The synthesis and evaluation of a series of 3,5-disubstituted isoxazoles as antipicornavirus agents have led to the discovery of several compounds effective in vitro against rhinovirus type 2 and poliovirus type 2. Compound 32 was found more effective than 4',6-dichloroflavan against both viruses and was evaluated orally in mice infected intracerebrally with polio-2. At 31 mg/kg bid, compound 32 showed a 53% survival rate as compared to 22% for the nonmedicated animals.

The discovery that 4-[3-ethyl-6-[(3,4-methylenedioxy)phenyl]-3-hexenyl]-3,5-heptanedione (40) exhibited an in vitro inhibitory effect against equine rhinovirus led to a structure--activity study to establish the criteria for optimum activity. Modification of the bridge included removal of the ethyl group and reduction of the double bond. The heptanedione was replaced with hexanedione and pentanedione with a minimal effect. The effect of replacing the heptanedione with beta-keto esters and monoketones was also investigated. Maintaining the hexamethylene bridge and heptanedione, the methylenedioxy group was replaced with various substitutents. In general, most substituents did not adversely affect activity particularly against equine rhinovirus although there was some variation in activity against herpesvirus. Strongly hydrophilic groups significantly reduced activity. Finally, the effect of varying the length of the alkyl bridge was examined in the 4-hydroxyphenyl series, where peak activity was attained with n = 8.

A series of bis(beta-diketones) was synthesized and tested in vitro for antiviral actitity against herpes simplex type 2. Two parameters which were studied in an effort to optimize activity were the nature of the aryl group and the length of the alkyl bridge. One of the more active compounds, 4,4'-[(1,4-phenylenedioxy)bis(6,1-hexanediyl)]-bis[3,5-heptanedione] (6), was evaluated more extensively and found to inhibit the cytopathic effect in tissue culture of herpes simplex virus type 1 as well as type 2. Compound 6 was evaluated in vivo topically against herpes simplex type 1 in experimentally induced skin infections in guinea pigs. A topical treatment with 2% of 6 in a vanishing cream base, administered 24 h postinfection applied five times daily for 4 days, significantly reduced the number and size of herpetic vesicles.

The naturally occurring halogenated pyrroles 1-5 have all yielded to synthesis.1-9 All of these materials possess antibacterial properties of potential interest in human chemotherapy. We have prepared variations of pyoluteorin structure 1 and have examined them for in vitro and in vivo activity against a variety of pathogens and for antimalarial activity in mice. In addition, selected members of the series were examined for anthelmintic and antischistosomal activities.

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