S. Sudarslal

Anti-oxidant activity of Centella asiatica on lymphoma-bearing mice.

Oral treatment with 50 mg X kg(-1) day(-1) of crude methanol extract of Centella asiatica for 14 days significantly increased the anti-oxidant enzymes, like superoxide dismutase (SOD), catalase and glutathione peroxidase (GSHPx), and anti-oxidants like glutathione (GSH) and ascorbic acid decreased in lymphoma-bearing mice.

Sodium Channel Modulating Activity in a δ-Conotoxin from an Indian Marine Snail

A 26 residue peptide (Am 2766) with the sequence CKQAGESCDIFSQNCCVG‐TCAFICIE‐NH2 has been isolated and purified from the venom of the molluscivorous snail, Conus amadis, collected off the southeastern coast of India. Chemical modification and mass spectrometric studies establish that Am 2766 has three disulfide bridges. C‐terminal amidation has been demonstrated by mass measurements on the C‐terminal fragments obtained by proteolysis. Sequence alignments establish that Am 2766 belongs to the δ‐conotoxin family. Am 2766 inhibits the decay of the sodium current in brain rNav1.2a voltage‐gated Na+ channel, stably expressed in Chinese hamster ovary cells. Unlike δ‐conotoxins have previously been isolated from molluscivorous snails, Am 2766 inhibits inactivation of mammalian sodium channels.

Characterization of contryphans from Conus loroisii and Conus amadis that target calcium channels

Distinctly different effects of two closely related contryphans have been demonstrated on voltage-activated Ca(2+) channels. The peptides Lo959 and Am975 were isolated from Conus loroisii, a vermivorous marine snail and Conus amadis, a molluscivore, respectively. The sequences of Lo959 and Am975 were deduced by mass spectrometric sequencing (MALDI-MS/MS) and confirmed by chemical synthesis. The sequences of Lo959, GCP(D)WDPWC-NH(2) and Am975, GCO(D)WDPWC-NH(2) (O: 4-trans-hydroxyproline: Hyp), differ only at residue 3; Pro in Lo959, Hyp in Am975, which is identical to contryphan-P, previously isolated from Conus purpurascens, a piscivore; while Lo959 is a novel peptide. Both Lo959 and Am975 undergo slow conformational interconversion under reverse-phase chromatographic conditions, a characteristic feature of all contryphans reported thus far. Electrophysiological studies performed using dorsal root ganglion neurons reveal that both peptides target high voltage-activated Ca(2+) channels. While Lo959 increases the Ca(2+) current, Am975 causes inhibition. The results establish that subtle sequence effects, which accompany post-translational modifications in Conus peptides, can have dramatic effects on target ion channels.

Novel peptides of therapeutic promise from Indian Conidae.

Highly structured small peptides are the major toxic constituents of the venom of cone snails, a family of widely distributed predatory marine molluscs. These animals use the venom for rapid prey immobilization. The peptide components in the venom target a wide variety of membrane‐bound ion channels and receptors. Many have been found to be highly selective for a diverse range of mammalian ion channels and receptors associated with pain‐signaling pathways. Their small size, structural stability, and target specificity make them attractive pharmacologic agents. A select number of laboratories mainly from the United States, Europe, Australia, Israel, and China have been engaged in intense drug discovery programs based on peptides from a few snail species. Coastal India has an estimated 20–30% of the known cone species; however, few serious studies have been reported so far. We have begun a comprehensive program for the identification and characterization of peptides from cone snails found in Indian Coastal waters. This presentation reviews our progress over the last 2 years. As expected from the evolutionary history of these venom components, our search has yielded novel peptides of therapeutic promise from the new species that we have studied.

Kannurin, a Novel Lipopeptide from Bacillus Cereus Strain AK1: Isolation, Structural Evaluation and Antifungal Activities

This study was performed to isolate and characterize novel antifungal lipopeptide from Bacillus cereus.