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Butylated hydroxytoluene, lipid-enveloped viruses, and AIDS
Mrdicol H~poihe.ws (1987) 23, 3942 ( Longman Group UK Ltd 1987
BUTYLATED HYDROXYTOLUENE, LIPID-ENVELOPED VIRUSES, AND AIDS Eric lieimund.1912 Green Mnt. Dr., #227N, Little Rock, Arkansas 72212-4018 ABSTBACT Butylated hydroxytoluene (BHT) is a potent inactivator of lipid-enveloped viruses. The viral envelope structure is physically disturbed by BHT, thereby interfering with viral adsorption to host cells. Sinoe the virus responsible for AIDS (HTLV III) oontains a lipid envelope, BHT warrant8 investigation as a potential antiviral agent against the AIDS virus. INTRODUCTION Butylated hydroxytoluene (BHT) is a potent synthetio antioxidant of low toxicity that Is widely used as a food preservative. BHT Is a hydrophobic compound, and its antioxidant effectiveness is due to its ability to prevent lipid peroxidatlon in lipid-rich regions. Due to.its antioxidant properties, BHT has been reported to extend lifespan in mloe and reduoe chemical oaroinogenesis and toxicity (1). BHT IS a relatively nontoxic compound. LD-50 values range from approximately 1800 mg/kg for the rat to 10,700 mg/kg for the guinea pig (1). Adverse effsots of BHT use inolude hepatic and pulmonary hypertrophy, and an increase in the activity of hepatio mlorosomal mixed function oxidases. However, very large doses of BHT are required before these effeots become significant (e.g. 400 to 500 mg/kg is a common dosage in these studies) (1). The average daily consumption of BHT per person in the United States is approximately 2 mg, yielding a concentration In body fat of approximately 1.3 parts per million (6 tam) (2).
39
BHT AS AN ANTIVIHALAGENT --In 1975 It was reportedby Snipes,et al, that BHT is a Potent lnaativatorof lipid-containing viruses (2). BHT, at conoentrations of approximately100 um, was oapableof inactivating( reventlngplaque-forming unit8 on appropriatehoet cellsP herpes simplexvirus (HSV) by over 90s and bacteriophage$6 by 100%. In oontrast,the polio virus,which does not oontaina lipid envelope,was not affectedby similaroonoentrations of BHT. Subsequent studieshave shown that toploalBHT is effectiveIn reduolngthe clearancetime of autaneousHSV infeotlone in mioe (3) and herpes simplexlablalisin humans (4). In ohiokens,BHT is effeotlvein preventingmortality from exposureto Newoastlediseasevirus (NDV) (5,6). In vitro, the infeotivltyof NDV was reduoed99.9% et 17 p&ml BHT In the assay used (5). Cytomegalovirus (CMV) is inaotlvatedby BHT; 299% of human CMV wa8 inactivatedat 40 &ml BHT, while 320 j&g/mlwas required Semlikiforest virus ie alao inaotifor murlne CMV (7). vated by BHT (30% at 80 &ml) (7). However,vacolnia virus (whichis lipid-enveloped) was inaotlvatedto a muoh leoser extent than the othere,demonstratingthat differentlipid-oontalning virusesmay vary in their responsres to BHT (7).
The hydrophobioity of the BHT moleouleoauaes it to selectivelylooalizein lipid-richregions,suoh as membranes. By lnoorporatlnginto the viral lipid envelope, BHT oan potentiallyperturb the envelopegeometry, physioallydleruptthe membranesuoh that leakageooour~, or lnteraotwith a hydrophobloregion of an envelope protein suoh that the proteinoan no longer reoognizeand bind to speoif'io cell-surfacereoeptors. Perturbation oould peeslblyinduoea oonformationalohange in a speoifioenvelopeproteinor disorientthe protein suoh that the adsorption process is interferedwith. It is known that BHT treatmentoauses oompletedestruotion of the envelopeof baoteriophagePM2 (8). However,oomplete deetruotionef the envelopehas not been observed in BHT-treatedeukaryotlooell viruses. For these viruses it ie generallybelievedt.hatperturbationof the envelope somehow Interfereawith the adsorptionprooee6. Eleotron mloroeoopyof BHT-treatedNDV demonetratesoonaiderable perturbationand partialdisruptionsf the envelopeat Surprirrlngly, BHT Beem to have only a minimal 50 N&l. effeot on host oell membranes. Furthermore,pretreatment of ohlokenembryonal0811s with BHT was found to inhibit NDV progeny 8ynthe8isby 65% (6).
40
The Infeotiousagent of aoquiredImmune deficiencysyndrome has been Identifiedas a retrovIru8,the human T-oell leukemiavirus, Type III (HTLV III). This virus seleotivelyInactivateshelper T-oells (T4-oells), resultingIn an exoess of suppressorT-oells (T8-cells). The disease Is fatal and ourrentlythere Is no adequate tksatmentnor oure. Eventualcure will be dependentupon attaokingthe virus Itself. To date, few antiviralagents have been effeotiveagainst HTLV III in vitro and the only ones that are being seriouslyInvestigatedare the reverse transoriptaseInhibitors,such as suraminand HPA-23. AlthoughseeminglyeffectiveIn vitro, these drugs have been disappointingIn olinioaltrials. A survey of the availableliteratureindicatesthat nobody has consideredtestingBHT on BTLV III, or any other retrovirus for that matter. Since HTLV III containsa lipid envelope,BHT oould theoreticallypreventIts Infeotive spreadwithin the body at a dosage of about 1 to 2 g/day. Interestingly, none of the publishedresearohon antiAIDS drirgsoonsidersthe possibilityof alteringthe envelopeas a therapeutiostrategy. This is very puzzling beoause the Interactionof the envelopeproteinswith oellsurfacereceptorsis of paramountImportanceIn determining viral Infectivity. CONCLUSIONS BHT Is a potent antiviralagent that has not been investigated against the AIDS virus. Beciause BHT Is effective against lipid-enveloped viruses,It warrantsInvestigation againstHTLV III, whioh Is lipid-enveloped.Even if BHT Is Ineffectiveby Itself,It may be of value in combinationdrug therapy (e.g.a reverse transcriptase Inhibitorplus an envelopeperturbermay providea very strong "punoh"against the virus), It may be of value in amOlIOratIngthe effectsof opportunistic CMV Infeotions (the most common opportunisticInfeotionIn AIDS patients), and It may stimulatethe searoh for more effeotiverelated oompounds. BEFEHENCES 1.
BabIoh H. Butylatedhydroxytoluene(BHT):a review. Environmental Besearoh2gt l-29, 1982.
2. SnipesW, Person.& Keith A, and Cupp J. Butylated hydroxytoluene Inactivateslipid-containing viruses. SoIence188: 64-6, 1975. 3.
Keith AD, Arruda D, Snipes W, and Frost P. The antiviral effeotivenessof butylatedhydroxytoluene on herpes outaneousInfeotionsIn hairlessmice (41425). Prooeedingsof the Societyfor ExperimentalBiology and Medicine170; 237-44,1982. 41
4.
Freeman DJ, Wenerstrom G, and Spruanoe SL. Treatment of reourrent herpes simplex labialis with topioal butylated hydroxytoluene. Clinical Pharmaoology and Therapeutios 38s 56-g, 1985.
5.
Brugh M. Butylated hydroxytoluene proteots ohickens exposed to Newcastle disease virus. Solenoe 197: 1291-2, 1977.
6.
Winston M, Bolen JB, and Consigli HA. Effect of butylated hydroxytoluene on Newcastle disease virus. Amm;ican Journal of Veterinary Besearoh 41s 391-4, .
7. Kim KS, Moon HS, Sapienza V, Carp RI, and Pullarkat H.
Inactivation of cytomegalovirus and Semliki forest virus by butylated hydroxytoluene. Journal of Infeotious Diseases 138s 91-3, 1978.
8.
Cupp J, Wanda P, Keith A, and Snipes W. Inactivation of the lipid-oontalnlng bacteriophage PM2 by butylated hydroxytoluene. AntlmicarobialAgents and Chemotherapy 8: 498-706, 1975.
42
BUTYLATED HYDROXYTOLUENE, LIPID-ENVELOPED VIRUSES, AND AIDS Eric lieimund.1912 Green Mnt. Dr., #227N, Little Rock, Arkansas 72212-4018 ABSTBACT Butylated hydroxytoluene (BHT) is a potent inactivator of lipid-enveloped viruses. The viral envelope structure is physically disturbed by BHT, thereby interfering with viral adsorption to host cells. Sinoe the virus responsible for AIDS (HTLV III) oontains a lipid envelope, BHT warrant8 investigation as a potential antiviral agent against the AIDS virus. INTRODUCTION Butylated hydroxytoluene (BHT) is a potent synthetio antioxidant of low toxicity that Is widely used as a food preservative. BHT Is a hydrophobic compound, and its antioxidant effectiveness is due to its ability to prevent lipid peroxidatlon in lipid-rich regions. Due to.its antioxidant properties, BHT has been reported to extend lifespan in mloe and reduoe chemical oaroinogenesis and toxicity (1). BHT IS a relatively nontoxic compound. LD-50 values range from approximately 1800 mg/kg for the rat to 10,700 mg/kg for the guinea pig (1). Adverse effsots of BHT use inolude hepatic and pulmonary hypertrophy, and an increase in the activity of hepatio mlorosomal mixed function oxidases. However, very large doses of BHT are required before these effeots become significant (e.g. 400 to 500 mg/kg is a common dosage in these studies) (1). The average daily consumption of BHT per person in the United States is approximately 2 mg, yielding a concentration In body fat of approximately 1.3 parts per million (6 tam) (2).
39
BHT AS AN ANTIVIHALAGENT --In 1975 It was reportedby Snipes,et al, that BHT is a Potent lnaativatorof lipid-containing viruses (2). BHT, at conoentrations of approximately100 um, was oapableof inactivating( reventlngplaque-forming unit8 on appropriatehoet cellsP herpes simplexvirus (HSV) by over 90s and bacteriophage$6 by 100%. In oontrast,the polio virus,which does not oontaina lipid envelope,was not affectedby similaroonoentrations of BHT. Subsequent studieshave shown that toploalBHT is effectiveIn reduolngthe clearancetime of autaneousHSV infeotlone in mioe (3) and herpes simplexlablalisin humans (4). In ohiokens,BHT is effeotlvein preventingmortality from exposureto Newoastlediseasevirus (NDV) (5,6). In vitro, the infeotivltyof NDV was reduoed99.9% et 17 p&ml BHT In the assay used (5). Cytomegalovirus (CMV) is inaotlvatedby BHT; 299% of human CMV wa8 inactivatedat 40 &ml BHT, while 320 j&g/mlwas required Semlikiforest virus ie alao inaotifor murlne CMV (7). vated by BHT (30% at 80 &ml) (7). However,vacolnia virus (whichis lipid-enveloped) was inaotlvatedto a muoh leoser extent than the othere,demonstratingthat differentlipid-oontalning virusesmay vary in their responsres to BHT (7).
The hydrophobioity of the BHT moleouleoauaes it to selectivelylooalizein lipid-richregions,suoh as membranes. By lnoorporatlnginto the viral lipid envelope, BHT oan potentiallyperturb the envelopegeometry, physioallydleruptthe membranesuoh that leakageooour~, or lnteraotwith a hydrophobloregion of an envelope protein suoh that the proteinoan no longer reoognizeand bind to speoif'io cell-surfacereoeptors. Perturbation oould peeslblyinduoea oonformationalohange in a speoifioenvelopeproteinor disorientthe protein suoh that the adsorption process is interferedwith. It is known that BHT treatmentoauses oompletedestruotion of the envelopeof baoteriophagePM2 (8). However,oomplete deetruotionef the envelopehas not been observed in BHT-treatedeukaryotlooell viruses. For these viruses it ie generallybelievedt.hatperturbationof the envelope somehow Interfereawith the adsorptionprooee6. Eleotron mloroeoopyof BHT-treatedNDV demonetratesoonaiderable perturbationand partialdisruptionsf the envelopeat Surprirrlngly, BHT Beem to have only a minimal 50 N&l. effeot on host oell membranes. Furthermore,pretreatment of ohlokenembryonal0811s with BHT was found to inhibit NDV progeny 8ynthe8isby 65% (6).
40
The Infeotiousagent of aoquiredImmune deficiencysyndrome has been Identifiedas a retrovIru8,the human T-oell leukemiavirus, Type III (HTLV III). This virus seleotivelyInactivateshelper T-oells (T4-oells), resultingIn an exoess of suppressorT-oells (T8-cells). The disease Is fatal and ourrentlythere Is no adequate tksatmentnor oure. Eventualcure will be dependentupon attaokingthe virus Itself. To date, few antiviralagents have been effeotiveagainst HTLV III in vitro and the only ones that are being seriouslyInvestigatedare the reverse transoriptaseInhibitors,such as suraminand HPA-23. AlthoughseeminglyeffectiveIn vitro, these drugs have been disappointingIn olinioaltrials. A survey of the availableliteratureindicatesthat nobody has consideredtestingBHT on BTLV III, or any other retrovirus for that matter. Since HTLV III containsa lipid envelope,BHT oould theoreticallypreventIts Infeotive spreadwithin the body at a dosage of about 1 to 2 g/day. Interestingly, none of the publishedresearohon antiAIDS drirgsoonsidersthe possibilityof alteringthe envelopeas a therapeutiostrategy. This is very puzzling beoause the Interactionof the envelopeproteinswith oellsurfacereceptorsis of paramountImportanceIn determining viral Infectivity. CONCLUSIONS BHT Is a potent antiviralagent that has not been investigated against the AIDS virus. Beciause BHT Is effective against lipid-enveloped viruses,It warrantsInvestigation againstHTLV III, whioh Is lipid-enveloped.Even if BHT Is Ineffectiveby Itself,It may be of value in combinationdrug therapy (e.g.a reverse transcriptase Inhibitorplus an envelopeperturbermay providea very strong "punoh"against the virus), It may be of value in amOlIOratIngthe effectsof opportunistic CMV Infeotions (the most common opportunisticInfeotionIn AIDS patients), and It may stimulatethe searoh for more effeotiverelated oompounds. BEFEHENCES 1.
BabIoh H. Butylatedhydroxytoluene(BHT):a review. Environmental Besearoh2gt l-29, 1982.
2. SnipesW, Person.& Keith A, and Cupp J. Butylated hydroxytoluene Inactivateslipid-containing viruses. SoIence188: 64-6, 1975. 3.
Keith AD, Arruda D, Snipes W, and Frost P. The antiviral effeotivenessof butylatedhydroxytoluene on herpes outaneousInfeotionsIn hairlessmice (41425). Prooeedingsof the Societyfor ExperimentalBiology and Medicine170; 237-44,1982. 41
4.
Freeman DJ, Wenerstrom G, and Spruanoe SL. Treatment of reourrent herpes simplex labialis with topioal butylated hydroxytoluene. Clinical Pharmaoology and Therapeutios 38s 56-g, 1985.
5.
Brugh M. Butylated hydroxytoluene proteots ohickens exposed to Newcastle disease virus. Solenoe 197: 1291-2, 1977.
6.
Winston M, Bolen JB, and Consigli HA. Effect of butylated hydroxytoluene on Newcastle disease virus. Amm;ican Journal of Veterinary Besearoh 41s 391-4, .
7. Kim KS, Moon HS, Sapienza V, Carp RI, and Pullarkat H.
Inactivation of cytomegalovirus and Semliki forest virus by butylated hydroxytoluene. Journal of Infeotious Diseases 138s 91-3, 1978.
8.
Cupp J, Wanda P, Keith A, and Snipes W. Inactivation of the lipid-oontalnlng bacteriophage PM2 by butylated hydroxytoluene. AntlmicarobialAgents and Chemotherapy 8: 498-706, 1975.
42