Isolation, identification, and degradation mechanism by multi-omics of mesotrione-degrading Amycolatopsis nivea La24.

Mesotrione is a herbicide used in agricultural production; however, its stability and long-term residues pose ecological risks to soil health and subsequent crops. In this research, the strain Amycolatopsis nivea La24 was identified as capable of completely degrading 50 mg∙L-1 mesotrione within 48 h. It exhibited a broad adaptability to various environment and could degrade three sulfonylurea herbicides (nicosulfuron, chlorimuron-methyl, and cinosulfuron). Non-target metabonomic and mass spectrometry demonstrated that La24 strain broke down the mesotrione parent molecule by targeting the ß-diketone bond and nitro group, resulting in the production of five possible degradation products. The differentially expressed genes were significantly enriched in fatty acid degradation, amino acid metabolism, and other pathways, and the differentially metabolites in glutathione metabolism, arginine/proline metabolism, cysteine/methionine metabolism, and other pathways. Additionally, it was confirmed by heterologous expression that nitroreductase was directly involved in the mesotrione degradation, and NDMA-dependent methanol dehydrogenase would increase the resistance to mesotrione. Finally, the intracellular response of La24 during mesotrione degradation was proposed. This work provides insight for a comprehensive understanding of the mesotrione biodegradation mechanism, significantly expands the resources for pollutant degradation, and offers the potential for a more sustainable solution to address herbicide pollution in soil.

Phytohabitans maris sp. nov., isolated from marine sediment.

A novel actinobacterium, strain ZYX-F-186T, was isolated from marine sediment sampled on Yongxing Island, Hainan Province, PR China. Based on the results of 16S rRNA gene sequence analysis, strain ZYX-F-186T belongs to the genus Phytohabitans, with high similarity to Phytohabitans kaempferiae KK1-3T (98.3 %), Phytohabitans rumicis K11-0047T (98.1 %), Phytohabitans flavus K09-0627T (98.1 %), Phytohabitans houttuyneae K11-0057T (97.9 %), Phytohabitans suffuscus K07-0523T (97.7 %), and Phytohabitans aurantiacus RD004123T (97.7 %). Phylogenetic analysis of 16S rRNA gene sequences showed that the strain formed a single subclade in the genus Phytohabitans. The novel isolate contained meso-diaminopimelic acid, d-glutamic acid, glycine, d-alanine, and l-lysine in the cell wall. The whole-cell sugars were xylose, arabinose, ribose, and rhamnose. The predominant menaquinones were MK-9(H8), MK-9(H6), and MK-9(H4). The characteristic phospholipids were phosphatidylethanolamine, phosphatidylinositol, phosphatidylmethylethanolamine, phosphatidylglycerol, and an unknown phospholipid. The major fatty acids (>5 %) were iso-C16 : 0, anteiso-C17 : 0, and iso-C18 : 0. Genome sequencing showed a DNA G+C content of 71.9 mol%. Low average nucleotide identity, digital DNA-DNA hybridization, and average amino acid identity values demonstrated that strain ZYX-F-186T could be readily distinguished from its closely related species. Based on its phylogenetic, chemotaxonomic, and physiological characteristics, strain ZYX-F-186T represents a novel species of the genus Phytohabitans, for which the name Phytohabitans maris sp. nov. is proposed. The type strain is ZYX-F-186T (=CGMCC 4.8025T=CCTCC AA 2023025T=JCM 36507T).

Diaporchalasins A-E, New Cytochalasins from the Endophytic Fungus Diaporthe sp. BMX12 Isolated from Aquilaria sinensis.

Five new cytochalasins, diaporchalasins A-E (1-5), together with 14 known congeners (6-19) were isolated from the endophytic fungus Diaporthe sp. BMX12, which was isolated from the branches of Aquilaria sinensis. The structures of the new compounds were elucidated by extensive spectroscopic analyses including high-resolution electron spray ionization mass spectrometry (HR-ESI-MS) and nuclear magnetic resonance (NMR). Their absolute configurations were assigned by theoretical electronic circular dichroism (ECD) calculations. Compounds 11 and 12 featuring a keto carbonyl at C-21 displayed cytotoxicity toward K562, BEL-7402, SGC-7901, A549, and HeLa cell lines with IC50 values ranging from 4.4 to 47.4 µM.

Anti-diabetic and anti-inflammatory indole diterpenes from the marine-derived fungus Penicillium sp. ZYX-Z-143.

Seven new indole-diterpenoids, penpaxilloids A-E (1-5), 7-methoxypaxilline-13-ene (6), and 10-hydroxy-paspaline (7), along with 20 known ones (8-27), were isolated from the marine-derived fungus Penicillium sp. ZYX-Z-143. Among them, compound 1 was a spiro indole-diterpenoid bearing a 2,3,3a,5-tetrahydro-1H-benzo[d]pyrrolo[2,1-b][1,3]oxazin-1-one motif. Compound 2 was characterized by a unique heptacyclic system featuring a rare 3,6,8-trioxabicyclo[3.2.1]octane unit. The structures of the new compounds were established by extensive spectroscopic analyses, NMR calculations coupled with the DP4 + analysis, and ECD calculations. The plausible biogenetic pathway of two unprecedented indole diterpenoids, penpaxilloids A and B (1 and 2), was postulated. Compound 1 acted as a noncompetitive inhibitor against protein tyrosine phosphatase 1B (PTP1B) with IC50 value of 8.60 ± 0.53 µM. Compound 17 showed significant α-glucosidase inhibitory activity with IC50 value of 19.96 ± 0.32 µM. Moreover, compounds 4, 8, and 22 potently suppressed nitric oxide production on lipopolysaccharide-stimulated RAW264.7 macrophages.

Diverse ansamycin derivatives from the marine-derived Streptomyces sp. ZYX-F-97 and their antibacterial activities.

Four new ansamycin derivatives, named 1,19-epithio-geldanamycin A (1), 17-demethoxylherbimycin H (2), herbimycin M (3), and seco-geldanamycin B (4), together with eight known ansamycin analogues (5-12) were isolated from the solid fermentation of marine-derived actinomycete Streptomyces sp. ZYX-F-97. The structures of new compounds were elucidated by extensive spectroscopic analysis as well as nuclear magnetic resonance (NMR) and electronic circular dichroism (ECD) calculations. All the compounds were assayed for their antibacterial activity. Among them, compounds 4, 8, and 12 exhibited remarkable inhibition against Listeria monocytogenes with minimum inhibitory concentrations (MIC) values ranging from 8 µg·mL-1 to 64 µg·mL-1, and displayed moderate inhibition against methicillin-resistant Staphylococcus aureus (MRSA) with MIC value of 64 µg·mL-1. Compounds 4, 8, 9, and 12 showed moderate inhibition activities against both Staphylococcus aureus and Bacillus subtilis with MIC values ranging from 32 µg·mL-1 to 128 µg·mL-1.

Chemical constituents of the marine-derived fungus Acremonium sp. AN-13.

Two new compounds named 3(S)-hydroxy-1-(2,4,5-trihydroxy-3,6- dimethylphenyl)-hex-4E-en-1-one (1) and acremonilactone (2), together with nine known compounds (3-11), were isolated from the fermentation broth of Acremonium sp. associated with marine sediments collected from South China Sea. NMR and HRESIMS spectroscopic analysis elucidated the structure of two new compounds. Compound 2 had characteristic rotary gate shape skeleton with a six-membered lactone. Compounds 1 and 9 showed DPPH radical scavenging activity with inhibition rates of 96.50 and 85.95% at the concentration of 0.5 mg/ml, respectively. Moreover, compounds 4, 6 and 11 showed definite antibacterial activity against Staphylococcus aureus ATCC 6538.

Lanostane triterpenoids from the fruiting bodies of Ganoderma amboinense.

Lanostane-type triterpenoids are the main characteristic constituents in Ganoderma mushrooms. Phytochemical analysis on the ethanol extract of the fruiting bodies of Ganoderma amboinense led to isolation and identification of twelve previously undescribed lanostane triterpenoids (1-12). Their chemical structures were determined by HR-ESI-MS, IR, and NMR spectroscopic analysis, NMR calculation, as well as X-ray crystallography. All isolates were evaluated for the α-glucosidase inhibitory and anti-inflammatory activities. Compounds 1, 5, 6, and 11 showed significant α-glucosidase inhibitory activity with IC50 values ranging from 33.5 µM to 96.0 µM. Moreover, compound 12 showed anti-inflammatory activity with IC50 value of 21.7 ± 2.1 µM.

Endophytic Bacterium Flexivirga meconopsidis sp. nov. with Plant Growth-Promoting Function, Isolated from the Seeds of Meconopsis integrifolia.

Strain Q11T of an irregular coccoid Gram-positive bacterium, aerobic and non-motile, was isolated from Meconopsis integrifolia seeds. Strain Q11T grew optimally in 1% (w/v) NaCl, pH 7, at 30 °C. Strain Q11T is most closely related to Flexivirga, as evidenced by 16S rRNA gene analysis, and shares the highest similarity with Flexivirga aerilata ID2601ST (99.24%). Based on genome sequence analysis, the average nucleotide identity and digital DNA-DNA hybridization values of strains Q11T and D2601ST were 88.82% and 36.20%, respectively. Additionally, strain Q11T showed the abilities of nitrogen fixation and indole acetic acid production and was shown to promote maize growth under laboratory conditions. Its genome contains antibiotic resistance genes (the vanY gene in the vanB cluster and the vanW gene in the vanI cluster) and extreme environment tolerance genes (ectoine biosynthetic gene cluster). Shotgun proteomics also detected antibiotic resistance proteins (class A beta-lactamases, D-alanine ligase family proteins) and proteins that improve plant cold tolerance (multispecies cold shock proteins). Strain Q11T was determined to be a novel species of the genus Flexivirga, for which the name Flexivirga meconopsidis sp. nov. is proposed. The strain type is Q11T (GDMCC 1.3002T = JCM 36020 T).

Diverse indole-diterpenoids with protein tyrosine phosphatase 1B inhibitory activities from the marine coral-derived fungus Aspergillus sp. ZF-104.

Eight previously undescribed indole-diterpenoids named penerpenes O-V (1-8), together with seven known analogues (9-14), were isolated from the marine soft coral-derived fungus Aspergillus sp. ZF-104. Their structures including the absolute configurations of these compounds were assigned on the basis of spectroscopic data and ECD analysis along with quantum ECD and NMR calculations. Compounds 4 and 5 bear rare indolin-2-one units in their structures and 6 bears a reconstructed novel skeleton in which the indole ring and the terpenoid substructure are cleaved before they are reconnected through the nitrogen atom. Compounds 1, 2, 7, and 10 showed protein tyrosine phosphatase 1B (PTP1B) inhibitory activities comparable to that of the positive control NaVO3.

Lanostane triterpenoids with anti-proliferative and PTP1B/α-glucosidase inhibitory activities from the fruiting bodies of Ganoderma calidophilum.

Twelve previously undescribed and four known lanostane triterpenoids were isolated from the fruiting bodies of Ganoderma calidophilum. The structures of undescribed compounds, ganodecalones H-S (1-12), were elucidated by extensive spectroscopic analysis as well as ECD and NMR calculations. Compound 4 showed significant inhibitory activity against human leukaemia cell line K562, gastric cancer cell line SGC-7901, and cervical cancer cell line HeLa with IC50 values of 13.10 ± 0.19, 17.26 ± 4.75, and 4.36 ± 0.58 µM, respectively. Compound 16 exhibited inhibitory potency against protein tyrosine phosphatase 1B (PTP1B) and α-glucosidase with IC50 values of 30.2 ± 0.13 µM and 120.6 ± 0.14 µM, respectively. The binding sites and interactions of 16 with PTP1B and α-glucosidase were revealed using molecular docking simulations.

Chryseobacterium herbae Isolated from the Rhizospheric Soil of Pyrola calliantha H. Andres in Segrila Mountain on the Tibetan Plateau.

A non-motile, Gram-staining-negative, orange-pigmented bacterium called herbae pc1-10T was discovered in Tibet in the soil around Pyrola calliantha H. Andres' roots. The isolate thrived in the temperature range of 10-30 °C (optimal, 25 °C), pH range of 5.0-9.0 (optimum, pH = 6.0), and the NaCl concentration range of 0-1.8% (optimal, 0%). The DNA G+C content of the novel strain was 37.94 mol%. It showed the function of dissolving organophosphorus, acquiring iron from the environment by siderophore and producing indole acetic acid. Moreover, the genome of strain herbae pc1-10T harbors two antibiotic resistance genes (IND-4 and AdeF) encoding a ß-lactamase, and the membrane fusion protein of the multidrug efflux complex AdeFGH; antibiotic-resistance-related proteins were detected using the Shotgun proteomics technology. The OrthoANIu values between strains Chryseobacterium herbae pc1-10T; Chryseobacterium oleae CT348T; Chryseobacterium kwangjuense KJ1R5T; and Chryseobacterium vrystaatense R-23566T were 90.94%, 82.96%, and 85.19%, respectively. The in silico DDH values between strains herbae pc1-10T; C. oleae CT348T; C. kwangjuense KJ1R5T; and C. vrystaatense R-23566T were 41.7%, 26.6%, and 29.7%, respectively. Chryseobacterium oleae, Chryseobacterium vrystaatense, and Chryseobacterium kwangjuense, which had 16S rRNA gene sequence similarity scores of 97.80%, 97.52%, and 96.75%, respectively, were its closest phylogenetic relatives. Chryseobacterium herbae sp. nov. is proposed as the designation for the strain herbae pc1-10T (=GDMCC 1.3255 = JCM 35711), which represented a type species based on genotypic and morphological characteristics. This study provides deep knowledge of a Chryseobacterium herbae characteristic description and urges the need for further genomic studies on microorganisms living in alpine ecosystems, especially around medicinal plants.

Exposure to three herbicide mixtures influenced maize root-associated microbial community structure, function and the network complexity.

Herbicide mixtures are a new and effective agricultural strategy for managing suppress weed resistance and have been widely used in controlling weeding growth in maize fields. However, the potential ecotoxicological impact of these mixtures on the microbial community structure and function within various root-associated niches, remains inadequately understood. Here, the effects of nicosulfuron, mesotrione and atrazine on soil enzyme activity and microbial community structure and function were investigated when applied alone and in combination. The findings indicated that herbicide mixtures exhibit a prolonged half-life compared to single herbicides. Ecological niches are the major factor influencing the structure and functions of the microbial community, with the rhizosphere exhibiting a more intensive response to herbicide stress. Herbicides significantly inhibited the activities of soil functional enzymes, including dehydrogenase, urease and sucrose in the short-term. Single herbicide did not drastically influence the alpha or beta diversity of the soil bacterial community, but herbicide mixtures significantly increased the richness of the fungal community. Meanwhile, the key functional microbial populations, such as Pseudomonas and Enterobacteriaceae, were significantly altered by herbicide stress. Both individual and combined use of the three herbicides reduced the complexity and stability of the bacterial network but increased the interspecific cooperations of fungal community in the rhizosphere. Moreover, by quantification of residual herbicide concentrations in the soil, we showed that the degradation period of the herbicide mixture was longer than that of single herbicides. Herbicide mixtures increased the contents of NO3--N and NH4+-N in the soil in the short-term. Overall, our study provided a comprehensive insight into the response of maize root-associated microbial communities to herbicide mixtures and facilitated the assessment of the ecological risks posed by herbicide mixtures to the agricultural environment from an agricultural sustainability perspective.

Actinoplanes maris sp. nov., isolated from marine sediment.

A novel actinobacterium strain (M4I6T) was isolated from marine sediment collected in Megas Gialos, Syros, Greece. On the basis of 16S rRNA gene sequence analysis, strain M4I6T was indicated as belonging to the genus Actinoplanes, with high similarity to 'Actinoplanes solisilvae' LAM7112T (97.9 %), Actinoplanes ferrugineus IFO 15555T (97.6 %), Actinoplanes cibodasensis LIPI11-2-Ac042T (97.2 %) and Actinoplanes bogorensis LIPI11-2-Ac043T (97.2 %). Phylogenetic analysis of the 16S rRNA gene sequence of strain M4I6T showed that the strain formed a stable subclade with 'A. solisilvae' LAM7112T. The cell wall of the novel isolate contained meso-diaminopimelic acid and the whole-cell sugars were xylose, glucose and ribose. The predominant menaquinones were MK-9(H4), MK-9(H2) and MK-9(H8). The phospholipid profile comprised phosphatidylethanolamine, phosphatidylinositol, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol mannosides and an unknown phospholipid. The major fatty acids (>5 %) were anteiso-C16 : 0, iso-C17 : 0, 10-methyl-C16 : 0, C15 : 0, iso-C16 : 0 and C17 : 0. Genome sequencing showed a DNA G+C content of 70.9 mol%. However, the low average nucleotide identity value, digital DNA-DNA hybridization and average amino acid identity values demonstrated that strain M4I6T could be readily distinguished from its closest related species. Based on data from this polyphasic study, strain M4I6T represents a novel species of the genus Actinoplanes, for which the name Actinoplanes maris sp. nov. is proposed. The type strain is M4I6T (=DSM 101017T=CGMCC 4.7854T).

Two new alkaloids from the endophytic fungus Schizophyllum sp. HM230 isolated from Vincetoxicum mongolicum Maxim.

Endophytic fungi is an important source for the discovery of bioactive natural compounds. A chemical investigation of the ethyl acetate extract of the endophytic fungus Schizophyllum sp. HM230 derived from stems of the herb Vincetoxicum mongolicum Maxim led to isolation of five alkaloids, including two new compounds, schizophyllins M (1) and N (2), along with three known ones (3-5). The planar structures of two new compounds were elucidated by extensive spectroscopic methods including MS, 1D and 2D NMR. Their absolute configurations were determined by Mosher's method and comparison of the ECD data. All the isolates were evaluated for their cytotoxicity and antioxidant activities. Compounds 1-4 showed middle cytotoxicity against MCF-7 cells with IC50 values range of 68.1 ∼ 87.32 µM. Compounds 1-5 displayed obvious antioxidant activity with the IC50 values range of 0.86 ∼ 5.78 mg/mL.

Structure and Function Analysis of Cultivated Meconopsis integrifolia Soil Microbial Community Based on High-Throughput Sequencing and Culturability.

(1) Background: The structure, function, and community interactions of soil microbial communities of cultivated Meconopsis integrifolia were characterized by studying this alpine flower and traditional endangered Tibetan medicine. (2) Methods: Soil bacteria and fungi were studied based on high-throughput sequencing technology. Bacteria were isolated using culturomics and functionally identified as IAA-producing, organic phosphorus-dissolving, inorganic phosphorus-dissolving, and iron-producing carriers. (3) Results: The dominant bacterial phyla were found to be Proteobacteria and Acidobacteria, and unclassified_Rhizobiales was the most abundant genus. Ascomycota and Mortierellomycota were the dominant fungal phyla. The bacteria were mainly carbon and nitrogen metabolizers, and the fungi were predominantly Saprotroph-Symbiotroph. The identified network was completely dominated by positive correlations, but the fungi were more complex than the bacteria, and the bacterial keystones were unclassified_Caulobacteraceae and Pedobacter. Most of the keystones of fungi belonged to the phyla Ascomycetes and Basidiomycota. The highest number of different species of culturable bacteria belonged to the genus Streptomyces, with three strains producing IAA, 12 strains solubilizing organic phosphorus, one strain solubilizing inorganic phosphorus, and nine strains producing iron carriers. (4) Conclusions: At the cost of reduced ecological stability, microbial communities increase cooperation toward promoting overall metabolic efficiency and enabling their survival in the extreme environment of the Tibetan Plateau. These pioneering results have value for the protection of endangered Meconopsis integrifolia under global warming and the sustainable utilization of its medicinal value.

Characterization of a new chlorimuron-ethyl-degrading strain Cedecea sp. LAM2020 and biodegradation pathway revealed by multiomics analysis.

The widespread use of the herbicide chlorimuron-methyl is hazard to rotational crops and causes soil degradation problems. Biodegradation is considered a promising way for removing herbicide residues from the environment. Here, a new isolated strain, Cedecea sp. LAM2020, enabled complete degradation of 100 mg/L chlorimuron-methyl within five days. Transcriptome analysis revealed that ABC transporters, atrazine degradation and purine metabolism were enriched in the KEGG pathway. Integrating GO and KEGG classification with related reports, we predict that carboxylesterases are involved in the biodegradation of chlorimuron-methyl by LAM2020. Heterologous expression of the carboxylesterase gene carH showed 26.67% degradation of 50 mg/L chlorimuron-methyl within 6 h. The intracellular potential biological response and extracellular degradation process of chlorimuron-ethyl were analyzed by the nontarget metabolomic and mass spectrometry respectively, and the biodegradation characteristics and complete mineralization pathway was revealed. The cleavage of the sulfonylurea bridge and the ester bond achieved the first step in the degradation of chlorimuron-methyl. Together, these results reveal the presence of acidolysis and enzymatic degradation of chlorimuron-methyl by strain LAM2020. Hydroponic corn experiment showed that the addition of strain LAM2020 alleviated the toxic effects of chlorimuron-ethyl on the plants. Collectively, strain LAM2020 may be a promising microbial agent for plants chlorimuron-ethyl detoxification and soil biofertilizer.

Cedecea sulfonylureivorans sp. nov., a novel chlorimuron-ethyldegrading bacterium isolated from an herbicides-degrading consortium.

A Gram-stain-negative, motile, rod-shaped bacterium, designated strain LAM2020T, was isolated from a sulfonylurea herbicides-degrading bacterial consortium. The optimal temperature and pH for the growth of strain LAM2020T were 30 °C and 7.0, respectively. Strain LAM2020T formed a distinct phylogenetic subclade within the genus Cedecea in the phylogenetic trees built with 16S rRNA gene sequences and shared the highest similarity with Cedecea davisae DSM 4568T (98.4%). The values of digital DNA-DNA hybridization and average nucleotide identity (ANI) based on the genome sequences between LAM2020T and C. davisae DSM 4568T were 22.7% and 80.0%, respectively. It contained 54.0 mol% of G + C in the genomic DNA. The major cellular fatty acids of strain LAM2020T were summed feature 3 (C16:1 ω6c and/or C16:1 ω7c), C16:0 and summed feature 8 (C18:1 ω7c/C18:1 ω6c). The major polar lipids present in strain LAM2020T were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and aminophospholipid. The respiratory quinone of strain LAM2020T was ubiquinone-8 and ubiquinone-7. Based on the phenotypic characteristics, chemotaxonomic data and genotypic analyses, strain LAM2020T should be classified as a novel species of genus Cedecea, for which the name Cedecea sulfonylureivorans sp. nov. is proposed. The type strain is LAM2020T (= GDMCC 1.2363T = JCM 34640T).

Meroterpenoids and Steroids from the Marine-Derived Fungus Trametes sp. ZYX-Z-16.

Marine fungi can metabolize structurally diverse active components, and have become an important source of drug lead molecules. In the present study, the chemical investigation on the EtOAc extract of the fermentation broth of the marine-derived fungus Trametes sp. ZYX-Z-16 led to the isolation of eight meroterpenoids (1-8), including two undescribed ones, together with ten ergostane steroid analogues (9-18). The structures of two new spiromeroterpenoids, asnovolin H (1) and asnovolin I (2), were determined based on 1D, 2D NMR, and HRESIMS spectroscopic data along with ECD spectra calculations. All compounds were tested for antibacterial and α-glucosidase inhibitory activity. Among them, compound 12 showed definite antibacterial activities against Staphylococcus aureus ATCC 6538 (MIC 32 µg/mL) and Bacillus subtilis ATCC 6633 (MIC 16 µg/mL). In addition, compounds 9 and 10 showed superior inhibitory activity, with IC50 values of 104.1 and 111.3 µM, respectively, to the positive control acarbose (304.6 µM).

Polyketides with IDH1 R132h and PTP1B inhibitory activities from the desert-plant-derived fungus Alternaria sp. HM 134.

Five new polyketides named alternafurones A (1) and B (2), alternapyrones M-O (3-5), together with fourteen known ones (6-19), were isolated from the desert-plant-derived fungus Alternaria sp. HM 134. The structures of the new compounds were elucidated from spectroscopic data and ECD spectroscopic analyses. Alternafurones A and B represent polyketides with an unprecedented 6/5/6 skeleton core. Compounds 1, 2 and 4 showed definite inhibitory activities against isocitrate dehydrogenase 1 gene (IDH1 R132h) with IC50 values of 29.38, 19.41 and 14.14 µg/ml, respectively. Seven compounds (6, 7, 9-12, 14) showed potent protein tyrosine phosphatase 1B (PTP1B) inhibitory activity with IC50 values ranging from 0.97 µg/ml to 89.80 µg/ml.

Lanostane Triterpenoids and Ergostane Steroids from Ganoderma luteomarginatum and Their Cytotoxicity.

Macrofungus Ganoderma luteomarginatum is one of the main species of Ganoderma fungi distributed in Hainan province of China, the fruiting bodies of which have been widely used in folk as a healthy food to prevent tumors. To explore the potential cytotoxic constituents from G. luteomarginatum, the phytochemical investigation on the ethyl acetate soluble fraction of 95% ethanolic extract from the fruiting bodies of this fungus led to the isolation of twenty-six lanostane triterpenoids (1-26), including three undescribed ones (1-3), together with eight ergostane steroids (27-34). The structures of three new lanostane triterpenoids were elucidated as lanosta-7,9(11)-dien-3ß-acetyloxy-24,25-diol (1), lanosta-7,9(11)-dien-3-oxo-24,26-diol-25-methoxy (2), and lanosta-8,20(22)-dien-3,11,23-trioxo-7ß,15ß-diol-26-oic acid methyl ester (3) by the analysis of 1D, 2D NMR, and HRESIMS spectroscopic data. All isolates were assayed for their cytotoxic activities using three human cancer cell lines (K562, BEL-7402, and SGC-7901) and seven lanostane triterpenoids (1, 2, 7, 13, 18, 22, and 24), and one ergostane steroid (34) showed definite cytotoxicity with IC50 values that ranged from 6.64 to 47.63 µg/mL. Among these cytotoxic lanostane triterpenoids, compounds 2 and 13 showed general cytotoxicity against three human cancer cell lines, while compounds 1 and 18 exhibited significant selective cytotoxicity against K562 cells with IC50 values of 8.59 and 8.82 µg/mL, respectively. Furthermore, the preliminary structure-cytotoxicity relationships was proposed.