Chemodiversity, pharmacological activity, and biosynthesis of specialized metabolites from medicinal model fungi Ganoderma lucidum

Ganoderma lucidum is a precious fungus, particularly valued for its dual use as both medicine and food. Ganoderic acids (GAs), the distinctive triterpenoids found in the Ganoderma genus, exhibit a wide range of pharmacological activities. However, the limited resources of GAs restrict their clinic usage and drug discovery. In this review, we presented a comprehensive summary focusing on the diverse structures and pharmacological activity of GAs in G. lucidum. Additionally, we discussed the latest advancements in the elucidation of GA biosynthesis, as well as the progress in heterosynthesis and liquid fermentation methods aimed at further increasing GA production. Furthermore, we summarized the omics data, genetic transformation system, and cultivation techniques of G. lucidum, described as medicinal model fungi. The understanding of Ganoderic acids chemodiversity and biosynthesis in medicinal model fungi Ganoderma lucidum will provide important insights into the exploration and utilization of natural products in medicinal fungi.

Combined NMR and MS-based metabonomics and real-time PCR analyses reveal dynamic metabolic changes of Ganoderma lucidum during fruiting body growing

Ganoderma lucidum (G. lucidum) is a rare medicinal fungus with various beneficial properties. One of its main components, ganoderic acids (GAs), are important triterpenoids known for their sedative and analgesic, hepatoprotective, and anti-tumor activities. Understanding the growth and development of the G. lucidum fruiting body is crucial for determining the optimal time to harvest them. In this study, we used nuclear magnetic resonance (NMR) spectroscopy to systematically characterize the metabolites of G. lucidum at seven distinct developmental stages. We also measured the contents of seven kinds of GAs using LC-MS/MS. A total of 49 metabolites were detected in G. lucidum, including amino acids, sugars, organic acids and GAs. During the transition from the bud development period (I) to the budding period (II), we observed a rapid accumulation of glucose, tyrosine, nicotinamide ribotide, inosine and GAs. After the budding period, the contents of most metabolites decreased until the mature period (VII). In addition, the contents of GAs showed an initial raising, followed by a decline during the elongation period, except for GAF, which exhibited a rapid raise during the mature stage. We also detected the expression of several genes involved in GA synthesis, finding that most genes including 16 cytochrome P450 monooxygenase were all down-regulated during periods IV and VII compared to period I. These findings provide valuable insights into the dynamic metabolic profiles of G. lucidum throughout its growth stage, and it is recommended to harvest G. lucidum at period IV.

Biotransformation of triterpenoid ganoderic acids from exogenous diterpene dihydrotanshinone I in the cultures of Ganoderma sessile

BACKGROUND

Triterpenoids have shown a wide range of biological activities including antitumor and antiviral effects. Typically, triterpenes are synthesized through the mevalonate pathway and are extracted from natural plants and fungi. In this work, triterpenoids, ganoderic acids (GAs) were discovered to be produced via biotransformation of a diterpene, 15,16-dihydrotanshinone I (DHT) in the liquid cultured Ganoderma sessile mycelium.

RESULTS

Firstly, the biotransformation products, two rare GAs were isolated and purified by column chromatography, and characterized using HR-ESI-MS spectrometry and NMR spectrometry. The two compounds were Lanosta-7,9(11),24-trien-15α,22,β-diacetoxy-3β-hydroxy-26-oic acid (LTHA) and Lanosta-7,9(11),24-trien-15α,22,β-diacetoxy-3β-carbonyl-26-oic acid (LTCA). Then, transcriptome and proteome technologies were employed to measure the expression of mRNA and protein, which further confirmed that triterpenoid GAs could be transformed from exogenous diterpenoid DHT. At the molecular level, we proposed a hypothesis of the mechanism by which DHT converted to GAs in G. sessile mycelium, and the possible genes involved in biotransformation were verified by RT-qPCR.

CONCLUSIONS

Two rare GAs were obtained and characterized. A biosynthetic pathway of GAs from DHT was proposed. Although the synthetic route was not confirmed, this study provided important insights into omics resources and candidate genes for studying the biotransformation of diterpenes into triterpenes.

Enhancement of ganoderic acid production by promoting sporulation in a liquid static culture of Ganoderma species

Ganoderic acids (GAs) produced by Ganoderma are a type of lanostane-type triterpenoids with anticancer and antimetastatic activities; however, low production of GAs limits its wide application. In this study, a novel strategy by promoting sporulation of Ganoderma was developed to increase GA production. First, a high-spore producing Ganoderma strain G. 260125 was obtained from dikaryotic strain CGMCC 5.0026, and the sporulation-specific gene of this strain exhibits a higher transcription level than CGMCC 5.0026. Then, the effect of promoting sporulation on GA content was investigated. The maximum ganoderic acid (GA)-T, GA-Mk, and GA-Me contents in G. 260125 in shake flasks were 358.97, 78.32, and 12.75 μg/100 mg dry weight, respectively, which were 3.42, 2.91, and 1.73 times higher than those obtained in CGMCC 5.0026. Moreover, total and individual GA contents in spores were significantly higher than those in liquid static culture. Both concentrations of intermediates and transcription levels of GA biosynthetic genes also improved in G. 260125 during fermentation compared with those in CGMCC 5.0026. For scaling-up experiments, GA-T, GA-Me, and GA-Mk production in G. 260125 improved by 2.2-, 2.6-, and 2.1-fold compared with those in CGMCC 5.0026. In addition, the effectiveness of the developed strategy was also confirmed in three different Ganoderma strains. This work illustrated that promoting sporulation efficiently improves GA production in liquid static cultures of Ganoderma.

Ganoderic acid A is the effective ingredient of Ganoderma triterpenes in retarding renal cyst development in polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common life-threatening monogenetic diseases characterized by progressive enlargement of fluid-filled renal cysts. Our previous study has shown that Ganoderma triterpenes (GT) retards PKD renal cyst development. In the present study we identified the effective ingredient of GT in suppression of kidney cyst development. Using an in vitro MDCK cystogenesis model, we identified ganoderic acid A (GA-A) as the most promising candidate among the 12 ganoderic acid (GA) monomers. We further showed that GA-A (6.25−100 μM) significantly inhibited cyst growth in MDCK cyst model and embryonic kidney cyst model in vitro, and the inhibitory effect was reversible. In kidney-specific Pkd1 knockout (kPKD) mice displaying severe cystic kidney disease, administration of GA-A (50 mg· kg⁻¹ ·d⁻¹, sc) significantly attenuated renal cyst development. In both MDCK cells and kidney of kPKD mice, we revealed that GA-A dose-dependently downregulated the Ras/MAPK signaling pathway. The expression of proliferating cell nuclear antigen (PCNA) was also suppressed, suggesting a possible effect of GA-A on cell proliferation. These experimental data suggest that GA-A may be the main ingredient of GT as a potential therapeutic reagent for treating ADPKD.

Hydrogen sulfide, a novel small molecule signalling agent, participates in the regulation of ganoderic acids biosynthesis induced by heat stress in Ganoderma lucidum

Hydrogen sulfide (H₂S), an emerging small-molecule signalling agent, was recently shown to play a significant role in many physiological processes, but relatively few studies have been conducted on microorganisms compared with mammals and plants. By studying the pretreatment of H₂S donor sodium hydrosulfide (NaHS) and the scavenger hypotaurine (HT) and Cystathionine β-synthase silenced strains, we found that H₂S could alleviate the HS-induced ganoderic acids (GAs) biosynthesis. Our transcriptome results also showed that many signaling pathways and metabolic pathways, such as the glycolysis, TCA, oxidative phosphorylation and pentose phosphate pathway, are influenced by H₂S. Further experimental results indicated that H₂S could affect the physiological process of Ganoderma lucidum by interacting with multiple signals, including ROS, NO, AMPK, sphingolipid, mTOR, phospholipase D and MAPK, and physiological and pharmacological analyses showed that H₂S might alleviate the biosynthesis of GAs by inhibiting the intracellular calcium in G. lucidum.

SA inhibits complex III activity to generate reactive oxygen species and thereby induces GA overproduction in Ganoderma lucidum

Ganoderma lucidum has high commercial value because it produces many active compounds, such as ganoderic acids (GAs). Salicylic acid (SA) was previously reported to induce the biosynthesis of GA in G. lucidum. In this study, we found that SA induces GA biosynthesis by increasing ROS production, and further research found that NADPH oxidase-silenced strains exhibited a partial reduction in the response to SA, resulting in the induction of increased ROS production. Furthermore, the localization of ROS shows that mitochondria are sources of ROS production in response to SA treatment. An additional analysis focused on the relationship between SA-induced ROS production and mitochondrial functions, and the results showed that inhibitors of mitochondrial complexes I and II exert approximately 40–50% superimposed inhibitory effects on the respiration rate and H₂O₂ content when co-administered with SA. However, no obvious superimposed inhibition effects were observed in the sample co-treated with mitochondrial complex III inhibitor and SA, implying that the inhibitor of mitochondrial complex III and SA might act on the same site in mitochondria. Additional experiments revealed that complex III activity was decreased 51%, 62% and 75% after treatment with 100, 200, and 400 µM SA, respectively. Our results highlight the finding that SA inhibits mitochondrial complex III activity to increase ROS generation. In addition, inhibition of mitochondrial complex III caused ROS accumulation, which plays an essential role in SA-mediated GA biosynthesis in G. lucidum. This conclusion was also demonstrated in complex III-silenced strains. To the best of our knowledge, this study provides the first demonstration that SA inhibits complex III activity to increase the ROS levels and thereby regulate secondary metabolite biosynthesis.

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Mitochondria as a source of salicylic acid (SA) induced reactive oxygen species (ROS) production in Ganoderma lucidum.

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SA induces the accumulation of ganoderic acids in Ganoderma lucidum by mitochondria ROS overproduction.

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SA inhibits mitochondrial complex III activity to increase ROS and thereby induces ganoderic acids biosynthesis.

Roles of the Skn7 response regulator in stress resistance, cell wall integrity and GA biosynthesis in Ganoderma lucidum

The transcription factor Skn7 is a highly conserved fungal protein that participates in a variety of processes, including oxidative stress adaptation, fungicide sensitivity, cell wall biosynthesis, cell cycle, and sporulation. In this study, a homologous gene of Saccharomyces cerevisiae Skn7 was cloned from Ganoderma lucidum. RNA interference (RNAi) was used to study the functions of Skn7, and the two knockdown strains Skn7i-5 and Skn7i-7 were obtained in G. lucidum. The knockdown of GlSkn7 resulted in hypersensitivity to oxidative and cell wall stresses. The concentrations of chitin and β-1,3-glucan distinctly decreased in the GlSkn7 knockdown strains compared with those of the wild type (WT). In addition, the expression of cell wall biosynthesis related genes was also significantly down-regulated and the thickness of the cell wall also significantly reduced in the GlSkn7 knockdown strains. The intracellular reactive oxygen species (ROS) content and ganoderic acids biosynthesis increased significantly in the GlSkn7 knockdown strains. Interestingly, the level of intracellular ROS and the content of ganoderic acids decreased after N-acetyl-L-cysteine (NAC), an ROS scavenger, was added, indicating that GlSkn7 might regulate ganoderic acids biosynthesis via the intracellular ROS level. The transcript level of GlSkn7 were up-regulated in osmotic stress, heat stress and fungicide condition. At the same time, the content of ganoderic acids in the GlSkn7 knockdown strains also changed distinctly in these conditions. Overall, GlSkn7 is involved in stress resistance, cell wall integrity and ganoderic acid biosynthesis in G. lucidum.

Distinguishing commercially grown Ganoderma lucidum from Ganoderma lingzhi from Europe and East Asia on the basis of morphology, molecular phylogeny, and triterpenic acid profiles

In China and other countries of East Asia, so-called Ling-zhi or Reishi mushrooms are used in traditional medicine since several centuries. Although the common practice to apply the originally European name 'Ganoderma lucidum' to these fungi has been questioned by several taxonomists, this is still generally done in recent publications and with commercially cultivated strains. In the present study, two commercially sold strains of 'G. lucidum', M9720 and M9724 from the company Mycelia bvba (Belgium), are compared for their fruiting body (basidiocarp) morphology combined with molecular phylogenetic analyses, and for their secondary metabolite profile employing an ultra-performance liquid chromatography-electrospray ionization mass spectrometry (UPLC-ESIMS) in combination with a high resolution electrospray ionization mass spectrometry (HR-ESI-MS). According to basidiocarp morphology, the strain M9720 was identified as G. lucidum s.str. whereas M9724 was determined as Ganoderma lingzhi. In molecular phylogenetic analyses, the M9720 ITS and beta-tubulin sequences grouped with sequences of G. lucidum s.str. from Europe whereas those from M9724 clustered with sequences of G. lingzhi from East Asia. We show that an ethanol extract of ground basidiocarps from G. lucidum (M9720) contains much less triterpenic acids than found in the extract of G. lingzhi (M9724). The high amount of triterpenic acids accounts for the bitter taste of the basidiocarps of G. lingzhi (M9724) and of its ethanol extract. Apparently, triterpenic acids of G. lucidum s.str. are analyzed here for the first time. These results demonstrate the importance of taxonomy for commercial use of fungi.

Novel binding patterns between ganoderic acids and neuraminidase: Insights from docking, molecular dynamics and MM/PBSA studies

Recently, ganoderic acids (GAs) give rise to the attractive candidates of novel neuraminidase (NA) inhibitors. However, there is still no evident conclusion about their binding patterns. To this end, docking, molecular dynamics and MM/PBSA methods were combined to study the binding profiles of GAs with the N1 protein and familiar H274Y and N294S mutations (A/Vietnam/1203/04 stain). It was found that the binding affinities of ganoderic acid DM and Z (ΔGbind, -16.83 and -10.99 kcal mol(-1)) are comparable to that of current commercial drug oseltamivir (-23.62 kcal mol(-1)). Electrostatic interaction is the main driving force, and should be one important factor to evaluate the binding quality and rational design of NA inhibitors. The 150-loop residues Asp151 and Arg152 played an important role in the binding processes. Further analysis revealed that ganoderic acid DM is a potential source of anti-influenza ingredient, with novel binding pattern and advantage over oseltamivir. It had steric hindrance on the 150 cavity of N1 protein, and exerted activities across the H274Y and N294S mutations. This work also pointed out how to effectively design dual-site NA inhibitors and reinforce their affinities. These findings should prove valuable for the in-depth understanding of interactions between NA and GAs, and warrant the experimental aspects to design novel anti-influenza drugs.

Submerged fermentation production and characterization of intracellular triterpenoids from Ganoderma lucidum using HPLC-ESI-MS

As the main bioactive metabolites of Ganoderma lucidum, triterpenoids have various pharmacological effects. In this paper, the nutritional requirements and culture conditions of a submerged culture of G. lucidum were optimized using the response surface methodology; maximum mycelia biomass and intracellular triterpenoid production reached 1.87 g/100 ml and 93.21 mg/100 ml, respectively, for a culture consisting of wort 4.10% (0.041 g/ml) and yeast extract 1.89% (0.0189 g/ml), pH 5.40. For the first time, we established that wort, which is cheap and abundant, can replace the more commonly used glucose as the sole source of carbohydrate. Using high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS), 10 major ganoderic acids were tentatively identified based on the predominant fragmentation pathways with the elimination of H2O and CO2, as well as cleavage of the D-ring.

Sucrose fed-batch strategy enhanced biomass, polysaccharide, and ganoderic acids production in fermentation of Ganoderma lucidum 5.26

Ganoderma, as a Chinese traditional medicine, has multiple bioactivities. However, industrial production was limited due to low yield during Ganoderma fermentation. In this work, sucrose was found to greatly enhance intracellular polysaccharide (IPS) content and specific extracellular polysaccharide (EPS) production rate. The mechanism was studied by analyzing the activities of enzymes related to polysaccharide biosynthesis. The results revealed that sucrose regulated the activities of phosphoglucomutase and phosphoglucose isomerase. When glucose and sucrose mixture was used as carbon source, biomass, polysaccharide and ganoderic acids (GAs) production was greatly enhanced. A sucrose fed-batch strategy was developed in 10-L bioreactor, and was scaled up to 300-L bioreactor. The biomass, EPS and IPS production was 25.5, 2.9 and 4.8 g/L, respectively, which was the highest biomass and IPS production in pilot scale. This study provides information for further understanding the regulation mechanism of Ganoderma polysaccharide biosynthesis. It demonstrates that sucrose fed-batch is a useful strategy for enhancing Ganoderma biomass, polysaccharide and GAs production.

A reproducible analytical system based on the multi-component analysis of triterpene acids in Ganoderma lucidum

Ultra-performance liquid chromatography (UPLC) and Single Standard for Determination of Multi-Components (SSDMC) are becoming increasingly important for quality control of medicinal herbs; this approach was developed for Ganoderma lucidum. Special attention was necessary for the appropriate selection of markers, for determining the reproducibility of the relative retention times (RRT), and for the accuracy of conversion factors (F). Finally, ten components were determined, with ganoderic acid A serving as single standard. Stable system parameters were established, and with successful resolution of those issues, this analytical method could be used more broadly.

Secondary metabolites from Ganoderma

Ganoderma is a genus of medicinal mushrooms. This review deals with secondary metabolites isolated from Ganoderma and their biological significance. Phytochemical studies over the last 40years led to the isolation of 431 secondary metabolites from various Ganoderma species. The major secondary compounds isolated are (a) C30 lanostanes (ganoderic acids), (b) C30 lanostanes (aldehydes, alcohols, esters, glycosides, lactones, ketones), (c) C27 lanostanes (lucidenic acids), (d) C27 lanostanes (alcohols, lactones, esters), (e) C24, C25 lanostanes (f) C30 pentacyclic triterpenes, (g) meroterpenoids, (h) farnesyl hydroquinones (meroterpenoids), (i) C15 sesquiterpenoids, (j) steroids, (k) alkaloids, (l) prenyl hydroquinone (m) benzofurans, (n) benzopyran-4-one derivatives and (o) benzenoid derivatives. Ganoderma lucidum is the species extensively studied for its secondary metabolites and biological activities. Ganoderma applanatum, Ganoderma colossum, Ganoderma sinense, Ganoderma cochlear, Ganoderma tsugae, Ganoderma amboinense, Ganoderma orbiforme, Ganoderma resinaceum, Ganoderma hainanense, Ganoderma concinna, Ganoderma pfeifferi, Ganoderma neo-japonicum, Ganoderma tropicum, Ganoderma australe, Ganoderma carnosum, Ganoderma fornicatum, Ganoderma lipsiense (synonym G. applanatum), Ganoderma mastoporum, Ganoderma theaecolum, Ganoderma boninense, Ganoderma capense and Ganoderma annulare are the other Ganoderma species subjected to phytochemical studies. Further phytochemical studies on Ganoderma could lead to the discovery of hitherto unknown biologically active secondary metabolites.

Ganoderic Acid and Lucidenic Acid (Triterpenoid)

Ganoderma species is known as a functional mushroom used in many Asian countries. Triterpenoids, ganoderic acids, and lucidenic acids have been isolated from Ganoderma species (Ganodermataceae family), such as Ganoderma lucidum. Triterpenoids have been investigated for their biological activities, including antibacterial, antiviral, antitumor, antiosteoclastic differentiation activity, anti-HIV-1, hepatoprotection, antioxidation, antihypertension, cholesterol reduction, and antiaggregation functions. In this chapter, the sources, biosynthesis, biological functions (including cell cytotoxicity, cell apoptosis, cell cycle arrest, anti-invasion, autophagy, anti-inflammation, antiosteoclastogenesis, antiasthma, and antihepatitis B activity), and pharmacokinetics of lucidenic acids and ganoderic acids are considered in detail here. This chapter briefly summarizes the multiple functions of lucidenic acids and ganoderic acids and their potential for fighting against human diseases.

Ganoderic Acid DM: An Alternative Agent for the Treatment of Advanced Prostate Cancer

Prostate cancer is the most commonly diagnosed cancer in men and accounts for significant morbidity and mortality in the western world. While traditional therapies are effective at clearing early stage cancer, they often fail to treat late stage metastatic disease. Thus, an effective therapy that targets prostate tumor growth and metastasis is desired for alleviating the disease and improving patient outcomes. Natural extracts have been the focus of recent investigation, particularly those with reduced cellular toxicity to healthy tissue. In this review, we discuss one potential candidate, ganoderic acid, an extract from the Ganoderma lucidum mushroom that has been tested in multiple cancer models. Interestingly, ganoderic acid DM (GA-DM) has shown toxicity to both androgen-dependent and independent prostate cancer cells with reduced osteoclastogenesis in late stage metastatic disease. This review will discuss the current knowledge on this GA-DM extract and the potential benefit in treating advanced prostate cancer. We will also provide an overview on the targeted delivery of GA-DM through nanoparticles that would reduce bystander toxicity and improve the drug's effectiveness. An improved understanding of this drug and its uses will advance the field of natural chemotherapeutics, particularly in treating advanced prostate cancer.