Evaluation of Immune Boosting Properties and Combating of Multiple Respiratory Viral Infections by fifteen Euphorbiaceae Plant Extracts

Objective: Fifteen Euphorbiaceae plant extracts were evaluated for their antiviral and immune boosting properties. Methods: The maximum non-toxic concentration of each extract in specific pathogen–free embryonated chicken eggs was estimated and their antiviral efficacy was determined in terms of reduction in viral titers, measured by the hemagglutination inhibition (HI) assay. The antiviral efficacy was compared with ribavirin. The active extract was further subjected to estimation of total polyphenolic and flavonoid contents. Also, GC/ MS analysis was used to analyze its unsaponifiable and saponifiable matters. Results: The cytotoxic concentration fifty (CC₅₀) of Breynia distacha recorded the value of >200 and >300 for Newcastle disease virus (NDV) and avian influenza virus (AIV) H5N1, respectively. This extract showed antiviral inhibition concentration (IC₅₀) values of ≤ 2 and ≤ 3, respectively and antiviral therapeutic index of 100% compared with ribavirin as standard. The serum of the vaccinated chicks treated with B. distacha has recorded the highest HI titers (7.1 and 8.3 log2) at the day of 28 post vaccination with high protection percentage (100 and 90%) post NDV and AIV H5N1 challenge, respectively. Also, a high HI titer (6.9 log2) was recorded in serum of the vaccinated chicks treated with Aleurites moluccana, Jatropha curcas, Ricinus communis, Putranjiva roxburghii with protection percentage of 95-100% post-NDV challenge. GC/MS analysis allowed identification of 91.10% of the total unsaponifiable matter, (1-heptatriacotanol represented the major component, 24.61%) and 82.51% of the fatty acid methyl esters content (methyl palmitate represented the major component, 26.13 %). Conclusion: This study highlighted the potential of many Euphorbiaceae plants especially B. distacha, to be new candidate of plant-based prototypes that carry antiviral and immunogenic features against respiratory viral infections.