Bufotenine is able to block rabies virus infection in BHK-21 cells

Abstract

BackgroundRabies is a fatal zoonotic neglected disease that occurs in more than 150 countries, and kills more than 55.000 people every year. It is caused by an enveloped single stranded RNA virus that affects the central nervous system, through an infection initiated by the muscular nicotinic acetylcholine receptor, according to many authors. Alkaloids, such as acetylcholine, are widespread molecules in nature. They are present in numerous biological fluids, including the skin secretion of many amphibians, in which they act (together with proteins, peptides and steroids) as protection agents against predators and/or microorganisms. Among those amphibians that are rich in alkaloids, there is the genus Rhinella.MethodsBufotenine was isolated from Rhinela jimi skin secretion after a liquid-liquid partition (H2O:CH2Cl2) and reversed phase high-performance liquid chromatography analyses (RP-HPLC). Bufotenine was also extracted from seeds of Anadenanthera colubrina in acetone solution and purified by RP-HPLC, as well. Structural characterization was performed by mass spectrometry and nuclear magnetic resonance analyses. Cytotoxic tests of bufotenine were performed over baby hamster kidney (BHK-21) cells using MTT test. For the antiviral activity, Rabies virus strain Pasteur vaccine (PV) was used on fluorescence inhibition test and fluorescent foci inhibition test, with both simultaneous and time course treatment of the cells with the virus and bufotenine.ResultsIn the present work we describe the effects of bufotenine, obtained either from toads or plants, that can inhibit the penetration of rabies virus in mammalian cells through an apparent competitive mechanism by the nicotinic acetylcholine receptor. Moreover, this inhibition was dose- and time-dependent, pointing out to a specific mechanism of action.ConclusionsThis work do not present or propose bufotenine as a drug for the treatment of rabies due to the hallucinogen and psychotropic effects of the molecule. However, continued studies in the elucidation of the antiviral mechanism of this molecule, may lead to the choice or development of a tryptamine analogue presenting potential clinical use.Electronic supplementary materialThe online version of this article (doi:10.1186/1678-9199-20-45) contains supplementary material, which is available to authorized users.

Antiviral activity of animal venom peptides and related compounds

“…Cecropins, isolated mostly from the hemolymph of infected pupae of the silk moth Hyalophora cecropia, but also from other insects, tunicates and Ascaris nematodes, are a family of AMPs, containing 35-37 amino acid residues arranged in two amphiphilic α-helices linked by a Gly-Pro hinge. Synthetic hybrid peptides, namely cecropin A (1-8)-magainin 2 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), exhibited potent antiviral activity by a mechanism mainly based on the compound hydrophobicity and α-helical content, inhibiting the virushost cell fusion [85] (Table 2).…”

“…All these facts together have propelled the prospection for new antiviral drugs, particularly from natural products, as they constitute more than 25% of the new drug prototypes approved in the last decades [4]. Among sources of natural products, animal venoms have revealed a great potential for drug discovery [5][6][7], and despite the harmful action mechanism of animal venoms, most of them have components holding potential medicinal properties to cure diseases.…”

Toxins and pharmacologically active compounds from species of the family Bufonidae (Amphibia, Anura)

“…In fact, acetone is the best organic solvent for preparing a toad extract to obtain indole alkaloids (Cei et al, 1968;Erspamer, 1959). Semi-preparative separations by employing aluminum oxide and conventional C-18 columns have been frequently obtained (Erspamer, 1959;Sciani et al, 2013;Vigerelli et al, 2014). However, because of its indole moiety, polar copolymerized C-18 and phenyl-hexyl columns have allowed better separations (Li et al, 2014b;Zhang et al, 2005).…”

“…The alkaloid 106 is able to prevent the penetration of rabies virus in the baby hamster kidney cell line, BHK-21, when tested at a concentration of 0.5 to 3 mg/mL. Although the mechanism of action is unclear, apparently the inhibition of the infection is through a competition for the nicotinic acetylcholine receptor (Vigerelli et al, 2014).…”

Bufotenine, a tryptophan-derived alkaloid, suppresses the symptoms and increases the survival rate of rabies-infected mice: the development of a pharmacological approach for rabies treatment

“…Taking this into account, we have performed the bio-monitored screening of the amphibian skin secretion targeting anti-rabies molecules, based on that one possible mechanism of the virus penetration in mammal cells is via the nicotinic acetylcholine receptor (nAChR) [19], and some amphibians secrete a myriad of alkaloids in their skin, which would bind these receptors [20]. We have successfully described that bufotenine inhibits rabies virus infection in mammalian cells in a dose and time-dependent manner [21]. Moreover, bufotenine acted synergistically with a synthetic tetrapeptide derived from the natural ocellatin-F1 [22], similar to the rabies virus glycoprotein region associated with the viral cell penetration [23].…”