The Protective Effect of Mangiferin on Formaldehyde-Induced HT22 Cell Damage and Cognitive Impairment.

Formaldehyde (FA) has been found to induce major Alzheimer's disease (AD)-like features including cognitive impairment, Aß deposition, and Tau hyperphosphorylation, suggesting that it may play a significant role in the initiation and progression of AD. Therefore, elucidating the mechanism underlying FA-induced neurotoxicity is crucial for exploring more comprehensive approaches to delay or prevent the development of AD. Mangiferin (MGF) is a natural C-glucosyl-xanthone with promising neuroprotective effects, and is considered to have potential in the treatment of AD. The present study was designed to characterize the effects and mechanisms by which MGF protects against FA-induced neurotoxicity. The results in murine hippocampal cells (HT22) revealed that co-treatment with MGF significantly decreased FA-induced cytotoxicity and inhibited Tau hyperphosphorylation in a dose-dependent manner. It was further found that these protective effects were achieved by attenuating FA-induced endoplasmic reticulum stress (ERS), as indicated by the inhibition of the ERS markers, GRP78 and CHOP, and downstream Tau-associated kinases (GSK-3ß and CaMKII) expression. In addition, MGF markedly inhibited FA-induced oxidative damage, including Ca2+ overload, ROS generation, and mitochondrial dysfunction, all of which are associated with ERS. Further studies showed that the intragastric administration of 40 mg/kg/day MGF for 6 weeks significantly improved spatial learning ability and long-term memory in C57/BL6 mice with FA-induced cognitive impairment by reducing Tau hyperphosphorylation and the expression of GRP78, GSK-3ß, and CaMKII in the brains. Taken together, these findings provide the first evidence that MGF exerts a significant neuroprotective effect against FA-induced damage and ameliorates mice cognitive impairment, the possible underlying mechanisms of which are expected to provide a novel basis for the treatment of AD and diseases caused by FA pollution.

The potential diagnostic accuracy of urine formaldehyde levels in Alzheimer's disease: A systematic review and meta-analysis.

Background: Formaldehyde (FA), a toxic aldehyde, has been shown to be associated with a variety of cognitive disorders, including Alzheimer's disease (AD). There is increasing evidence that FA levels are significantly increased in AD patients and may be involved in the pathological process of AD. The aim of this study was to assess the potential diagnostic value of urine FA levels in AD using meta-analysis techniques. Methods: Original reports of morning urine FA levels in AD patients and healthy controls (HCs) were included in the meta-analysis. Standardized mean differences (SMD) were calculated using a random-effects model, heterogeneity was explored using methodological, age, sex difference and sensitivity analyses, and receiver operating characteristic (ROC) curves were constructed to assess the diagnostic value of urine FA levels in AD. Results: A total of 12 studies were included, and the urine FA levels of 874 AD patients and 577 HCs were reviewed. Compared with those in HCs, the FA levels were significantly increased in AD patients. The heterogeneity of the results did not affect their robustness, and results of the area under the curve (AUC) suggested that urine FA levels had good potential diagnostic value. Conclusion: Urine FA levels are involved in AD disease progression and are likely to be useful as a potential biomarker for clinical auxiliary diagnosis. However, further studies are needed to validate the results of this study.

Two new 8-isopentenyl isoflavane derivatives from Astragalus dolichochaete diels.

Astragali Radix (Huangqi) is one of the well-known traditional Chinese medicines and has been used in China for more than two thousand years. As a close species, Astragalus dolichochaete Diels was found to possess cytotoxicity during our preliminary study of Astragalus plants from Yunnan Province, China. To better understand the chemical foundation of the cytotoxicity, the major constituents of A. dolichochaete were studied. As a result, two new 8-isopentenyl isoflavane derivatives, dolichochaeteins A and B (1 and 2), together with ten known constituents were isolated, and their structures were elucidated by means of spectroscopy, mainly 1D and 2D NMR techniques. The cytotoxic activities were evaluated for the raw extract, ethyl acetate fraction, compound 2 and glyasperin H (3) against human gastric carcinoma cell line SGC-7901, human hepatoma cell line SMMC-7721 and human leukemic cell line K562. All the samples exhibited significant cytotoxicity.

Astrernestin, a novel aurone-phenylpropanoid adduct from the roots of Astragalus ernestii.

Astragalus ernestii has been used as a substitute for Radix Astragali (Huang-Qi) in southwest China. To better understand the chemical rationale for the medicinal usage, the phytochemistry of A. ernestii was recently studied. As a result, a novel aurone-phenylpropanoid adduct astrernestin (1), together with five known phenoloids calycosin-7-O-ß-D-glucopyranoside (2), 4,4'-dimethoxy-3'-hydroxy-7,9':7',9-diepoxylignan-3-O-ß-D-glucopyranoside (3), syringaresinol-4-O-ß-D-monoglucoside (4), hedyotol D 4″-O-ß-D-glucopyranoside (5) and trifolirhizin (6), were isolated from the roots of A. ernestii. The structure of compound 1 was elucidated by extensive spectroscopic analysis and optical rotation calculation.

Hispidanins A-D: four new asymmetric dimeric diterpenoids from the rhizomes of Isodon hispida.

Hispidanins A-D (1-4), four unprecedented asymmetric dimeric diterpenoids, were obtained from the rhizomes of Isodon hispida. Their structures were elucidated by extensive spectroscopic analysis (1D and 2D NMR, MS, UV, IR), as well as single-crystal X-ray diffraction analysis. Hispidanin B showed significant cytotoxicities against tumor cell lines SGC7901, SMMC7721, and K562, with IC50 values of 10.7, 9.8, and 13.7 µM, respectively.

[Pharmacognostical study on seven species from Astragalus genus in Yunnan].

OBJECTIVE: For the identification and utilization of the Astragalus plants from Yunnan, pharmacognostical studies were systematically performed for seven Astragalus plants which were selected from four subgenera of Astragalus genus. METHODS: Standard pharmacognosy methods and HPLC method were adopted, and microscopic characteristics and major chemical constituents of the test plant samples were compared. RESULTS: There were differences in root transverse section, powder and chemical constituents of the seven Astragalus plants. CONCLUSION: This study can provide the pharmacognosy experimental basis for the future study of Astragalus plants.