Hojun Kim

Evaluation of novel antioxidant triterpenoid saponins from the halophyte Salicornia herbacea.

As a part of an ongoing search for novel antioxidants from the salt marsh plants, bioactivity-isolation and structure determination of constituents from Salicornia herbacea were performed. One new triterpenoid saponin (4), along with three known saponins (1-3), has been isolated from n-BuOH fraction of S. herbacea. On the basis of the spectroscopic methods, the structure of the new saponin 4 was elucidated as 3β-hydroxy-23-oxo-30-noroleana-12, 20(29)-diene-28-oic acid 3-O-β-D-glucuronopyranosyl-28-O-β-d-glucopyranoside. Scavenging effects of saponins 1-4 were examined on 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical and peroxynitrite. Particularly, saponin 3 exerted significant antioxidant activity on both authentic peroxynitrite and peroxynitrite generated from morpholinosydnonimine (SIN-1).

Evaluation of Inhibitory Effect of Phlorotannins from Ecklonia cava on Triglyceride Accumulation in Adipocyte

In the present study, a methanolic extract of Ecklonia cava and its solvent-partitioned fractions were evaluated for their antiadipogenic effect in 3T3-L1 adipocytes. One of them, the n-BuOH fraction, effectively reduced lipid accumulation and glucose consumption. In addition, the presence of the n-BuOH fraction in adipocytes suppressed the regulations of adipogenic transcription factors, PPARγ and SREBP1c, and adipogenic specific genes, FABP4, FABP1, FAS, LPL, HSL, and ACS1. Further purification of n-BuOH fractions led to the isolation of six phlorotannins (1-6). The six phlorotannins effectively suppressed triglyceride accumulation. Comparative analysis showed that lipid accumulation in adipocytes was dramatically attenuated in the presence of eckstolonol (4).

Evaluation of flavonoids from Zostera asiatica as antioxidants and nitric oxide inhibitors

Zostera asiatica is one of the five members of the genus Zostera that can be found in Korea. Studies have reported the phytochemical properties and bioactivities of Zostera species. Current study focused on the antioxidant effects of Z. asiatica as a part of ongoing research for bioactive substances from marine resources. Results indicated that a crude extract of Z. asiatica not only scavenged on peroxynitrite in vitro and on intracellular reactive oxygen species (ROS) but also inhibited production of nitric oxide (NO). The crude extract was subjected to solvent fractionation for bioactivity-based separation using aforementioned three bioassay systems. From the active n-butanol fraction, two flavonoids were isolated and characterized as luteolin (1) and luteolin-3’-sulfate (2). Both flavonoids showed significant antioxidant effects. In conclusion, Z. asiatica was demonstrated to possess antioxidant effect partly attributed to isolated flavonoids, the first such effect reported from Z. asiatica, to the best of our knowledge.

Antiinflammatory Activity of Solvent-partitioned Fractions from Atriplex gmelinii C. A. Mey. in LPS-stimulated RAW264.7 Macrophages

As a part of ongoing research to elucidate and characterize antiinflammatory nutraceuticals, the crude extracts from Atriplex gmelinii C. A. Mey. and their solvent-partitioned fractions were tested for their antiinflammatory potential in lipopolysaccharide (LPS)-stimulated RAW 264.7 mouse macrophages. The crude extracts of A. gmelinii C. A. Mey. were fractioned according to polarity with n-hexane, 85% aqueous methanol (85% aq. MeOH), n-butanol, and H₂O. Their antiinflammatory activities were investigated in LPS-induced inflammation in mouse macrophages by measuring nitric oxide (NO) generation and mRNA expression of inflammation mediators, namely, inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β), and IL-6. As a result, we confirmed that the crude extracts of A. gmelinii C. A. Mey. inhibited LPS-stimulated NO production and mRNA expression of iNOS and COX-2 as important inflammatory factors. The inhibition of NO production through the downregulation of important inflammatory factors such as iNOS, COX-2, IL-1β, and IL-6 was found by treatment with all solvent-partitioned fractions. Among all tested fractions, 85% aq. MeOH showed the strongest antiinflammatory response. Based on the current results, A. gmelinii C. A. Mey. was suggested to possess natural antiinflammatory components, indicating that it could be used as a valuable source of antiinflammatory substances.

Evaluation of a furochromone from the halophyte Corydalis heterocarpa for cytotoxic activity against human gastric cancer (AGS) cells

A furochromone, heterocarpin (1), was isolated from the halophyte Corydalis heterocarpa, along with four known compounds (2-5), which were obtained for the first time from this genus. The chemical structures of these compounds were determined by extensive 2-D NMR experiments and by comparison with the data reported in the literature. Compound 1 showed significant cytotoxic activities against four human cancer cells, AGS (human gastric cancer), HT-29 (human colon cancer), HT-1080 (human fibrosarcoma) and MCF-7 (human breast carcinoma). According to the cytotoxicity results, the mechanism behind the cytotoxic presence of compound 1 on AGS cells was investigated through the mRNA and protein levels of apoptotic pathway factors such as p21, p53, Bax, Bcl-2, XIAP, and caspases-3 and -9. The results indicated that heterocarpin (1) showed the cytotoxic effect on cancer cells by inducing apoptosis via regulated Bax-Bcl-2 ratio, overproduced caspases and suppressed XIAP. The inhibition of NFκB and activation of JNK and ERK pathways were also observed in the presence of heterocarpin (1). Therefore, heterocarpin and its source C. heterocarpa were suggested to be utilized as a functional food with potential pro-apoptotic activity against cancer cells.

Antioxidant Activity of a Chitin-degrading Bacterium Bacillus idriensis (CGH18)

A bacterium CGH18 exhibiting antioxidizing and chitin-degrading activities in the colloidal chitin culture medium was isolated from salt-fermented crab. This strain was identified as Bacillus idriensis based on 16S rDNA sequence homology search. Its crude extract was partitioned between n-BuOH and . The organic layer was further partitioned between and . Antioxidant activities of crude extract and its solvent fractions were evaluated using five different bioassay methods, including the degree of occurrence of intracellular reactive oxygen species (ROS), peroxynitrite scavenging (ONOO), and oxidative damage of genomic DNA. All fractions exhibited significant antioxidant activity in bioassay systems used.

Effect of the Arctic terrestrial plant Ranunculus hyperboreus on LPS-induced inflammatory response via MAPK pathways

Abstract The Arctic flora hosts a limited number of species due to its extreme environmental conditions which also yield novel and unique secondary metabolites from withstanding plants. Considering a lack of research on bioactivity potential of Arctic flora, Ranunculus hyperboreus, an Arctic plant, was studied for its anti-inflammatory potential as a part of ongoing research on discovering novel natural bioactive products. Solvent-based fractions (H2O, n-BuOH, 85% aq. MeOH, n-hexane) from R. hyperboreus extract were observed to decrease the elevated nitrate amount during the inflammatory response of lipopolysaccharide-induced mouse macrophage RAW264.7 cells. To some extent, treatment with fractions was able to regulate the expression and protein levels of inflammation-related enzymes, iNOS and COX-2, and pro-inflammatory cytokines, TNF-α, IL-1β, and IL-6. The most active fractions, H2O and 85% aq. MeOH, were suggested to exert their effect through suppressed activation of MAPK pathways, especially JNK. Based on the studies of same species, phenolic glycosides were suggested to be the main active ingredients. To our knowledge, this is the first report of any bioactivity of R. hyperboreus which could be a valuable source of natural bioactive agents against inflammation.