Narayanasamy Mathivanan

Synthesis of novel spiropyrrolizidines as potent antimicrobial agents for human and plant pathogens

A series of novel dispirooxindolopyrrolizidine derivatives have been synthesized through 1,3-dipolar cycloaddition reaction of azomethine ylide generated from proline and isatin with the dipolarophile (E)-2-arylidine-1-keto carbazoles. The synthesized cycloadducts were evaluated for antimicrobial activities. Compounds 7d and 7e showed relatively good antibacterial and antifungal activities.

Purification, crystal structure and antimicrobial activity of phenazine-1-carboxamide produced by a growth-promoting biocontrol bacterium, Pseudomonas aeruginosa MML2212.

Aim:  To purify and characterize an antimicrobial compound produced by a biocontrol bacterium, Pseudomonas aeruginosa MML2212, and evaluate its activity against rice pathogens, Rhizoctonia solani and Xanthomonas oryzae pv. oryzae.

Regioselective synthesis and antimicrobial screening of novel ketocarbazolodispiropyrrolidine derivatives

A series of novel dispiropyrrolidine derivatives have been synthesized through 1,3-dipolar cycloaddition reaction of azomethine ylide generated from sarcosin and di/tri ketone with the dipolarophile (E)-2-arylidine-1-keto-carbazoles. The cycloadducts ketocarbazalo spiro N-methyl pyrrolidines showed the most interesting antimicrobial activity at lower concentration.

Synthesis of novel carbazole based macrocyclic amides as potential antimicrobial agents

A series of carbazole based macrocyclic diamides with thia and oxy linkages have been synthesized and the inhibitory activity of the cyclophane amides against human pathogenic bacteria and plant pathogenic fungi are documented. (S)-1,10-Bi-2-naphthol [(S)-BINOL] based chiral carbazolophane amide emerged as the most interesting compound in this series exhibiting excellent antibacterial and antifungal activities.

Synthesis of novel β-lactam fused spiroisoxazolidine chromanones and tetralones as potent antimicrobial agent for human and plant pathogens.

Synthesis of novel beta-lactam fused spiroisoxazolidine chromanones and tetralones ring systems has been achieved by intermolecular 1,3-dipolar cycloaddition reaction of bicyclic nitrone with unusual dipolarophiles, arylidene chromanones/tetralones under different reaction conditions. The synthesized compounds were evaluated for antimicrobial activities. It was observed that two of the synthesized compounds exhibited relatively good antibacterial and antifungal activities.

Structural and functional studies on urease from pigeon pea (Cajanus cajan)

Urease is an enzyme that catalyzes the hydrolysis of urea, forming ammonia and carbon dioxide, and is found in plants, microorganisms and invertebrates. Although plant and bacterial ureases are closely related at amino acid and at the structural level, the insecticidal activity is seen only in the plant ureases. In contrast, both plant and bacterial ureases exhibit antifungal activity. These two biological properties are independent of its ureolytic activity. However, till date the mechanism(s) behind the insecticidal and fungicidal activity of ureases are not clearly understood. Here we report the crystal structure of pigeon pea urease (PPU, Cajanus cajan) which is the second structure from the plant source. We have deduced the amino acid sequence of PPU and also report here studies on its stability, insecticidal and antifungal activity. PPU exhibits cellulase activity. Based on the structural analysis of PPU and docking studies with cellopentoase we propose a possible mechanism of antifungal activity of urease.

Synthesis of some novel imidazole-based dicationic carbazolophanes as potential antibacterials

Synthesis of fluorescent imidazole-based dicationic carbazolophanes incorporating various spacer units is described. Interestingly, the cyclophanes 2a and 5a incorporating a pyridine moiety exhibited superior antibacterial activity against most of the pathogenic bacteria in the tested concentrations as compared to the other cyclophanes as well as the test control, benzalkonium chloride (BAC), cetylpyridinium chloride (CPC) and tetracycline.

The Effect of Fungal Secondary Metabolites on Bacterial and Fungal Pathogens

Fungi are an extremely diverse group of organisms, with about 230,000 species distributed widely essentially in every ecosystem. Among them, only limited species are considered to be effective biocontrol agents . The fungal antagonists restrict the growth of plant pathogens by the three suggested mechanisms: antibiosis , competition and parasitism. Besides, they also induce the defense responses in host plants, termed “induced systemic resistance” (van Loon et al. 1998). Among the abovementioned mechanisms, antibiosis is considered the most important, in which the antagonists produce an array of secondary metabolites such as antibiotics and toxin, which contribute to the antagonistic activity of fungal biocontrol agents against plant pathogens. Antagonistic strains belonging to the Trichoderma and Fusarium genera were able to produce various secondary metabolites which can play a role in the mechanism of their biological activity (http://www.item.ba.cnr.it/ biopesti.htm). Production of antimicrobial secondary metabolites has been reported in many fungal biocontrol agents (Gottlieb and Shaw 1970; Fries 1973; Hutchinson 1973; Sivasithamparam and Ghisalberti 1998; Vyas and Mathur 2002). In this review, we highlight the secondary metabolites of selected fungal biocontrol agents and their involvement in the control of plant pathogens.

Synthesis and SAR study of novel anticancer and antimicrobial naphthoquinone amide derivatives

A series of novel naphthoquinone amide derivatives of the bioactive quinones, plumbagin, juglone, menadione and lawsone, with various amino acids were synthesized. The compounds were characterized by (1)H NMR, (13)C NMR, Mass, IR and elemental analysis. All the compounds were evaluated for their anticancer activity against HeLa and SAS cancer cell lines and 3D-QSAR indicated the presence of electron donating group near sulphur enhanced the activity against HeLa cells. Among the derivatives synthesized, compounds 11f, 10a, 10b and 10g were the most active with IC50 values of 16, 12, 14 and 24.5 μM, respectively. The analogues were also screened for antimicrobial activity against two human bacterial pathogens, the Gram-positive Methicillin resistant Staphylococcus aureus (MRSA) and the Gram-negative Pseudomonas aeruginosa and a human yeast pathogen, Fluconazole resistant Candida albicans (FRCA). Among the synthesized compounds, 8g, 10g and 11g exhibited maximum antibacterial activity towards MRSA and antifungal activity against FRCA in well diffusion method.

Synthesis, characterization and biological evaluation of chromen and pyrano chromen-5-one derivatives impregnated into a novel collagen based scaffold for tissue engineering applications

In this article, we describe the synthesis and biological evaluation of a novel 2-(methylamino)-3-nitro-4-(4-oxo-4H-chromen-3-yl) pyrano[3,2-c]chromen-5(4H)-one (CCN). It is also determined that CCN impregnated into the collagen scaffold has the potential to mimic the function of the extracellular matrix as a biomaterial in the field of tissue engineering. The series of pyrano[3,2-c]chromen-5(4H)-one derivatives (4a–4j), was analyzed by 1H NMR, 13C NMR, mass spectra and FTIR analysis. Compound 4c was confirmed by single crystal XRD studies. All the compounds were screened for antimicrobial activity against Gram positive, Gram negative bacteria and yeast. Among all the compounds, compound (4aCCN) showed activity against Gram positive and Gram negative bacteria, when compared to the synthesized compounds. Further, compound CCN was evaluated for cytotoxicity against MCF-7, Hep-2 and Vero cancer cell lines with IC50 values of 5.4 μg ml−1, 5.3 μg ml−1 and 68.4 μg ml−1 respectively. In addition, the results of flow cytometry and docking (PDBID: 1A27 with the ligand) studies supported the activity of the synthesized compound (4a). FTIR and NMR analysis of the CCN impregnated collagen scaffold were done to reveal the existence of the CCN molecule in the scaffold. The inherent property of the collagen scaffold was not significantly affected by the structure of the CCN molecule. The thermal and mechanical properties of the collagen scaffold impregnated with CCN molecules gives stability as well as supports the swelling. However, the COL-CCN scaffold showed an enhanced cell attachment and proliferation of NIH 3T3 fibroblast cells. Based on the results, the novel CCN molecule impregnated within a collagen scaffold has potential application as a biomaterial in tissue engineering.