Bactericida

Perumal Samy RR, Gopalakrishnakone PP, Pachiappan AA, Thwin MM, Hian YE, Bow H, Chow VT, Tuck Weng JT.

ABSTRACT: BACKGROUND: Burkholderia pseudomallei are the causative agent of melioidosis. Increasing resistance of the disease to antibiotics is a severe problem in treatment regime and has led to intensification of the search for new drugs. Antimicrobial peptides are the most ubiquitous in nature as part of the innate immune system and host defense mechanism. METHODS: Here, we investigated a group of venoms (snakes, scorpions and honey bee venoms) for antimicrobial properties against two strains of Gram-negative bacteria Burkholderia pseudomallei by using disc diffusion assay for in vitro susceptibility testing. The antibacterial activities of the venoms were compared with that of the isolated L-amino acid oxidase (LAAO) and phospholipase A2 (PLA2s) enzymes. MICs were determined using broth dilution method. Bacterial growth was assessed by measurement of optical density at the lowest dilutions (MIC 0.25 mg/mL). The cell viability was measured using tetrazolium salts (XTT) based cytotoxic assay. RESULTS: The studied venoms showed high antimicrobial activity. The venoms of C. adamanteus, Daboia russelli russelli, A. halys, P. australis, B. candidus and P. guttata were equally as effective as Chloramphenicol and Cefazidime (30 ug/disc). Among those tested, phospholipase A2 enzymes (crotoxin B and daboiatoxin), showed the most potent antibacterial activity against Gram-negative (TES) bacteria. Naturally occurring venom peptides and phospholipase A2 proved to possess highly potent antimicrobial activity against Burkholderia pseudomallei. The XTT-assay results showed that the cell survival decreased with increasing concentrations (0.05-10 mg/mL) of Crotalus adamanteus venom, with no effect on the cell viability evident at 0.5 mg/mL. CONCLUSION: This antibacterial profile of snake venoms reported herein will be useful in the search for potential antibacterial agents against drug resistant microorganisms like B. pseudomallei.

Comp Biochem Physiol C Toxicol Pharmacol. 2006 Mar-Apr;142(3-4):371-81. Epub 2006 Jan 24

Roberto PG, Kashima S, Marcussi S, Pereira JO, Astolfi-Filho S, Nomizo A, Giglio JR, Fontes MR, Soares AM, Franca SC.

Cloning and identification of a complete cDNA coding for a bactericidal and antitumoral acidic phospholipase A2 from Bothrops jararacussu venom.

In order to better understand the function of acidic phospholipases A2 (PLA2s) from snake venoms, expressed sequence tags (ESTs) that code for acidic PLA2s were isolated from a cDNA library prepared from the poly(A)+ RNA of venomous glands of Bothrops jararacussu. The complete nucleotide sequence (366 bp), named BOJU-III, encodes the BthA-I-PLA2 precursor, which includes a signal peptide and the mature protein with 16 and 122 amino acid residues, respectively. Multiple comparison of both the nucleotide and respective deduced amino acid sequence with EST and protein sequences from databases revealed that the full-length cDNA identified (BOJU III--AY145836) is related to an acidic PLA2 sharing similarity, within the range 55-81%, with acidic phospholipases from snake venoms. Moreover, phylogenetic analysis of amino acid sequences of acidic PLA2s from several pit viper genera showed close evolutionary relationships among acidic PLA2s from Bothrops, Crotalus, and Trimeresurus. The molecular modeling showed structural similarity with other dimeric class II PLA2s from snake venoms. The native protein BthA-I-PLA2, a nontoxic acidic PLA2 directly isolated from Bothrops jararacussu snake venom, was purified and submitted to various bioassays. BthA-I-PLA2 displayed high catalytic activity and induced Ca2+-dependent liposome disruption. Edema induced by this PLA2 was inhibited by indomethacin and dexamethasone, thus suggesting involvement of the cyclo-oxygenase pathway. BthA-I-PLA2 showed anticoagulant activity upon human plasma and inhibited phospholipid-dependent platelet aggregation induced by collagen or ADP. In addition, it displayed bactericidal activity against Escherichia coli and Staphylococcus aureus and antitumoral effect upon breast adrenocarcinoma as well as upon human leukemia T and Erlich ascitic tumor. Following chemical modification with p-bromophenacyl bromide, total loss of the enzymatic and pharmacological activities were observed. This is the first report on the isolation and identification of a cDNA encoding a complete acidic PLA2 from Bothrops venom, exhibiting bactericidal and antitumoral effects.

1CAMBRAIA, R.S.; 2RODRIGUES, V.M.; 1MALTA-NETO., N.R.; 1,3MARCUSSI, S.; 4SANT´ANA, C.D.; 1ARAÚJO, A.L.; 1SILVEIRA, L.B.; 2FERRO, E.A.V.; 3GIGLIO, J.R.; 2HOMSI-BRANDEBURGO, M.I.; 1,*SOARES, A.M.

Proteínas de venenos de serpentes têm sido utilizadas como ferramentas em laboratórios, como modelos na elaboração de novos fármacos e até mesmo diretamente na clínica médica. As PLA2s desempenham papéis importantes no catabolismo de lipídios da dieta e no metabolismo geral de lipídios estruturais de membranas celulares, estando envolvidas em uma grande variedade de doenças inflamatórias humanas, nos envenenamentos ofídicos e por abelhas, sendo de grande interesse médico-científico. O estudo destas proteínas podem responder questões sobre os mecanismos de ação durante o envenenamento ou resultar na cura para algumas doenças.

XII Congresso de Iniciação Científica da Universidade Federal de São Carlos - UFSCar