Antimicrobial activity of kojic acid from endophytic fungus Colletotrichum gloeosporioides isolated from Sonneratia apetala, a mangrove plant of the Sundarbans

Objective: To isolate and evaluate the antimicrobial activity of the active principle(s) from the ethyl acetate (EtOAc) extract of endophytic fungus Colletotrichum gloeosporioides (C. gloeosporioides) isolated from Sonneratia apetala. Methods: Water agar technique was used to isolate the fungus, and both microscopic and molecular techniques were used for identification of the strain. Potato dextrose broth was used to grow the fungus in large-scale. Reversed-phase preparative HPLC analysis was performed to isolate the major active compound, kojic acid. The EtOAc extract and kojic acid were screened for their antimicrobial activity against two Gram-positive and two Gram-negative bacteria as well as a fungal strain using the resazurin 96-well microtitre plate antimicrobial assay. Results: The fungus C. gloeosporioides was isolated from the leaves of Sonneratia apetala. Initial identification of the fugal isolate was carried out using spore characteristics observed under the microscope. Subsequently, the ITS1-5.8S-ITS2 sequencing was employed for species-level identification of the fungus C. gloeosporioides. Five litres of liquid culture of the fungus produced approximately 610 mg of a mixture of secondary metabolites. Kojic acid (1) was isolated as the main secondary metabolite present in the fungal extract, and the structure was confirmed by 1D, 2D NMR and mass spectrometry. The EtOAc extract and compound 1 exhibited considerable antimicrobial activity against all tested microorganisms. Whilst the minimum inhibitory concentration (MIC) values from the EtOAc extract ranged between 2.4× 10

Antimicrobial activity of kojic acid from endophytic fungus Colletotrichum gloeosporioides isolated from Sonneratia apetala, a mangrove plant of the Sundarbans

Objective:To isolate and evaluate the antimicrobial activity of the active principle(s) from the ethyl acetate (EtOAc) extract of endophytic fungus Colletotrichum gloeosporioides (C. gloeosporioides) isolated from Sonneratia apetala.Methods:Water agar technique was used to isolate the fungus, and both microscopic and molecular techniques were used for identification of the strain. Potato dextrose broth was used to grow the fungus in large-scale. Reversed-phase preparative HPLC analysis was performed to isolate the major active compound, kojic acid. The EtOAc extract and kojic acid were screened for their antimicrobial activity against two Gram-positive and two Gram-negative bacteria as well as a fungal strain using the resazurin 96-well microtitre plate antimicrobial assay.Results:The fungus C. gloeosporioides was isolated from the leaves of Sonneratia apetala. Initial identification of the fugal isolate was carried out using spore characteristics observed under the microscope. Subsequently, the ITS1-5.8S-ITS2 sequencing was employed for species-level identification of the fungus C. gloeosporioides. Five litres of liquid culture of the fungus produced approximately 610 mg of a mixture of secondary metabolites. Kojic acid (1) was isolated as the main secondary metabolite present in the fungal extract, and the structure was confirmed by 1D, 2D NMR and mass spectrometry. The EtOAc extract and compound 1 exhibited considerable antimicrobial activity against all tested microorganisms. Whilst the minimum inhibitory concentration (MIC) values from the EtOAc extract ranged between 2.4× 10Conclusions:The results revealed that the endophytic fungus C. gloeosporioides could be a good source of commercially important kojic acid, which exhibited antimicrobial properties.

In vitro antioxidant property of the extract of Excoecaria agallocha [Euphorbiaceae]

Excoecaria agallocha L. [Family: Euphorbiaceae] is a Bangladeshi medicinal plant found predominantly in the tidal forests and swamps of the Sundarbans and other coastal areas in Bangladesh. As part of our on-going phytochemical and bioactivity studies on medicinal plants from Bangladeshi flora, the in vitro antioxidant property on the bark of this plant was evaluated. The hydroalcohol extract of the dried and ground bark of E. agallocha was assessed for antioxidant activity using a series of well-established assays including the 2, 2-diphenyl-1-picrylhydrazyl [DPPH], the lipid peroxidation by thiobarbituric acid [TBA], the reducing power, the nitric oxide [NO.] and the hydrogen peroxide [H[2] O[2]] scavenging assays. In the DPPH, the NO and the H[2]O[2] scavenging assays, the extract of E. agallocha displayed significant antioxidant activities with the IC[50] values of 179.16, 120.24 and 134.29 microg/ml, respectively. The reducing power of the extract increased dose-dependently, and the extract reduced the most Fe[3+] ions to the extent less than butylated hydroxy toluene [BHT]. In the lipid peroxidation assay, the extract showed significant inhibition of peroxidation effect at all concentrations, with an IC[50] value of 189.27 microg/ml. Since reactive oxygen species are important contributors to serious ailments such as atherosclerosis, alcoholic liver cirrhosis and cancer, the antioxidant property of the extract of E. agallocha as observed in the present study might be useful for the development of newer and more potent antioxidants

Two bioactive ferulic acid derivatives from eremostachys glabra

Two ferulic acid derivatives, hexacosyl-[E]-ferulate [1] and leucosceptoside A [2], have been isolated from the rhizomes of Eremostachys glabra. The chemical structures of these compounds have been elucidated by UV, ESIMS, 1H NMR and 13C NMR spectroscopic analyses, and also by comparing experimental data with respective literature data. The free radical scavenging activity and general toxicity of these compounds have been assessed. While none of these compounds has shown any significant general toxicity in the brine shrimp lethality assay [LD50>1 mg/mL], compounds 1 and 2 displayed significant antioxidant activity in the DPPH assay [RC50 = 0.0976 mg/mL and 0.0148 mg/mL, respectively]

Bioactive lignans from the seeds of centaurea macrocephala

The essential oil from flowering aerial parts of Nepeta depauperata Benth., an endemic Iranian plant, obtained by steam distillation was analyzed by GC/MS. The constituents were identified by their mass spectra and Kovats' indices. Thirty-three compounds consisting 82.52% of the total components were identified from the oil obtained with a yield of 0.3%v/w. Among them, spathulenol [31.84%], beta caryophyllene [12.93%] and caryophyllene oxide [10.27%] were the major components of the oil