Bioconversion of eugenol into food flavouring agent vanillin

Microorganisms have the ability to chemically modify a wide variety of organic compounds by a process referred to as biological or microbial transformation, or in general, bioconversion. The microbial cells and their catalytic machinery (enzymes) accept a wide array of complex molecules as substrates, yielding products with unparallel chiral (enantio-), positional (region-) and chemical (chemo-) selectivity through various biochemical reactions. The present study was formulated on the objective of the conversion of abundantly available phytomolecules eugenol into vanillin, a compound of industrial importance, using microorganisms Aspergillus flavus, Aspergillus niger and Pseudomonas aeruginosa. These microbes were found to be capable of converting eugenol to industrially important cost-effective products, vanillin (used as flavouring agent). The results were analyzed using thin layer and gas chromatographic techniques. Our results demonstrated that A. flavus, A. niger and P. aerouginosa were able to transform eugenol to vanillin. Our findings may provide a novel approach for the production of cost-effective vanillin using microorganisms

Antioxidant Phytochemicals as Novel Therapeutic Strategies against Drug-Resistant Bacteria

The antibiotic resistance in pathogenic bacteria is a major concern and the emergence of novel multidrug-resistant (MDR) strains are a growing threat worldwide. Bacterial resistance to antibiotics has become a serious problem of public health that concerns almost all antibacterial agents and that manifests in all fields of their application. Therefore, novel antimicrobial compounds against new bacterial targets and drug resistance mechanisms are urgently needed. Plants are well-known sources of structurally diverse phytochemicals such as alkaloids, flavonoids, phenolics, and terpenes, which plays important roles in human health. Plant-derived antimicrobial agents are an attractive and ongoing source of new therapeutics. Natural compounds that prevent and treat infections through dual action mechanisms such as oxidative stress against pathogens and antioxidant action in the host cell hold promising potential for developing novel therapeutics. Identification of detailed mechanisms of action of such phytomolecules with both antioxidant and antimicrobial activities may help to develop novel antimicrobial therapeutics and benefit overall human health. The purpose of this chapter is to summarize important antioxidant phytochemicals, and focusing on their potential role in the management of drug-resistant bacterial infections

Biotransformation of artemisinin mediated through fungal strains for obtaining derivatives with novel activities

Artemisinin, a sesquiterpene lactone, is the active antimalarial constituent of Artemisia annua. Several fungal strains Saccharomyces cerevisiae, Aspergillus flavus, Aspergillus niger and Picchia pastoris were used to biotransform artemisinin. Among these strains, A. flavus was the only microorganism capable of transforming artemisinin to deoxyartemisinin in higher yields than the previous reports. The structure of deoxyartemisinin was elucidated by spectroscopy. Deoxyartemisinin showed antibacterial activity against Staphylococcus aureus, S. epidermidis and S. mutans at a minimum inhibitory concentration (MIC) of 1 mg/mL compared to artemisinin whose MIC was >2 mg/mL

<span style="font-size:11.0pt;mso-bidi-font-size: 10.0pt;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB;mso-fareast-language:EN-US;mso-bidi-language:AR-SA" lang="EN-GB">Probing the evolutionary conserved regions within functional site of drug-resistant target proteins of<i style="mso-bidi-font-style:normal"> Staphylococcus aureus: In silico</i> phylogenetic motif profiling approach</span>

442-450Staphylococcus aureus is one of the major causes of clinical infections and increasing mortality due to multi-drug resistance. In this study, eight drug-resistant genes, beta-lactamase, metallo-beta-lactamase, vanB, mecA, norA, qacA, qacB and qacC of S. aureus strain Mu50 (vancomycin resistant) were studied to predict the evolutionary conserved functional site residues in their protein sequences. It was found that in beta-lactamase, Tyr, Gly, Thr, Asn and in metallo-beta-lactamase, Thr, His, Gly, Leu, Arg and Asp residues were highly conserved. In vanB, Gly, His and Asp residues were highly conserved. Whereas in mecA, His, Val, Phe, Gln, Lys and in norA, Ser, Leu and Ala residues showed conservedness at moderate level. In the multi-drug efflux pump (corresponding to qacA, qacB and qacC), Gly residue was found to be highly conserved. The homology clustering of target proteins through SCI-PHY algorithm and homologues identified through PSI-BLAST were compared to identify the degree of conservation of functional residues. The phylogenetic motifs identified using homologues of target proteins were validated through domain search to locate their site and functionality in the protein sequences. Interactome analysis was performed to understand the possible mode of interaction of target proteins with their functional partners

Low levels of genetic diversity detected by RAPD analysis in geographically distinct accessions of Bacopa monnieri

Brahmi (Bacopa monnieri) is a traditional Indian medicinal plant known for its natural nootropic action of saponins present in large amount in its shoots. A collection of 24 B. monnieri accessions from different agro-climatic zones of India and an introduction from Malaysia maintained in the field genebank at CIMAP was analysed for RAPD variation. Among the 40 random primers tested, 29 primers generated one or more polymorphic bands. The number of polymorphic bands generated was primer dependent, ranging from 2 to maximum of 8. Similarity matrices were generated from the RAPD data on the basis of Nei's estimates of similarity indices and dendrograms were constructed based on UPGMA clustering. All the accessions were found to be in the range of 0.8-1.0 of similarity, which is indicative of a narrow genetic base among the various accessions with a medium level of polymorphism. It was possible to differentiate individual accessions, showing differences in morphological and growth properties at DNA level. The observed low levels of genetic variation were attributed to interplay of sexual and vegetative modes of reproduction and similarity of local environments in habitats of B. monnieri

New triglycerides from antimicrobial extracts of <i>Nepeta hindostana</i> weed

542-550Three new triglycerides (21, 22 and 23) along with several known fatty compounds: palmitic acid (1), oleic acid (2), linoleic acid (3), palmitic acid methyl ester (4), oleic acid methyl ester (5), alkane: tetracosane (6), alkenes: docos-1-ene (7), 1,3,3-trimethyl-cyclo-prop-1-ene (8), triglycerides: glycerol-1,2,3-triolein (14), glycerol-1,2,3-tripalmitin (10), glycerol-1,3-dipalmitate-2-oleate (11), glycerol-2,3-dioleo-1-palmitate (12), glycerol-1,2-dipalmito-3-oleate (13), steroids: lupeone (15), stigmasterol (16), β-sitosterol (17), monoterpenoid: linalool (9), triterpenoids: oleanonic acid (18), oleanolic acid (19), and ursolic acid (20) have been isolated from the hexane, ethyl acetate and methanol extracts of the aerial part of N. hindostana. Their structures have been elucidated on the basis of spectroscopic techniques including 1D, 2D NMR and MS. The hexane, ethyl acetate and methanol extracts have shown good antimicrobial activity

Antioxidant potential of the root of Vetiveria zizanioides (L.) Nash

122-125Vetiveria zizanioides, an aromatic plant commonly known as vetiver has been used for various ailments. The essential oil of vetiver root has been shown to possess antioxidant activity. However, antioxidant potential of spent root extract has not been reported. Hence, in the present study, ferric reducing, free radical scavenging and antioxidant activity of two genotypes namely KS1 and gulabi of V. zizanioides L. Nash root were investigated using in vitro assays — the ferric reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), total phenolic content (TPC), total antioxidant capacity (TAC) and reducing power (RP). KS1 genotype showed higher FRAP values, DPPH inhibition, TPC and RP potential compared to gulabi and the antioxidant activity increased with the concentration of the extract (10-1000 µg/mL). A significant protective effect of cv KS1 (100 µg/mL) extract was also observed in reduced glutathione (GSH) and malondialdehyde (MDA) concentrations of erythrocytes subjected to oxidative stress by tert-butyl hydroperoxide (t-BHP) and hydrogen peroxide (H₂O₂). The cv KS1 showed better antioxidant activity, compared to cv gulabi indicating the possibility of exploring the presence of different phytoconstituents in the two varieties

Isolation and HPLC profiling of chemical constituents of <i>Saraca asoca</i> stem bark

353-361Saraca asoca (Roxb.) de Wilde, a common tree of India, is popularly used in the ayurvedic and modern herbal systems of medicine for genito-urinary problems of women. In the current herbal market there happens to be mixing of adulterants with authentic S. asoca stem bark. In order to identify the right bark material, there exists hardly any laboratory testing possibilities to authenticate the stem bark samples. The <i style="mso-bidi-font-style: normal">n-hexane, methanol and aqueous methanol extracts have been investigated by isolating and characterizing major compounds and developing the HPLC profiling of methanol and aqueous methanol extracts. The n-hexane, methanol and 60% aqueous methanol extracts of stem bark of S. asoca after isolation, have yielded a total of 17 compounds whose structures were established by spectroscopic methods. A series of experiments were run to develop the HPLC conditions for the chemical profiling of the bark. The n-hexane extract has been found to contain mainly triterpenoids and sterols while methanol extract has yielded several flavanol derivatives along with a few triterpenoids. The aqueous methanol extract afforded flavanol derivatives. Out of the isolated compounds, ursolic acid, lupeol, glochidiol, 5,3'-dimethoxy epicatechin, 3'-eoxyepicatechin-3-O-β<span style="mso-bidi-font-style: italic">--glucopyranoside, 3'-deoxycatechin-3-O-α<span style="mso-bidi-font-style: italic">--rhamnopyranoside and epigallocatechin have been isolated from <i style="mso-bidi-font-style: normal">S. asoca bark for the first time. HPLC profiling of methanol and aqueous methanol extracts of the bark has been developed by using mainly the isolated compounds as references. The percent composition of the major compounds was determined by HPLC and can be used to monitor the possible adulterations in the commercial bark materials. The antibacterial tests showed that the methanol and aqueous methanol extracts and few compounds have mild activity on some of the bacterial strains whereas they did not show any antifungal activity.</span