Geeta Singh

Evaluation of Antimicrobial Efficacy of Flavonoids of Withania Somnifera L.

In the present study antimicrobial activity of Withania somnifera L. Dunal (Solanaceae) has been evaluated against selected pathogens. Free and bound flavonoids of different parts (root, stem, leaf and fruit) of W. somnifera have been studied for their antimicrobial activity using disc diffusion assay against three Gram negative bacteria (Escherichia coli MTCC 46, Proteus mirabilis MTCC 3310 and Pseudomonas aeruginosa MTCC 1934), one Gram positive bacteria (Staphylococcus aureus MTCC 3160) and three fungi (Candida albicans MTCC 183, Aspergillus flavus MTCC 277 and Aspergillus niger MTCC 282). Minimum inhibitory concentration (MIC) of the extracts was evaluated through micro broth dilution method, while minimum bactericidal/fungicidal concentration was determined by sub culturing the relevant samples. C. albicans was found to be the most susceptible organism followed by S. aureus, P. mirabilis, E. coli and P. aeruginosa. Out of the tested organisms, A flavus and A. niger were observed to be resistant as none of the tested extracts showed activity against them. Total activity (TA) of extracts (ml/g) against each sensitive pathogens was also evaluated. Bound flavonoid extract of root showed best activity against C. albicans (IZ 30, MIC 0.039, MFC 0.039, respectively). However all the microorganisms were found to be sensitive against the extracts tested. Total activity of bound flavonoid extract of root was found to be same for E.coli, P. mirabilis, S. aureus and C. albicans (153.84 ml/g). Results of the present study reveal that extracts of W. somnifera showing great antimicrobial potential against test microorganisms may be exploited for future antimicrobial drugs.

Treatment of dermatophytosis by a new antifungal agent 'apigenin'.

Dermatophytes are the most common causative agents of cutaneous mycosis and remain a major public health problem in spite of the availability of an increasing number of antifungal drugs. It was, therefore considered necessary to pursue the screening of different extracts (compounds) of selected traditional medicinal plants reportedly having antidermatophyte potential. The aim of this study was to isolate and identify specific compound from the most active extract (free flavonoid) of stem of Terminalia chebula of the selected plants to treat dermatophytosis induced on experimental mice. Mice which were experimentally induced with Trichophyton mentagrophytes were grouped in six of five animals each. To treat the lesions on infected mice, two concentrations of isolated apigenin ointment, i.e. 2.5 mg g−1 (Api I) and 5 mg g−1 (Api II), and terbinafine (standard) of concentration 5 mg g−1 were used. Complete recovery from the infection was recorded on 12th day of treatment for reference drug Terbinafine and Api II (5 mg g−1) concentration of ointment, whereas Api I (2.5 mg g−1) ointment showed complete cure on 16th day of treatment. Fungal burden was also calculated by culturing skin scraping from infected mices of different groups. Apigenin has shown potency as the infected animals recover completely by Api II comparable to the standard drug in 12th day. So Apigenin can be explored as an antifungal agent in the clinical treatment of dermatophytosis in future.

Extraction, gas chromatography-mass spectrometry analysis and screening of fruits of Terminalia chebula Retz. for its antimicrobial potential

Background: Terminalia chebula is called the “king of medicines” in Tibet and is always listed first in the Ayurvedic meteria medica because of its extraordinary powers of healing. Objective: Identification, isolation and screening of pyrogallol which are responsible for antimicrobial property of fruits of Terminalia chebula. Materials and Methods: Ethyl acetate fraction of fruits of Terminalia chebula was subjected to Gas chromatography–mass spectrometry (GC-MS) for the components present in the extract. Results: Sixty four constituents were identified out of which kaempferol-3-O-rutinoside flavonoid and Vitamin E has been detected for the first time in fruits of this plant. Pyrogallol (46.26%) which was the major component of the extract in GC-MS analysis was isolated and screened for antimicrobial activity against selected test pathogens by Disc Diffusion Assay. Crude ethyl acetate fraction of the fruits was showing the same activity potential as was observed for pure pyrogallol which was the major component as per GC-MS analysis. The most sensitive species among the bacteria was Enterobacter aerogenes with highest inhibition zone (IZ = 31 mm; AI = 1.409 ± 0.046) even at minimum inhibitory concentration (0.039 mg/ml). Conclusion: Hence activity shown by crude ethyl acetate fraction might be due to pyrogallol present in the extract. On the basis of results it can be advocate that achieved crude ethyl acetate fraction can be explored for preparing antimicrobial drugs in future for the infectious caused by the pathogens tested in the study.

Phytochemical study and screening for antimicrobial activity of flavonoids of Euphorbia hirta

Objective: This study aims to phytochemical and antimicrobial study of Euphorbia hirta Euphorbiaceae). Materials and Methods: Antimicrobial activity of flavonoids (free and bound) of Euphorbia hirta L. was determined by disc diffusion assay against four bacteria (Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, and Staphylococcus aureus) and four fungi (Aspergillus flavus, Aspergillus niger, Trichophyton mentagrophytes, and Candida albicans). Minimum inhibitory concentration (MIC) of the extract was evaluated through micro broth dilution method, while minimum bactericidal/fungicidal concentration was determined by subculturing the relevant samples. Total activity (TA) of extracts against each sensitive pathogen was also evaluated. Results: Out of fungi; A. flavus, A. niger, and T. mentagrophytes were found to be resistant, against which none of the tested extracts showed activity. Bound flavonoids extract of root showed best activity against C. albicans (inhibition zone (IZ) 27.66, MIC 0.039, minimum fungicidal concentration (MFC) 0.039). TA of free flavonoid extract of root was found to be the same for P. mirabilis and S. aureus (192.30 ml/g). Two flavonoids quercetin and kaempferol were identified in the bound flavonoids of stem extract which showed activity against all the microorganisms. Conclusion: Results of the present investigation indicate that E. hirta has good antimicrobial activity with low range of MIC, hence can be exploited for future plant-based antimicrobial drugs.

In vitro biopesticide effect of alkaloids and flavonoids of some plants against Fusarium oxysporum

Alkaloids and flavonoids of three plants, namely Withania somnifera, Euphorbia hirta and Terminalia chebula, were tested for their antifungal potential against plant pathogenic fungi Fusarium oxysporum. The spore counting technique was followed for the antibiotic properties of the extracts tested at three different concentrations (2.5, 5 and 10 mg/ml). Results revealed that the bound flavonoid of root of W. somnifera and free flavonoids of stem bark and fruits of T. chebula totally inhibited spore germination of the fungi (100%). The range of minimum inhibitory concentration and minimum fungicidal concentration of extracts recorded was 0.039–0.625 and 0.039–1.25 mg/ml, respectively. Bound flavonoids of selected plants were more effective than free flavonoids and alkaloids. The study suggests that both alkaloids and flavonoids extracts of selected plants have a potential antifungal properties for the control of diseases of various crops.

Phytochemical and Antibacterial Studies of Different Parts of Euphorbia hirta L.

Flavonoid extracts from Euphorbia hirta were screened for antibacterial activity by “Disc Diffusion Assay.” Minimum inhibitory concentration (MIC) of extracts was by broth microdilu-tion method. Extracts found sensitive against test pathogens were also evaluated for minimum bactericidal concentration (MBC) and total activity (TA). The highest inhibition zone (IZ) of 17 mm and AI 0.607 ± 0.090 was shown by bound flavonoids of leaves against Agrobacterium tumifacians. Bacillus subtilis was the most sensitive to flavonoids (free and bound) compared to the other bacteria. MIC of the extracts against Bacillus subtilis, Agrobacterium tumefaciens, and Klebsiella pneumoniae was recorded as 0.039 mg.mL−1.

Phytochemical study and bioefficacy of Terminalia chebula Retz. against some human pathogens

Objective: The antimicrobial activity of flavonoids of different parts (leaf, stem, stem bark, fruits) of T. chebula have been evaluated against seven bacterial (Gram +ve and Gram −ve) and three fungal strains. Materials and Methods: These flavonoids were screenedfor their antimicrobial activity by Disc Diffusion Assay. Minimum inhibitory concentration of the extracts was evaluated through micro broth dilution method, while minimum bactericidal/fungicidal concentration was determined by sub culturing the relevant samples. Results: In antimicrobial assay highest activity was observed by free flavanoid of fruits (IZ 30.83 mm, AI 1.39 + 0.024) against Enterobacter aerogenes. The range of minimum inhibitory concentration of tested extracts was 0.039-0.625 mg/ml while minimum bactericidal/fungicidal concentration ranged from 0.078-1.25 mg/ml. Conclusion: Result reveals that all the eight tested plant extracts inhibit the growth of selected pathogens, indicating broad spectrum bioactive nature of selected plant and hence can be exploited for future plant based antimicrobials. Key words: Terminalia chebula, Enterobacter aerogenes, minimum inhibitory concentration, minimum bactericidal/fungicidal concentration, antibacterial activity, antifungal activity, total activity