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The existence of cancer stem cells (CSCs) is considered to be the main reason for chemoresistance, metastasis and the ultimate failure of treatment in hepatocellular carcinoma (HCC). However, there are a few chemical agents that may inhibit CSCs. The present study identified that 4,4′-bond secalonic acid D (4,4′-SAD), a compound isolated from the marine-derived fungus Penicillium oxalicum, inhibited the growth of side population (SP) cells isolated from human liver cancer cell lines PLC/PRF/5 and HuH-7 by attenuating the expression of ATP-binding cassette superfamily G member 2. Furthermore, the results of wound healing, Transwell, western blotting and reverse transcription-quantitative PCR assays demonstrated that 4,4′-SAD suppressed the invasion and migration of SP cells by downregulating matrix metallopeptidase 9 (MMP-9) and upregulating the antagonist tissue inhibitor of metalloproteinases 1 in vitro. Moreover, in vivo study results found that 4,4′-SAD had anti-lung metastasis efficacy via the decrease of MMP-9 expression in the H22 HCC model of Kunming mice. Therefore, the present study identified the potential of 4,4′-SAD as a promising candidate for the treatment of advanced liver cancer.

Marine life has proved to be an invaluable source of new compounds with significant bioactivities, such as xanthones. This review summarizes the advances made in the study of marine-derived xanthones from 2010 to 2021, from isolation towards synthesis, highlighting their biological activities. Most of these compounds were isolated from marine-derived fungi, found in marine sediments, and associated with other aquatic organisms (sponge and jellyfish). Once isolated, xanthones have been assessed for different bioactivities, such as antibacterial, antifungal, and cytotoxic properties. In the latter case, promising results have been demonstrated. Considering the significant bioactivities showed by xanthones, efforts have been made to synthesize these compounds, like yicathins B and C and the secalonic acid D, through total synthesis.

Marine-derived fungi have become a vital resource for the discovery of novel secondary metabolites with diverse structures and significant biological activities. This study focuses on a systematic chemical investigation of the sponge-associated fungus Talaromyces stipitatus HF05001, leading to the isolation and identification of 20 compounds, including one new marine ketal natural product (Compound 17, Talarobispiral A). These compounds were structurally elucidated using comprehensive spectroscopic analyses, including 1D and 2D NMR, HRESIMS. All isolates were screened for their anti-inflammatory and anti-adipogenic properties. Among them, compound 4 (Secalonic acid D, SAD), 7 (Sch 725680) and 16 (bacillisporins C) demonstrated significant anti-inflammatory potential by markedly suppressing nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Notably, compound 4 showed superior inhibitory effect, with an IC50 value of 0.22 μM. Additionally, compound 4 exhibited the strongest dose-dependent inhibition of lipid droplet accumulation in 3T3-L1 preadipocytes. These findings highlight the dual therapeutic potential of metabolites from Talaromyces stipitatus, identifying promising lead compounds for the development of novel treatments for inflammatory and metabolic disorders.

The bioactive compounds of the fungus Aspergillus aculeatus strain KKU-CT2, have been studied. The crude extracts from this fungus showed good antimicrobial activity against human pathogens, including Gram-positive and Gram-negative bacteria and yeast-like fungi. Its chemical components were isolated and purified by chromatographic methods. The structures of the secondary metabolites were elucidated by spectroscopic methods (IR, 1H, and 13C NMR). They were identified as ergosterol peroxide (1), secalonic acid D (2), secalonic acid F (3), variecolin (4), variecolactone (5), and ergosterol (6). Compounds 1 and 4–6 are reported for the first time as fungal metabolites from this species. Compound 1 displayed inhibitory effects on HSV-1 with an IC50 of 11.01 μg/ml. Compounds 3, 4, and 6 exhibited antimalarial activity against Plasmodium falciparum with IC50 of 1.03, 1.47, and 5.31 µg/ml, respectively. Additionally, all compounds from A. aculeatus KKU-CT2 showed unprecedented anticancer activities against human epidermoid carcinoma in the mouth (KB) (compounds 1–6), human breast cancer (MCF-7) (compounds 2, 4, and 5), and human lung cancer cells (NCI-H187) (compounds 1–4 and 6). These results suggest that secondary metabolites from A. aculeatus KKU-CT2 might be interesting for further derivatization, targeting diseases such as cancer.

A novel fungal species, Aspergillus labruscus sp. nov., has been found in Brazil during an investigation of the fungal species present on the surface of grape berries ( Vitis labrusca L.) for use in the production of concentrated grape juice. It seems to be associated to V . labrusca , and has never been recovered from Vitis vinifera . This new species belonging to Aspergillus subgenus Circumdati section Nigri is described here using morphological characters, extrolite profiling, partial sequence data from the BenA and CaM genes, and internal transcribed spacer sequences of ribosomal DNA. Phenotypic and molecular data enabled this novel species to be clearly distinguished from other black aspergilli. A . labruscus sp. nov. is uniseriate, has yellow mycelium, poor sporulation on CYA at 25 °C, abundant salmon to pink sclerotia and rough conidia. Neoxaline and secalonic acid D were consistently produced by isolates in this taxon. The type strain of A . labruscus sp. nov. is CCT 7800 (T) = ITAL 22.223 (T) = IBT 33586 (T).

Penicillium chrysogenum is a commonly occurring mould in indoor environments and foods, and has gained much attention for its use in the production of the antibiotic penicillin. Phylogenese analysis of the most important penicillin producing P. chrysogenum isolates revealed the presence of two highly supported clades, and we show here that these two clades represent two species, P. chrysogenum and P. rubens . These species are phenotypically similar, but extrolite analysis shows that P. chrysogenum produces secalonic acid D and F and/or a metabolite related to lumpidin, while P. rubens does not produce these metabolites. Fleming’s original penicillin producing strain and the full genome sequenced strain of P. chrysogenum are re-identified as P rubens . Furthermore, the well-known claim that Alexander Fleming misidentified the original penicillin producing strain as P. rubrum is discussed.

Metabolites of microorganisms have long been considered as potential sources for drug discovery. In this study, five new depsidone derivatives, talaronins A-E ( 1–5 ) and three new xanthone derivatives, talaronins F–H ( 6–8 ), together with 16 known compounds ( 9–24 ), were isolated from the ethyl acetate extract of the mangrove-derived fungus Talaromyces species WHUF0362. The structures were elucidated by analysis of spectroscopic data and chemical methods including alkaline hydrolysis and Mosher’s method. Compounds 1 and 2 each attached a dimethyl acetal group at the aromatic ring. A putative biogenetic relationship of the isolated metabolites was presented and suggested that the depsidones and the xanthones probably had the same biosynthetic precursors such as chrysophanol or rheochrysidin. The antimicrobial activity assay indicated that compounds 5 , 9 , 10 , and 14 showed potent activity against Helicobacter pylori with minimum inhibitory concentration (MIC) values in the range of 2.42–36.04 μmol/L. While secalonic acid D ( 19 ) demonstrated significant antimicrobial activity against four strains of H. pylori with MIC values in the range of 0.20 to 1.57 μmol/L. Furthermore, secalonic acid D ( 19 ) exhibited cytotoxicity against cancer cell lines Bel-7402 and HCT-116 with IC 50 values of 0.15 and 0.19 μmol/L, respectively. The structure–activity relationship of depsidone derivatives revealed that the presence of the lactone ring and the hydroxyl at C-10 was crucial to the antimicrobial activity against H. pylori . The depsidone derivatives are promising leads to inhibit H. pylori and provide an avenue for further development of novel antibiotics.

Cancer cells adapted to the microenvironment in tumor such as hypoxic and nutrient-starved conditions are now paid much attention as the therapeutic target of cancer. In the course of search for selective cytotoxic substances against cancer cells adapted to nutrient starvation, xanthone derivative of secalonic acid D ( 1 ) was isolated from culture extract of marine-derived Penicillium oxalicum . Compound 1 showed cytotoxic activity on the human pancreatic carcinoma PANC-1 cells adapted to glucose-starved conditions with IC 50 value of 0.6 µM, whereas IC 50 value of compound 1 against PANC-1 cells under general culture conditions was calculated to be more than 1000 µM. Further study indicated that compound 1 inhibited the Akt signaling pathway under glucose-starved conditions, and slightly affected the induction of glucose-regulated protein 78 (GRP78), and these effects would be mediated by the uncoupling action of compound 1 on the mitochondria.

Secalonic acid D (SAD), a cleft palate-inducing teratogen, has been shown to inhibit proliferation/cell cycle progression in association with alteration in the levels of cell cycle regulators, p21 and cyclin E. These studies were conducted to test the hypotheses that p21 and cyclin E play an important functional role in normal human embryonic palatal mesenchymal (HEPM) cell cycle and that their up- and down-regulation, respectively, by SAD is functionally significant to its cell cycle block. Using small interfering RNA (siRNA) to silence p21gene and transient transfection to overexpress cyclin E in control & SAD-treated HEPM cells, cell proliferation was assessed using a combination of cell numbers, thymidine uptake, CDK2 activity and Ki-67 expression. The results showed that silencing of p21 gene, although increased cell proliferation/numbers and CDK2 activity in normal HEPM cells, failed to counteract SAD-induced anti-proliferative effect despite inducing partial recovery of CDK2 activity. Similar effects were apparent with cyclin E overexpression. It is concluded that p21 and cyclin E are important for normal HEPM cell proliferation. However, SAD-induced deregulation of either protein, singly, may not be sufficient to induce anti-proliferative effect. Involvement of other cell cycle proteins such as cyclin D1 or of multiple proteins in SAD-induced cell cycle block needs to be examined.

Cell cycle progression and thus proper cell number is essential for normal development of organs and organisms. Craniofacial tissues including the secondary palate are vulnerable to disruption of cell cycle progression and proliferation by many chemicals including mycotoxin, secalonic acid D (SAD), glucocorticoids, retinoic acid and 2,3,7,8-tetrachlorodibenzodioxin. Induction of cleft palate (CP) by SAD in mice occurs from a reduction in the size of developing palatal shelves. This is associated with an inhibition of proliferation of murine and human embryonic palatal mesenchymal (MEPM and HEPM) cells as well as a G1/S block of cell cycle. In murine embryonic palates and HEPM cells, SAD inhibited G1/S-phase-specific cyclin-dependent kinase (CDK)2 activity, reduced the level of cyclin E and increased the level of the CDK2 inhibitor, p21. These results, together with those from other laboratories, suggest that common cell cycle protein targets (biomarkers), relevant to the pathogenesis of CP by multiple chemical exposures, that can form the basis for the diagnosis and the development of preventive strategies, are likely to exist.