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To elucidate the anti-inflammatory properties and constituents of Agrimonia pilosa Ledeb. (A. pilosa), a comprehensive investigation was conducted employing activity-guided isolation. The anti-inflammatory effects were evaluated through an in vitro nitric oxide (NO) assay on lipopolysaccharide (LPS)-treated RAW 264.7 macrophage cells. Seven bio-active compounds with anti-inflammatory properties were successfully isolated from the butanol fraction and identified as follows: quercetin-7-O-β-d-rhamnoside (1), apigenin-7-O-β-d-glucopyranoside (2), kaempferol-7-O-β-d-glucopyranoside (3), quercetin (4), kaempferol (5), apigenin (6), and apigenin-7-O-β-d-glucuronide-6″-butylester (7). All isolated compounds showed strong NO inhibitory activity with IC50 values ranging from 1.4 to 31 µM. Compound 6 demonstrated the most potent NO inhibition. Compound 7, a rare flavonoid, was discerned as a novel anti-inflammatory agent, ascertained through its inaugural demonstration of nitric oxide inhibition. Subsequently, a comprehensive structure-activity relationship (SAR) analysis was conducted employing eight flavonoids derived from A. pilosa. The outcomes elucidated that flavones exhibit superior NO inhibitory effects compared to flavonols, and the aglycone form manifests greater potency in NO inhibition than the glycone counterpart. These results highlight A. pilosa as a promising source of effective anti-inflammatory agents and indicate its potential as a health-beneficial dietary supplement and therapeutic material.

Ecklonia cava is edible seaweed that is found in Asian countries, such as Japan and Korea; and, its major components include fucoidan and phlorotannins. Phlorotannins that are isolated from E. cava are well-known to have an antioxidant effect and strong antiviral activity against porcine epidemic diarrhea virus (PEDV), which has a high mortality rate in piglets. In this study, the bioactive components were determined based on two different approaches: (i) bio-guided isolation using the antiviral activity against the H1N1 viral strain, which is a representative influenza virus that originates from swine and (ii) high-resolution mass spectrometry-based dereplication, including relative mass defects (RMDs) and HPLC-qTOFMS fragmentation analysis. The EC70 fraction showed the strongest antiviral activity and contained thirteen phlorotannins, which were predicted by dereplication. Ten compounds were directly isolated from E. cava extract and then identified. Moreover, the dereplication method allowed for the discovery of two new phlorotannins. The structures of these two isolated compounds were elucidated using NMR techniques and HPLC-qTOFMS fragmentation analysis. In addition, molecular modelling was applied to determine the absolute configurations of the two new compounds. The antiviral activities of seven major phlorotannins in active fraction were evaluated against two influenza A viral strains (H1N1 and H9N2). Six of the compounds showed moderate to strong effects on both of the viruses and phlorofucofuroeckol A (12), which showed an EC50 value of 13.48 ± 1.93 μM, is a potential active antiviral component of E. cava.

To find good antifungal substances by the bioactivity-guided isolation method, we tracked down the effective antifungal substances in the bark and leaves of Zanthoxylum avicennae, and isolated three antifungal compounds 1, 2, and 3. The structures were identified as xanthyletin, luvangetin, and avicennin by 1H-NMR, 13C-NMR, and HRMS spectra. Particularly, compound 2 had several isomers, and the 1H-NMR spectra of 2 in different solvents showed a significant difference. To determine the stereo structure of 2, a single crystal was prepared and identified by X-ray diffraction as Luvangetin. Moreover, the difference of 1H-NMR data of 2 between in solvent dimethyl sulfoxide-d6 (DMSO-d6) and deuterated chloroform (CDCl3), and other reported isomers were discussed for the first time. The bioassay results indicated that the three compounds 1, 2, and 3 displayed low to high antifungal activities against tested phytopathogenic fungi. In particular, all compounds 1, 2, and 3 showed excellent antifungal activities against Pyricularia oryzae and Z. avicennae, with the values of half maximal effective concentration (EC50) ranging from 31 to 61 mg/L, and compound 3 was also identified as a more potent inhibitor against Fusaium graminearum (EC50 = 43.26 ± 1.76 mg/L) compared with fungicide PCA (phenazine-1-carboxylic acid) (EC50 = 52.34 ± 1.53 mg/L). The results revealed that compounds 1, 2, and 3 were the main antifungal substances of Z. avicennae, and can be used as lead compounds of a fungicide, which has good development value and prospect.

The edible fungus Phellinus baumii Pilat (Hymenochaetaceae) has been used in Korean traditional medicines for strengthening health and prolonging life. An extract of the fruiting bodies of P. baumii was subjected to bioassay-guided fractionation based on its anti-inflammatory effects in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. The resulting fractions were chemically investigated, leading to isolation of three phenolic compounds (1–3), a sesquiterpene (4), two steroids (5–6), a fatty acid (7), and a cerebroside (8). Spectroscopic analyses including 1D and 2D NMR spectroscopy and LC/MS were used to determine their chemical structures. Compounds 2, 4, 5, 7 and 8 were identified in P. baumii for the first time. Since all compounds were isolated from active fractions with anti-inflammatory activity, their ability to inhibit LPS-stimulated nitric oxide (NO) production in RAW264.7 cells were evaluated in vitro. Compounds 1, 2, 3, 5 and 7 inhibited LPS-stimulated NO production, and compounds 1–3 had IC50 values <10 μM. Treatment of LPS-stimulated RAW264.7 cells with compounds 1–3 inhibited phosphorylation of IKKα and IκBα. In addition, treatment of compounds 1–3 reduced LPS-induced increases of nuclear factor-kappa B (NF-κB) p65, iNOS and COX-2 protein expressions. Collectively, compounds 1–3 inhibited NF-κB-dependent inflammation in RAW264.7 cells. Thus, P. baumii is a potential source of natural anti-inflammatory agents, and active compounds 1–3 could be promising lead compounds for the development of novel anti-inflammatory agents.

Resveratrol is a well-known natural polyphenol with a plethora of pharmacological activities. As a potent antioxidant, resveratrol is highly oxidizable and readily reacts with reactive oxygen species (ROS). Such a reaction not only leads to a decrease in ROS levels in a biological environment but may also generate a wide range of metabolites with altered bioactivities. Inspired by this notion, in the current study, our aim was to take a diversity-oriented chemical approach to study the chemical space of oxidized resveratrol metabolites. Chemical oxidation of resveratrol and a bioactivity-guided isolation strategy using xanthine oxidase (XO) and radical scavenging activities led to the isolation of a diverse group of compounds, including a chlorine-substituted compound (2), two iodine-substituted compounds (3 and 4), two viniferins (5 and 6), an ethoxy-substituted compound (7), and two ethoxy-substitute,0d dimers (8 and 9). Compounds 4, 7, 8, and 9 are reported here for the first time. All compounds without ethoxy substitution exerted stronger XO inhibition than their parent compound, resveratrol. By enzyme kinetic and in silico docking studies, compounds 2 and 4 were identified as potent competitive inhibitors of the enzyme, while compound 3 and the viniferins acted as mixed-type inhibitors. Further, compounds 2 and 9 had better DPPH scavenging activity and oxygen radical absorbing capacity than resveratrol. Our results suggest that the antioxidant activity of resveratrol is modulated by the effect of a cascade of chemically stable oxidized metabolites, several of which have significantly altered target specificity as compared to their parent compound.

The search for natural inhibitors with anti-diabetes properties has gained increasing attention. Among four selected Smilacaceae family plants, Smilax china L. stems (SCS) showed significant in vitro anti-glycation and rat lens aldose reductase inhibitory activities. Bioactivity-guided isolation was performed with SCS and four solvent fractions were obtained, which in turn yielded 10 compounds, including one phenolic acid, three chlorogenic acids, four flavonoids, one stilbene, and one phenylpropanoid glycoside; their structures were elucidated using nuclear magnetic resonance and mass spectrometry. All solvent fractions, isolated compounds, and stem extracts from plants sourced from six different provinces of South Korea were next tested for their inhibitory effects against advanced glycation end products, as well as aldose reductase. α-Glucosidase, and lipase assays were also performed on the fractions and compounds. Since compounds 3, 4, 6, and 8 appeared to be the superior inhibitors among the tested compounds, a comparative study was performed via high-performance liquid chromatography with photodiode array detection using a self-developed analysis method to confirm the relationship between the quantity and bioactivity of the compounds in each extract. The findings of this study demonstrate the potent therapeutic efficacy of SCS and its potential use as a cost-effective natural alternative medicine against type 2 diabetes and its complications.

Nandina domestica (Berberidaceae) has been used in traditional medicine for the treatment of cough. This plant is distributed in Korea, Japan, China, and India This study aimed to investigate the anti-inflammatory phytochemicals obtained from the N. domestica fruits. We isolated a biflavonoid-type phytochemical, robustaflavone (R), from N. domestica fruits through bioactivity-guided fractionation based on its capacity to inhibit inflammation. The anti-inflammatory mechanism of R isolated from N. domestica has not yet been studied. In the present study, we evaluated the anti-inflammatory activities of R using lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. We have shown that R reduces the production of nitric oxide (NO), pro-inflammatory cytokine interleukin-1 beta (IL-1β), and IL-6. Western blot analysis showed that R suppresses the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and downregulates the expression of LPS-induced nuclear factor-kappa B (NF-κB) and the phosphorylation of extracellular-regulated kinases (pERK 1/2). Moreover, R inhibited IL-8 release in LPS-induced human colonic epithelial cells (HT-29). These results suggest that R could be a potential therapeutic candidate for inflammatory bowel disease (IBD).

This study aimed to separate the anti-acetylcholinesterase (anti-AChE) compounds from Odontites vulgaris Moench, a member of the Orobanchaceae famly, using a bioactivity-guided isolation strategy. Active fractions were selected according to the results of AChE-inhibitory activities. Then, various chromatographic packings were performed to separate the compounds from the active fractions, followed by identifying their structures using 1D NMR and HR–ESI–MS analyses. In addition, the isolated compounds were tested for their AChE-inhibitory activities. As a result, the bioactivity-guided isolation of O. vulgaris resulted in the acquisition of twenty-three compounds. Aloe emodin ( 10) had a significant AChE-inhibitory activity (IC 50  = 13.48 ± 1.35 µM). The IC 50 values of eight compounds ( 4 , 5 , 7 , 9 , 15 , 19 , 21 and 23 ) were in the range of 40.24 ± 5.73 to 69.26 ± 3.56 µM, indicating their moderate AChE-inhibitory activities. Compounds 3 , 11 , 13 , 14 , 17 and 18 showed weak AChE-inhibitory activities, for their IC 50 values ranged from 82.47 ± 2.12 to 147.98 ± 4.93 µM. The majority of the isolated compounds had AChE-inhibitory activities, indicating O. vulgaris is a source of natural anti-AChE inhibitors. Compounds 1 – 3 , 5 , 7 – 10 , 12 , 15 and 16–21 were first reported from the genus and the plant. These findings enriched the results of the phytochemical study of Odontites and O. vulgaris . The IC 50 values of the positive control galantamine was 0.59 ± 0.03 µM. AChE-inhibitory activities of the tested compounds were much weaker than galantamine. Further seperation to the active subfractions need to be carried out to search for more minor compounds with higher AChE-inhibitory activities. Additionally, whether the isolated compounds have other anti-Alzheimer’s disease activities need further investigations to unveil.

A comprehensive linear gradient solvent system for centrifugal partition chromatography (CPC) was developed for the bioassay-guided isolation of natural compounds. The gradient solvent system consisted of three different ternary biphasic solvents types: n-hexane–acetonitrile–water (10:2:8, v/v), ethyl acetate–acetonitrile–water (10:2:8, v/v), and water-saturated n-butanol–acetonitrile–water (10:2:8, v/v). The lower phase of the n-hexane–acetonitrile–water (10:2:8, v/v) was used as the stationary phase, while its upper phase, as well as ethyl acetate–acetonitrile–water (10:2:8), and water-saturated n-butanol–acetonitrile–water (10:2:8, v/v) were pumped to generate a linear gradient elution, increasing the mobile phase polarity. We used the gradient CPC to identify antioxidant response elements (AREs), inducing compounds from Centipeda minima, using an ARE-luciferase assay in HepG2 cells, which led to the purification of the active molecules 3-methoxyquercetin and brevilin A. The developed CPC solvent systems allow the separation and isolation of compounds with a wide polarity range, allowing active molecule identification in the complex crude extract of natural products.

In this study, three fungal steroids (1–3) were isolated from the fruiting bodies of the poisonous mushroom Gymnopilus orientispectabilis, based on bioactivity-guided isolation methods. The chemical structures of the isolates (1–3) were determined using NMR spectroscopic methods. Compounds 1–3 exhibited inhibition activity against E. coli, and their interactions with several bacterial drug targets were studied via in silico molecular docking, where the lowest binding energies were observed for penicillin binding protein 3 (PBP3) (−62.89, −75.89 and −74.47 kcal/mol, for compounds 1, 2 and 3, respectively). An MD simulation was performed to examine the conformational stability, motion and flexibility of protein–ligand complexes. In conclusion, this study investigates fungal steroids from G. orientaspectabilis as potential sources for new antimicrobial agents, encouraging further research to develop novel therapies.