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

Evaluation of Antioxidant, Anti-inflammatory and Antimicrobial Activities of the Leaf Extracts of Luffa cylindrica

Introduction: Luffa cylindrica have been used traditionally in the treatment and management of several disease conditions. This study aimed to evaluate the antioxidant, anti-inflammatory and antimicrobial properties of leaf extracts of the plant, and identifying some of its phytoconstituents. Methods: The crude ethanol and ethyl acetate extracts were evaluated for antioxidant and anti-inflammatory activities using the 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) and paw-fluid displacement methods, respectively. The extracts were tested for antimicrobial activity using the agar well diffusion and agar dilution methods. The ethyl acetate leaf extract of the plant was further subjected to high-performance liquid chromatography-diode-array detection (HPLC-DAD) analysis for the identification of the bioactive compounds. Results: The ethanol and ethyl acetate extracts of L. cylindrica showed average antioxidant properties at 100 µg/mL, with inhibitions of 53.31% and 54.73% respectively. The ethanol extract displayed significant anti-inflammatory activity at 50 mg/Kg with an inhibition of 31.1% compared to 39.7% recorded for the control (diclofenac). The ethyl acetate extract produced an inhibition of 15%. In the antimicrobial evaluation, the ethanol and ethyl acetate extracts showed moderate antibacterial activity against S. aureus, S. Typhi and B. subtilis. The ethyl acetate extract exhibited considerable antimicrobial activity against the test isolates compared to the ethanol extract. HPLC-DAD analysis of the ethyl acetate extract suggested the presence of two flavonoid compounds - luteolin and apigenin as key components of the leaf extract of L. cylindrica. These compounds are known to possess anti-inflammatory, antioxidant and antimicrobial activities. Conclusions: The results of this study showed that the leaf extracts of L. cylindrica possess antioxidant, anti-inflammatory and antimicrobial properties

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

Secondary Metabolites of the Lichen-Associated Fungus Apiospora montagnei

The endolichenic fungus Apiospora montagnei isolated from the lichen Cladonia sp. was cultured on solid rice medium, yielding the new diterpenoid libertellenone L (1), the new pyridine alkaloid, 23-O-acetyl-N-hydroxyapiosporamide (2) and the new xanthone derivative 8-hydroxy-3-hydroxymethyl-9-oxo-9H-xanthene-1-carboxylic acid methyl ether (3) together with 19 known compounds (4–22). The structures of the new compounds were elucidated by 1D and 2D NMR spectra as well as by HRESIMS data. The absolute configuration of the new 6,7-seco-libertellenone derivative 1 was determined by single-crystal X-ray diffraction. Four additional known compounds 23–26 were isolated when NaCl or NH4Cl were added to solid rice medium. Compounds 7–9, 18 and 26 exhibited significant cytotoxicity against the L5178 murine lymphoma cell line with IC50 values of 2.6, 0.2, 2.1, 2.7 and 1.7 μM, respectively