Phytochemical composition of Dichrocephala integrifolia crude extracts, antiviral activity and toxicity

Abstract

Abstract. Hadun AH, Mbaria J, Aboge GO. 2022. Phytochemical composition of Dichrocephala integrifolia crude extracts, antiviral activity and toxicity. Asian J Trop Biotechnol 19: 72-81. Human herpes simplex viruses are among the world's most ubiquitous human infections. Generally, there are two types of Human Herpex simplex viruses (HSV), HSV-1 and HSV-2, infecting over 90% of people with either one or both. HSV-1 is a viral disease to cause genital and oral lesions. As a major antiviral drug to treat HSV infections, Acyclovir has proven unsatisfactory as resistance, and severe side effects in pregnant mothers and infants have been frequently reported. The high prevalence of HSV, lack of vaccines, and limited treatment options warrant an urgent need for more effective anti-HSV agents. The aim of this study was to investigate phytochemical composition, in vitro anti-HSV, and in vivo and in vitro toxicity of Dichrocephala integrifolia (L.fil.) Kuntze crude extracts. Leaves, roots, flowers, and stems of D. integrifolia were collected from Mabariri Village in Nyamira County, Kenya. The identification by a botanist in the school of biological sciences, University of Nairobi, Kenya. The materials were extracted with methanol and water, and Qualitative tests were conducted to determine alkaloids, flavonoids, saponins, tannins, glycosides, and terpenoids presences. The MTT assay investigated in vitro cytotoxic activity using Vero cell lines from the center for viral research Kenya Medical Research Institute (KEMRI). Antiviral activity has assessed the ability to protect normal cells (Vero cell lines) from HSV attack. In vivo toxic effects in female Swiss albino mice using oral acute toxicity protocols by OECD. The qualitative phytochemical showed the extracts contained tannins, flavonoids, alkaloids, terpenoids, phenols, glycosides, and saponins. It was not cytotoxic to Vero cells except the flower's methanolic extract, which had a CC₅₀ value of 71.31± 2.65 µg/mL. The extracts interference adsorption step of HSV-1 blocks the virus's epitopes on the cell's membrane. Methanolic extracts of the stem, leaves and aqueous extracts of leaves inhibited HSV-1 virus from causing a cytopathic effect, with IC₅₀ values of 63.95±5.36 µg/mL, 54.45±3.45 µg/mL, 86.20±7.56 µg/mL. Methanolic flower, aqueous root, and methanolic leaves extract show virucidal with IC₅₀ values of 45.27±2.41 µg/mL, 0.333±1.23 µg/mL, and 30.53±4.51 µg/mL. Oral administration to mice at 300 mg/kg and 2,000 mg/kg did not result in any toxic effects or mortality. In all the groups, no major behavioral or appearance changes were observed. Pharmacologically phytochemicals such as flavones, phenols, terpenoids, and tannins in antimicrobial action support this plant's pathologies management. The cytotoxicity, efficacy, and acute oral show no major toxicity; preparing antiviral herbal remedies may be safe for patients. Further research into plant mechanisms and isolating the bioactive agents are needed; studying toxic effects is also recommended to formulate pharmacological products.