Antioxidant farnesylated hydroquinones from Ganoderma capense

Insights into Ganoderma fungi meroterpenoids opening a new era of racemic natural products in mushrooms

Ganoderma meroterpenoids (GMs) containing 688 structures to date were discovered to have multiple remarkable biological activities. 65.6% of meroterpenoids featuring stereogenic centers from Ganoderma species are racemates. Further, GMs from different Ganoderma species seem to have their own characteristics. In this review, a comprehensive summarization of GMs since 2000 is presented, including GM structures, structure corrections, biological activities, physicochemical properties, total synthesis, and proposed biosynthetic pathways. Additionally, we especially discuss the racemic nature, species-related structural distribution, and structure-activity relationship of GMs, which will provide a likely in-house database and shed light on future studies on GMs.

Structural diversity, hypothetical biosynthesis, chemical synthesis, and biological activity of Ganoderma meroterpenoids

Covering: 2018 to 2022Meroterpenoids found in fungal species of the genus Ganoderma and known as Ganoderma meroterpenoids (GMs) are substances composed of a 1,2,4-trisubstituted benzene and a polyunsaturated side chain. These substances have attracted the attention of chemists and pharmacologists due to their diverse structures and significant bioactivity. In this review, we present the structures and possible biosynthesis of representative GMs newly found from 2018 to 2022, as well as chemical synthesis and biological activity of some interesting GMs. We propose for the first time a plausible biosynthetic pathway for GMs, which will certainly motivate further research on the biosynthetic pathway in Ganoderma species, as well as on chemical synthesis of GMs as important bioactive compounds for the purpose of drug development.

Diverse meroterpenoids with α-glucosidase inhibitory activity from Ganoderma cochlear

Three new meroterpenoids, cochlearins J-L (1-3) and three known meroterpenoids (4-6) were isolated from the fruiting bodies of Ganoderma cochlear. NMR (¹H and ¹³C NMR, ¹H - ¹H COSY, HSQC, HMBC and ROESY), and HRESIMS were employed for the structure elucidation of new compounds. The stereostructures of 1-3 were confirmed by calculated ECD and optical rotation methods. Furthermore, compounds (+)-1, (-)-1, (+)-2, (-)-2, (+)-3, (-)-3, and 4-6 were evaluated for their α-glucosidase inhibitory activity. The results showed that compounds (+)-1, (-)-1 and (+)-2 exhibited stronger inhibition against α-glucosidase with IC₅₀ values of 24.18 ± 1.98, 26.49 ± 3.20 and 29.68 ± 2.73 μM, respectively, compared to the positive control ursolic acid (49.65 ± 2.21 μM). The molecular docking experiments reveal that (+)-2 and (-)-2 had different binding mode with α-glucosidase, leading to their different inhibition.

Biological activities of meroterpenoids isolated from different sources

Meroterpenoids are natural products synthesized by unicellular organisms such as bacteria and multicellular organisms such as fungi, plants, and animals, including those of marine origin. Structurally, these compounds exhibit a wide diversity depending upon the origin and the biosynthetic pathway they emerge from. This diversity in structural features imparts a wide spectrum of biological activity to meroterpenoids. Based on the biosynthetic pathway of origin, these compounds are either polyketide-terpenoids or non-polyketide terpenoids. The recent surge of interest in meroterpenoids has led to a systematic screening of these compounds for many biological actions. Different meroterpenoids have been recorded for a broad range of operations, such as anti-cholinesterase, COX-2 inhibitory, anti-leishmanial, anti-diabetic, anti-oxidative, anti-inflammatory, anti-neoplastic, anti-bacterial, antimalarial, anti-viral, anti-obesity, and insecticidal activity. Meroterpenoids also possess inhibitory activity against the expression of nitric oxide, TNF- α, and other inflammatory mediators. These compounds also show renal protective, cardioprotective, and neuroprotective activities. The present review includes literature from 1999 to date and discusses 590 biologically active meroterpenoids, of which 231 are from fungal sources, 212 are from various species of plants, and 147 are from marine sources such as algae and sponges.

Antioxidant Activity of Natural Hydroquinones

Secondary metabolites derived from hydroquinone are quite rare in nature despite the original simplicity of its structure, especially when compared to other derivatives with which it shares biosynthetic pathways. However, its presence in a prenylated form is somewhat relevant, especially in the marine environment, where it is found in different algae and invertebrates. Sometimes, more complex molecules have also been identified, as in the case of polycyclic diterpenes, such as those possessing an abietane skeleton. In every case, the presence of the dihydroxy group in the para position gives them antioxidant capacity, through its transformation into para-quinones.This review focuses on natural hydroquinones with antioxidant properties referenced in the last fifteen years. This activity, which has been generally demonstrated in vitro, should lead to relevant pharmacological properties, through its interaction with enzymes, transcription factors and other proteins, which may be particularly relevant for the prevention of degenerative diseases of the central nervous system, or also in cancer and metabolic or immune diseases. As a conclusion, this review has updated the pharmacological potential of hydroquinone derivatives, despite the fact that only a small number of molecules are known as active principles in established medicinal plants. The highlights of the present review are as follows: (a) sesquiterpenoid zonarol and analogs, whose activity is based on the stimulation of the Nrf2/ARE pathway, have a neuroprotective effect; (b) the research on pestalotioquinol and analogs (aromatic ene-ynes) in the pharmacology of atherosclerosis is of great value, due to their agonistic interaction with LXRα; and (c) prenylhydroquinones with a selective effect on tyrosine nitration or protein carbonylation may be of interest in the control of post-translational protein modifications, which usually appear in chronic inflammatory diseases.

The chemistry and biology of fungal meroterpenoids (2009-2019)

Fungal meroterpenoids are secondary metabolites from mixed terpene-biosynthetic origins. Their intriguing chemical structural diversification and complexity, potential bioactivities, and pharmacological significance make them attractive targets in natural product chemistry, organic synthesis, and biosynthesis. This review provides a systematic overview of the isolation, chemical structural features, biological activities, and fungal biodiversity of 1585 novel meroterpenoids from 79 genera terrestrial and marine-derived fungi including macrofungi, Basidiomycetes, in 441 research papers in 2009-2019. Based on the nonterpenoid starting moiety in their biosynthesis pathway, meroterpenoids were classified into four categories (polyketide-terpenoid, indole-, shikimate-, and miscellaneous-) with polyketide-terpenoids (mainly tetraketide-) and shikimate-terpenoids as the primary source. Basidiomycota produced 37.5% of meroterpenoids, mostly shikimate-terpenoids. The genera of Ganoderma, Penicillium, Aspergillus, and Stachybotrys are the four dominant producers. Moreover, about 56% of meroterpenoids display various pronounced bioactivities, including cytotoxicity, enzyme inhibition, antibacterial, anti-inflammatory, antiviral, antifungal activities. It's exciting that several meroterpenoids including antroquinonol and 4-acetyl antroquinonol B were developed into phase II clinically used drugs. We assume that the chemical diversity and therapeutic potential of these fungal meroterpenoids will provide biologists and medicinal chemists with a large promising sustainable treasure-trove for drug discovery.

Traditional uses, chemical components and pharmacological activities of the genus Ganoderma P. Karst.: a review

In recent years, some natural products isolated from the fungi of the genus Ganoderma have been found to have anti-tumor, liver protection, anti-inflammatory, immune regulation, anti-oxidation, anti-viral, anti-hyperglycemic and anti-hyperlipidemic effects. This review summarizes the research progress of some promising natural products and their pharmacological activities. The triterpenoids, meroterpenoids, sesquiterpenoids, steroids, alkaloids and polysaccharides isolated from Ganoderma lucidum and other species of Ganoderma were reviewed, including their corresponding chemical structures and biological activities. In particular, the triterpenes, polysaccharides and meroterpenoids of Ganoderma show a wide range of biological activities. Among them, the hydroxyl groups on the C-3, C-24 and C-25 positions of the lanostane triterpenes compound were the necessary active groups for the anti-HIV-1 virus. Previous study showed that lanostane triterpenes can inhibit human immunodeficiency virus-1 protease with an IC50 value of 20-40 μM, which has potential anti-HIV-1 activity. Polysaccharides can promote the production of TNF α and IFN-γ by macrophages and spleen cells in mice, and further inhibit or kill tumor cells. Some meroterpenoids contain oxygen-containing heterocycles, and they have significant antioxidant activity. In addition, Ganoderma has been used as a medicine to treat diseases for more than 2000 years, and we also reviewed its traditional uses.

Meroterpenoids produced by fungi: Occurrence, structural diversity, biological activities, and their molecular targets

Meroterpenoids are partially derived from the terpenoids, distributing widely in the plants, animals and fungi. The complex structures and diverse bioactivities of meroterpenoids have attracted more attention for chemists and pharmacologists. Since the first review summarized by Geris in 2009, there are absent of systematic reviews reported about meroterpenoids from the higher and lower fungi up to now. In the past decades, myriads of meroterpenoids were discovered, and it is necessary to summarize these meroterpenoids about their unique structures and promising bioactivities. In this review, we use a new classification method based on the non-terpene precursors, and also highlight the structural features, bioactivity of natural meroterpenoids from the higher and lower fungi covering the period of September 2008 to February 2020. A total of 709 compounds were discussed and cited the 182 references. Meanwhile, we also primarily summarize their occurrence, structural diversity, biological activities, and molecular targets.

Lanostane triterpenoids with anti-inflammatory activities from Ganoderma lucidum

Ganoderma lucidum is one of the most famous medicinal fungi and is traditional Chinese medicine with various biological activities in Asian countries. To clarify its pharmacodynamic material basis, 15 lanostane triterpenoidswere obtained from the fruiting bodies of G. lucidum, including 8 previously undescribed lanostanoids. Their structures, including absolute configuration, were established based on ultraviolet, infrared, high-resolution electrospray ionisation mass spectrometry, 1D and 2D nuclear magnetic resonance, and X-ray crystallographic analysis. Ganoluciduone A was an unusual octonorlanostane, which was isolated from Ganoderma for the first time. In addition, the anti-inflammatory activities of all isolates were evaluated by observing their inhibitory effects on nitric oxide production in RAW264.7 cells activated by a lipopolysaccharide. Ganoluciduone B exhibited moderate inhibitory activity on nitric oxide production, with an inhibition rate of 45.5% at a concentration of 12.5 μM.

A Ganoderma-Derived Compound Exerts Inhibitory Effect Through Formyl Peptide Receptor 2

Formyl peptide receptors (FPRs) are G protein-coupled receptors (GPCRs) widely expressed in neutrophils and other phagocytes. FPRs play important roles in host defense, inflammation, and the pathogenesis of infectious and inflammatory diseases. Because of these functions, FPRs are potential targets for anti-inflammatory therapies. In order to search for potentially novel anti-inflammatory agents, we examined Ganoderma (Lingzhi), a Chinese medicinal herbs known for its anti-inflammatory effects, and found that compound 18 (C18) derived from Ganoderma cochlear could limit the inflammatory response through FPR-related signaling pathways. Further studies showed that C18 could bind to FPR2 and induce conformation change of the receptor that differed from the conformational change induced by the pan-agonist, WKYMVm. C18 inhibited at the receptor level and blocked WKYMVm signaling through FPR2, resulting in reduced superoxide production and compromised cell chemotaxis. These results identified for the first time that a Ganoderma-derived component with inhibitory effects that acts through a G protein-coupled receptor FPR2. Considering its less than optimal IC₅₀ value, further optimization of C18 would be necessary for future applications.

Triterpenes and Aromatic Meroterpenoids with Antioxidant Activity and Neuroprotective Effects from Ganoderma lucidum

Reactive oxygen/nitrogen species generated in the human body can cause oxidative damage associated with many degenerative diseases such as atherosclerosis, dementia, coronary heart diseases, aging, and cancer. There is a great interest in developing new antioxidants from Ganoderma fungus due to its low toxicity. As part of our ongoing search for antioxidative constituents from the fruiting bodies of Ganoderma lucidum, the chemical constituents were investigated and seven secondary metabolites, including one new lanostane triterpene (1), two known aromatic meroterpenoids (6–7), and four known triterpenes (2–5), were isolated by a series of chromatographic methods. The structures of the seven compounds were elucidated by spectroscopic techniques. The isolated compounds were tested in vitro for antioxidant potencies and neuroprotective activities against H₂O₂ and aged Aβ-induced cell death in SH-SY5Y cells. As a result, compounds 1, 6, and 7 exhibited potent antioxidant and neuroprotective activities. Additionally, all isolated compounds were tested for radical scavenging activities. Compounds 6 and 7 showed the comparable free radical scavenging activities with the standard drug in both ABTS (2, 2’-azobis (3-ethylbenzothiazole-6-sulfonaic acid)) and ORAC (oxygen radical absorbance capacity) experiments. The results from this study suggested that G. lucidum and its metabolites (especially the meroterpenoids) may be potential functional food ingredients for the antioxidation and prevention of neurogenerative diseases.

Five New Meroterpenoids from the Fruiting Bodies of the Basidiomycete Clitocybe clavipes with Cytotoxic Activity

Five new meroterpenoids, clavipols A-B (1-2) with a 12-membered ether ring and clavilactones G-I (3-5) having a 10-membered carbocycle connected to a hydroquinone and an α,β-epoxy/unsaturated lactone, were obtained from the fruiting bodies of the basidiomycete Clitocybe clavipes. Their structures were determined by comprehensive analysis of their spectroscopic data, and the absolute configuration of 1 was established by quantum chemical calculations of electronic circular dichroism (ECD). All the isolated compounds (1-5) were tested for their cytotoxic activity against three human tumor cell lines (Hela, SGC-7901, and SHG-44) in vitro after treatment for 48 h. Compound 4 exhibited moderate cytotoxic activity against Hela and SGC-7901 tumor cell lines, with IC₅₀ values of 23.5 and 14.5 µM, respectively.

Aromatic constituents from Ganoderma lucidum and their neuroprotective and anti-inflammatory activities

Five new aromatic compounds, designed as lucidumins A-D (1-4) and lucidimine E (9), along with seven known aromatic compounds (5-8, 10-12) were isolated from Ganoderma lucidum. Their structures were determined by spectroscopic method. Bioactive evaluation showed that compounds 2-4 and 6-10 displayed remarkable neuroprotective activities against corticosterone-induced PC12 cell damage, with the cell viability ranging from 69.99% to 126.00%; and compounds 1-4, 9 and 10 exhibited significant anti-inflammatory activities against LPS-induced nitric oxide (NO) production in RAW264.7 macrophages, with IC₅₀ values ranging from 4.68 to 15.49 μM. In particular, compound 10 showed remarkable neuroprotection with EC₅₀ value of 2.49 ± 0.12 μM, and potent anti-inflammation with IC₅₀ value of 4.68 ± 0.09 μM.

Meroterpenoids from Ganoderma Species: A Review of Last Five Years

Meroterpenoids are hybrid natural products that partially originate from the terpenoid pathway. Ganoderma meroterpenoids (GMs) are a type of meroterpenoids containing a 1,2,4-trisubstituted phenyl and a polyunsaturated terpenoid part. Over last 5 years, great efforts have been made to conduct phytochemistry research on the genus Ganoderma, which have led to the isolation and identification of a number of GMs. These newly reported GMs showed diverse structures and a wide range of biological activities. This review gives an overview of new GMs from genus Ganoderma and their biological activities and biosynthetic pathway, focusing on the period from 2013 until 2018.

Laccase-Mediated Enhancement of the Antioxidant Activity of Propolis and Poplar Bud Exudates

The treatment of propolis and poplar bud exudates with laccase from Trametes versicolor and 2,2,6,6-tetramethyl-1-piperidinyloxy free radical increased the antioxidant activity, as evaluated by the 2,2'-diphenyl picrylhydrazyl (DPPH)- and t-butyl-OOH-induced DNA breakage comet assay analyses. The effect was highest for shorter reaction times. Propolis showed the highest antioxidant activity in the DPPH test, whereas poplar bud exudates were more active in reducing the t-butyl-OOH-induced lesions in the Chinese hamster ovary cell line. Even if the concentration of polyphenols decreased during the oxidation, the formation of low-molecular-weight phenols phloroglucinol 4 (1,3,5-trihydroxy benzene), hydroquinone 5 (1,4-dihydroxy benzene), and catechol 6 (1,2-dihydroxy benzene), characterized by the radical-scavenging activity, can account for the observed increase in the antioxidant activity.

(±)-Ganoapplanin, a Pair of Polycyclic Meroterpenoid Enantiomers from Ganoderma applanatum

(±)-Ganoapplanin (1), a pair of novel meroterpenoid enantiomers featuring an unprecedented dioxaspirocyclic skeleton constructed from a 6/6/6/6 tetracyclic system and an unusual tricyclo[4.3.3.0^3',7']dodecane motif, were isolated from Ganoderma applanatum. Its structure and absolute configurations were determined by spectroscopic analyses, X-ray crystallography, and ECD (electronic circular dichroism calculations). A plausible biogenetic pathway, involving a key Gomberg-Bachmann reaction, was also proposed for (±)-1. Biological studies showed that (±)-1 and its enantiomers exhibited different inhibitory activities on T-type voltage-gated calcium channels.

Total synthesis of (±)-ganocins B and C

The first total synthesis of structurally unique polycyclic phenolic meroterpenoids, ganocins B and C is reported.