Herpes simplex virus type 1 (HSV-1) infection has a prevalence of 70% in the human population. Treatment is based on acyclovir, valacyclovir, and foscarnet, three drugs that share the same mechanism of action and of which resistant strains have been isolated from patients. In this aspect, innovative drug therapies are required. Natural products offer unlimited opportunities for the discovery of antiviral compounds. In this study, 28 extracts corresponding to 24 plant species and 4 alga species were assayed in vitro to detect antiviral activity against HSV-1. Six of the methanolic extracts inactivated viral particles by direct interaction and 14 presented antiviral activity when incubated with cells already infected. Most interesting antiviral activity values obtained are those of Limonium brasiliense, Psidium guajava, and Phyllanthus niruri, which inhibit HSV-1 replication in vitro with 50% effective concentration (EC50) values of 185, 118, and 60 μg/mL, respectively. For these extracts toxicity values were calculated and therefore selectivity indexes (SI) obtained. Further characterization of the bioactive components of antiviral plants will pave the way for the discovery of new compounds against HSV-1.

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The exudate of Salpichroa origanifolia (Solanaceae) foliar glandular trichomes has been characterized chemically. It was demonstrated to be a complex mixture of hexaesters of short chain fatty acids and sucrose. Of the total exudates, 80% was 1´,6´-diacetyl-2,3,4,6-tetra(3-methyl valerianyl)-sucrose, a new natural product, which showed antifungal properties against Aspergillus niger. It is the first report of sugar esters in the genus Salpichroa.

Aiming to evaluate the effects of Solanum sisymbriifolium extracts on the development of Spodoptera frugiperda, a leaf dichloromethane extract was obtained and subjected to further purification following a bioguided methodology. The structure of the two main compounds isolated from S. sisymbriifolium Type IV glandular trichomes have been completely elucidated by a combination of chemical and spectroscopic methods. They are glycosides of 3-(R)-hydroxypalmitic acid and xylo (β-1-5) furanoarabinoside (Compound 1) and its 3-O-palmitoyl derivative (Compound 2). These compounds greatly influenced the survival and the development of S. frugiperda, when compared to an in vitro test control. The extracts delayed the development, decreased survival and promote abnormalities in the immatures (larvae and pupae). They also showed increasing toxicity towards S. frugiperda in the purification following a bioguided fractionation. The pure compounds had the most deleterious activity, increasing the larval and pupal toxicity (100% mortality for Compound 2 at 2.50 mg mL-1 and 90% mortality for Compound 1 at 1.00 mg mL-1).