<i>In ovo</i> antiviral potency of the leaf constituents of Tanzanian <i>Toussaintia</i> species against Infectious Bursal Disease Virus and Newcastle Disease Virus

Abstract

The chemical constituents of Toussantia orientalis and T. patriciae (Annonaceae) leaf extracts were evaluated for their antiviral activities in ovo against Infectious Bursal Disease Virus (IBDV) and Newcastle Disease Virus (NDV). The nine-day-old embryonated eggs in a set of five were used for testing through the allantoic route inoculation assay for each tested compound and controls. For NDV assay, the allantoic fluids from the specimens were further harvested to determine viral contagion. The tested compounds exhibited potency with varying levels of significance at a screening concentration of 360 µg/ml against the two viral strains. Embryos infected with IBDV survived, grew to normal size with complete organ formation and had mean weights comparable to those of the uninfected ones when treated with the aminocinnamoyl tetraketides 1, 2, and 4, glucosylflavonoid 7 from T. orientalis and ursolic acid derivatives 9 and 10 from T. patriciae demonstrating high efficacy against IBDV. The compounds also exhibited antiviral activity against NDV, showing viral titre reduction ranging from 1:16 - 1:256 in the haemagglutination test, with compound 11 having the lowest titre value (1:16) followed by compound 7 (1:32). The compounds that exhibited significant antiviral efficacy could be considered potential leads for the development of antiviral agents.

Keywords: Aminocinnamoyl tetraketides, ursolic acids, Toussaintia orientalis, Toussaintia patriciae, Annonaceae.