Anti-HSV agents

Three oral agents are licensed for the treatment of HSV and VZV infections acyclovir, valacyclovir, and famciclovir. They have similar mechanisms of action and similar indications for clinical use all are well tolerated. Acyclovir, licensed first, has been the most extensively studied in addition, it is the only anti-HSV agent available for intravenous use in the United States. Neither valacyclovir nor famciclovir have been fully evaluated in pediatric patients thus, they are not indicated for the treatment of varicella infection. 

The importance of red macroalgae as a source of novel anti-HSV agents has been recognized and reported by many researchers. According to Serkedjieva (2000), the water extract of Polysiphonia denudate exhibited... 

In order to find new sources of antiviral agents with different mechanisms of action, extracts of marine algae from all over the world were assayed for anti-HSV activity. The first screening of 89 types of seaweed collected from British Columbia, Canada and Korea for antiviral activity was reported by Kim et al. [66]. Analipus japonicus was the most potent anti-herpes algae. Extracts from 13 types of Korean seaweed previously shown to contain antiviral activity were investigated in more detail in order to learn their mechanism of action [14]. Four species, Enteromorpha linza, Colpomenia bullosa, Scytosiphon lomentaria and Undaria pinnatifida were active against HSV. In experiments to determine the site of action of these antiviral extracts, the predominant activity was virucidal (i.e., direct inactivation of virus particles) rather than inhibition of virus replication. 

The anti-HSV-1 activity of Ca-SP was assessed by plaque yield reduction and compared with those of dextran sulphate as a representative sulphated PS. These data indicate that Ca-SP is a potent antiviral agent against HSV-1, as even at low concentrations of Ca-SP, no enhancement of virus-induced syncytium formation was observed, as occurred in dextran sulphate-treated cultures. Reeently, Lee et al. [73] investigated the effects of structural modifications of Ca-SP on antiviral activity. Calcium ion binding with the anionic part of the molecule was replaeed with various metal cations, and their inhibitory effects on the replication of HSV-1 were evaluated. Replacement of calcium ion with sodium and potassium ions maintained the antiviral activity, while divalent and trivalent metal cations reduced the activity. Depolymerization of sodium spirulan with hydrogen peroxide decreased the antiviral activity as its molecular weight decreased. 

GA has shown promising results as an anti-HSV-2 (Herpes simplex virus) agent [65]. It is also used in the pharmaceutical industry as an astringent and styptic agent. 

Isobomeol demonstrated potent anti-Tierpes simplex virus-1 (anti-HSV-1) activity by inhibition of virus replication and the glycosylation of viral proteins. As a result, HSV-1 loses its infectivity [36]. Monoterpene derivatives cineol and bomeol have also been shown to be potent anti-HSV-1 agents. It has been shown that putranjivain A, isolated from Euphorbia jolkini Euphorbiaceae), may affect late stages of HSV-2 replication by inhibiting viral attachment and cell penetration... 

SJS was for many years considered a severe variant of erythema multiforme major (EMM) however, over the past decade some experts have reclassified SJS as a less severe variant of toxic epidermal necrolysis (TEN) rather than a form of EMM. However, this perspective is not universally accepted. SJS occurs acutely in all ages, with 20% in children and a peak incidence in adults between the second and fourth decades of life. SJS is a potentially fatal disorder with a mortality of approximately 5%.TEN has a mortality rate of approximately 30%. About 50% of cases of these disorders are idiopathic. Identifiable causal factors include microbial infection, particularly with Mycoplasma pneumoniae and HS Vj and medications, including sulfonamides, tetracycline, penicillin, nonsteroidal anti-inflammatory drugs (NSAIDs), psychotropic agents, antiepileptics, and immunizing vaccines. Recent research suggests that HSV infection is a principal fector in the genesis of EMM, whereas medications are a more likely precipitant of SJS and TEN. 

Later was reported that variabilin (7a) is a good inhibitor of human secretory and cytosolic PLA2 with anti-inflammatory activity [32] and shows in vitro antiviral activity against Herpes simplex (HSV) and Polio vaccine (PV1) viruses [33]. The high cytotoxicity against the BSC cell line exhibited by variabilin severely limits its potential usefulness as antiviral agent [33]. 

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