Honokiol dimers and magnolol derivatives with new carbon skeletons from the roots of Magnolia officinalis and their inhibitory effects on superoxide anion generation and elastase release

Neuropharmacological potential of honokiol and its derivatives from Chinese herb Magnolia species: understandings from therapeutic viewpoint

Honokiol is a neolignan biphenol found in aerial parts of the Magnolia plant species. The Magnolia plant species traditionally belong to China and have been used for centuries to treat many pathological conditions. Honokiol mitigates the severity of several pathological conditions and has the potential to work as an anti-inflammatory, anti-angiogenic, anticancer, antioxidant, and neurotherapeutic agent. It has a long history of being employed in the healthcare practices of Southeast Asia, but in recent years, a greater scope of research has been conducted on it. Plenty of experimental evidence suggests it could be beneficial as a neuroprotective bioactive molecule. Honokiol has several pharmacological effects, leading to its exploration as a potential therapy for neurological diseases (NDs), including Alzheimer's disease (AD), Parkinson's disease (PD), cerebral ischemia, anxiety, depression, spinal cord injury, and so on. So, based on the previous experimentation reports, our goal is to discuss the neuroprotective properties of honokiol. Besides, honokiol derivatives have been highlighted recently as possible therapeutic options for NDs. So, this review focuses on honokiol's neurotherapeutic actions and toxicological profile to determine their safety and potential use in neurotherapeutics.

Regioselective Pd-Catalyzed Suzuki–Miyaura Borylation Reaction for the Dimerization Product of 6-Bromoimidazo[1,2-a]pyridine-2-carboxylate: Mechanistic Pathway, Cytotoxic and Tubercular Studies

In the pharmaceutical industry, boronic acid and esters play an important role in API-based synthesis. The most efficient way of preparing various active agents is palladium-catalyzed Suzuki–Miyaura borylation reactions. Herein, we report the formation of dimerization product [6,6′-biimidazo[1,2-a]pyridine]-2,2′-dicarboxamide derivatives 7a–j from 6-bromoimidazo[1,2-a]pyridine-2-carboxylate by employing the same conditions. A regioselective borylation of ethyl 6-bromoimidazo[1,2-a]pyridine-2-carboxylate (3) was examined for the formation of ethyl 6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)imidazo[1,2-a]pyridine-2-carboxylate (4a) but it was found to be directed towards the dimerization product 5. The nitrogen-rich system was incorporated into potential anti-cancer and anti-TB agents through acid amine coupling reactions between acid 6 and various amines (dialkyl/cyclic sec./tert.) to form the final adducts 7. Five derived scaffolds were identified as moderately active in TB activity against the H37Rv strain, while two compounds were found to be particularly potent in NCI-60 anti-cancer screening in nine cancer panels.

Application of Multiple-Source Data Fusion for the Discrimination of Two Botanical Origins of Magnolia Officinalis Cortex Based on E-Nose Measurements, E-Tongue Measurements, and Chemical Analysis

Magnolia officinalis Rehd. et Wils. and Magnolia officinalis Rehd. et Wils. var. biloba Rehd. et Wils, as the legal botanical origins of Magnoliae Officinalis Cortex, are almost impossible to distinguish according to their appearance traits with respect to medicinal bark. The application of AFLP molecular markers for differentiating the two origins has not yet been successful. In this study, a combination of e-nose measurements, e-tongue measurements, and chemical analyses coupled with multiple-source data fusion was used to differentiate the two origins. Linear discriminant analysis (LDA) and quadratic discriminant analysis (QDA) were applied to compare the discrimination results. It was shown that the e-nose system presented a good discriminant ability with a low classification error for both LDA and QDA compared with e-tongue measurements and chemical analyses. In addition, the discriminating capacity of LDA for low-level fusion with original data, similar to a combined system, was superior or equal to that acquired individually with the three approaches. For mid-level fusion, the combination of different principals extracted by PCA and variables obtained on the basis of PLS-VIP exhibited an analogous discrimination ability for LDA (classification error 0.0%) and was significantly superior to QDA (classification error 1.67-3.33%). As a result, the combined e-nose, e-tongue, and chemical analysis approach proved to be a powerful tool for differentiating the two origins of Magnoliae Officinalis Cortex.

Biphenyl-type neolignans from stem bark of Magnolia officinalis with potential anti-tumor activity

Six new biphenyl-type neolignans (1-6), and eighteen known compounds (7-24) were isolated from the EtOH extract of Magnolia officinalis. Their structures were determined by 1D and 2D NMR, and by HRMS. The anti-tumor activities of the isolated compounds were evaluated on HepG2, HCT-116, H1975 and HUVEC cell lines. Among the isolated compounds, nine compounds (3, 5, 7, 8, 12, 14, 20, 22, and 24) showed moderate cytotoxicities, and compound 23 showed the best cytotoxicity with IC₅₀ value lower than 10 μM.

Thin-layer chromatographic quantification of magnolol and honokiol in dietary supplements and selected biological properties of these preparations

Two isomeric biphenyl neolignans, magnolol and honokiol, are considered as constituents responsible for the healing effect of magnolia bark, a traditional Oriental medicine. To survey the increasing number of dietary supplements that contain magnolia bark or its extract, an affordable quantitative thin-layer chromatography (TLC) - densitometry method was developed. The methanol extracts were analyzed on the silica gel plates after manual sample application using n-hexane - ethyl acetate - ethanol (16:3:1, v/v/v) as a mobile phase. For quantitation, the chromatograms were scanned in the absorbance mode at the wavelength λ = 290 nm. The limits of detection and quantitation were 90 and 280 ng/zone for magnolol and 70 and 200 ng/zone for honokiol, respectively. None of the two targeted neolignans were detected in two of the six analyzed supplements. In the other four samples, the measured amounts were between 0.95-114.69 mg g^-1 for magnolol and 4.88-84.86 mg g^-1 for honokiol. Moreover, separations of these two neolignans on the TLC and high-performance TLC (HPTLC) layers were compared and HPTLC was combined with antioxidant (DPPH) and antibacterial (Bacillus subtilis and Aliivibrio fischeri) assays and mass spectrometry (MS), using the elution-based interface. Both magnolol and honokiol exhibited effects in all bioactivity assays. The HPTLC-MS tests confirmed purity of neolignan zones in the extracts of dietary supplements and supported tentative identification of the alkaloid piperine and the isoflavone daidzein as additional bioactive components of the investigated dietary supplements. Using the same mobile phase in the orthogonal directions 2D-HPTLC-MS experiments proved degradation, i.e., instability of magnolol and honokiol on the silica gel adsorbent.

A review of the phytochemistry and pharmacological activities of Magnoliae officinalis cortex

ETHNOPHARMACOLOGICAL RELEVANCE

Magnoliae Officinalis Cortex (the dried bark of Magnolia officinalis), a widely used traditional Chinese medicine, is also known as 'Houpo' (Chinese: ). Magnoliae Officinalis Cortex has a wide range of pharmacological effects and has been used to treat conditions such as abdominal distention, vomiting, diarrhea, food accumulation, Qi stagnation, constipation, phlegm and fluid retention and cough resulting from asthma.

AIMS OF THE REVIEW

The present paper reviews advances in research relating to the botany, ethnopharmacology, phytochemistry, pharmacology and toxicology of Magnoliae Officinalis Cortex. Prospects for future investigation and application of this herb are also discussed.

MATERIALS AND METHODS

Information on Magnoliae Officinalis Cortex was obtained from published materials, including ancient and modern books; PhD and MSc dissertations; monographs on medicinal plants; the pharmacopoeia of different countries and electronic databases, such as SCI finder, PubMed, Web of Science, ACS, Science Direct, Wiley, Springer, Taylor, AGRIS, Europe PMC, EBSCO host, CNKI, WanFang DATA, J-STAGE and Google Scholar.

RESULTS

More than 200 chemical compounds have been isolated from Magnoliae Officinalis Cortex, including lignans, phenylethanoid glycosides, phenolic glycosides, alkaloids, steroids and essential oils. The plant has been reported to have pharmacological effects on the digestive system, nervous system and cardiovascular and cerebrovascular systems, as well as antibacterial, anti-tumour, analgesic, anti-inflammatory and anti-oxidative effects.

CONCLUSIONS

Magnoliae Officinalis Cortex is an essential traditional Chinese medicine with pharmacological activities that mainly affect the digestive system, nervous system and cardiovascular and cerebrovascular systems. This review summarises its botany, ethnopharmacology, phytochemistry, pharmacology and toxicology. These information suggest that we should focus on the development of new drugs related to Magnoliae Officinalis Cortex, including specific constituents, so that Magnoliae Officinalis Cortex can exert greater therapeutic potential. Meanwhile, it is important to pay attention to the rational use of Magnolia resources, avoiding over-harvesting which could lead to lack of resources. We should also pursue research on Magnolia substitutes and develop resources such as Magnoliae Officinalis Flos and Magnolia Leaf.

Identification, characterization and HPLC quantification of formulation-related impurities of honokiol, an antitumor natural drug candidate in clinical trials

Natural products and their derivatives have historically been invaluable as a source of therapeutic agents. Honokiol, as a well-known natural product in Chinese herbal medicine Houpu, is finally being studied in a Phase I clinical trial (CTR20170822) in patients with Advanced Non-Small Cell Lung Cancer (NSCLS) in China this year. During the honokiol liposome formulation process, five major impurities were present in the range of 0.05-0.1% based on the HPLC analysis. These five major impurities were obtained from the forced degradation product of honokiol through countercurrent chromatography and prep-HPLC. The structure were elucidated with ¹H NMR, ¹³C NMR, 2D NMR and MS spectral data. The proposed HPLC method was validated for specificity, linearity (concentration range 0.01-1.62, 0.003-0.96, 0.05-7.98, 0.04-6.52, 0.03-5.18 μg/ml for impurities I-V respectively, R2 > 0.9988), accuracy (99.11-100.67%), precision (CV < 1.6%), and sensitivity (LOD 3.3, 0.1, 16.7, 13.3, 10.0 ng/ml for impurities I-V respectively). The validated method was employed in the further study of the honokiol drug substance.

Dineolignans of 3-O-4' diphenyl ether-type from fruits of Magnolia obovata

Seven dineolignans of the 3-O-4' diphenyl ether-type (obovatalignans C-I, respectively), were isolated from fruits of Magnolia obovata through repeated silica gel (SiO₂), octadecyl SiO₂, and Sep-Pak chromatographies. Their chemical structures were determined based on various spectroscopic methods including NMR, HR-MS, IR, specific rotation, and CD spectrometry. Especially, compounds 1-5 include the relatively rare 1,4-benzodioxane ring moiety in the molecular structure.

Chemical Constituents from Flueggea virosa and the Structural Revision of Dehydrochebulic Acid Trimethyl Ester

In an attempt to study the chemical constituents from the twigs and leaves of Flueggea virosa, a new terpenoid, 9(10→20)-abeo-ent-podocarpane, 3β,10α-dihydroxy-12-methoxy-13- methyl-9(10→20)-abeo-ent-podocarpa-6,8,11,13-tetraene (1), as well as five known compounds were characterized. Their structures were elucidated on the basis of spectroscopic analysis. In addition, the structure of dehydrochebulic acid trimethyl ester was revised as (2S,3R)-4E-dehydrochebulic acid trimethyl ester based on a single-crystal X-ray diffraction study. The in vitro anti-hepatitis C virus (anti-HCV) activity and cytotoxicity against Huh7.5 cells for the isolated compounds were evaluated.

Terpenoids from Flueggea virosa and their anti-hepatitis C virus activity

Phytochemical study of the methanolic root extract of Flueggea virosa allowed for the characterization of 18 non-alkaloid terpenoids. Their structures have skeletons composed of six rearranged ent-podocarpanes, 11 ent-podocarpanes, and a 3,4-seco-30-nor-friedelane. These were characterized based on 2D NMR, IR, UV, and MS spectroscopic analysis and their absolute configurations were determined by single-crystal X-ray studies, as well as by (1)H NMR spectroscopic analysis for the corresponding chiral derivatives. The isolates were evaluated for therapeutic potential against hepatitis C virus (HCV) infection to human hepatoma Huh7.5 cells.

Ursolic acid inhibits superoxide production in activated neutrophils and attenuates trauma-hemorrhage shock-induced organ injury in rats

Neutrophil activation is associated with the development of organ injury after trauma-hemorrhagic shock. In the present study, ursolic acid inhibited the superoxide anion generation and elastase release in human neutrophils. Administration of ursolic acid attenuated trauma-hemorrhagic shock-induced hepatic and lung injuries in rats. In addition, administration of ursolic acid attenuated the hepatic malondialdehyde levels and reduced the plasma aspartate aminotransferase and alanine aminotransferase levels after trauma-hemorrhagic shock. In conclusion, ursolic acid, a bioactive natural compound, inhibits superoxide anion generation and elastase release in human neutrophils and ameliorates trauma-hemorrhagic shock-induced organ injury in rats.

Magnolia extract (BL153) ameliorates kidney damage in a high fat diet-induced obesity mouse model

Accumulating evidence demonstrated that obesity is a risk factor for renal structural and functional changes, leading to the end-stage renal disease which imposes a heavy economic burden on the community. However, no effective therapeutic method for obesity-associated kidney disease is available. In the present study, we explored the therapeutic potential of a magnolia extract (BL153) for treating obesity-associated kidney damage in a high fat diet- (HFD-) induced mouse model. The results showed that inflammation markers (tumor necrosis factor-α and plasminogen activator inhibitor-1) and oxidative stress markers (3-nitrotyrosine and 4-hydroxy-2-nonenal) were all significantly increased in the kidney of HFD-fed mice compared to mice fed with a low fat diet (LFD). Additionally, proteinuria and renal structure changes in HFD-fed mice were much more severe than that in LFD-fed mice. However, all these alterations were attenuated by BL153 treatment, accompanied by upregulation of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) and hexokinase II (HK II) expression in the kidney. The present study indicates that BL153 administration may be a novel approach for renoprotection in obese individuals by antiinflammation and anti-oxidative stress most likely via upregulation of PGC-1α and HK II signal in the kidney.