<i>Xenorhabdus </i>: A potential nano-pharmaceutical perspective

Abstract

<i>Xenorhabdus </i>spp. and <i>Photorhabdus </i>spp. are Gram-negative bacteria belonging to the family Enterobacteriaceae

which are found in mutualistic symbiosis with Entomopathogenic Nematodes (EPNs) of the families of the

Steinernematidae and Heterorhabditidae, respectively. These bacteria produce secondary metabolites that have

antibiotic activity against a wide range of bacterial and fungal species including human pathogenic fungi and yeasts

and multi-drug resistant human pathogenic bacteria. More than 30 bioactive compounds of diverse chemical structures

had been identified which have a broad range of bioactivities of medicinal and agricultural interest, such as antibiotic,

antimycotic, insecticidal, nematicidal, antiulcer, antineoplastic and antiviral. Their antibiotic activity against a wide

variety of microorganisms including Gram positive <i>Micrococc</i>us, <i>Staphylococcus </i>and <i>Bacillus</i>, Gram negative

<i>Escherichia, Shigella, Enterobacter, Serratia, Proteuserwinia, Flavobacterium </i>and <i>Pseudomonas </i>and the yeasts

<i>Candida </i>and <i>Saccharomyces </i>is already known. Some biotoxins with strong antimycotic activity against a range of fungi including <i>Botrytis cinera, Fusarium oxysporum, Fusarium solani, Mucor piriformis, Pythium coloratum,</i>

<i>Pythium ultimum, Penicillium </i>spp. <i>Trichoderma pseudokingii, </i>had also been reported. <i>Xenorhabdus </i>synthesizes

and secretes broad spectral antibiotics as well as species-specific bacteriocins. An antimicrobial protein (Xenoprotec)

produced from <i>Xenorhabdus, </i>had a great effect on <i>Staphylococcus, Salmonella, Pseudomonas </i>and <i>Enterococcus</i>

<i>faecalis </i>which are potential human pathogens. Some antibacterial proteins effective against <i>Staphylococcus aureus</i>

[Penicillin Resistant Strains (PRS) and Methicillin Resistant Strains (MRS)] and <i>Pseudomonas fluorescence </i>(PRS),

which probably constitute a group of new generation antibiotics. <i>Xenorhabdus </i>showed potent cytotoxicity against a

wide range of cancerous cells from lung, colon, prostate, skin, renal, breast and cervical, and found to be a potent

preventative of the effects of a carcinogen on normal rat tracheal epithelial cells.

Xenoprotec biotoxins may prove to be a boon for medical and pharmaceutical industries as novel eco-friendly costeffective

antimicrobial agents effective in nano-doses, unlike other available drugs. Experiments had been conducted

on rat, rabbit and other animal models throughout the world and may extend to humans, thus may open vistas

for nano-pharmacology.