This study reports the chemical investigation and bioactivity of the secondary metabolites produced by the endophytic fungus Fusarium solani isolated from Cassia alata Linn. growing in Bangladesh. This plant was collected from conservation forest in Bangladesh and belongs to the Caesalpiniaceae family. The endophytic fungus Fusarium solani was isolated from the tissue of root of this plant. The fungal strain was identified by morphological characters and DNA sequencing. The crude organic extract of the fungal strain was proven to be active when tested for cytotoxicity against Brine Shrimp Lethality Bioassay, antimicrobial and antioxidant activity. The bioactivity guided fractionation of the ethyl acetate extract leads to the isolation of seven secondary metabolites in pure form. The structures of the isolated compounds were determined by the analysis of NMR and mass spectroscopic data. Bioassay investigation of the isolated secondary metabolites suggested aza-anthraquinones are more potent bioactive compounds as anticancer and antimicrobial agent.

Endophytes have the potential to synthesize various bioactive secondary metabolites. The aim of the study was to find new cytotoxic and antibacterial metabolites from endophytic fungus, Cladosporium sp. isolated from the leaves of Rauwolfia serpentina (L.) Benth. ex Kurz. (Fam: Apocyanaceae). The endophytic fungus was grown on potato dextrose agar medium and extracted using ethyl acetate. Secondary metabolites were isolated by chromatographic separation and re-crystallization, and structures were confirmed by 1H NMR, 13C NMR and mass spectroscopic data. The cytotoxicity was determined by WST-1 assay and brine shrimp lethality bioassay, while antibacterial activity was assessed by disc diffusion method. Two naphthoquinones, namely anhydrofusarubin (1) and methyl ether of fusarubin (2), were isolated from Cladosporium sp. The isolated compounds 1 and 2, by WST-1 assay against human leukemia cells (K-562) showed potential cytotoxicity with IC50 values of 3.97 μg/mL and 3.58 μg/mL, respectively. Initial screening of crude ethyl acetate extract and column fractions F-8 and F-10 exhibited noticeable cytotoxicity to brine shimp nauplii with LC50 values of 42.8, 1.2 and 2.1 μg/mL, respectively. Moreover, the isolated compound 2 (40 μg/disc) showed prominent activities against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Bacillus megaterium with an average zone of inhibition of 27 mm, 25 mm, 24 mm and 22 mm, respectively and the activities were compared with kanamycin (30 μg/disc). Our findings indicate that anhydrofusarubin (1) and methyl ether of fusarubin (2) might be useful lead compounds to develop potential cytotoxic and antimicrobial drugs.

Holigarna caustica (Dennst.), a popular plant used in folk medicine in Bangladesh, is often used by the local folk practitioner to treat a variety of chronic diseases. The present research is an attempt to find out an innovative therapeutic prospect for the management of neuropsychiatric disorders. The methanol extract of H. caustica leaves (MEHC) were utilized on various behavioral tests for assessing anxiolytic, anti-depressant, and anti-inflammatory activities. The antioxidant potentials and quantitative phytochemicals were evaluated through spectrophotometric methods. Results revealed that treatment of MEHC (200 and 400 mg/kg) significantly reduced anxiety like behaviors in mice, particularly, 400 mg/kg efficiently improved % of entries and time spent (p < 0.05) in the open arms in elevated plus maze test, whereas, superior head dipping tendency (p < 0.05) was observed in hole-board test. In contrast, mice treated with 200 mg/kg revealed better anxiolytic effect in both open field and hole-cross tests. During antidepressant evaluation, mice administrated with MEHC exhibited active behaviors (swimming and struggling) in forced swimming and tail suspension tests. In parallel, MEHC manifested a noteworthy (p < 0.001) suppression of inflammatory response induced by histamine. The MEHC also showed strong antioxidant activities in 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) (IC₅₀: 57.64 μg/mL) scavenging, H₂O₂ (IC₅₀: 51.60 μg/mL) scavenging, and ferric reducing power assay. The levels of total phenol, flavonoid, flavonol, condensed tannin, and antioxidant were estimated as higher in MEHC. Moreover, 11 compounds were documented as bioactive, displayed good binding affinities to potassium channel receptor, human serotonin receptor, cyclooxygenase (COX-1 and 2), and xanthine oxidoreductase enzyme targets in molecular docking experiments. Furthermore, ADME/T and Prediction of Activity Spectra for Substances (PASS) analyses exposed their drug-likeness, nontoxic upon consumption, and likely pharmacological actions. Overall, the H. caustica is potentially bioactive as evident by in vivo, in vitro, and computational analysis. Our findings support the folkloric value of this plant, which may provide a potential source towards developing drug leads.

This study explored the great potential of endophytic fungi associated with red seaweed Gracilaria sp. and brown seaweed Sargassum sp. of the Bay of Bengal, Bangladesh, for the first time. Endophytic fungi were identified taxonomically by morphological features and molecular characterisation (ITS sequence). The identification of six fungal isolates revealed five different fungal species belonging to four genera, namely, Aspergillus subversicolor, A. terreus and Cladosporium halotolerans isolated from Gracilaria sp. and Chaetomium globosum, A. terreus and Curvularia perotidis isolated from Sargassum sp. The ethyl acetate extracts of fungal endophytes were evaluated for antimicrobial activity, DPPH radical scavenging activity, and brine shrimp lethality bioassay. Amongst all the fungal extracts evaluated in this study, four showed mild to moderate inhibitory activity (10–14 mm) against the tested bacterial strains. Exceptionally, Chaetomium globosum exerted significant antibacterial activity with the highest zone of inhibition (21 ± 0.3 mm) against the Gram-negative bacterial strain Pseudomonas aeruginosa and also showed moderate antifungal activity (13 ± 0.9 mm) against A. niger. Sargassum sp.-derived A. terreus exhibited the strongest DPPH radical scavenging activity (IC₅₀ value of 7.88 ± 0.09 µg/mL). All the fungal extracts have significant lethality against brine shrimp nauplii (LC₅₀ value of ≤ 20.39 ± 4.04 µg/mL), while Curvularia perotidis and Cladosporium halotolerans were the most effective (LC₅₀ values of 9.30 ± 2.96 µg/mL and 9.94 ± 3.49 µg/mL, respectively). Gas chromatography-mass spectrometry (GC-MS) analysis of the crude extracts identified the presence of several chemical compounds. These bioactive chemical constituents might contribute to the exhibited bioactivity in this study. The current study’s findings support the beneficial impacts of the fungal endophytes on exerting biological activities and consequently as valuable resources of bioactive compounds.

Background: Due to increasing number of individuals within the world having health issues caused by varied cancers, drug-resistant microorganism, parasitic protozoans, and fungi could be a cause for alarm. Endophyte’s are a unique source of medicinal compounds which requires an intensive seek for newer and simpler agents to handle these sickness issues is currently advancing. This study explores the description of endophytic fungi of Ceriops decandra (Griff.) W. Theob., a mangrove plant growing in mangrove forest, Sundarban, Bangladesh. Methods: The endophytic fungi of experimental plants were identified by DNA amplification and sequencing of the internal transcribed spacer (ITS) region Moreover, cytotoxicity, antioxidant and antimicrobial tests were assessed. In addition, the screening of extracts was performed by visual detection using UV light. Results: Three fungi namely CEDBE-1, CEDLE-6 and CEDLE-10 (internal strain no) were isolated as endophytic fungi and identified as Fusarium oxysporum, Clonostachys spp. and Fusarium solani respectively on the basis of morphological characteristics and DNA sequencing. The isolates were cultured at 28⁰ C±2 for 21 days in Potato Dextrose Agar (PDA) media. The extracts of fungal isolates were examined at 100 µg/disc concentration for the screening of antibacterial activity and exhibited no activity against tested human pathogenic bacteria. The strain CEDBE-1 showed highest antioxidant activity of IC₅₀ value of 31.07 µg/mL comparing with the positive control ascorbic acid (0.74) and BHA (7.79) µg/mL. All isolates exhibited strong cytotoxic activity using brine shrimp lethality bioassay compared with the positive control tamoxifen. Preliminary chemical screening of the fungal extracts by thin layer chromatography technique revealed the presence of various compounds. Conclusions: The findings indicate that endophytic fungal isolates explored from C. decandra has diversified biological activities which may be potential source of leads for new drug development.