Five novel and highly efficient endophytic fungi isolated from Huperzia serrata expressing huperzine A for the treatment of Alzheimer's disease

A review on nonviral, nonbacterial infectious agents toxicity involved in neurodegenerative diseases

Neuronal death, decreased activity or dysfunction of neurotransmitters are some of the pathophysiological reasons for neurodegenerative diseases like Alzheimer's, Parkinson's and multiple sclerosis. Also, there is evidence for the role of infections and infectious agents in neurodegenerative diseases and the effect of some metabolites in microorganisms in the pathophysiology of these diseases. In this study, we intend to evaluate the existing studies on the role of infectious agents and their metabolites on the pathophysiology of neurodegenerative diseases. PubMed, Scopus, Google Scholar and Web of Science search engines were searched. Some infectious agents have been observed in neurodegenerative diseases. Also, isolations of some fungi and microalgae have an improving effect on Parkinson's and Alzheimer's.

Isolation and Characterization of Novel Huperzine-Producing Endophytic Fungi from Lycopodiaceae Species

Huperzine A (HupA) is an important drug for treating Alzheimer's disease (AD) and is primarily extracted from the Huperzia serrata (Lycopodiaceae). Failures in the chemical synthesis of Hup and in vitro culture have put H. serrata in danger of extinction, and there is a need for an extensive investigation of Hup from alternative perspectives. The aim of this study is to identify endophytic fungi that produce high Hup or simultaneously produce many types of Hup and have high genetic stability derived from other Lycopodiaceae species as a source of materials for natural Hup production. In this work, Hup-producing endophytic fungi were isolated from three species: Lycopodium clavatum, Phlegmariurus squarrosus, and P. phlegmaria. Of these, L. clavatum and P. squarrosus were confirmed as novel sources of Hup-producing fungi. Based on morphological characteristics and nuclear ribosomal DNA ITS sequences, four endophytic fungi Colletotrichum siamense THG1-17, Epicoccum sorghinum THG01-18, Phoma sp. TKH3-2, and Phyllosticta sp. THG2-27 were firstly isolated from these Lycopodiaceae plants, which were capable of simultaneously producing both HupA and HupB, as evidenced by high-performance liquid chromatography analysis. The four strains showed stability in Hup yield over 50 generations of culture with an in vitro storage period of 3 months. These isolated fungi will provide a new source of materials for further research to develop drugs containing HupA as well as HupB for AD treatment in the future.

Endophytic fungi: a potential source for drugs against central nervous system disorders

Neuroprotection is one of the important protection methods against neuronal cells and tissue damage caused by neurodegenerative diseases such as Alzheimer's, Parkinson's, Huntington's, and multiple sclerosis. Various bioactive compounds produced by medicinal plants can potentially treat central nervous system (CNS) disorders. Apart from these resources, endophytes also produce diverse secondary metabolites capable of protecting the CNS. The bioactive compounds produced by endophytes play essential roles in enhancing the growth factors, antioxidant defence functions, diminishing neuroinflammatory, and apoptotic pathways. The efficacy of compounds produced by endophytic fungi was also evaluated by enzymes, cell lines, and in vivo models. Acetylcholine esterase (AChE) inhibition is frequently used to assess in vitro neuroprotective activity along with cytotoxicity-induced neuronal cell lines. Some of drugs, such as tacrine, donepezil, rivastigmine, galantamine, and other compounds, are generally used as reference standards. Furthermore, clinical trials are required to confirm the role of these natural compounds in neuroprotection efficacy and evaluate their safety profile. This review illustrates the production of various bioactive compounds produced by endophytic fungi and their role in preventing neurodegeneration.

Molecular docking and dynamics simulation approach of Camellia sinensis leaf extract derived compounds as potential cholinesterase inhibitors

The tea plant (Camellia sinensis) belongs to the family Theaceae and contains many phytochemicals that are effective against various diseases, including neurodegenerative disorders. In this study, we aimed to characterize the phytochemicals present in the methanolic and n-hexane leaf extracts of C. sinensis using GC-MS, FTIR, and UV-visible analysis. We detected a total of 19 compounds of different chemical classes. We also performed molecular docking studies using the GC-MS detected phytochemicals, targeting acetylcholinesterase (AChE, PBD ID: 4BDT) and butyrylcholinesterase (BChE, PDB ID: 6QAB), which are responsible for the breakdown of the neurotransmitter acetylcholine (ACh). This breakdown leads to dementia and cognitive decline in Alzheimer's patients. The compounds Ergosta-7,22-dien-3-ol, (3.beta.,5.alpha.,22E)- and Benzene, 1,3-bis(1,1-dimethylethyl) showed better binding affinity against AChE, while dl-.alpha.-Tocopherol and Ergosta-7,22-dien-3-ol, (3.beta.,5.alpha.,22E)- showed better binding affinity against BChE. We determined the stability and rigidity of these best docked complexes through molecular dynamics simulation for a period of 100 ns. All complexes showed stability in terms of SASA, Rg, and hydrogen bonds, but some variations were found in the RMSD values. Our ADMET analysis revealed that all lead compounds are non-toxic. Therefore, these compounds could be potential inhibitors of AChE and BChE.

Graphical abstract

Cholinesterase Inhibitors from an Endophytic Fungus Aspergillus niveus Fv-er401: Metabolomics, Isolation and Molecular Docking

Alzheimer’s disease poses a global health concern with unmet demand requiring creative approaches to discover new medications. In this study, we investigated the chemical composition and the anticholinesterase activity of Aspergillus niveus Fv-er401 isolated from Foeniculum vulgare (Apiaceae) roots. Fifty-eight metabolites were identified using UHPLC-MS/MS analysis of the crude extract. The fungal extract showed acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory effects with IC50 53.44 ± 1.57 and 48.46 ± 0.41 µg/mL, respectively. Two known metabolites were isolated, terrequinone A and citrinin, showing moderate AChE and BuChE inhibitory activity using the Ellman’s method (IC50 = 11.10 ± 0.38 µg/mL and 5.06 ± 0.15 µg/mL, respectively for AChE, and IC50 15.63 ± 1.27 µg/mL and 8.02 ± 0.08 µg/mL, respectively for BuChE). As evidenced by molecular docking, the isolated compounds and other structurally related metabolites identified by molecular networking had the required structural features for AChE and BuChE inhibition. Where varioxiranol G (−9.76 and −10.36 kcal/mol), penicitrinol B (−9.50 and −8.02 kcal/mol), dicitrinol A (−8.53 and −7.98 kcal/mol) and asterriquinone CT5 (−8.02 and −8.25 kcal/mol) showed better binding scores as AChE and BuChE inhibitors than the co-crystallized inhibitor (between −7.89 and 7.82 kcal/mol) making them promising candidates for the development of new drugs to treat Alzheimer’s.

Anti-Neuroinflammatory Potential of Natural Products in the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is an age-related chronic progressive neurodegenerative disease, which is the main cause of dementia in the elderly. Much evidence shows that the onset and late symptoms of AD are caused by multiple factors. Among them, aging is the main factor in the pathogenesis of AD, and the most important risk factor for AD is neuroinflammation. So far, there is no cure for AD, but the relationship between neuroinflammation and AD may provide a new strategy for the treatment of AD. We herein discussed the main etiology hypothesis of AD and the role of neuroinflammation in AD, as well as anti-inflammatory natural products with the potential to prevent and alleviate AD symptoms, including alkaloids, steroids, terpenoids, flavonoids and polyphenols, which are available with great potential for the development of anti-AD drugs.

The temporal and spatial endophytic fungal community of Huperzia serrata: diversity and relevance to huperzine A production by the host

BACKGROUND

Plants maintain the steady-state balance of the mutually beneficial symbiosis relationship with their endophytic fungi through secondary metabolites. Meanwhile endophytic fungi can serve as biological inducers to promote the biosynthesis and accumulation of valuable secondary metabolites in host plants through a variety of ways. The composition and structure of endophytic fungal community are affected by many factors, including tissues, seasons and so on. In this work, we studied the community diversity, temporal and spatial pattern of endophytic fungi detected from the roots, stems and leaves of Huperzia serrata in different seasons. The correlation between endophytic fungi and huperzine A (HupA) content in plants was analyzed.

RESULTS

A total of 7005 operational taxonomic units were detected, and all strains were identified as 14 phyla, 54 classes, 140 orders, 351 families and 742 genera. Alpha diversity analysis showed that the diversity of endophytic fungi in stem and leaf was higher than that in root, and the diversity in summer (August) was lower than that in other months. NMDS analysis showed that the endophytic fungal communities of leaves, stems and roots were significantly different, and the root and leaf communities were also different between four seasons. Through correlation analysis, it was found that 33 genera of the endophytic fungi of H. serrata showed a significant positive correlation with the content of HupA (p < 0.05), of which 13 genera (Strelitziana, Devriesia, Articulospora, Derxomyces, Cyphellophora, Trechispora, Kurtzmanomyces, Capnobotryella, Erythrobasidium, Camptophora, Stagonospora, Lachnum, Golubevia) showed a highly significant positive correlation with the content of HupA (p < 0.01). These endophytic fungi may have the potential to promote the biosynthesis and accumulation of HupA in plant.

CONCLUSIONS

This report is the first time to analyze the diversity of endophytic fungi in tissues of H. serrata in different seasons, which proves that there is variability in different tissues and seasonal distribution patterns. These findings provide references to the study of endophytic fungi of H. serrata.

The Neuroprotective Potential of Endophytic Fungi and Proposed Molecular Mechanism: A Current Update

Millions of people are affected by neuronal disorders that are emerging as a principal cause of death after cancer. Alzheimer's disease, ataxia, Parkinson's disease, multiple system atrophy, and autism comprise the most common ones, being accompanied by loss of cognitive power, impaired balance, and movement. In past decades, natural polyphenols obtained from different sources including bacteria, fungi, and plants have been utilized in the traditional system of medicine for the treatment of several ailments. Endophytes are one such natural producer of secondary metabolites, namely, polyphenols, which exhibit strong abilities to assist in the management of such affections, through modifying multiple therapeutic targets and weaken their complex physiology. Limited research has been conducted in detail on bioactive compounds present in the endophytic fungi and their neuroprotective effects. Therefore, this review aims to provide an update on scientific evidences related to the pharmacological and clinical potential along with proposed molecular mechanism of action of endophytes for neuronal protection.

Diversity of endophytic fungal community in Huperzia serrata from different ecological areas and their correlation with Hup A content

Background

Huperzine A (Hup A) has attracted considerable attention as an effective therapeutic candidate drug used to treat Alzheimer’s disease. Whereas, the production of Hup A from wild plants faced a major challenge, which is the wild Huperzia Serrata harbor a low Hup A content, has a long-life cycle, and has a small yield. At present, several reports showed that Hup A is produced by various endophytic fungal strains isolated from H. serrata, thereby providing an alternative method to produce the compound and reduce the consumption of this rare and endangered plant. However, till now, very few comprehensive studies are available on the biological diversity and structural composition of endophytic fungi and the effects of endophytic fungi on the Hup A accumulation in H. serrata.

Results

In this research, the composition and diversity of fungal communities in H. serrata were deciphered based on high-throughput sequencing technology of fungal internal transcribed spacer regions2 (ITS2). The correlation between endophytic fungal community and Hup A content was also investigated. Results revealed that the richness and the diversity of endophytic fungi in H. serrata was various according to different tissues and different ecological areas. The endophytic fungal communities of H. serrata exhibit species-specific, ecological-specific, and tissue-specific characteristics. There are 6 genera (Ascomycota_unclassified, Cyphellophora, Fungi_unclassified, Sporobolomyces, and Trichomeriaceae_unclassified) were significantly positively correlated with Hup A content in all two areas, whereas, there are 6 genera (Auricularia, Cladophialophora, Cryptococcus, Mortierella, and Mycena) were significantly negatively correlated with Hup A content of in all two areas.

Conclusions

This study indicated a different composition and diverse endophytic fungal communities in H. serrata from different organs and ecological areas. The current study will provide the realistic basis and theoretical significance for understanding the biological diversity and structural composition of endophytic fungal communities in H. serrata, as well as providing novel insights into the interaction between endophytic fungi and Hup A content.