Isolation of Fucoxanthin from Sargassum oligocystum Montagne, 1845 Seaweed in Vietnam and Its Neuroprotective Activity

Fucoxanthin extracted and purified from Vietnamese Sargassum oligocystum Montagne, 1845 exhibits various biological activities. In this study, the ability of fucoxanthin to inhibit acetylcholinesterase (AChE), the antioxidant activities, and the expression of antioxidant enzymes were investigated. Fucoxanthin isolated from Vietnamese S. oligocystum showed no cytotoxic effects; moreover, it exhibited AChE inhibitory activity (with an IC50 value of 130.12 ± 6.65 μg mL-1) and antioxidant activity (with an IC50 value of 3.42 ± 0.15 mg mL-1). At concentrations of 50 and 100 µg mL-1, fucoxanthin provided protection against amyloid β-protein fragment 25-35-induced neurotoxicity in a C6 neuronal cell line, and the survival of C6 cells was higher than 81.01% and 80.98%, respectively, compared to the control group (59%). Moreover, antioxidant enzyme activity and quantitative PCR analysis suggested that the neuroprotective effect of fucoxanthin resulted from regulation of the gene expression of antioxidant enzymes (CAT and GPx) and ER pathways (caspase-3 and Bax), as well as the promotion of expression of genes involved in PI3K/Akt signaling (GSK-3β), autophagy (p62 and ATG5), and the biosynthesis of ACh (VAChT and ChAT). Therefore, fucoxanthin extracted from the seaweed S. oligocystum in Vietnam is a potential feedstock source for the production of health foods that exert neuroprotective effects.

N-Substituted piperidine-3-carbohydrazide-hydrazones against Alzheimer's disease: Synthesis and evaluation of cholinesterase, beta-amyloid inhibitory activity, and antioxidant capacity

A series of piperidine-3-carbohydrazide-hydrazones bearing phenylethyl, phenylpropyl, and phenylbutyl substituents on piperidine nitrogen were designed and synthesized as cholinesterase (ChE) inhibitors. The title compounds were screened for acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) inhibitory activities and antioxidant capacities, and the active ones for Aβ₄₂ self-aggregation inhibition, in vitro. The chemiluminescence method was used to determine the effect of the selected compounds on the reactive oxygen species (ROS) levels in brain tissue. Physicochemical properties were calculated by the MOE program. Kinetic analysis and molecular modeling studies were also carried out for the most active compounds. Generally, the final compounds exhibited moderate to good AChE or BuChE inhibitory activity. Among them, 3g and 3j showed the most potent activity against AChE (IC₅₀  = 4.32 µM) and BuChE (IC₅₀  = 1.27 µM), respectively. The kinetic results showed that both compounds exhibited mixed-type inhibition. Among the selected compounds, nitro derivatives (3g, 4g, and 5g) provided better Aβ₄₂ inhibition. According to the chemiluminescence assay, 4i exhibited the most active superoxide free-radical scavenger activity and 3g, 3j, and 4i showed similar scavenger activity on other ROS. All results suggested that 3g, 3j, and 4i have good AChE/BuChE, Aβ₄₂ inhibitory potentials and antioxidant capacities and can therefore be suggested as promising multifunctional agents to combat Alzheimer's disease.

Utilization of the By-Product of Corn: Guided Identification of Bioactive Terpenoids from Stigma Maydis (Corn Silk)

Stigma maydis (corn silk) (S. maydis) is a food-based by-product of maize and possesses great nutritional and pharmaceutical value. This study aimed to explore bioactive components from S. maydis. By the guidance of bioactivity-guided approach and Global Natural Products Social (GNPS) molecular networking, 12 terpenoids were discovered from S. maydis. The structures of 11 undescribed compounds (1-11) were determined by detailed spectroscopic analyses, single-crystal X-ray diffraction analysis, specific rotation calculations, electronic circular dichroism (ECD) calculations, and NMR calculations. The neuroprotective and acetylcholinesterase (AChE) inhibitory effects of 1-12 were examined, and most of them showed significant or moderate activities. The underlying neuroprotective mechanism of 4 and 5 was revealed by Hoechst 33258, AO-EB, and JC-1 staining assays. This work illustrated the potential of S. maydis as a prospective natural source of bioactive compounds in food and pharmaceutical industries.

Novel Bisamide Alkaloids Enantiomers from Pepper Roots (Piper nigrum L.) with Acetylcholinesterase Inhibitory and Anti-Neuroinflammatory Effects

The roots of Piper nigrum L., a seasoning for cooking various types of broths, are renowned for their high nutritional content and potential medicinal benefits. In this study, nine pairs of novel cyclohexene-type bisamide alkaloids (1a/1b-9a/9b) were isolated from the pepper roots using molecular network analysis strategies. Their structures were determined by extensive spectroscopic data, electronic circular dichroism (ECD) calculations, and X-ray diffraction analyses. Using an intermolecular Diels-Alder reaction, a strategy for the synthesis of bisamide alkaloids from different monomeric amide alkaloids was developed. Furthermore, these compounds were chirally separated for the first time, and compounds 3a and 5a/5b showed significant anti-neuroinflammation effects in the models of lipopolysaccharide(LPS)-induced BV2 microglial cells. Meanwhile, compounds 6b and 7a displayed concentration-dependent inhibitory activities against acetylcholinesterase with IC₅₀ values of 6.05 ± 1.10 and 3.81 ± 0.10 μM, respectively. These findings confirmed that these bisamide alkaloids could be applied in functional food formulations and pharmaceutical products as well as facilitate the further development and usage of pepper roots.

Glycoside constituents from Miliusa sinensis leaves and their anti-inflammatory and acetylcholine protective effects

Repeated column chromatography resulted in the isolation of two new glycosides, miliusides A-B (1 and 7), along with six known metabolites (2-6, and 8) from the leaves of Miliusa sinensis Finet and Gagnep. The structures of the purified phytochemicals were elucidated by interpreting their spectroscopic data (NMR, HRMS), as well as comparison with the previous literature. The biological evaluation of acetylcholinesterase (AChE) inhibitory effects and anti-inflammatory activity by measuring nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW264.7 mouse macrophage cells, were also conducted. Among them, compounds 5 and 7 exhibited significant AChE inhibitory activities (IC₅₀ = 53.36 ± 4.20 and 88.50 ± 8.79 µM, respectively), compared with the positive control (Galanthamine, IC₅₀ = 1.65 ± 0.15 µM). Only the MeOH extract showed suppression effects on NO production in LPS-induced RAW264.7 cells (IC₅₀ = 38.18 ± 3.25 μg/mL) comparable to that of the positive control, l-NMMA (IC₅₀ = 2.21 ± 0.56 μg/mL).

Asperbenzophenone A and Versicolamide C, New Fungal Metabolites from the Soft Coral Derived Aspergillus sp. SCSIO 41036

Two new compounds, asperbenzophenone A (1) and versicolamide C (5), together with fifteen known compounds were isolated from a soft coral derived fungus Aspergillus sp. SCSIO 41036. Their structures were elucidated by spectroscopic methods, ECD analysis, and by a comparison with data from the literature. In bioassay, compound 8 showed significant inhibitory activity against lipopolysaccharide-inducted nitric oxide (NO) in RAW264.7 cells at the concentration of 10 μM. Additionally, the anti-acetylcholinesterase activity assay showed that 14 exhibited weak inhibition with an IC₅₀ value of 157.8 μM.

Essential Oils from Spices Inhibit Cholinesterase Activity and Improve Behavioral Disorder in AlCl3 Induced Dementia

The chemical compositions of essential oils (EOs) prepared from six spices including cinnamon, amomum tsao-ko, cardamom, amomum, black pepper and white pepper were analyzed by gas chromatography-mass spectrometry (GC/MS), which led to identify almost 200 volatile compounds. All EOs of spices showed cholinesterase inhibitory activity. Among them, pepper EO showed most potent acetylcholinesterase (AChE) inhibitory activity with IC₅₀ values of 8.54 μg/mL (black pepper EO) and 5.02 μg/mL (white pepper EO). Molecular docking and in vitro validation suggested that 3-carene, α-pinene and β-pinene with IC₅₀ value of 1.73, 2.66, and 14.75 μg/mL, respectively, might be active constituents of spices oil in inhibiting AChE. Furthermore, amomum tsao-ko EO and amomum EO can improve behavioral disorder in dementia zebrafish induced by aluminum trichloride (AlCl₃ ).

Accelerated Solvent Extraction of Antioxidant Compounds from Gardeniae Fructus and Its Acetylcholinesterase Inhibitory and PC12 Cell Protective Activities

Gardeniae fructus is a common neuroprotective medicinal food in China, however the extraction efficiency and mixture activities are rarely mentioned. In this study, accelerated solvent extraction (ASE) parameters were optimized by a response surface methodology to extract antioxidants from Gardeniae fructus. Neuroprotective activity was evaluated using H₂O₂ and amyloid-β_25–35 peptide-treated PC12 cells. By comparing with three other extract methods (i.e., heated refluxing extraction (HRE), ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE)), it was found that the yield (35.10%), total iridoids (27.69%), total flavonoid (6.12%) content, antioxidant activities (IC₅₀ on DPPH, 164.46 µg/mL; FRAP value 4703.54 μmol/L), and acetylcholinesterase inhibitory ability (IC₅₀ 92.58 µg/mL) of ASE extract under the optimal condition (150 °C temperature, 10 min static time, 60% ethanol, 2 extract cycles) were significantly higher than other extract methods. The strongest ability to protect PC12 cells from damage was also present in ASE extract, as evidenced by decreasing lactate dehydrogenase and malondialdehyde levels, elevating superoxide dismutase and glutathioneperoxidase activities. Compositional analysis indicated that the extremely high crocetin level in ASE extract (1.30 μg/mg) may offer great potential. Our results indicated that ASE is a proper extraction method that could offer great potential for finding the neuroprotective ability of Gardeniae fructus for the treatment of AD.

A Comparative Study on the Phenolic Composition and Biological Activities of Morus alba L. Commercial Samples

Morus alba L. (white mulberry) has been commonly used as a functional food and for medicinal purposes. Hence, the aim of the study was to compare the phenolic profile of white mulberry commercial samples in relation to their antioxidant potential and acetylcholinesterase (AChE) inhibitory activity. It is of interest to determine whether herbal products originating from different commercial sources differ in their phenolic profiles. For this purpose, a simple and rapid high-performance liquid chromatography (HPLC) method was used for the separation and determination of ten major phenolic compounds. Total phenolic (TPC), total flavonoid (TFC), and total phenolic acid contents (TPAC), as well as l(+)-ascorbic acid (ASA) contents, were determined. The antioxidant potential was assessed by DPPH (2,2-diphenyl-1-picrylhydrazyl radical) scavenging activity and ferric-reducing/antioxidant power (FRAP) assay, while the AChE inhibitory activity was determined by the Ellman assay for water extracts. The study revealed that excluding two herbal products containing fruits and a sample containing leaves of white mulberry, yerba mate and lemon, the remaining samples were generally consistent in terms of phenolic composition as well as antioxidant potential and AChE inhibitory activity. This reflects the health-promoting properties of the samples under study. Moreover, the results showed that the water extracts of white mulberry were richer in phenolic compounds and presented higher antioxidant activity than the hydromethanolic extracts. However, the water extracts showed low inhibitory activity against AChE. Moreover, the correlation analysis indicated a high positive relationship between phenolic composition and antioxidant activity in extracts of white mulberry. Overall, the obtained results may be useful in the evaluation of new dietary supplements and food products. The water extracts of white mulberry could be used for antioxidant purposes, while the hydromethanolic extracts could be incorporated in antioxidant formulations.

Three New 2-(2-Phenylethyl)chromone Derivatives of Agarwood Originated from Gyrinops salicifolia

Two new 2-(2-phenylethyl)chromone derivatives (1–2), comprising 5,6,7,8-tetrahydro-2-(2-phenylethyl)chromone and benzylacetone moieties, together with one new 2-(2-phenylethenyl)chromone (3) were isolated from the ethyl acetate extraction of agarwood originated from Gyrinops salicifolia Ridl. All structures were unambiguously elucidated on the basis of 1D and 2D NMR spectra as well as by HRESIMS data. All isolated compounds were tested for acetylcholinesterase (AChE) inhibitory activity and cytotoxic activity against human myeloid leukemia cell line (K562). However, none of the compounds displayed AChE inhibitory activity at a concentration of 50 µg mL⁻¹ or cytotoxic activity against K562 cell line.

New spinosin derivatives from the seeds of Ziziphus mauritiana

Three new acylated flavonoid C-glycosides, 6‴-(-)-phaseoylspinosin (1), 6‴-(3″″,4″″,5″″-trimethoxyl)-(E)-cinnamoylspinosin (2), and 6‴-(4″″-O-β-D-gluco-pyranosyl)-benzoylspinosin (3), were isolated from the seeds of Ziziphus mauritiana (Rhamnaceae). A further 19 known compounds including eight spinosin analogues (4–11) were also isolated. Their structures were elucidated by means of spectroscopic analysis and chemical method. Among spinosin derivatives 1, 2, 4, 7, 8, and triterpenoid saponin 14, jujuboside A (14) displayed moderate acetylcholinesterase (AchE) inhibitory activity with an inhibition value of 46.2% at a concentration of 1 µM.