The aim of the present study was to evaluate the comparative anti-Alzheimer's disease (AD) activities of different parts of Nelumbo nucifera (leaves, de-embryo seeds, embryos, rhizomes, and stamens) in order to determine the selectivity and efficient use of its individual components. Anti-AD activities of different parts of N. nucifera were evaluated via inhibitory activities on acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and β-site amyloid precursor protein-cleaving enzyme 1 (BACE1) along with scavenging activity on peroxynitrite (ONOO(-)). Among the evaluated parts of N. nucifera, the embryo extract exhibited significant inhibitory potential against BACE1 and BChE as well as scavenging activity against ONOO(-). Thus, the embryo extract was selected for detailed investigation on anti-AD activity using BACE1- and ChEs-inhibitory assays. Among the different solvent-soluble fractions, the dichloromethane (CH2Cl2), ethyl acetate (EtOAc), and n-butanol (n-BuOH) fractions showed promising ChEs and BACE1 inhibitory activities. Repeated column chromatography of the CH2Cl2, EtOAc and n-BuOH fractions yielded compounds 1-5, which were neferine (1), liensinine (2), vitexin (3), quercetin 3-O-glucoside (4) and northalifoline (5). Compound 2 exhibited potent inhibitory activities on BACE1, AChE, and BChE with respective IC50 values of 6.37 ± 0.13, 0.34 ± 0.02, and 9.96 ± 0.47 µM. Likewise, compound 1 showed potent inhibitory activities on BACE1, AChE, and BChE with IC50 values of 28.51 ± 4.04, 14.19 ± 1.46, and 37.18 ± 0.59 µM, respectively; the IC50 values of 3 were 19.25 ± 3.03, 16.62 ± 1.43, and 11.53 ± 2.21 µM, respectively. In conclusion, we identified potent ChEs- and BACE1-inhibitory activities of N. nucifera as well as its isolated constituents, which may be further explored to develop therapeutic and preventive agents for AD and oxidative stress related diseases.
The aim of the present study was to evaluate the anti-diabetic, anti-inflammatory, antioxidant potential, and total phenolic content (TPC) of green and red kohlrabi cultivars. Anti-diabetic and anti-inflammatory activities were evaluated via protein tyrosine phosphatase (PTP1B) and rat lens aldose reductase inhibitory assays and cell-based lipopolysaccharide (LPS)-induced nitric oxide (NO) inhibitory assays in RAW 264.7 murine macrophages. In addition, scavenging assays using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical, and peroxynitrite (ONOO−) were used to evaluate antioxidant potential and TPC was selected to assess phytochemical characteristics. Between the two kohlrabi cultivars, red kohlrabi (RK) had two times more TPC than green kohlrabi (GK) and showed significant antioxidant effects in DPPH, ABTS, and ONOO− scavenging assays. Likewise, methanol (MeOH) extracts of RK and GK inhibited LPS-induced NO production in a dose dependent manner that was further clarified by suppression of iNOS and COX-2 protein production. The MeOH extracts of RK and GK exhibited potent inhibitory activities against PTP1B with the corresponding IC50 values of 207±3.48 and 287±3.22 μg/mL, respectively. Interestingly, the RK MeOH extract exhibited significantly stronger anti-inflammatory, anti-diabetic, and antioxidant effects than that of GK MeOH extract. As a result, our study establishes that RK extract with a higher TPC might be useful as a potent anti-diabetic, antioxidant, and anti-inflammatory agent.
As part of our ongoing isolation of cholinesterase (ChE) inhibitors from natural marine sources, the bioactivity of the ethanolic extracts from 12 Korean seaweeds were screened for their inhibitory activities against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and total reactive oxygen species (ROS) generation. Eisenia bicyclis exhibited promising inhibitory properties against AChE, BChE and total ROS with inhibition percentages (%) of 68.01 ± 1.37, 95.72 ± 3.80, and 73.20 ± 1.82 at concentrations of 25 µg/mL, respectively. Among the different solvent-soluble fractions obtained from the ethanolic extract, the ethyl acetate (EtOAc) fraction was found to cause the most potent scavenging, or inhibitory activities, against 2,2-diphenyl-1-picrylhydrazyl (DPPH), peroxynitrite (ONOO(-)) and total ROS with the respective IC50 values of 2.48 ± 0.01, 8.70 ± 0.06, and 0.81 ± 0.03 µg/mL. Likewise, the EtOAc fraction also exhibited potent inhibitory activities against AChE and BChE with IC50 values of 2.78 ± 0.07 and 3.48 ± 0.32 µg/mL, respectively. Silica gel column chromatography of the EtOAc fraction yielded a phlorotannin, 974-B, based on the comparison with reported (1)H- and (13)C-NMR spectroscopic data. 974-B showed strong scavenging/or inhibitory potential against DPPH, ONOO(-), total ROS, AChE, and BChE with the respective IC50 values of 0.86 ± 0.02, 1.80 ± 0.01, 6.45 ± 0.04, 1.95 ± 0.01, and 3.26 ± 0.08 µM, respectively. These results indicate that the potential of E. bicyclis and its phlorotannin for use in the development of therapeutic or preventive agents of Alzheimer's disease mainly through ChE inhibition and additional antioxidant capacities.
The aim of the present study was to evaluate the comparative anti-inflammatory activities of Ixeris dentata (ID), Ixeris dentata var. albiflora (IDA), and Ixeris sonchifolia (IS) and to identify the main compounds present in extracts. The anti-inflammatory activity was evaluated through lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 murine macrophages. Five main compounds consisting of chlorogenic acid, caffeic acid, luteolin 7-O-glucoside, luteolin 7-O-glucuronide, and luteolin were used for simultaneous high-performance liquid chromatography quantification. The total phenolic content present in ID (30 mg/g GAE), IDA (35.33 mg/g GAE), and IS (43.79 mg/g GAE) was correlated to the corresponding LPS-induced NO production inhibitory effect in RAW 264.7 cells as expressed with IC(50) values 26.19, 21.43, and 7.59 μg/mL, respectively. Luteolin 7-O-glucoside was found as the major compound in ID (8.76 mg/g dry weight) and IDA (10.35 mg/g dry weight) and luteolin 7-O-glucuronide was the major compound in IS (34.66 mg/g dry weight). Luteolin 7-O-glucoside and luteolin 7-O-glucuronide inhibited LPS-induced NO production with IC(50) values of 30 and 4.5 μM, respectively. Furthermore, luteolin, luteolin 7-O-glucoside, and luteolin 7-O-glucuronide suppressed the expression of iNOS and COX-2, and t-BHP-induced ROS generation in LPS-stimulated RAW 264.7 cells. These results clearly showed that the anti-inflammatory potential of ID, IDA, and IS extract are primarily due to their contents of luteolin 7-O-glucoside and luteolin 7-O-glucuronide, respectively.
Context: Artemisia iwayomogi Kitamura (Compositae) has been very widely used for the treatment of acute or chronic hepatitis, jaundice, and gastritis. In the course of our continuing efforts to identify and quantify peroxynitrite scavengers from Compositae plants, A. iwayomogi was used in this study. Objective: The present study was aimed to identify and quantify the peroxynitrite scavengers of A. iwayomogi. Materials and methods: Silica gel and ODS were used for column chromatography. The isolated compounds were quantified using an HPLC equipped with a Capcell Pak C18 column (5 mm, 250 mm  4.6 mm i.d.), and the method was validated for the quality control. Peroxynitrite (ONOO À )-scavenging activities of the compounds and extracts were evaluated on the measurement of highly fluorescent rhodamine 123 converted from non-fluorescent dihydrorhodamine (DHR)-123 under the presence of peroxynitrite. Results: Based on the spectroscopic evidences, a new compound, 2 00 -O-caffeoylrutin (2 00 -O-trans-caffeic acid ester of quercetin 3-O-a-L-rhamnopyranosyl(1 ! 6)-b-D-glucopyranoside) was isolated and determined together with patuletin 3-O-glucoside, scopolin, scopoletin, rutin, 3,4-dicaffeoylquinic acid, and chlorogenic acid. All of them were potent peroxynitrite scavengers (IC 50 1.88 mg/mL). Discussion and conclusion: The peroxynitrite scavengers were mainly distributed in the EtOAc fraction rather than the ether and BuOH fractions. The 70% MeOH extract exhibited a high peroxynitrite-scavenging activity. Through the validation, the present HPLC method was verified to be sufficiently sensitive, accurate, precise, and stable. Therefore, this method can be used for the quality control of A. iwayomogi.
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