Antimicrobial activities of secondary metabolites of endophytic fungi isolated from Catharanthus roseus

Introduction: Recently, several endophytes have been shown to possess the potentials to synthesize novel bioactive compounds that have found use for drug discovery. We isolated endophytic fungi associated with Catharanthus roseus collected from the river banks of Amassoma in Southern Nigeria, and identified some of their bioactive secondary metabolites. Methods: The fungi were subjected to solid-state fermentation on rice medium and the metabolites were extracted using ethyl acetate. The fungal crude extracts were screened for antimicrobial activity and were also subjected to high-performance liquid chromatography-diode-array detection (HPLC-DAD) analysis for the identification of the bioactive compounds. Results: The fungal extracts showed both antibacterial and antifungal activities with minimum inhibitory concentrations ranging from 0.0625 to 1 mg/mL. The HPLC-DAD analysis of the extracts suggested the presence of citreoisocoumarin, citreoisocoumarinol, questinol, hydroxyemodin, acropyrone, methyl 2-(4-hydroxyphenyl) acetate, nigricinol, and cladosporin. Conclusion: The results of this study suggest that endophytic fungi associated with C. roseus could be a promising source of novel bioactive compounds with pharmaceutical and industrial importance

Antimicrobial activities of secondary metabolites of endophytic fungi isolated from Catharanthus roseus

Introduction: Recently, several endophytes have been shown to possess the potentials to synthesize novel bioactive compounds that have found use for drug discovery. We isolated endophytic fungi associated with Catharanthus roseus collected from the river banks of Amassoma in Southern Nigeria, and identified some of their bioactive secondary metabolites. Methods: The fungi were subjected to solid-state fermentation on rice medium and the metabolites were extracted using ethyl acetate. The fungal crude extracts were screened for antimicrobial activity and were also subjected to high-performance liquid chromatography-diode-array detection (HPLC-DAD) analysis for the identification of the bioactive compounds. Results: The fungal extracts showed both antibacterial and antifungal activities with minimum inhibitory concentrations ranging from 0.0625 to 1 mg/mL. The HPLC-DAD analysis of the extracts suggested the presence of citreoisocoumarin, citreoisocoumarinol, questinol, hydroxyemodin, acropyrone, methyl 2-(4-hydroxyphenyl) acetate, nigricinol, and cladosporin. Conclusion: The results of this study suggest that endophytic fungi associated with C. roseus could be a promising source of novel bioactive compounds with pharmaceutical and industrial importance

Biologically active phenolic acids produced by Aspergillus sp., an endophyte of Moringa oleifera

This study investigates the secondary metabolites of an endophytic Aspergillus sp. isolated from leaves of M. oleifera growing in Anambra State, South-Eastern Nigeria. Antimicrobial and antioxidant screening of the fungal extract and isolated compounds, as well as cytotoxicity assay of the extract against cisplatin-sensitive A2780 (sens) and cisplatin-resistant A2780 (cisR) ovarian cancer cell lines were carried out using standard methods. Chemical investigations of the fungal extract involving a combination of different chromato-graphic methods and spectroscopic techniques were carried out to isolate and characterize the constituents of the extract. At a concentration range of 1-4 mg/ml, the crude extract of Aspergillus sp. showed mild antimicrobial activity against Bacillus subtilis, Klebsiella pneumoniae, and Candida albicans. The fungal extract showed good antioxidant activity at 500 µg/ml, with an inhibition of 72.1%. Also, at 100 µg/ml, the extract showed excellent cytotoxic activity against A2780 (sens) and A2780 (cisR), with growth inhibitions of 105.1% and 105.5% respectively. Two known pharmacologically active phenolic compounds (p-hydroxyphenyl acetic acid and ferulic acid) were isolated from the fermentation extract of the endophytic fungus. At 250 µg/ml, ferulic acid exhibited an excellent antioxidant activity with an inhibition of 90.4%, while an inhibition of 35.4% was recorded for p-hydroxyphenyl acetic acid. Ferulic acid also showed a mild antifungal activity at 500 µg/ml against A. niger with an IZD of 2 mm. p-Hydroxyphenyl acetic acid showed no antimicrobial activity. These results further confirm the potentials of endophytic fungi associated with Nigerian plants as source of bioactive compounds with pharmaceutical or industrial applications. DOI: http://dx.doi.org/10.5281/zenodo.140498

Screening of endophytic fungal metabolites from Cola nitida leaves for antimicrobial activities against clinical isolates of Pseudomonas aeruginosa

Endophytic fungi of selected Nigerian plants are important sources of bioactive products with enormous potentials for the discovery of new drug molecules for drug development. Pseudomonas aeruginosa is one of the major causes of healthcare-associated bacterial infections, leading to increased mortality and morbidity. In this study, isolated endophytic fungi from Cola nitida were screened for anti-pseudomonas properties. Endophytic fungi associated with healthy leaves of C. nitida were isolated using standard methods. Fungi were identified through their morphological, cultural and microscopic characteristics. The fungi were subjected to solid-state fermentation and secondary metabolites extracted using ethyl acetate and concentrated under vacuum. The crude extracts were screened for antimicrobial activity against clinical and laboratory strains of Pseudomonas aeruginosa using the agar diffusion method. The bioactive components of the fungal extracts were identified using High-Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD) analysis. Three endophytic fungi; Acremonium sp., Aspergillus sp. and Trichophyton sp. were isolated. At 1 mg/ml, extracts of the three fungi displayed antipseudomonal activity with inhibition zone diameter ranging from 6 - 4 mm. HPLC-DAD analysis revealed the presence of compounds, such as 4-hydroxyphenyl acetate. indole-3-acetic acid, and protocatechuic acid among others in the fungal extracts. The findings in this study reveal that endophytic fungi associated with C. nitida possess promising antipseudomonal properties. This finding can open new doors for the discovery of new agents against P. aeruginosa

Toxic, but beneficial compounds from endophytic fungi of Carica papaya

Fungi remain a promising source of novel biologically active compounds with potentials in drug discovery and development. This study was aimed at investigating the secondary metabolites from endophytic Fusarium equiseti and Epicoccum sorghinum associated with leaves of Carica papaya collected from Agulu, Anambra State, Nigeria. Isolation of the endophytic fungi, taxonomic identification, fermentation, extraction and isolation of fungal secondary metabolites were carried out using standard procedures. Chromatographic separation and spectroscopic analyses of the fungal secondary metabolites yielded three toxigenic compounds - equisetin and its epimer 5’- epiequisetin from F. equiseti and tenuazonic acid from E. sorghinum These compounds are known to possess several beneficial biological properties that can be explored for pharmaceutical, agricultural or industrial purposes

Antimicrobial Properties and Characterization of Secondary Metabolites Obtained from Curvularia lunata, an Endophyte of Azadirachta indica

Background: Endophyte phytochemicals have piqued interest in drug development programs due to their enormous potential for assisting in the discovery of novel biologically active compounds. Aim and objectives: The study was aimed to isolate, evaluate the antimicrobial properties and characterize the secondary metabolites of Curvularia lunata endophyte isolated from A. indica. Method: C. lunata isolated from A. indica leaves using standard extraction protocols were screened for their potential antimicrobial activities using agar diffusion well method. HPLC-DAD, GC-FID, GC-MS, and FTIR techniques were used to characterize secondary metabolites. Results: At 1 mg/mL, growth inhibition of bacteria by the extracts of C. lunata were observed with Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis, and Candida albicans with zones of inhibition diameters of 6, 5, 4, and 4 mm respectively.  The vacuum liquid chromatography sub-fraction of the extract showed the best antimicrobial activity. HPLC-DAD analysis revealed the presence of 2-carboxymethyl-3-n-hexylmaleic acid anhydride and aspernigin A. GC-FID analysis showed remarkably high concentrations of flavonones and catechins. The results of GC-MS analysis also showed the presence of hexadecanoic acid, and 1,6-Anhydro-beta-D-glucopyranose. FTIR results established the presence of functional groups like carboxylic acids, which may be associated with some of the detected compounds. Conclusion: C. lunata (OM337582) extract of A. indica have potent antimicrobial activity which could be related to a high content of flavonoids and alkaloids. Keywords: Antimicrobial, Azadirachta indica, HPLC-DAD, Chromatography, Curvularia lunata

Biologically active phenolic acids produced by Aspergillus sp., an endophyte of Moringa oleifera

This study investigates the secondary metabolites of an endophytic Aspergillus sp. isolated from leaves of M. oleifera growing in Anambra State, South-Eastern Nigeria. Antimicrobial and antioxidant screening of the fungal extract and isolated compounds, as well as cytotoxicity assay of the extract against cisplatin-sensitive A2780 (sens) and cisplatin-resistant A2780 (cisR) ovarian cancer cell lines were carried out using standard methods. Chemical investigations of the fungal extract involving a combination of different chromato-graphic methods and spectroscopic techniques were carried out to isolate and characterize the constituents of the extract. At a concentration range of 1-4 mg/ml, the crude extract of Aspergillus sp. showed mild antimicrobial activity against Bacillus subtilis, Klebsiella pneumoniae, and Candida albicans. The fungal extract showed good antioxidant activity at 500 µg/ml, with an inhibition of 72.1%. Also, at 100 µg/ml, the extract showed excellent cytotoxic activity against A2780 (sens) and A2780 (cisR), with growth inhibitions of 105.1% and 105.5% respectively. Two known pharmacologically active phenolic compounds (p-hydroxyphenyl acetic acid and ferulic acid) were isolated from the fermentation extract of the endophytic fungus. At 250 µg/ml, ferulic acid exhibited an excellent antioxidant activity with an inhibition of 90.4%, while an inhibition of 35.4% was recorded for p-hydroxyphenyl acetic acid. Ferulic acid also showed a mild antifungal activity at 500 µg/ml against A. niger with an IZD of 2 mm. p-Hydroxyphenyl acetic acid showed no antimicrobial activity. These results further confirm the potentials of endophytic fungi associated with Nigerian plants as source of bioactive compounds with pharmaceutical or industrial applications. DOI: http://dx.doi.org/10.5281/zenodo.140498

Antimicrobial and Antioxidant Activities of Secondary Metabolites of an Endophytic fungus of Azadirachta indica

Background: Recent upsurge in the mortality rate and long hospital stays as a result of antimicrobial resistance caused by multi-drug resistant bacteria is a huge burden to public health sector. Intensive search for more effective and newer agents to deal with these problems. Endophytes are a novel source of potentially useful medicinal compounds. Aim: The study aimed at evaluating the antimicrobial and antioxidant activities of an endophytic fungus isolated from Azadirachta indica against multi drug resistant bacteria species. Method: Endophytic fungus was isolated from fresh leaves of Azadirachta indica. The fungus was fermented in rice medium, and the secondary metabolites were extracted. The antimicrobial activity of the extract against laboratory strains of Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia and Bacillus subtilis, Candida albicans, Aspergillus niger) was determined. The fungal extract was also evaluated for antioxidant activity using the DPPH assay method. Using GC-FID analysis, some constituents of the fungal extracted were identified. Result: At 1 and 0.5 mg/mL, the fungal extract demonstrated antibacterial activity against Klebsiella pneumoniae but no activity against the other test microbes. However, the fungal extract of A. indica showed excellent antioxidant activity due to possession of bioactive secondary metabolites. Conclusion: The result of GC-FID showed the presence of Rutin, Lunamarin, Anthocyanin, Catechin, Naringenin, Flavan 3 ol, Sapogernin, Tannin, Spartein, Naringin, Flavonones, Steroids, Kaemferol, Cyanogenic glycoside, Phytate, Epicatechin, Reseveratol, Cardic glycoside and Epihedrine at different concentrations. This study reveals the dynamic potentials of the endophytic fungus of A. indica as the bedrock of naturally occurring bioactive agent.  Keywords: Azadirachta indica, endophytes, GC-FID, secondary metabolites, medicinal plants, phytochemicals

A new benzophenone glycoside from the leaves of <i>Mitracarpus villosus</i>

<p>A new benzophenone glycoside, mitraphenone A (<b>1</b>), together with three known compounds (<b>2</b>–<b>4</b>) were isolated from the leaves of the traditionally used medicinal plant <i>Mitracarpus villosus</i> (Rubiaceae) collected in Nigeria. A combination of one- and two-dimensional NMR spectroscopic and mass spectrometric measurements were carried out to identify the structure of <b>1</b>. All isolated compounds (<b>1</b>–<b>4</b>) were screened for their antibacterial activity against several Gram-positive and Gram-negative bacteria. Compound <b>1</b> exhibited moderate activity against <i>Enterococcus faecium</i> (strains ATCC 35667 and ATCC 700221) and <i>Staphylococcus aureus</i> ATCC 25923 with MIC values ranging from 25 to 50 μM.</p

New amide and dioxopiperazine derivatives from leaves of Breynia nivosa

The first chemical investigation of leaves of Breynia nivosa from Nigeria resulted in the isolation of two new amide derivatives breynivosamides A and B (1 and 2) and two new dioxopiperazine derivatives breynivosines A and B (4 and 5) together with seven known compounds (3, 6–11). The structures of the new compounds were elucidated by 1D, 2D NMR and HRESIMS data as well as by comparison with the literature. All isolated compounds were tested for the cytotoxic and antimicrobial activities. Only cristatin A (6) showed cytotoxicity against the L5178Y mouse lymphoma cell line with an IC50 value of 13.9 μM while breynivosamide A (1) exhibited moderate antimicrobial activity against Mycobacterium tuberculosis with an MIC value of 25 μM