title: Aqueous Extracts of Hibiscus sabdariffa Calyces to Control Aichi Virus.
abstract: Aqueous Hibiscus sabdariffa extracts possess antimicrobial properties with limited information available on their antiviral effects. Aichi virus (AiV) is an emerging foodborne pathogen that causes gastroenteritis. Vaccines are currently unavailable to prevent their disease transmission. The objective of this study was to determine the antiviral effects of aqueous H. sabdariffa extracts against AiV. AiV at ~5 log PFU/ml was incubated with undiluted (200 mg/ml), 1:1 (100 mg/ml) or 1:5 (40 mg/ml) diluted aqueous hibiscus extract (pH 3.6), phosphate-buffered saline (pH 7.2 as control), or malic acid (pH 3.0, acid control) at 37 °C over 24 h. Treatments were stopped by serially diluting in cell-culture media containing fetal bovine serum and titers were determined using plaque assays on confluent Vero cells. Each treatment was replicated thrice and assayed in duplicate. AiV did not show any significant reduction with 1:1 (100 mg/ml) or 1:5 (40 mg/ml) diluted aqueous hibiscus extracts or malic acid after 0.5, 1, or 2 h at 37 °C. However, AiV titers were reduced to non-detectable levels after 24 h with all the three tested concentrations, while malic acid showed only 0.93 log PFU/ml reduction after 24 h. AiV was reduced by 0.5 and 0.9 log PFU/ml with undiluted extracts (200 mg/ml) after 2 and 6 h, respectively. AiV treated with 1:1 (100 mg/ml) and 1:5 (40 mg/ml) diluted extracts showed a minimal ~0.3 log PFU/ml reduction after 6 h. These extracts show promise to reduce AiV titers mainly through alteration of virus structure, though higher concentrations may have improved effects.
authors.affiliation: Department of Food Science and Technology, University of Tennessee-Knoxville, 2600 River Drive, Room 102 FSPB, Knoxville, TN, 37996, USA. ddsouza@utk.edu.
authors.forename: Doris H
authors.initials: DH
authors.lastname: D'Souza
authors.affiliation: Department of Food Science and Technology, University of Tennessee-Knoxville, 2600 River Drive, Room 102 FSPB, Knoxville, TN, 37996, USA.
authors.forename: Lezlee
authors.initials: L
authors.lastname: Dice
authors.affiliation: Department of Food Science and Technology, University of Tennessee-Knoxville, 2600 River Drive, Room 102 FSPB, Knoxville, TN, 37996, USA.
authors.forename: P Michael
authors.initials: PM
authors.lastname: Davidson
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000302:isolation & purification / Q000494:pharmacology*; D002522:Chlorocebus aethiops; D035264:Flowers / Q000737:chemistry; D031584:Hibiscus / Q000737:chemistry*; D052699:Kobuvirus / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D014709:Vero Cells
chemical_list: D000998:Antiviral Agents; D010936:Plant Extracts
keywords: Aichi virus; Aqueous H. sabdariffa calyces; Reduction