*4.2. Astrovirus*

Astroviruses are non-enveloped, positive-sense single-stranded RNA viruses causing GIT disorders particularly pediatric diarrhea. The astrovirus capsid acts as enterotoxin and thus disrupts gu<sup>t</sup> epithelial barrier [191]; *Achyrocline bogotensis* (Kunth) DC. extracts were evaluated for their antirotavirus (RRV) and anti-astrovirus (Yuc8) activities. The nontoxic concentrations displayed considerable antiviral potentials against both viruses. The activity can be attributed to the presence of steroids, sterols, terpenes, phenols, flavonoids and sesquiterpene lactones [192]. *Spirulina platensis* ethanolic extract was tested and revealed a considerable decline in vitro for infectious units of various types of viruses including adenovirus (type 7), astrovirus (type 1), Coxsackievirus B4, rotavirus (Wa strain) and adenovirus (type 40) [193]. Northern Nigerian plants have been investigated against poliovirus, astrovirus, herpes simplex viruses and parvovirus. The obtained results showed that the test samples showed considerable activity against viruses at 100–400 mg/100 mL dose [194].

### *4.3. Hepatitis-A Virus*

The hepatitis A virus (HAV), a picornavirus is a widespread cause of hepatitis and is transmitted via oral intake of contaminated food, water and blood transfusion [195]. Medicinal plants including *Alnus japonica* (Thunb.) Steud. have revealed significant virucidal activity against HAV and at a concentration of 50-μg/mL has reduced HAV titer by 3.43 ± 0.24 logs. Similarly, *Artemisia annua* L., *Allium sativum* L., *Allium fistulosum* L. and *Agrimonia pilosa* Ledeb. extracts exhibited 2.33 ± 0.43, 2.10 ± 0.41, 2.07 ± 0.60 and 2.03 ± 0.26-log reductions, respectively [196]. It has been observed that green tea extract has a strong anti-HAV activity with a direct effect on the viral particles. Supplementing tap water with the extract with continuous shaking every 15 min for 1 h caused a significant reduction in the percentage of HAV plaque counts. There is a strong recommendation of supplementing water with a small concentration of green tea extract that does not cause an observed change in its color and taste for 1 h with persistent shaking before usage in endemic areas for HAV infections [197].
