Tuberculosis is an infection caused by Mycobacterium tuberculosis, which commonly affects the respiratory tract, i.e. lungs.1) It is termed as "a global health emergency" by world health organization (WHO) in 1993 as it affects 1.7 billion people per year, that is equal to one-third of the entire world population. The first line of drugs used in the treatment of tuberculosis (TB) is a combination of isoniazid, rifampicin, pyrazinamide and ethambutol. The high concentration of lipids in the cell wall of M. tuberculosis has been attributed to its resistant to antibiotics. The lipid fraction of cell wall consists of three major components mycolic acids, cord factor and wax-D. Isoniazid is known to inhibit the synthesis of mycolic acid. Ethambutol is known to inhibit the incorporation of mycolic acid into the cell wall. Rifampicin acts by binding to DNA-dependent RNA polymerase and inhibits initiation of RNA synthesis. Pyrazinoic acid, the active form of pyrazinamide, is reported by Zhang Y., et al. to inhibit M. tuberculosis membrane transport function and disrupt membrane energetics.2) It is expected that the disease can be completely eliminated with the help of combination therapy, but these hopes were dashed with the advent of drug resistant strains. The development of drug resistant strains is due to point mutations in the bacterial chromosome, resulting in changes in the antibiotic target that renders the strain no longer susceptible to the drug.Thus the increasing clinical importance of tuberculosis has lent additional urgency to researchers to identify new and effective antimycobacterial compounds. Literature survey reveals that chalcones, flavones and flavanones possess antiinflammatory, 3) anticancer, 4) antileishmanial, 5) antimalarial, 6) antimicrobial and antioxidant 7) activities. It is reported that the chalcones and their derivatives are more effective against Gram-positive bacteria than against Gram-negative bacteria. 8)But it is interesting to note that they are also effective against this acid-fast bacillus which is neither Gram-positive nor negative. These compounds show very good activity against H37Rv strain. Understanding the effect of structural features on the activity would help the researchers to design new molecules that may exhibit higher activity. Quantitative structure activity relationship (QSAR) approach is better for designing new drugs when the target is not known or if there are multiple targets.QSAR studies on heterocyclic analogues of salicylanilides performed through the combination of Free-Wilson and Hansch approach explains the influences of electronic and hydrophobic properties.9) Gupta M. K., et al. have observed that topological descriptors are correlated with the antimycobacterial activity of nitro/acetamido alkenol and chloro/amino alkenol derivatives.10) 3D-QSAR uses three-dimensional properties of the molecules (particularly steric and electrostatic factors) and correlates these descriptors with the biological activity. 3D-QSAR studies carried out by Shagufta, et al. o...

Synthesis, antioxidant activity, and quantitative structure-activity relationship (QSAR) of 25 of chalcone derivatives is reported here. They were synthesized by Claisen-Schmidt reaction and were characterized by FTIR, NMR, and mass spectroscopy. Antioxidant activity is evaluated through four different methods namely, superoxide radical-scavenging, hydrogen peroxide scavenging, reducing power, and DPPH radical-scavenging assays. Generally, compounds with -SCH 3 and -OCH 3 in the para position of the A-ring and -OH in the B-ring were more active than others. In few cases some of the compounds were more active than ascorbic acid or butylated hydroxytoluene. QSAR was developed correlating the antioxidant activity with the structural features of the compounds and the predictive capability of the models was estimated using internal and external validation methods. All the predictions were within the 99% confidence level. Spatial, structural, and lipophilic properties of the compounds determine their antioxidant properties.

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The authors Ponnurengam Malliappan Sivakumar, Suresh Ganesan and Prabhawathi Veluchamy wishes to dedicate this work to their guide Prof MD on the occassion of his birthdayNovel sixteen chalcones and thirteen 1,3,5-triphenyl-2-pyrazolines were synthesized and characterized using FT-IR, HR-Mass, NMR ( C CoSY) and XRD. These compounds were evaluated for their antibacterial activity against six micro-organisms, namely Bacillus subtilis NCIM 2718, Staphylococcus aureus NCIM 5021, Salmonella typhi NCIM 2501, Enterobacter aerogenes NCIM 5139, Pseudomonas aeruginosa NCIM 5029, and Proteus vulgaris NCIM 2813 by twofold dilution method using resazurin as the indicator dye. In the case of chalcones, compounds with hydroxyl and bromo substitutions in the B-ring favor activity and benzyloxy substitution irrespective of its position in the A-ring. In the case of 1,3,5-triphenyl-2-pyrazolines, chloro substitution in the A-ring favors activity. Hydrophilic ⁄ lipophilic balance of the compounds plays a major role in their antibacterial activity.

In this paper, the synthesis of 48 chalcones and their in vitro antifungal activity against Aspergillus flavus NCIM 594, Fusarium proliferatum NCIM1105, Aspergillus niger NCIM 596 and Candida tropicalis NCIM 3556 are reported. Predominantly, the active compounds (6, 9, 14, 27, and 47) against all four fungi have found to have electron withdrawing substitutions in their para substitution in B-ring. Quantitative structure-activity relationship indicated that the antifungal activities are correlated with absorption distribution metabolism and excretion, electrophilicity, spatial and topological descriptors. The statistical measures such as r(2) (0.68-0.71), r(2)-adj (0.62-0.66), q(2) (0.60-0.61) and F-ratio (12-17) are reasonable. The data is divided into training and a test set, the former is used to develop the models, and the later is used to test their predictive capability. The predictions are found to be within the 99% confidence level except for two of the cases. SEM (scanning electron microscopy) and BacLight Live/Dead assay indicate that the chalcones act by disrupting the fungal cell wall.

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Forty-eight chalcone analogs were synthesized and their in vitro antibacterial activity against Staphylococcus aureus NCIM 5021, Bacillus subtilis NCIM 2718, Phaseolus vulgaris NCIM 2813, Escherichia coli NCIM 2931, Salmonella typhi 2501 and Enterobacter aerogenes NCIM 5139 were evaluated by microdilution broth assay. Quantitative structure-activity relationships were developed for all the cases (r 2 = 0.68-0.79; r 2 adj = 0.58-0.78; q 2 = 0.51-0.68; F = 13.02-61.51). Size, polarizability, electron-donating ⁄ withdrawing and hydrophilic nature of the molecule determine the activity against these Gram-positive and Gramnegative bacteria. Staphylococcus aureus was the most and S. typhi was the least hydrophobic of these organisms. These chalcones act better against more hydrophobic organisms. The more active chalcones have log P between 1.5 and 3. Compound 24, one of the most active compounds, was found to act by damaging the cell wall of S. aureus. Slimicidal activity of five of the most active compounds (24, 31, 32, 34 and 37) was found to be in the range of 48-60% against S. aureus and 40-54% against E. coli. A correlation was observed among the hydrophobicity of the compounds, hydrophobicity of the bacterial cell surface and the antibacterial activity of the compound.Key words: cell membrane damage, chalcone, hydrophilic ⁄ lipophilic balance, quantitative structure-activity relationship, slime production Abbreviations: ADME, absorption distribution metabolism and excretion; BATH, bacterial adherence to hydrocarbons test; GFA, genetic function approximation; HOMO, highest occupied molecular orbital; Jurs RPCG, charge of most positive atom divided by the total positive charge; Jurs RPCS, solvent-accessible surface area of the most positive atom divided by descriptor; Jurs WNSA, surface-weighted charged partial surface areas; LUMO, lowest unoccupied molecular orbital; MIC, minimum inhibitory concentration; MR, molar refractivity; NIAIP's, National Institute of Allergy and Infection Diseases; PI, propidium iodide; PUM, phosphate urea magnesium; QSAR, quantitative structureactivity relationship; SEM, scanning electron microscopy. Antibiotic resistance is a major concern in public health. More than 70% of the hospital-related bacterial isolates are resistant to most of the antibiotics. National Institute of Allergy and Infectious diseases have mentioned that developing newer drugs will address the problem of antibiotic resistant exhibited by Gram-negative or Grampositive micro-organisms a . Alteration of the target site, drug inactivation or modification, reduced drug accumulation or changes in the metabolic pathway are the major causes for the drug resistance. Methicillin-resistant Staphylococcus aureus produces PBP2a, a penicillin-binding protein, which binds less with methicillin and other b-lactams present in the bacterial cell wall. Escherichia coli develop resistant to b-lactam by producing b-lactamases. Vancomycin-resistant Enterococcus produces changes in the cell wall by mutations at gene vanA, vanB and van...

Subtilisin was immobilized on polycaprolactam and used for food packaging applications to reduce the transference of microorganisms from the packaging material to the packaged food material. The optimized conditions for subtilisin immobilization was as follows: pH, 8; temperature, 4 °C; glutaraldehyde, 0.5%; incubation time, 25 h; and subtilisin concentration, 600 μL. The formation of -CH═N- at 1576 cm(-1) in the Fourier transform infrared (FTIR) spectrum confirmed the immobilization. Subtilisin-immobilized polycaprolactam (SIP) exhibited the highest residual activity of 106.67 ± 4.41% and 104.67 ± 0.88% at 40 °C and pH 8 and retained residual activity of 94% at the end of 56 days when compared to 21.33 ± 4.10% in the case of free subtilisin. SIP significantly (p < 0.05) lowered the colony forming units (CFU), dry weight, and protein and carbohydrate contents in bacterial and fungal biofilm. Practical application of the SIP on ham steaks at 4 and 20 °C showed a 2-3 times reduction of Staphylococcus aureus as well as Escherichia coli cells in the range of p < 0.05.