Two minor chalcone acetylglycosides from the roots extract of Glycyrrhiza uralensis

Neuroprotective Effects of Glycyrrhiza glabra Total Extract and Isolated Compounds

Glycyrrhiza glabra L. is a plant commonly utilized in herbal medicine and stands out as one of the more extensively researched medicinal plants globally. It has been documented with respect to several pharmacological activities, notably, neuroprotective effects, among others. However, the neuroprotective activity of pure phenolic compounds has not been reported yet. The chromatographic of a methanolic extract yielded twenty-two compounds, viz.: naringenin 4'-O-glucoside (1), 3',4',7-trihydroxyflavanone (butin) (2), liquiritin (3), liquiritin apioside (4), abyssinone (5), glabrol (6), isoliquiritin (7), neoisoliquiritin (8), isoliquiritin apioside (9), licuraside (10). 3'[O], 4'-(2,2-dimethylpyrano)-3,7-dihydroxyflavanone (11), glabrocoumarin (12), glabrene (13), isomedicarpin (14), 7-hydroxy-4'-methoxyflavone (formononetin) (15), ononin (16), glycyroside (17), (3S)-7,4'-dihydroxy-2'-methoxyisoflavan (18), glabridin (19), neoliquiritin (20), 3,11-dioxooleana-1,12-dien-29-oic acid (21), and 3-oxo-18β-glycyrrhetinic acid (22). The results of the neuroprotection evaluation showed that G. glabra total extract (TE) and compounds 1, 7, 11, 16, and 20 protected SH-SY5Y cells by inhibiting the depletion of ATP and elevated caspase 3/7 activities induced by MPP+. Indeed, this study reports for the first time the structure and activity of compound 11 and the neuroprotective activity of some phenolic constituents from G. glabra.

Glycoside Compounds From Glycyrrhiza uralensis and Their Neuroprotective Activities

This paper concerns the study of the roots and rhizomes of Glycyrrhiza uralensis where one new alkaloid glycoside, 3,4-dihydroxyquinoline 4- O-β-d-glucopyranoside, along with 13 known compounds (12 phenolic glycosides and one triterpene glycoside) were isolated and identified. The structure of the new compound and the known ones were identified on the basis of nuclear magnetic resonance (NMR) and mass spectrometric (MS) analysis. All the glycosides were tested for their anti-neuroinflammatory activities by inhibiting nitric oxide (NO) release in lipopolysaccharide (LPS)-induced murine microglial BV-2 cells. Several compounds were tested for their antioxidant activities in rat adrenal pheochromocytoma PC12 cells. A structure–activity relationship (SAR) analysis was carried out and revealed that the position and amount of sugar moieties have significant impact on antioxidant activities.

Advances in Pharmacological Activities and Mechanisms of Glycyrrhizic Acid

Licorice (Glycyrrhiza glabra L.) is widely regarded as an important medicinal plant and has been used for centuries in traditional medicine because of its therapeutic properties. Studies have shown that metabolites isolated from licorice have many pharmacological activities, such as antiinflammatory, anti-viral, participation in immune regulation, anti-tumor and other activities. This article gives an overview of the pharmacological activities and mechanisms of licorice metabolites and the adverse reactions that need attention. This review helps to further investigate the possibility of licorice as a potential drug for various diseases. It is hoped that this review can provide a relevant theoretical basis for relevant scholars' research and their own learning.

Chemical Constituents from the Aerial Parts of Elsholtzia ciliata and Their Protective Activities on Glutamate-Induced HT22 Cell Death

A new phenolic glucoside, (7E,9E)-3-hydroxyavenalumic acid-3-O-[6'-O-(E)-caffeoyl]-β-d-glucopyranoside (1), and three new acetylated flavone glycosides, acacetin-7-O-[β-d-glucopyranosyl(1″″→2″)-4‴-O-acetyl-α-l-rhamnopyranosyl(1‴→6″)]-β-d-glucopyranoside (3), acacetin-7-O-[6″″-O-acetyl-β-d-glucopyranosyl(1″″→2″)-3‴-O-acetyl-α-l-rhamnopyranosyl(1‴→6″)]-β-d-glucopyranoside (5), and acacetin-7-O-[3″″,6″″-di-O-acetyl-β-d-glucopyranosyl(1″″→2″)-4‴-O-acetyl-α-l-rhamnopyranosyl(1‴→6″)]-β-d-glucopyranoside (7), as well as 34 known compounds (2, 4, 6, and 8-38) were isolated from the aerial parts of Elsholtzia ciliata. The chemical structures of the new compounds were determined by spectroscopic/spectrometric data interpretation using NMR and HRESIMS. The neuroprotective effect of the isolated compounds was evaluated by a cell viability assay on HT22 murine hippocampal neuronal cells. Among them, 23 compounds, including new substances 1 and 3, exhibited neuroprotective effects against glutamate-induced HT22 cell death. In particular, compounds 2, 16, 17, 20, 22, 28, 29, and 31 presented potent neuroprotective effects with EC₅₀ values of 1.5-8.3 μM.

Chalcone hybrids as potential anticancer agents: Current development, mechanism of action, and structure-activity relationship

The continuous emergency of drug-resistant cancers and the low specificity of anticancer agents have been the major challenges in the control and treatment of cancer, making an urgent need to develop novel anticancer agents with high efficacy. Chalcones, precursors of flavonoids and isoflavonoids, exhibit structural heterogeneity and can act on various drug targets. Chalcones which demonstrated potential in vitro and in vivo activity against both drug-susceptible and drug-resistant cancers, are useful templates for the development of novel anticancer agents. Hybridization of chalcone moiety with other anticancer pharmacophores could provide the hybrids which have the potential to overcome drug resistance and improve the specificity, so it represents a promising strategy to develop novel anticancer agents. This review emphasizes the development, the mechanisms of action as well as structure-activity relationships of chalcone hybrids with potential therapeutic application for many cancers in recent 10 years.

Seven new flavonoid glycosides from the roots of Glycyrrhiza uralensis and their biological activities

As part of our ongoing investigation of the bioactive constituents from the roots of Glycyrrhiza uralensis Fisch., seven new flavonoid glycosides (1-7) were obtained along with 19 known compounds (8-26). All of the isolates possessed one or more sugar moieties. Their structures, as well as the absolute configurations, were elucidated on the basis of spectroscopic data (UV, IR, HRESIMS, 1D and 2D NMR, and CD). In the in vitro assay, compounds 3 and 7 showed moderate antioxidant activities at a concentration of 0.1 μM; compound 2 showed hepatoprotective activity at a concentration of 10 μM.

Licoflavonol Reduces Aβ Secretion by Increasing BACE1 Phosphorylation to Facilitate BACE1 Degradation

SCOPE

In the previous study, Glycyrrhiza uralensis Fisch extract (GUE) inhibited Aβ secretion by inhibiting β-site APP-cleaving enzyme 1 (BACE1) transcription, and the active compounds semilicoisoflavone B (SB) and licoflavonol (LF) inhibited Aβ secretion. SB corresponds to the same mechanism as GUE, but LF has a different mechanism. In this study, the mechanism underlying inhibition of Aβ by LF is investigated.

METHODS AND RESULTS

The effects of LF on Aβ, sAPPα, and sAPPβ secretion are evaluated by ELISA, and the effect of LF on BACE1 expression is detected by western blotting. It is found that the effect of LF on Aβ secretion is due to promotion of BACE1 protein degradation, and that the effect of LF on Aβ and BACE1 expression is attenuated after cotreatment with the lysosome inhibitor chloroquine. In a subsequent mechanistic study, it is found that LF increases BACE1 phosphorylation to increase its interactions with ADP ribosylation factor-binding proteins 1 and 3 (GGA1 and GGA3, respectively) and eventually facilitate BACE1 delivery to lysosomes for degradation.

CONCLUSION

This study is the first to demonstrate that the BACE1 phosphorylation inducer LF can modulate BACE1 trafficking and lead to facilitating degradation of BACE1, eventually decreasing Aβ secretion.

Glycyrrhiza uralensis and Semilicoisoflavone B Reduce Aβ Secretion by Increasing PPARγ Expression and Inhibiting STAT3 Phosphorylation to Inhibit BACE1 Expression

SCOPE

Glycyrrhiza uralensis extract (GUE) has been reported to improve amyloid beta (Aβ)-induced cognitive deficits in mice. However, the mechanisms underlying this effect and the components involved have not been previously explored. Extracellular Aβ plaques are one of the major pathological hallmarks of Alzheimer's disease (AD). Therefore, decreasing Aβ levels is one strategy for preventing the etiology of AD. This study aims to test the effect of GUE and semilicoisoflavone B (SB) on Aβ secretion and investigates the mechanism underlying this effect.

METHODS AND RESULTS

GUE and its bio-activated compound SB reduce Aβ secretion. We find that this effect contribute to the downregulation of the β-secretase-1 (BACE1) protein and mRNA. In a subsequent mechanism study, we find that GUE and SB regulate BACE1 transcription factors by inducing the expression of peroxisome proliferator activated receptor γ (PPARγ) and inhibiting the phosphorylation of signal transducer and activator of transcription 3. In addition, the effect of GUE and SB on BACE1 expression and Aβ secretion are attenuated by treatment with PPARγ-siRNA or its antagonist, GW9662.

CONCLUSION

These findings indicate that GUE and SB may function as PPARγ agonists, thereby inhibiting BACE1 expression and ultimately reducing the secretion of Aβ.

Natural Products Screening for the Identification of Selective Monoamine Oxidase-B Inhibitors

Aims

Monoamine oxidase-B inhibitors (MAO-BIs) are used for the initial therapy of Parkinson’s disease. Also, MAO-BIs have shown to be effective neuroprotective agents in several neurodegenerative diseases. However, some concerns exist regarding the long-term use of these compounds. Meanwhile, natural compounds showed potential MAO-B selective inhibitions. To date, few selective natural MAO-BIs have been identified. Therefore, the current study is designed to identify plants with potent and specific MAO-B inhibition.

Study Design

In this work, we utilized high throughput screening to evaluate the different plants ethanolic extract for their effectiveness to inhibit recombinant human (h)MAO-A and hMAO-B and to determine the relative selectivity of the top MAO-BI.

Methodology

Recombinant human isozymes were verified by Western blotting, and the 155 plants were screened. A continuous fluorometric screening assay was performed followed by two separate hMAO-A and hMAO-B microtiter screenings and IC₅₀ determinations for the top extracts.

Results

In the screened plants, 9% of the extracts showed more than 1.5-fold relative inhibition of hMAO-B (RI_B) and another 9% showed more than 1.5-fold relative inhibition of hMAO-A. The top extracts with the most potent RI_Bs were Psoralea corylifolia seeds, Phellodendron amurense bark, Glycyrrhiza uralensis roots, and Ferula assafoetida roots, with the highest RI_B of 5.9-fold. Furthermore, extensive maceration of the promising extracts led to increase inhibitory effects with a preserved RI_B as confirmed with luminescence assay. The top four extracts hMAO-BIs were equally potent (IC₅₀= 1.3 to 3.8 μg/mL) with highly significant relative selectivities to inhibit hMAO-B (4.1- to 13.4-fold).

Conclusion

The obtained results indicate that Psoralea corylifolia seeds, Ferula assafoetida, Glycyrrhiza uralensis roots, and Phellodendron amurense ethanolic extracts have selective inhibitions for human MAO-B. Investigating these plant extracts as natural resources for novel selective MAO-BIs may lead to the development of molecules that can be used in the therapeutic management of neurodegenerative diseases including Parkinson’s disease.

Phenolic compounds from Glycyrrhiza pallidiflora Maxim. and their cytotoxic activity

Twenty-one phenolic compounds (1-21) including dihydrocinnamic acid, isoflavonoids, flavonoids, coumestans, pterocarpans, chalcones, isoflavan and isoflaven, were isolated from the roots of Glycyrrhiza pallidiflora Maxim. Phloretinic acid (1), chrysin (6), 9-methoxycoumestan (8), isoglycyrol (9), 6″-O-acetylanonin (19) and 6″-O-acetylwistin (21) were isolated from G. pallidiflora for the first time. Isoflavonoid acetylglycosides 19, 21 might be artefacts that could be produced during the EtOAc fractionation process of whole extract. Compounds 2-4, 10, 11, 19 and 21 were evaluated for their cytotoxic activity with respect to model cancer cell lines (CEM-13, MT-4, U-937) using the conventional MTT assays. Isoflavonoid calycosin (4) showed the best potency against human T-cell leukaemia cells MT-4 (CTD₅₀, 2.9 μM). Pterocarpans medicarpin (10) and homopterocarpin (11) exhibit anticancer activity in micromolar range with selectivity on the human monocyte cells U-937. The isoflavan (3R)-vestitol (16) was highly selective on the lymphoblastoid leukaemia cells CEM-13 and was more active than the drug doxorubicin.