic liver disease (ALD) is a significant risk factor in the global disease burden. The stem bark of the Betulaceae plant Alnus japonica, which is indigenous to Korea, has been used as a popular folk medicine for hepatitis and cancer. However, the preventive effect of Alnus japonica leaf extracts on alcohol-related liver damage has not been investigated. The objective of this study was to investigate the hepatoprotective effects of the extracts of Alnus japonica leaf (AJL) against ethanol-induced liver damage in HepG2/2E1 cells. Treatment with AJL significantly prevented ethanol-induced cytotoxicity in HepG2/2E1 cells by reducing the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). This protective effect was likely associated with antioxidant potential of AJL, as evidenced by the attenuation of reactive oxygen species (ROS) and malondialdehyde (MDA) production and restoration of the depleted glutathione (GSH) levels in ethanol-induced HepG2/2E1 cells. Our findings suggest that FCC might be considered as a useful agent in the prevention of liver damage induced by oxidative stress by increasing the antioxidant defense mechanism.