Limonoids from the Fresh Young Leaves and Buds of Toona sinensis and Their Potential Neuroprotective Effects

Erythrocarpines IN, new limonoids from the barks of Chisocheton erythrocarpus and their neuroprotective effects against hydrogen peroxide in NG108-15 cells

A phytochemical study on the bark of Chisocheton erythrocarpus Hiern (Meliaceae) has led to the isolation of six new phragmalin-type limonoids named erythrocarpines I - N (1-6) along with one known limonoid, erythrocarpine F (7). Their structures were fully characterized by spectroscopic methods. The pre-treatment of NG108-15 cells with 1-5, 7 (2 h) demonstrated low to good protective effects against H2O2 exposure; 1 (83.77% ± 1.84 at 12.5 μM), 2 (69.07 ± 2.01 at 12.5 μM), 3 (80.38 ± 2.1 at 12.5 μM), 4 (62.33 ± 1.95 at 25 μM),5 (58.67 ± 1.85 at 50 μM) and 7 (66.07 ± 2.03 at 12.5 μM). Interestingly, 1 and 3 demonstrated comparable protective effects to positive control epigallocatechin gallate (EGCG) with similar cell viability capacity (≈ 80%), having achieved that at lower concentration (12.5 μM) than EGCG (50 μM). Collectively, the results suggested the promising use of 1 and 3 as potential neuroprotective agents against hydrogen peroxide-induced cytotoxicity in neuronal model.

Traditional Uses, Chemical Constituents and Pharmacological Activities of the Toona sinensis Plant

Toona sinensis (A. Juss.) Roem., which is widely distributed in China, is a homologous plant resource of medicine and food. The leaves, seeds, barks, buds and pericarps of T. sinensis can be used as medicine with traditional efficacy. Due to its extensive use in traditional medicine in the ancient world, the T. sinensis plant has significant development potential. In this review, 206 compounds, including triterpenoids (1-133), sesquiterpenoids (134-135), diterpenoids (136-142), sterols (143-147), phenols (148-167), flavonoids (168-186), phenylpropanoids (187-192) and others (193-206), are isolated from the T. sinensis plant. The mass spectrum cracking laws of representative compounds (64, 128, 129, 154-156, 175, 177, 179 and 183) are reviewed, which are conducive to the discovery of novel active substances. Modern pharmacological studies have shown that T. sinensis extracts and their compounds have antidiabetic, antidiabetic nephropathy, antioxidant, anti-inflammatory, antitumor, hepatoprotective, antiviral, antibacterial, immunopotentiation and other biological activities. The traditional uses, chemical constituents, compound cracking laws and pharmacological activities of different parts of T. sinensis are reviewed, laying the foundation for improving the development and utilization of its medicinal value.

In Vitro Anti-Inflammatory Study of Limonoids Isolated from Chisocheton Plants

Chisocheton plants from the family Meliaceae have traditionally been used to treat several diseases; however, scientific evidence is limited. The most abundant chemical constituents of this plant are the limonoids, which are known for their various biological activities, including anti-inflammatory effects. However, the anti-inflammatory effects and underlying mechanisms of action of the constituents of Chisocheton plants have not been fully explored. In this report, we evaluated the anti-inflammatory activity of 17 limonoid compounds from Chisocheton plant primarily by measuring their inhibitory effects on the production of pro-inflammatory cytokines, including TNF-α, IL-6, IL-1β, and MCP-1, in LPS-stimulated THP-1 cells using an ELISA assay. Compounds 3, 5, 9, and 14-17 exhibited significant activity in inhibiting the evaluated pro-inflammatory markers, with IC50 values less than 20 µM and a high selectivity index (SI) range. Compounds 3, 5, 9, and 15 significantly suppressed the expression of phosphorylated p38 MAPK in THP-1 cells stimulated with LPS. These findings support the use of limonoids from Chisocheton plants as promising candidates for anti-inflammatory therapy.

Xanthones with Potential Anti-Inflammatory and Anti-HIV Effects from the Stems and Leaves of Cratoxylum cochinchinense

Four new xanthones, cratocochinones A-D (1-4), together with eight known analogues (5-12), were isolated from the stems and leaves of Cratoxylum cochinchinense. The chemical structures of cratocochinones A-D (1-4) were elucidated by comprehensive spectroscopic analyses and the known compounds were identified by comparisons with the spectral data reported in the literature. All isolated compounds 1-12 were evaluated for their anti-inflammatory activities and anti-HIV-1 activities. Compounds 1-12 showed remarkable inhibitory activities on nitric oxide (NO) production induced by lipopolysaccharide in mouse macrophage RAW 264.7 cells in vitro, with IC50 values in the range of 0.86 ± 0.05 to 18.36 ± 0.21 µM. Meanwhile, compounds 1-12 exhibited significant anti-HIV-1 activities with EC50 which ranged from 0.22 to 11.23 µM. These findings indicate that the discoveries of these xanthones, isolated from the stems and leaves of C. cochinchinense, showing significant anti-inflammatory and anti-HIV-1 effects could be of great importance to the research and development of new natural anti-inflammatory and anti-HIV agents.

Integrated volatilomic profiles and chemometrics provide new insights into the spatial distribution and aroma differences of volatile compounds in seven Toona sinensis cultivars

As a popular vegetable, the unique and pleasant aroma is the key quality characteristic of Toona sinensis. To explore the sources and differences of aroma, the volatilomic profiling in the leaves and shoots of seven T. sinensis cultivars were investigated by chemometric analysis. The results indicated that aroma differences of each cultivar can be distinguished by W5S, W1S, W1W and W2S sensors during E-nose analysis. More than two thirds of all volatile organic compounds (VOCs) were derived from the leaves of most cultivars, except for Ximu toon. Notably, 2-mercapto-3,4-dimethyl-2,3-dihydrothiophene, 3,4-dimethyl thiophene, methyl thiirane, isocaryophyllene and hexanal were the major VOCs in both the leaves and shoots of T. sinensis. By constructing a weighted correlation network model, 5 modules and 11 hub VOCs were identified in the leaf samples of all cultivars. The data indicate that differential intracellular metabolic responses are responsible for the aroma formation of seven T. sinensis cultivars.

Insights into the promising prospect of medicinal chemistry studies against neurodegenerative disorders

Medicinal chemistry is an interdisciplinary field that incorporates organic chemistry, biochemistry, physical chemistry, pharmacology, informatics, molecular biology, structural biology, cell biology, and other disciplines. Additionally, it considers molecular factors such as the mode of action of the drugs, their chemical structure-activity relationship (SAR), and pharmacokinetic aspects like absorption, distribution, metabolism, elimination, and toxicity. Neurodegenerative disorders (NDs), which are defined by the breakdown of neurons over time, are affecting an increasing number of people. Oxidative stress, particularly the increased production of Reactive Oxygen Species (ROS), plays a crucial role in the growth of various disorders, as indicated by the identification of protein, lipid, and Deoxyribonucleic acid (DNA) oxidation products in vivo. Because of their inherent nature, most biological molecules are vulnerable to ROS, even if they play a role in metabolic parameters and cell signaling. Due to their high polyunsaturated fatty acid content, low antioxidant barrier, and high oxygen uptake, neurons are particularly vulnerable to oxidation by nature. As a result, excessive ROS generation in neurons looks especially harmful, and the mechanisms associated with biomolecule oxidative destruction are several and complex. This review focuses on the formation and management of ROS, as well as their chemical characteristics (both thermodynamic and kinetic), interactions, and implications in NDs.

Screening of Monoamine Oxidase B Inhibitors from Fragaria nubicola by Ligand Fishing and Their Neuroprotective Effects

Fragaria nubicola, known as Tibetan strawberry, is an edible plant possessing various health-promoting effects. However, its functional compositions were rarely studied. In this work, monoamine oxidase B (MAO-B) inhibitors in this plant were rapidly screened using the enzyme-functionalized magnetic nanoparticles coupled with UPLC-QTOF-MS. Two inhibitors, quercetin-3-O-β-d-glucuronide-6″-methyl ester (1) and kaempferol-3-O-β-d-glucuronide-6″-methyl ester (2), were identified from this plant with the IC₅₀ values of 19.44 ± 1.17 and 22.63 ± 1.78 μM, respectively. Enzyme kinetic analysis and molecular docking were carried out to investigate the mechanism of inhibition. Contents of both compounds as well as those of total phenolics and flavonoids were quantified to be 24.76 ± 1.26, 35.59 ± 1.17, 837.67 ± 10.62, and 593.46 ± 10.37 μg/g, respectively. In addition, both compounds exhibited significant neuroprotective effects on 6-hydroxydopamine-induced PC12 cells. This is the first report on the neuroprotective components of F. nubicola, suggesting its potential for developing neuroprotective functional food.

Leaves of Cedrela sinensis Attenuate Chronic Unpredictable Mild Stress-Induced Depression-like Behavior via Regulation of Hormonal and Inflammatory Imbalance

This study aimed to evaluate the protective effects of ethyl acetate fraction from Cedrela sinensis (EFCS) against chronic unpredictable mild stress (CUMS)-induced behavioral dysfunction and stress response in C57BL/6 mice. The physiological compounds of EFCS were identified as rutin, isoquercitrin, ethyl gallate, quercitrin, kaempferol-3-O-rhamnoside, and ethyl digallate, using UPLC-Q-TOF/MS^E. To evaluate the neuroprotective effect of EFCS, H₂O₂^- and corticosterone-induced neuronal cell viability was conducted in human neuroblastoma MC-IXC cells. It was found that EFCS alleviated depression-like behavior by conducting the sucrose preference test (SPT), forced swimming test (FST), open field test (OFT), and tail suspension test (TST). EFCS inhibited mitochondrial dysfunction related to neuronal energy metabolism by regulating reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP), and ATP contents in brain tissue. In addition, the administration of EFCS regulated the stress hormones in serum. EFCS regulated stress-related indicators such as CRF, ACTH, CYP11B1, and BDNF. Moreover, EFCS downregulated the inflammatory responses and apoptosis proteins such as caspase-1, TNF-α, IL-1β, p-JNK, BAX, and p-tau in brain tissues. These results suggest that EFCS might be a potential natural plant material that alleviates CUMS-induced behavior disorder by regulating inflammation in brain tissue against CUMS-induced depression.

Polyphenolic Glycosides from the Fruits Extract of Lycium ruthenicum Murr and Their Monoamine Oxidase B Inhibitory and Neuroprotective Activities

The fruits ofLycium ruthenicum Murr have long been consumed as health food and used in folk medicine in China. Apart from the well-known polysaccharides, the active small molecular constituents in this fruit have not been fully studied. In this work, a systematic phytochemical study was carried out to investigate the small molecules and their potential health benefits. Nine new polyphenolic glycosides, lyciumserin A-I (1-9), together with 16 known compounds (10-25), were isolated and elucidated by high-resolution electrospray ionization mass spectrometry and comprehensive NMR analyses in combination with chemical hydrolysis. Compounds 1, 2, and 16 exhibited moderate inhibitory activity of monoamine oxidase B (MAO-B), while compounds 1 (50 μM) and 2 (100 μM) displayed significant neuroprotective effects (69.22 and 72.38% of cell viability, respectively) in the 6-hydroxydopamine-induced injury of the PC12 cell model (54.41%), comparable to the positive drug rasagiline (70.45%). The neuroprotective effect of 1 and 2 was further evidenced by the observation of the morphological change and fluorescein diacetate/propidium iodide staining. In addition, the levels of the major active compounds (1, 3, 5/6, and 16-18) vary from 21.5 to 892.3 μg/g. This is the first report on phenolic glycosides from the fruits ofL. ruthenicum Murr that possess both significant MAO-B inhibitory and neuroprotective effects, indicating the promising potential of the fruits for the development of health care products and even therapeutic agents for the treatment of Parkinson's disease and other neurodegenerative diseases.

Research progress of meliaceous limonoids from 2011 to 2021

Covering: July 2010 to December 2021Limonoids, a kind of natural tetranortriterpenoids with diverse skeletons and valuable insecticidal and medicinal bioactivities, are the characteristic metabolites of most plants of the Meliaceae family. The chemistry and bioactivities of meliaceous limonoids are a continuing hot area of natural products research; to date, about 2700 meliaceous limonoids have been identified. In particular, more than 1600, including thirty kinds of novel rearranged skeletons, have been isolated and identified in the past decade due to their wide distribution and abundant content in Meliaceae plants and active biosynthetic pathways. In addition to the discovery of new structures, many positive medicinal bioactivities of meliaceous limonoids have been investigated, and extensive achievements regarding the chemical and biological synthesis have been made. This review summarizes the recent research progress in the discovery of new structures, medicinal and agricultural bioactivities, and chem/biosynthesis of limonoids from the plants of the Meliaceae family during the past decade, with an emphasis on the discovery of limonoids with novel skeletons, the medicinal bioactivities and mechanisms, and chemical synthesis. The structures, origins, and bioactivities of other new limonoids were provided as ESI. Studies published from July 2010 to December 2021 are reviewed, and 482 references are cited.

Limonoids from Swietenia macrophylla and their antitumor activities in A375 human malignant melanoma cells

Swietelinins A - C (1-3) and swieteliacates F - R (4-16), sixteen new limonoids and 18 known limonoids (17-34) were isolated from Swietenia macrophylla. The absolute configurations of these compounds were defined by using a combination of electronic circular dichroism data analysis and single-crystal X-ray diffraction data. Swieteliacate J (10) is the first limonoid possessing an unusual 8β, 9β-epoxy ring system. All of the compounds were tested for cytotoxicity against four human tumor cell lines (SMMC-7721, SW620, A549, and A375). Compounds 10, 11, and 19 exhibited selectively moderate cytotoxicity against four tumor cell lines, especially 19 exhibited significant cytotoxic effects against A375 with IC₅₀ an value of 9.8 μM and was more active than the positive control, dacarbazine with an IC₅₀ value of 22.4 μM. Compound 19 effectively induced apoptosis of A375, which was associated with G2/M-phase cell cycle arrest. Flow cytometric analysis showed that the treatment by 19 significantly induced A375 cell apoptosis in a dose-dependent manner.

Antioxidative role of Traditional Chinese Medicine in Parkinson's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Neuroprotective Traditional Chinese Medicine (TCM) has been practiced in alternative medicine from early days. TCM-derived neuroprotective compounds, such as Chrysin, Cannabidiol, Toonasinoids, and β-asaron, exert significant effectiveness's towards Parkinson's disease (PD). Further, these neuroprotective TCM showed antioxidative, anti-inflammatory, anti-tumor, anti-septic, analgesic properties. Recent research showed that the reduction in the reactive oxygen species (ROS) decreased the α-synuclein (α-syn) toxicity and enhanced the dopaminergic neuron regenerations, the main hallmarks of PD. Therefore, the neuroprotective effects of novel TCM due to its antiradical activities needed deep investigations.

AIMS OF THE STUDY

This review aims to enlighten the neuroprotective TCM and its components with their antioxidative properties to the scientific community for future research.

METHOD

The relevant information on the neuroprotective TCM was gathered from scientific databases (PubMed, Web of Science, Google Scholar, ScienceDirect, SciFinder, Wiley Online Library, ACS Publications, and CNKI). Information was also gained from MS and Ph.D. thesis, books, and online databases. The literature cited in this review dates from 2001 to June 2, 0201.

RESULTS

Novel therapies for PD are accessible, mostly rely on Rivastigmine and Donepezil, offers to slow down the progression of disease at an early stage but embraces lots of disadvantages. Researchers are trying to find a potential drug against PD, which is proficient at preventing or curing the disease progress, but still needed to be further identified. Oxidative insult and mitochondrial dysfunction are thought to be the main culprit of neurodegenerations. Reactive oxygen species (ROS) are the only causative agent in all interactions, leading to PD, from mitochondrial dysfunctions, α-syn aggregative toxicity, and DA neurons degenerations. It is evident from the redox balance, which seems an imperative therapeutic approach against PD and was necessary for the significant neuronal activities.

CONCLUSION

Our study is explaining the newly discovered TCM and their neuroprotective and antioxidative properties. But also bring up the possible treatment approaches against PD for future researchers.

Anthraquinones with potential antiproliferative activities from the fruits of Morinda citrifolia

The phytochemical investigation on the fruits of Morinda citrifolia led to the isolation and characterization of a new anthraquinone, moricitrifone (1), along with seven known anthraquinones (2-8). The chemical structure of 1 was elucidated by extensive spectral analyses. The known compounds (2-8) were identified by comparing their spectral data with those reported in the literature. The antiproliferative activities of all isolated anthraquinones (1-8) against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480 were evaluated in vitro. Compounds 1-8 exhibited remarkable antiproliferative activities with IC₅₀ values ranging from 0.26 ± 0.05 to 16.58 ± 0.18 μM, which were comparable to those of doxorubicin.

An efficient method based on an inhibitor-enzyme complex to screen an active compound against lipase from Toona sinensis

As a popular vegetable, Toona sinensis has a wide range of bioactivities including lipase inhibitory activity. In the present study, an efficient and rapid method using a ligand-enzyme complex was established for screening of an active compound against lipase from Toona sinensis. The ethyl acetate extract of Toona sinensis showed good lipase inhibitory activity. After incubation with lipase, one of the compounds in the extract decreased significantly while comparing the HPLC chromatograms before and after incubation, which indicated that it may be the active compound bound to lipase. Then, the compound was isolated using a Sephadex LH-20 column and identified as 1,2,3,4,6-penta-O-galloyl-β-D-glucose. The in vitro activity test showed that the compound had good inhibitory activity against lipase, and its IC₅₀ value was 118.8 ± 1.53 μg mL^-1. The kinetic experiments indicated that 1,2,3,4,6-penta-O-galloyl-β-D-glucose inhibited lipase through mixed competitive and non-competitive inhibitions. Further docking results showed that the target compound could bind to the active site of lipase stably through seven hydrogen bonds, resulting in a docking energy of -8.31 kcal mol^-1. The proposed method can not only screen the lipase inhibitors from Toona sinensis quickly and effectively, but also provide an effective way for the rapid screening of active substances in natural food and plants.

Prenylated coumarins from the fruits of Artocarpus heterophyllus with their potential anti-inflammatory and anti-HIV activities

A phytochemical investigation on the fruits of Artocarpus heterophyllus led to the isolation and characterisation of a new prenylated coumarin, artoheteronin (1), together with six known analogues (2-7). The chemical structure of 1 was elucidated using extensive spectral methods and the known compounds (2-7) were identified by comparing their spectral data with those reported in the literature. All known compounds (2-7) were isolated from the genus Artocarpus for the first time. The anti-inflammatory and anti-HIV activities of all isolated prenylated coumarins (1-7) were assessed in vitro. As a result, compounds 1-7 displayed notable inhibitory effects against nitric oxide (NO) production induced by lipopolysaccharide in mouse macrophage RAW 264.7 cells in vitro with the IC₅₀ values in range of 0.58 ± 0.06 to 6.29 ± 0.12 μM. Meanwhile, compounds 1-7 exhibited notable anti-HIV-1 reverse transcriptase (RT) activities possessing EC₅₀ values in the range of 0.18 to 9.12 µM.