Debdulal Banerjee

Production and characterization of extracellular and intracellular tannase from newly isolated Aspergillus aculeatus DBF 9

A comparative study on the simultaneous production of extra and intracellular tannase was made from newly isolated fungal strain Aspergillus aculeatus DBF 9. This strain produced five times more intracellular enzyme within 24 h in liquid culture than the extracellular form. Maximum tannase production occurred in the culture broth containing 1–2% (w/v) tannic acid and 0.05–0.1% (w/v) glucose. The pH and temperature optima of both the enzymes were found at 5.0 and 50–60 °C, respectively. Extra and intracellular tannase showed good stability at higher temperature, pH values and salt (NaCl) concentration. These properties make the enzyme suitable for pollution control and bioprocess industry.

Epidemiological profile of fungal keratitis in urban population of West Bengal, India

Background Corneal diseases are one of the major causes of visual loss and blindness, second only to cataract. Amongst corneal diseases, microbial keratitis is a major blinding disease. In some countries, fungal keratitis accounts for almost 50% of patients with culture-proven microbial keratitis. Aim This study was conducted to determine the epidemiological characteristics of fungal keratitis in an urban population of West Bengal and identify the specific pathogenic organisms. Methods The charts of patients with microbial keratitis who attended the Cornea Services of Priyamvada Birla Aravind Eye Hospital from January to December 2008 were retrospectively reviewed. Records of patients with 10% KOH mount and culture positive fungal keratitis were analyzed for epidemiological features, laboratory findings and treatment outcomes. Results Of the 289 patients of microbial keratitis included in the study, 110 patients (38.06%) were diagnosed with fungal keratitis (10% KOH mount positive). Of the 110 patients, 74 (67.27%) fitted the study inclusion criteria (10% KOH mount and culture positive). Forty five of 74 patients (60.81%) in the study group were in the older age group (>50 years). Ocular trauma in 35 cases (47.29%) was identified as a high risk factor and vegetative injuries in 17 cases (22.97%) were identified as a significant cause for fungal keratitis. Maximum organism source was from corneal scrapings in 41 cases (55%). The predominant fungal species isolated was Aspergillus sp (55.40%) followed by Candida albicans 14 cases (18.91%) and Fusarium sp. in 8 cases (10.81%). Agricultural activity related ocular trauma was the principal cause of mycotic keratitis and males were more commonly affected. Thirty of 74 cases (40.55%) of the culture positive patients healed with corneal scar formation with medical treatment whereas 44 cases (59.45%) required therapeutic keratoplasty. Conclusion Fungal keratitis is an important cause of microbial keratitis with injury to the cornea being a leading predisposing factor. Although Aspergillus sp. was implicated in most of the patients in our study population, Candida sp. were found in higher numbers than previously reported. Keratitis caused by filamentous fungi responds adequately to medical management. Therapeutic keratoplasty continues to remain an important treatment modality in infections with Candida sp. Early diagnosis with prompt identification of the pathogenic organism is mandatory to initiate appropriate therapy and thereby reduce morbidity.

Fungal Exopolysaccharide: Production, Composition and Applications

Fungal exopolysaccharides (EPSs) have been recognized as high value biomacromolecules for the last two decades. These products, including pullulan, scleroglucan, and botryosphaeran, have several applications in industries, pharmaceuticals, medicine, foods etc. Although fungal EPSs are highly relevant, to date information concerning fungal biosynthesis is scarce and an extensive search for new fugal species that can produce novel EPSs is still needed. In most cases, the molecular weight variations and sugar compositions of fungal EPSs are dependent to culture medium composition and different physical conditions provided during fermentation. An inclusive and illustrative review on fungal EPS is presented here. The general outline of the present work includes fungal EPS production, their compositions and applications. An emphasis is also given to listing out different fungal strains that can produce EPSs.

Pueraria tuberosa: a review on its phytochemical and therapeutic potential.

Pueraria tuberosa (Willd.) DC is a perennial herb commonly known as ‘vidarikanda’, distributed throughout south east Asia. The plants tuber is widely used in ethanomedicine as well as in traditional systems of medicine, particularly in ayurveda. It has been used in various ayurvedic formulations as restorative tonic, antiaging, spermatogenic and immune booster and has been recommended for the treatment of cardiovascular diseases, hepatosplenomegaly, fertility disorders, menopausal syndrome, sexual debility and spermatorrhoea. Numerous bioactive phytochemicals, mostly isoflavonoids such as puerarin, genistein, daidzein, tuberosin and so on have been identified in the tuber. In vivo and in vitro studies have provided the support against traditional demands of the tuber as spermatogenic, immune booster, aphrodisiac, anti-inflammatory, cardiotonic and brain tonic. However, further studies are required to define the active phytochemical compositions and to validate its clinical utilisation in the herbal formulations for human uses. This review provides an overview of traditional applications, current knowledge on the phytochemistry, pharmacology and toxicology of P. tuberosa. This review also provides plausible hypotheses about how various isoflavones particularly puerarin, genistein and daidzein, individually or collectively, may be responsible for the therapeutic potential against a wide range of ailments.

Fungal endophytes in three medicinal plants of Lamiaceae.

Three medicinal plants Ocimum sanctum, Ocimum bacilicum and Leucas aspera were screened to study endophytic diversity of the plants. Altogether 103 fungal endophytes belonging to fourteen genera were isolated. Leaves of all three medicinal plants were colonized by a great number of endophytic fungi. Leaves of O. sanctum were colonized by the most, that is, eleven endophytes. Highest Shannon-Wiener index (2.256) was exhibited by O. sanctum with the highest Simpsons diversity (0.8654) indicating great species specificity. O. bacilicum and L. aspera showed the highest similarity coefficient. Some fungal genera have been showed to be host specific. In the present study Curvularia sp., Hymenula sp., Tricoderma sp. and Tubercularia sp. exclusively colonized O. sanctum ; whereas Alternaria sp. and Spicaria sp. colonized only L. aspera .

Structural elucidation and bioactivity of a novel exopolysaccharide from endophytic Fusarium solani SD5

A bioactive exopolysaccharide [EPS (PS-I)], having Mw∼1.87×10(5) Da was produced by submerged culture of an endophytic fungus Fusarium solani SD5. Structural elucidation of the EPS (PS-I) was carried out by a series of experiments. Result indicates the presence of terminal α-L-rhamnopyranosyl, (1→2)-α-L-rhamnopyranosyl, (1→4)-β-D-galactopyranosyl, (1→4,6)-β-D-galactopyranosyl moieties in a molar ratio of nearly 1:1:3:1. TEM image showed fibril structure of the EPS with a diameter of approximately 1 nm. Melting point range of the EPS was found 172-178 °C. The isolated PS-I exhibit in vitro anti inflammatory and anti allergic activity. EPS (1000 μg/ml) protects 55% erythrocytes from hypotonic solution induced membrane lysis. Compound 48/80 induced mast cell degranulation was also protected by 56% with 100 μg/ml EPS.

Evaluation of in vitro antioxidant potency of exopolysaccharide from endophytic Fusarium solani SD5.

A potent endophytic fungus, Fusarium solani SD5 was used for exopolysaccharide (EPS) production. The isolated EPS were purified and major EPS fraction (PS-I); rhamno galactan was used to evaluate anti oxidant activities in vitro. EPS (PS-I) showed significant free radical scavenging effect on DPPH (1,1-diphenyl-2-picrylhydrazyl) and scavenging potency is indicated by IC(50) value 578.541 ± 33.256 μg/ml. EPS (PS-I) significantly induced antioxidant parameters of peritoneal macrophage cells at a concentration dependent manner and at 500 μg/ml it showed maximum protective effect against free radicals [malondialdehyde (MDA) 0.178 ± 0.015; super oxide dismutase (SOD) 41.287 ± 1.051; glutathione peroxidase (GPx) 30.182 ± 1.237; reduced glutathione (GSH) 56.892 ± 1.272; oxidized glutathione (GSSG) 8.458 ± 0.768]. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide] cytotoxicity assay indicated that EPS (PS-I) had no significant cytotoxic effect (concentration up to 500 μg/ml) on macrophage cells. Present findings suggested that the EPS (PS-I) may become a potential nontoxic exogenous antioxidant.

Optimization of a bioactive exopolysaccharide production from endophytic Fusarium solani SD5

Endophytic fungi were less investigated for exopolysaccharide production. In this study endophytic Fusarium solani SD5 was used for optimization of exopolysaccharide production. One variable at a time method and response surface methodology were employed to explore the optimum medium compositions and fermentation conditions. The organism produced maximum exopolysaccharide after 13.68 days of incubation at 28 °C in potato dextrose broth supplemented with (g%/l) glucose, 9.8; yeast extract, 0.69; KCl, 0.05; KH₂PO₄, 0.05 with medium pH 6.46. Use of 50 ml medium in 250 ml Erlenmeyer flask gives highest exopolysaccharide production. The organism produced more than two times higher exopolysaccharide (2.276 ± 0.032 g/l EPS) at optimized condition compared to pre-optimized condition (0.96 ± 0.021). In vivo toxicity test established nontoxic nature of the EPS (≤400 mg EPS/Kg of body weight). The EPS slightly altered intestinal indigenous bacteria and influenced the growth of beneficial Lactobacillus spp.

Diversity and screening for antimicrobial activity of endophytic fungi from Alstonia scholaris

Endophytic fungi of three tissues (petiole, bark and leaf) of Alstonia scholaris were assessed. A total number of 1,152 endophytic fungi were isolated from 1,002 different plant segments of seven different localities of Paschim Medinipur, West Bengal, India. The isolated fungi belong to nineteen genera, including four unidentified fungi and yeast. Colletotrichum sp. (20.39%) and Sordaria sp. (29.68%) were most commonly isolated from this plant. Hyalopus sp., Fusarium sp. and Curvularia sp. were also isolated. The colonization frequency of endophytic fungi is much higher in leaves (44.66%) in comparison to petioles (32.16%) and barks (23.17%). The study provided evidence for tissue specificity of endophytic fungi. The endophytic fungal species diversity was higher in plant segments collected from Gopegarh and Khoirullahchak, while diversity was the lowest in Rice mill area. Screenings of antimicrobial activity of these isolated endophytic fungi were done. Eight endophytic fungi showed antimicrobial activity. Among them Curvularia sp., Aspergillus sp. and one unidentified fungus showed maximum activity against test pathogens.

A validated RP-HPLC-UV method for quantitative determination of puerarin in Pueraria tuberosa DC tuber extract

Background: Pueraria tuberosa (Fabaceae) is a well-known medicinal herbs used in Indian traditional medicines. The puerarin is one of the most important bioactive constituent found in the tubers of this plant. Quantitative estimation of bioactive molecules is essential for the purpose of quality control and dose determination of herbal medicines. The study was designed to develop a validated reversed phase high-performance liquid chromatography (RP-HPLC) method for the quantification of puerarin in the tuber extract of P. tuberosa. Materials and Methods: The RP-HPLC system with Luna C18 (2) 100 Å, 250 × 4.6 mm column was used in this study. The analysis was performed using the mobile phase: 0.1% acetic acid in acetonitrile and 0.1% acetic acid in water (90:10, v/v) under column temperature 25°C. The detection wavelength was set at 254 nm with a flow rate of 1 ml/min. The method validation was performed according to the guidelines of International Conference on Harmonization. Results: The puerarin content of P. tuberosa extract was found to be 9.28 ±0.09%. The calibration curve showed good linearity relationship in the range of 200-1000μg/ml (r2>0.99). The LOD and LOQ were 57.12 and 181.26μg/ml, respectively and the average recovery of puerarin was 99.73% ±1.02%. The evaluation of system suitability, precision, robustness and ruggedness parameters were also found to produce satisfactory results. Conclusions: The developed method is very simple and rapid with excellent specificity, accuracy and precision which can be useful for the routine analysis and quantitative estimation of puerarin in plant extracts and formulations.