Indole diketopiperazines from endophytic Chaetomium sp 88194 induce breast cancer cell apoptotic death

What are the 100 most cited fungal genera?

The global diversity of fungi has been estimated between 2 to 11 million species, of which only about 155 000 have been named. Most fungi are invisible to the unaided eye, but they represent a major component of biodiversity on our planet, and play essential ecological roles, supporting life as we know it. Although approximately 20 000 fungal genera are presently recognised, the ecology of most remains undetermined. Despite all this diversity, the mycological community actively researches some fungal genera more commonly than others. This poses an interesting question: why have some fungal genera impacted mycology and related fields more than others? To address this issue, we conducted a bibliometric analysis to identify the top 100 most cited fungal genera. A thorough database search of the Web of Science, Google Scholar, and PubMed was performed to establish which genera are most cited. The most cited 10 genera are Saccharomyces, Candida, Aspergillus, Fusarium, Penicillium, Trichoderma, Botrytis, Pichia, Cryptococcus and Alternaria. Case studies are presented for the 100 most cited genera with general background, notes on their ecology and economic significance and important research advances. This paper provides a historic overview of scientific research of these genera and the prospect for further research. Citation: Bhunjun CS, Chen YJ, Phukhamsakda C, Boekhout T, Groenewald JZ, McKenzie EHC, Francisco EC, Frisvad JC, Groenewald M, Hurdeal VG, Luangsa-ard J, Perrone G, Visagie CM, Bai FY, Błaszkowski J, Braun U, de Souza FA, de Queiroz MB, Dutta AK, Gonkhom D, Goto BT, Guarnaccia V, Hagen F, Houbraken J, Lachance MA, Li JJ, Luo KY, Magurno F, Mongkolsamrit S, Robert V, Roy N, Tibpromma S, Wanasinghe DN, Wang DQ, Wei DP, Zhao CL, Aiphuk W, Ajayi-Oyetunde O, Arantes TD, Araujo JC, Begerow D, Bakhshi M, Barbosa RN, Behrens FH, Bensch K, Bezerra JDP, Bilański P, Bradley CA, Bubner B, Burgess TI, Buyck B, Čadež N, Cai L, Calaça FJS, Campbell LJ, Chaverri P, Chen YY, Chethana KWT, Coetzee B, Costa MM, Chen Q, Custódio FA, Dai YC, Damm U, de Azevedo Santiago ALCM, De Miccolis Angelini RM, Dijksterhuis J, Dissanayake AJ, Doilom M, Dong W, Alvarez-Duarte E, Fischer M, Gajanayake AJ, Gené J, Gomdola D, Gomes AAM, Hausner G, He MQ, Hou L, Iturrieta-González I, Jami F, Jankowiak R, Jayawardena RS, Kandemir H, Kiss L, Kobmoo N, Kowalski T, Landi L, Lin CG, Liu JK, Liu XB, Loizides M, Luangharn T, Maharachchikumbura SSN, Makhathini Mkhwanazi GJ, Manawasinghe IS, Marin-Felix Y, McTaggart AR, Moreau PA, Morozova OV, Mostert L, Osiewacz HD, Pem D, Phookamsak R, Pollastro S, Pordel A, Poyntner C, Phillips AJL, Phonemany M, Promputtha I, Rathnayaka AR, Rodrigues AM, Romanazzi G, Rothmann L, Salgado-Salazar C, Sandoval-Denis M, Saupe SJ, Scholler M, Scott P, Shivas RG, Silar P, Souza-Motta CM, Silva-Filho AGS, Spies CFJ, Stchigel AM, Sterflinger K, Summerbell RC, Svetasheva TY, Takamatsu S, Theelen B, Theodoro RC, Thines M, Thongklang N, Torres R, Turchetti B, van den Brule T, Wang XW, Wartchow F, Welti S, Wijesinghe SN, Wu F, Xu R, Yang ZL, Yilmaz N, Yurkov A, Zhao L, Zhao RL, Zhou N, Hyde KD, Crous PW (2024). What are the 100 most cited fungal genera? Studies in Mycology 108: 1-411. doi: 10.3114/sim.2024.108.01.

UPLC-Q-TOF-MS/MS-Based Targeted Discovery of Chetomin Analogues from Chaetomium cochliodes

Chetocochliodin M (5) containing a rare cage-ring and chetocochliodin N (6) featuring an unusual piperazine-2,3-dione ring system together with known analogues chetomin (1), chetoseminudin C (2), chetocochliodin I (3), and oidioperazine E (4) were targeted for purification from the fungus Chaetomium cochliodes using a UPLC-Q-TOF-MS/MS approach. The structures of the new compounds were elucidated using HR-ESI-MS, NMR, and ECD spectra. Compounds 1, 3, and 6 exhibited strong cytotoxic activities against A549 and HeLa cancer cell lines.

Shielding Effects of Aromatic (Indole) Ring for Structural Analysis

This review provides a critical analysis of shielding effects induced by an aromatic (indole) ring of small molecules mainly including three members of naturally occurring secondary metabolites asterric acid analogs, diketopiperazines (DKPs) possessing an aromatic or an indole ring, and rubrolides. Empirical rules about the shielding effects induced by an aromatic (indole) ring are classified, based on which some 1H NMR chemical shift values in the A-ring and structures of asterric acid analogs are revised, and the relative configurations of some DKPs possessing an indole ring are also assigned or revised. The empirical rules could provide an efficient and convenient method for NMR data analysis and configuration determination for the three members of small molecules mentioned above.

Natural epidithiodiketopiperazine alkaloids as potential anticancer agents: Recent mechanisms of action, structural modification, and synthetic strategies

Cancer has become a grave health crisis that threatens the lives of millions of people worldwide. Because of the drawbacks of the available anticancer drugs, the development of novel and efficient anticancer agents should be encouraged. Epidithiodiketopiperazine (ETP) alkaloids with a 2,5-diketopiperazine (DKP) ring equipped with transannular disulfide or polysulfide bridges or S-methyl moieties constitute a special subclass of fungal natural products. Owing to their privileged sulfur units and intriguing architectural structures, ETP alkaloids exhibit excellent anticancer activities by regulating multiple cancer proteins/signaling pathways, including HIF-1, NF-κB, NOTCH, Wnt, and PI3K/AKT/mTOR, or by inducing cell-cycle arrest, apoptosis, and autophagy. Furthermore, a series of ETP alkaloid derivatives obtained via structural modification showed more potent anticancer activity than natural ETP alkaloids. To solve supply difficulties from natural resources, the total synthetic routes for several ETP alkaloids have been designed. In this review, we summarized several ETP alkaloids with anticancer properties with particular emphasis on their underlying mechanisms of action, structural modifications, and synthetic strategies, which will offer guidance to design and innovate potential anticancer drugs.

Novel indole diketopiperazine stereoisomers from a marine-derived fungus Aspergillus sp

Four dimeric diketopiperazine stereoisomers (1-4) including two new ones (1-2) had been isolated from the culture broth of one marine-derived fungus Aspergillus sp. Z3, which was found in the gut of a marine isopod Ligia exotica. The planner structures and absolute configurations of the new compounds were determined by combination of NMR, HRESIMS, electronic circular dichroism calculation, Marfey's method as well as single-crystal X-ray diffraction. Their cytotoxicity against the prostate cancer PC3 cell line was assayed by the MTT method.

Bioactive Microbial Metabolites in Cancer Therapeutics: Mining, Repurposing, and Their Molecular Targets

The persistence and resurgence of cancer, characterized by abnormal cell growth and differentiation, continues to be a serious public health concern critically affecting public health, social life, and the global economy. Hundreds of putative drug molecules of synthetic and natural origin were approved for anticancer therapy in the last few decades. Although conventional anticancer treatment strategies have promising aspects, several factors such as their limitations, drug resistance, and side effects associated with them demand more effort in repositioning or developing novel therapeutic regimens. The rich heritage of microbial bioactive components remains instrumental in providing novel avenues for cancer therapeutics. Actinobacteria, Firmicutes, and fungi have a plethora of bioactive compounds, which received attention for their efficacy in cancer treatment targeting different pathways responsible for abnormal cell growth and differentiation. Yet the full potential remains underexplored to date, and novel compounds from such microbes are reported regularly. In addition, the advent of computational tools has further augmented the mining of microbial secondary metabolites and identifying their molecular targets in cancer cells. Furthermore, the drug-repurposing strategy has facilitated the use of approved drugs of microbial origin in regulating cancer cell growth and progression. The wide diversity of microbial compounds, different mining approaches, and multiple modes of action warrant further investigations on the current status of microbial metabolites in cancer therapeutics. Hence, in this review, we have critically discussed the untapped potential of microbial products in mitigating cancer progression. The review also summarizes the impact of drug repurposing in cancer therapy and discusses the novel avenues for future therapeutic drug development against cancer.

Sulfur-Containing Compounds from Endophytic Fungi: Sources, Structures and Bioactivities

Endophytic fungi have attracted increasing attention as an under-explored source for the discovery and development of structurally and functionally diverse secondary metabolites. These microorganisms colonize their hosts, primarily plants, and demonstrate diverse ecological distribution. Among endophytic fungal natural products, sulfur-containing compounds feature one or more sulfur atoms and possess a range of bioactivities, e.g., cytotoxicity and antimicrobial activities. These natural products mainly belong to the classes of polyketides, nonribosomal peptides, terpenoids, and hybrids. Here, we reviewed the fungal producers, plant sources, chemical structures, and bioactivities of 143 new sulfur-containing compounds that were reported from 1985 to March 2022.

Putative Anticancer Compounds from Plant-Derived Endophytic Fungi: A Review

Endophytic fungi are microorganisms that exist almost ubiquitously inside the various tissues of living plants where they act as an important reservoir of diverse bioactive compounds. Recently, endophytic fungi have drawn tremendous attention from researchers; their isolation, culture, purification, and characterization have revealed the presence of around 200 important and diverse compounds including anticancer agents, antibiotics, antifungals, antivirals, immunosuppressants, and antimycotics. Many of these anticancer compounds, such as paclitaxel, camptothecin, vinblastine, vincristine, podophyllotoxin, and their derivatives, are currently being used clinically for the treatment of various cancers (e.g., ovarian, breast, prostate, lung cancers, and leukemias). By increasing the yield of specific compounds with genetic engineering and other biotechnologies, endophytic fungi could be a promising, prolific source of anticancer drugs. In the future, compounds derived from endophytic fungi could increase treatment availability and cost effectiveness. This comprehensive review includes the putative anticancer compounds from plant-derived endophytic fungi discovered from 1990 to 2020 with their source endophytic fungi and host plants as well as their antitumor activity against various cell lines.

4,6'-Anhydrooxysporidinone from Fusarium lateritium SSF2 Induces Autophagic and Apoptosis Cell Death in MCF-7 Breast Cancer Cells

Previous studies have reported that 4,6′-Anhydrooxysporidinone (SSF2-2), isolated from Fusarium lateritium SSF2, has neuroprotective effects on the HT-22 hippocampal neuronal cell line. However, the anti-cancer effect of SSF2-2 remains unclear. Here, we examined the viability of MCF-7 human breast cancer cells treated with SSF2-2 or left untreated using a cell viability assay kit. The underlying molecular mechanism was further investigated by Western blotting and immunocytochemistry studies. The results demonstrated that SSF2-2 inhibited the viability of MCF-7 cells. Treatment with SSF2-2 increased the levels of cleaved caspase-9, cleaved caspase-7, poly (ADP-ribose) polymerase (PARP), and LC3B. Additionally, SSF2-2 significantly increased the conversion of LC3-I to LC3II and LC3-positive puncta in MCF-7 cells.

Copper-catalyzed aerobic oxidative radical alkoxycyclization of tryptamines to access 3-alkoxypyrroloindolines

We report a copper-catalyzed alkoxycyclization of tryptamine derivatives with O₂ as the sole oxidant, leading to a variety of C3a-alkoxypyrroloindolines in good yields with high diastereoselectivities. This reaction involves an interesting double catalytic cycle in which copper-catalyzed carboamination cyclization is favored to form the C-3 radical pyrrolidinoindoline intermediate, then a copper-catalytic radical alkoxylation reaction proceeds smoothly.

Biologically Significant and Recently Isolated Alkaloids from Endophytic Fungi

A selection of the established and recently characterized alkaloids from the exploration of plant- and some marine-associated endophytic fungi is reviewed, with reference to alkaloids of biological significance.

Chaetocochin J, an epipolythiodioxopiperazine alkaloid, induces apoptosis and autophagy in colorectal cancer via AMPK and PI3K/AKT/mTOR pathways

Colorectal cancer (CRC) is the third commonly diagnosed malignancy and the second leading cause of cancer death worldwide. Development of novel chemotherapeutics is crucial. Natural products are the main source of drug discovery, and epipolythiodioxopiperazine (ETP) alkaloids are one kind of them have been reported to have potent biological activities. In the present study, we first isolated Chaetocochin J (CJ), an ETP alkaloid from the secondary metabolites of Chaetomium sp, and studied the anti-CRC activity and mechanism of it. The results showed that CJ exhibits potent proliferation inhibition effect, its IC₅₀ to CRC cells are around 0.5 µM. CJ also induces apoptosis of CRC cells in a dose-dependent manner, and this effect is stronger than topotecan. In addition, CJ treatment triggers autophagic flux in CRC cells, inhibition of autophagy by chloroquine didn't affect CJ-induced apoptosis and growth inhibition, suggesting CJ may simultaneously induced apoptosis and autophagy in CRC cells. We further explored the mechanism of action, and found that CJ exerts its anti-CRC function via AMPK and PI3K/AKT/mTOR pathways and further regulation of their downstream signaling cascade in CRC cells, including apoptosis and autophagy. These data potently suggest that CJ may be a potential drug candidate for CRC treatment.

Chemo-profiling of bioactive metabolites from Chaetomium globosum for biocontrol of Sclerotinia rot and plant growth promotion

Chaetomium globosum Kunze ex. Fries has been known to produce diverse bioactive metabolites, attracting researchers to exploit the biocontrol agent for plant disease management. However, distinct research gaps are visible regarding detail characterization of bioactive metabolites. Thus the current study has been planned to characterize volatile and nonvolatile compounds of most potential strain of C. globosum 5157. GC-MS analysis of hexane fraction revealed twenty-six volatile organic compounds, representing 65.5% of total components in which 3-octanone (21.4%) was found to be most abundant. UPLC-QTOF-MS/MS analysis of ethyl acetate and methanolic fractions resulted tentative characterization of fifteen and eleven metabolites, respectively. Among these, nine metabolites were isolated, purified and characterized using ¹H NMR and High resolution mass spectrometric analysis to delineate mass fragmentation pattern for the first time. Antifungal potential of hexane fraction exhibited high inhibitory action against Sclerotium rolfsii (139.2 μg mL^-1) whereas ethyl acetate fraction was highly effective against Sclerotinia sclerotiorum (112.1 μg mL^-1). Comparative assessment of C. globosum 5157 vis a vis Trichoderma harzianum A28 revealed promising effect of C. globosum 5157 with respect to antifungal properties and plant growth promotion of Brassica seedlings.

Chetocochliodins A-I, Epipoly(thiodioxopiperazines) from Chaetomium cochliodes

Nine new epipoly(thiodioxopiperazine) (ETP) analogues, chetocochliodins A-I (1-9), along with two known ones, chetoseminudins E and C (10 and 11), were purified from the fungus Chaetomium cochliodes. The planar structures and absolute configurations of these new compounds were determined by extensive NMR spectroscopic analysis, CD spectra, and chemical reactions. Shielding effects from the indole on the 3-SCH₃/3-OCH₃/3-OCH₂- groups facilitated the determination of relative configuration of the analogues. Compound 9 was cytotoxic, suggesting the importance of the sulfide bridge for the diketopiperazine bioactivities.

Nidulaxanthone A, a xanthone dimer with a heptacyclic 6/6/6/6/6/6/6 ring system from Aspergillus sp.-F029

Nidulaxanthone A (1), a xanthone dimer bearing an unprecedented heptacyclic 6/6/6/6/6/6/6 system, together with a new monomeric nidulalin D (2) and four known analogues (3, 4, 5 and 6), were isolated from Aspergillus sp. F029.

Discovery of Bioactive Indole-Diketopiperazines from the Marine-Derived Fungus Penicillium brasilianum Aided by Genomic Information

Identification and analysis of the whole genome of the marine-derived fungus Penicillium brasilianum HBU-136 revealed the presence of an interesting biosynthetic gene cluster (BGC) for non-ribosomal peptide synthetases (NRPS), highly homologous to the BGCs of indole-diketopiperazine derivatives. With the aid of genomic analysis, eight indole-diketopiperazines (1−8), including three new compounds, spirotryprostatin G (1), and cyclotryprostatins F and G (2 and 3), were obtained by large-scale cultivation of the fungal strain HBU-136 using rice medium with 1.0% MgCl₂. The absolute configurations of 1−3 were determined by comparison of their experimental electronic circular dichroism (ECD) with calculated ECD spectra. Selective cytotoxicities were observed for compounds 1 and 4 against HL-60 cell line with the IC₅₀ values of 6.0 and 7.9 μM, respectively, whereas 2, 3, and 5 against MCF-7 cell line with the IC₅₀ values of 7.6, 10.8, and 5.1 μM, respectively.

Anticancer potential of NF-κB targeting apoptotic molecule "flavipin" isolated from endophytic Chaetomium globosum

BACKGROUND

Anticancer compounds from natural sources have drawn attention due to their structural diversity and relatively lesser side effects. Endophytic fungi are one such natural resource from, which plethoras of anticancerous compounds have been isolated.

PURPOSE

The objective of the study was to isolate and characterize the bioactive metabolite from Chaetomium globosum that exhibits astonishing antiproliferative activity against cancerous cell lines.

METHODS

Flavipin was isolated by bioassay-guided fractionation and identified using FT-IR, EI-MS and NMR studies. MTT assay was used to determine the cytotoxicity. Fluorescent staining (AO/EB) and DNA fragmentation studies confirmed the occurrence of apoptosis. Real time PCR and Western blotting were used to analyze the expression of apoptosis related genes and its proteins, respectively.

RESULTS

Flavipin inhibited proliferation of A549, HT-29 and MCF-7 cancer cells in dose dependent manner with an IC₅₀ concentration of 9.89 µg/ml, 18 µg/ml and 54 µg/ml, respectively, whereas it was comparatively less sensitive (IC₅₀ = 78.89 µg/ml) against normal cell line (CCD-18Co). At IC₅₀ concentration cancerous cells exhibited cell shrinkage and fragmentation of DNA, which indicated that flavipin induced apoptotic cell death. In treated cells there is an up-regulation of p53 gene and its associated protein, whereas reciprocal expression was observed in BCL-2 gene and its protein. Furthermore, western blotting results also showed down-regulation of NFκB.

CONCLUSION

This is the first report on the antiproliferative activity of flavipin isolated from endophytic C. globosum and also proposed that interaction of flavipin with NFкB could be a possible mechanism for this activity. Flavipin induced apoptosis at low concentrations in cancer cell lines (A549, HT-29) and exhibited itself as a potential anticancer agent.

Cytotoxic and antimicrobial indole alkaloids from an endophytic fungusChaetomiumsp. SYP-F7950 ofPanax notoginseng

Two new compounds chetoseminudin F (1) and G (2) together with eleven known compounds were isolated from the solid fermentation products of the endophytic fungus Chaetomium sp. SYP-F7950. The structures of the isolated compounds were elucidated by extensive spectroscopic analyses, including 1D and 2D NMR, and HRFABMS experiments. The absolute configurations of chetoseminudin F (1) and G (2) were determined by comparing the electronic circular dichroism (ECD) spectrum with those of the reported references. A plausible biogenetic pathway for compounds 1–6 and 9–13 was proposed. These isolates were also evaluated for their antimicrobial and antitumor activity, revealing that chetoseminudin F (1) displayed more potent cytotoxicity against MDA-MB-231 cells with an IC₅₀ value of 26.49 μmol L⁻¹ more than the common chemotherapeutic agent (paclitaxel). In antimicrobial assay, compounds 6, 9, 11 and 12 had strong antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Enterococcus faecium and antifungal activity against Candida albicans with minimum inhibitory concentration (MIC) values ranging from 0.12 to 9.6 μg mL⁻¹; meanwhile compounds 6, 8, 9 and 12 exhibited strong cytotoxicity with IC₅₀ values of 2.75–8.68 μmol L⁻¹ against tumor cell lines A549 and MDA-MB-231. In addition, morphological observation showed that treatment with compounds 6, 9 and 12 increased the mean length of B. subtilis by 1.6 to 1.8-fold. In silico molecular docking was applied to study the binding interactions between the compounds and the active sites of filamentous temperature-sensitive protein Z (FtsZ) from B. subtilis. Compounds 6, 9 and 12 displayed the low binding energies, strong H-bond interactions with FtsZ. On the basis of the antimicrobial activities, cellular phenotype observation and docking studies, compounds 6, 9 and 12 are considered to be a promising antimicrobial inhibitor of FtsZ.

Two new compounds chetoseminudin F (1) and G (2) together with eleven known compounds were isolated from the solid fermentation products of the endophytic fungus Chaetomium sp. SYP-F7950.

Endophytic Fungus Isolated From Achyrocline satureioides Exhibits Selective Antiglioma Activity-The Role of Sch-642305

Glioblastoma is the most devastating primary brain tumor. Current treatment is palliative, making necessary the development of new therapeutic strategies to offer alternatives to patients. Therefore, endophytes represent an interesting source of natural metabolites with anticancer potential. These microorganisms reside in tissues of living plants and act to improve their growth. Evidence revealed that several medicinal plants are colonized by endophytic fungi producer of antitumor metabolites. Achyrocline satureioides is a Brazilian medicinal plant characterized by its properties against gastrointestinal disturbances, anticancer and antioxidant effects. However, there are no reports describing the endophytic composition of A. satureioides. The present study proposes the isolation of endophytic fungus from A. satureioides, extract preparation, phytochemical characterization and evaluation of its antiglioma potential. Our data showed that crude extracts of endophyte decreased glioma viability with IC50 values of 1.60-1.63 μg/mL to eDCM (dichloromethane extract) and 37.30-55.12 μg/mL to eEtAc (ethyl acetate extract), respectively. Crude extracts induced cell death by apoptosis with modulation of redox status. In order to bioprospect anticancer metabolites, endophytic fungus extracts were subjected to guided fractionation and purification yielded five fractions of each extract. Six of ten fractions showed selective antiproliferative activity against glioma cells, with IC50 values ranged from 0.95 to 131.3 μg/mL. F3DCM (from eDCM) and F3EtAc (from eEtAc) fractions promoted C6 glioma toxicity with IC50 of 1.0 and 27.05 μg/mL, respectively. F3EtAc fraction induced late apoptosis and arrest in G2/M stage, while F3DCM promoted apoptosis with arrest in Sub-G1 phase. Moreover, F3DCM increased antioxidant defense and decreased ROS production. Additionally, F3DCM showed no cytotoxic activity against astrocytes, revealing selective effect. Based on promising potential of F3DCM, we identified the production of Sch-642305, a lactone, which showed antiproliferative properties with IC50 values of 1.1 and 7.6 μg/mL to C6 and U138MG gliomas, respectively. Sch-642305 promoted arrest on cell cycle in G2/M inducing apoptosis. Furthermore, this lactone decreased glioma cell migration and modulated redox status, increasing superoxide dismutase and catalase activities and enhancing sulfhydryl content, consequently suppressing reactive species of oxygen generation. Taken together, these results indicate that metabolites produced by endophytic fungus isolated from A. satureioides have therapeutic potential as antiglioma agent.

Novel natural compounds from endophytic fungi with anticancer activity

Plant endophytes are microorganisms that live in healthy plant tissues in part or all of their life history without causing obvious symptoms of infection in the host plants. Endophytes, a new type of microbial resource that can produce a variety of biological constituents, have great values for research and broad prospects for development. This article reviewed the research and development progress of endophytic fungi with cytotoxic activity between 2014 and 2017, including endophytic fungi sources, microbial taxonomy, compound classification and cytotoxic activity. The results showed that the 109 strains of endophytic fungi belong to 3 phyla, 7 classes and 50 genera. The secondary metabolites mainly contained alkaloids, terpenes, steroids, polyketides, quinones, isocoumarins, esters etc. The results of this study provide references for the development of new antitumor drugs and endophytes resources.

Structural Diversity and Biological Activities of the Cyclodipeptides from Fungi

Cyclodipeptides, called 2,5-diketopiperazines (2,5-DKPs), are obtained by the condensation of two amino acids. Fungi have been considered to be a rich source of novel and bioactive cyclodipeptides. This review highlights the occurrence, structures and biological activities of the fungal cyclodipeptides with the literature covered up to July 2017. A total of 635 fungal cyclodipeptides belonging to the groups of tryptophan-proline, tryptophan-tryptophan, tryptophan-Xaa, proline-Xaa, non-tryptophan-non-proline, and thio-analogs have been discussed and reviewed. They were mainly isolated from the genera of Aspergillus and Penicillium. More and more cyclodipeptides have been isolated from marine-derived and plant endophytic fungi. Some of them were screened to have cytotoxic, phytotoxic, antimicrobial, insecticidal, vasodilator, radical scavenging, antioxidant, brine shrimp lethal, antiviral, nematicidal, antituberculosis, and enzyme-inhibitory activities to show their potential applications in agriculture, medicinal, and food industry.

Secondary metabolites from endophytic fungus Chaetomium sp. induce colon cancer cell apoptotic death

A rare depsipeptide, chaetomiamide A (1), together with two known diketopiperazines (2, 3) were isolated from the cultures of endophytic fungus Chaetomium sp., which was isolated from the root of Cymbidium goeringii. Compound 1 represents a rare skeleton with a 13-membered ring system. It structure was established on the basis of spectroscopic data interpretation. The configuration of 1 was determined by NOESY and Marfey's analysis. These isolates were evaluated for anticancer activity and 3 displayed more potent cytotoxicity than the positive control cisplatin associated with G2/M cell cycle arrest. In addition, 3 induced apoptosis via caspase-3 induction and PARP cleavage, concomitantly with the increase of Bax and decrease of Bcl-2.

Crocetin shifts autophagic cell survival to death of breast cancer cells in chemotherapy

The chemotherapy with fluorouracil is not always effective, in which some breast cancer cells may survive the fluorouracil treatment through enhanced autophagy. Crocetin is the major constituent of saffron, a Chinese traditional herb, which has recently found to have multiple pharmacological effects, including anticancer. However, the effects of Crocetin on the outcome of fluorouracil therapy for breast cancer have not been studied. Here, we showed that fluorouracil treatment inhibited the growth of breast cancer cells, in either a Cell Counting Kit-8 assay or an MTT assay. Inhibition of autophagy further suppressed breast cancer cell growth, suggesting that the breast cancer cells increased autophagic cell survival during fluorouracil treatment. However, Crocetin significantly increased the suppressive effects of fluorouracil on breast cancer cell growth, without affecting either cell apoptosis or autophagy. Inhibition of autophagy at the presence of Crocetin partially abolished the suppressive effects on breast cancer cell growth, suggesting that Crocetin may increase autophagic cell death in fluorouracil-treated breast cancer cells. Furthermore, Crocetin decreased Beclin-1 levels but increased ATG1 levels in fluorouracil-treated breast cancer cells. Together, these data suggest that Crocetin may shift autophagic cell survival to autophagic cell death in fluorouracil-treated breast cancer cells, possibly through modulation of the expression of ATG1 and Beclin-1.

Inhibition of biofilm in Bacillus amyloliquefaciens Q-426 by diketopiperazines

Biofilm formation can make significant effects on bacteria habits and biological functions. In this study, diketopiperazines (DKPs) produced by strain of Bacillus amyloliquefaciens Q-426 was found to inhibit biofilm formed in the gas-liquid interface. Four kinds of DKPs were extracted from B. amyloliquefaciens Q-426, and we found that 0.04 mg ml(-1) DKPs could obviously inhibit the biofilm formation of the strain. DKPs produced by B. amyloliquefaciens Q-426 made a reduction on extracellular polymeric substance (EPS) components, polysaccharides, proteins, DNAs, etc. Real-time PCR was performed to determine that whether DKPs could make an obvious effect on the expression level for genes related to biofilm formation in the strain. The relative expression level of genes tasA, epsH, epsG and remB which related to proteins, extracellular matrix, and polysaccharides, were downregulated with 0.04 mg ml(-1) DKPs, while the expression level of nuclease gene nuc was significantly upregulated. The quantitative results of the mRNA expression level for these genes concerted with the quantitative results on EPS levels. All of the experimental results ultimately indicated that DKPs could inhibit the biofilm formation of the strain B. amyloliquefaciens Q-426.

Fungal endophyte-derived Fritillaria unibracteata var. wabuensis: diversity, antioxidant capacities in vitro and relations to phenolic, flavonoid or saponin compounds

Diverse fungal endophytes are rich fungal resources for the production of an enormous quantity of natural products. In the present study, 53 fungal endophytes were isolated from the bulbs of Fritillaria unibracteata var. wabuensis (FUW). Of these, 49 strains were identified and grouped into 17 different taxa, and priority was conferred to the Fusarium genus. All fungal fermented filtrates displayed antioxidant activities. The DPPH activity, total antioxidant capacities (ABTS), reduction power (FRAP), total phenolic content (TPC), total flavonoid content (TFC) and total saponin content (TSC) were evaluated using petroleum ether, ethyl acetate, n-butyl alcohol and ethanol fractions extracted from five representative fungal cultures. The last three fractions showed more potent antioxidant activity than the first fraction. Significant positive correlations were found between the compositions (TPC, TFC and TSC) and antioxidant capacities (DPPH, ABTS and FRAP). In addition, multifarious natural antioxidant components were identified from the fungal extracts, including gallic acid, rutin, phlorizin, 2,4-di-tert-butylphenol and 2,6-di-tert-butyl hydroquinone; these were determined preliminarily by TLC-bioautography, HPLC and GC-MS analysis. This study showed abundant fungal resources in FUW. Phenolics, flavonoids and saponins are crucial bioactive constituents in these abundant fungal endophytes and can be viewed as new potential antioxidant resources.

Pyrophen Produced by Endophytic Fungi Aspergillus sp Isolated from Piper crocatum Ruiz and Pav Exhibits Cytotoxic Activity and Induces S Phase Arrest in T47D Breast Cancer Cells

Ethyl acetate extracts obtained from culture of endophytic fungi Aspergillus sp isolated from Piper crocatum Ruiz and Pav, have been shown to possess cytotoxic activity against T47D breast cancer cells. Investigations were here conducted to determine bioactive compounds responsible for the activity. Bioassay guided fractionation was employed to obtain active compounds. Structure elucidation was performed based on analysis of LC-MS, 1H-NMR, 13C-NMR, COSY, DEPT, HMQC, HMBC data. Cytotoxity assays were conducted in 96 well plates against T47D and Vero cell lines. Bioassay guided isolation and chemical investigation led to the isolation of pyrophen, a 4-methoxy-6-(1'-acetamido-2'-phenylethyl)-2H-pyran-2-one. Further analysis of its activity against T47D and Vero cells showed an ability to inhibit the growth of T47D cells with IC50 values of 9.2 μg/mL but less cytotoxicity to Vero cells with an IC50 of 109 μg/mL. This compound at a concentration of 400 ng/mL induced S-phase arrest in T47D cells.

Antifungal potential of marine natural products

Fungal diseases represent an increasing threat to human health worldwide which in some cases might be associated with substantial morbidity and mortality. However, only few antifungal drugs are currently available for the treatment of life-threatening fungal infections. Furthermore, plant diseases caused by fungal pathogens represent a worldwide economic problem for the agriculture industry. The marine environment continues to provide structurally diverse and biologically active secondary metabolites, several of which have inspired the development of new classes of therapeutic agents. Among these secondary metabolites, several compounds with noteworthy antifungal activities have been isolated from marine microorganisms, invertebrates, and algae. During the last fifteen years, around 65% of marine natural products possessing antifungal activities have been isolated from sponges and bacteria. This review gives an overview of natural products from diverse marine organisms that have shown in vitro and/or in vivo potential as antifungal agents, with their mechanism of action whenever applicable. The natural products literature is covered from January 2000 until June 2015, and we are reporting the chemical structures together with their biological activities, as well as the isolation source.

Spiro[pyrrolidine-3, 3´-oxindole] as potent anti-breast cancer compounds: Their design, synthesis, biological evaluation and cellular target identification

The spiro[pyrrolidine-3, 3´-oxindole] moiety is present as a core in number of alkaloids with substantial biological activities. Here in we report design and synthesis of a library of compounds bearing spiro[pyrrolidine-3, 3´-oxindole] motifs that demonstrated exceptional inhibitory activity against the proliferation of MCF-7 breast cancer cells. The synthesis involved a one pot Pictet Spengler-Oxidative ring contraction of tryptamine to the desired scaffolds and occurred in 1:1 THF and water with catalytic trifluoroacetic acid and stoichiometric N-bromosuccinimide as an oxidant. Phenotypic profiling indicated that these molecules induce apoptotic cell death in MCF-7 cells. Target deconvolution with most potent compound 5l from the library, using chemical proteomics indicated histone deacetylase 2 (HDAC2) and prohibitin 2 as the potential cellular binding partners. Molecular docking of 5l with HDAC2 provided insights pertinent to putative binding interactions.

Neolignans with a Rare 2-Oxaspiro[4.5]deca-6,9-dien-8-one Motif from the Stem Bark of Cinnamomum subavenium

Two pairs of racemic spirodienone neolignans with a rare 2-oxaspiro[4.5]deca-6,9-dien-8-one motif, named (±)-subaveniumins A (1) and B (2), were isolated from the bark of Cinnamomum subavenium. The chiral separation of the (+)-1, (-)-1, (+)-2, and (-)-2 enantiomers was accomplished via high-performance liquid chromatography on a chiral column. Their structures were elucidated using single-crystal X-ray diffraction and spectroscopic analyses (UV, IR, HRESIMS, and 1D and 2D NMR). The absolute configurations of the enantiomers were determined by comparing the experimental and calculated electronic circular dichroic spectra. The (+)-1, (-)-1, (+)-2, and (-)-2 enantiomers exhibited moderate inhibitory effects against NO production in RAW264.7 mouse macrophages induced by lipopolysaccharide, with IC50 values of 17.9, 5.6, 15.1, and 4.3 μM, respectively.