Hakjoon Choi

Mx. Hakjoon Choi


Research Focus & Metrics

Academic Career Length

10Years (2017-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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27 September 2017 in Nutrients
Verified
Journal Article
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GLGyuok Lee
Gyuok Lee
JSJawon Shin
Jawon Shin
HCHakjoon Choi
Hakjoon Choi
AJAra Jo
Ara Jo
SPSangO Pan
SangO Pan
CCChul-yung Choi
Chul-yung Choi
Benign prostatic hyperplasia (BPH) is characterized by uncontrolled proliferation of the prostate gland. Cynanchum wilfordii has been reported to improve sexual behavior in male rats. In this study, we investigated the protective effect of an aqueous extract of C. wilfordii (CWW) against BPH development in a testosterone-induced BPH rat model. The rats were divided into the following six groups: sham/vehicle; BPH/vehicle; BPH/finasteride; and three CWW doses (50, 100, and 200 mg/kg). After a 4-week treatment with CWW, the rats were euthanized at scheduled times, and their prostates were weighed, followed by a histopathological examination. Prostate growth inhibition rates in rats administered CWW 50, 100, and 200 mg/kg were 54.5%, 51.8%, and 50.1%, respectively. The BPH/CWW group showed decreased serum testosterone and dihydrotestosterone (DHT) levels compared to the BPH/vehicle group. Furthermore, the BPH/CWW group showed reduced prostate testosterone and DHT levels compared to the BPH/vehicle group. Mechanistically, the reverse transcription-polymerase chain reaction revealed downregulated mRNA expression levels of the androgen receptor, 5α-reductase, and B-cell lymphoma-2 (Bcl-2) in the BPH/CWW200 group compared with those in the testosterone-induced groups. In conclusion, these findings show the effectiveness of CWW in slowing the progression of testosterone-induced BPH in rats.

26 February 2020 in Nutrients
Verified
Journal Article
Open access
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KLKi Hoon Lee
Ki Hoon Lee
EJEui-Seon Jeong
Eui-Seon Jeong
GJGoeun Jang
Goeun Jang
JNJu-Ryun Na
Ju-Ryun Na
SPSoyi Park
Soyi Park
Sunoh KimSunoh Kim
Sunoh Kim
Our previous study demonstrated that a 5% ethanol extract of unripe Rubus coreanus (5-uRCK) has hypo-cholesterolemic and anti-obesity activity. However, the molecular mechanisms of its effects are poorly characterized. We hypothesized that 5-uRCK and one of its major bioactive compounds, ellagic acid, decrease cellular and plasma cholesterol levels. Thus, we investigated the hypocholesterolemic activity and mechanism of 5-uRCK in both hepatocytes and a high-cholesterol diet (HCD)-induced rat model. Cholesterol in the liver and serum was significantly reduced by 5-uRCK and ellagic acid. The hepatic activities of HMG-CoA and CETP were reduced, and the hepatic activity of LCAT was increased by both 5-uRCK extract and ellagic acid, which also caused histological improvements. The MDA content in the aorta and serum was significantly decreased after oral administration of 5-uRCK or ellagic acid. Further immunoblotting analysis showed that AMPK phosphorylation in the liver was induced by 5-uRCK and ellagic acid, which activated AMPK, inhibiting the activity of HMGCR by inhibitory phosphorylation. In contrast, 5-uRCK and ellagic acid suppressed the nuclear translocation and activation of SREBP-2, which is a key transcription factor in cholesterol biosynthesis. In conclusion, our results suggest that 5-uRCK and its bioactive compound, ellagic acid, are useful alternative therapeutic agents to regulate blood cholesterol.

22 January 2018 in Nutrients
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Journal Article
Open access
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JKJaeyong Kim
Jaeyong Kim
HKHeesook Kim
Heesook Kim
HCHakjoon Choi
Hakjoon Choi
AJAra Jo
Ara Jo
HKHuwon Kang
Huwon Kang
SISojeong Im
Sojeong Im
The fruit of Stauntonia hexaphylla is commonly used as a traditional anthelmintic in Korea, Japan, and China. However, its anti-inflammatory activity and the underlying mechanisms have not been studied systematically. In the present study, we examined the anti-inflammatory activities of an aqueous extract of S. hexaphylla fruit (SHF) in lipopolysaccharide (LPS)-activated RAW 264.7 cells. The SHF extract contained anti-inflammatory compounds, such as neochlorogenic acid, chlorogenic acid, and cryptochlorogenic acid. The extract inhibited protein levels of inducible nitric oxide synthase and the activity of cyclooxygenase enzyme, with concomitant reductions in the production of nitric oxide and prostaglandin E2 in LPS-activated RAW 264.7 cells. Additionally, the SHF extract reduced the production of pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin (IL)-1β, and IL-6. The SHF extract attenuated LPS-induced nuclear factor-κB (NF-κB) activation by decreasing the phosphorylation of its inhibitor, IκBα. Furthermore, the SHF extract showed a significant anti-inflammatory effect in vivo by reducing the volume of carrageenan-induced paw edema in rats. Our results suggest that the SHF extract exerts potential anti-inflammatory properties against LPS-activated RAW 254.7 cells, and in an animal model of inflammation.

Verified
Journal Article
Open access
PDF file
WKWanseok Kang
Wanseok Kang
HCHakjoon Choi
Hakjoon Choi
GJGoeun Jang
Goeun Jang
KLKi Hoon Lee
Ki Hoon Lee
EKEun Kim
Eun Kim
Sunoh KimSunoh Kim
Sunoh Kim
We investigated the time-dependent deleterious ocular changes induced by urban particulate matter (UPM) in vitro and in vivo. UPM treatment decreased human corneal epithelial cell migration and survival. Fluorescein scores were consistently increased by UPM application for 16 weeks. One week of rest at 2 or 4 weeks led to a recovery trend, whereas two weeks of rest at 8 weeks induced no change. UPM treatment decreased the tear film break-up time at 2 weeks, which was thereafter maintained until 16 weeks. No changes were found after periods of rest. UPM-treated eyes exhibited greater corneal epithelium thickness than normal eyes at 2 weeks, which recovered to normal at 4 and 8 weeks and was significantly decreased at 16 weeks. Apoptotic cell number in the epithelium was increased at 2 weeks, which remained constant except at 8 weeks. IL-6 expression in the cornea of the right eye continually increased for 16 weeks, and significant recovery was only observed at 8 weeks after 2 weeks of rest. Ocular pressure was significantly increased in the right eye at 12 and 16 weeks. Topical UPM application to the eye induced deleterious changes to various closely related parts of the eye.

1 June 2018 in Molecules
Verified
Journal Article
Open access
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YKYonguk Kim
Yonguk Kim
HCHakjoon Choi
Hakjoon Choi
JSJawon Shin
Jawon Shin
AJAra Jo
Ara Jo
KLKyung-Eun Lee
Kyung-Eun Lee
CCChul-yung Choi
Chul-yung Choi
The tuber of Cynanchum wilfordii (Baekshuoh Radix in Korean) is an important medicinal herb in Korea and China; however, it is difficult to differentiate C. wilfordii from a related medicinal herb, C. auriculatum (Baishouwu Radix in Chinese). We sought to develop a molecular method that could be used to distinguish between the tubers of C. wilfordii and C. auriculatum. We aligned the chloroplast genome sequences (available in the NCBI database) of the two species and identified three species-specific insertion and deletion (InDel) sites in the trnQ-psbK, rps2-rpoC2, and psaJ-rpl33 intergenic spacer (IGS) regions. To confirm the presence of these three InDels and validate their use as markers, we designed three primer pairs to amplify the trnQ-psbK, rps2-rpoC2, and psaJ-rpl33 IGS regions. Polymerase chain reaction (PCR) amplification of the trnQ-psbK IGS region yielded a 249 bp fragment for C. wilfordii, and 419 bp fragment for C. auriculatum, whereas the rps2-rpoC2 IGS primers produced a 629 bp fragment from C. wilfordii and a 282 bp fragment from C. auriculatum. In the psaJ-rpl33 IGS region, allele fragments of 342 and 360 bp in length were amplified from C. wilfordii, whereas 249 and 250 bp fragment were amplified from C. auriculatum. We propose these three InDel markers as a valuable, simple, and efficient tool for identifying these medicinal herbs and will thus reduce adulteration of these herbal materials in commercial markets.

29 May 2023 in Antioxidants
Verified
Journal Article
Open access
PDF file
WKWanseok Kang
Wanseok Kang
EKEun Kim
Eun Kim
HCHakjoon Choi
Hakjoon Choi
KLKI HOON LEE
KI HOON LEE
KKKyeog Jo Kim
Kyeog Jo Kim
Sunoh KimSunoh Kim
Sunoh Kim
Blue light is reported to be harmful to eyes by inducing reactive oxygen species (ROS). Herein, the roles of Peucedanum japonicum Thunb. leaf extract (PJE) in corneal wound healing under blue light irradiation are investigated. Blue-light-irradiated human corneal epithelial cells (HCECs) show increased intracellular ROS levels and delayed wound healing without a change in survival, and these effects are reversed by PJE treatment. In acute toxicity tests, a single oral administration of PJE (5000 mg/kg) does not induce any signs of clinical toxicity or body weight changes for 15 days post-administration. Rats with OD (oculus dexter, right eye) corneal wounds are divided into seven treatment groups: NL (nonwounded OS (oculus sinister, left eye)), NR (wounded OD), BL (wounded OD + blue light (BL)), and PJE (BL + 25, 50, 100, 200 mg/kg). Blue-light-induced delayed wound healing is dose-dependently recovered by orally administering PJE once daily starting 5 days before wound generation. The reduced tear volume in both eyes in the BL group is also restored by PJE. Forty-eight hours after wound generation, the numbers of inflammatory and apoptotic cells and the expression levels of interleukin-6 (IL-6) largely increase in the BL group, but these values return to almost normal after PJE treatment. The key components of PJE, identified by high-performance liquid chromatography (HPLC) fractionation, are CA, neochlorogenic acid (NCA), and cryptochlorogenic acid (CCA). Each CA isomer effectively reverses the delayed wound healing and excessive ROS production, and their mixture synergistically enhances these effects. The expression of messenger RNAs (mRNAs) related to ROS, such as SOD1, CAT, GPX1, GSTM1, GSTP1, HO-1, and TRXR1, is significantly upregulated by PJE, its components, and the component mixture. Therefore, PJE protects against blue-light-induced delayed corneal wound healing via its antioxidative, anti-inflammatory, and antiapoptotic effects mechanistically related to ROS production.