Exploring anti-Herpes Simplex Virus agents from Malaysian medicinal plant biodiversity: Asplenium nidus L. and Phaleria macrocarpa (Scheff.) Boerl.

Abstract

Plant-derived compounds offer promising alternatives for antiviral drug development due to their structure and bioactivity. This study explores the potential of two Malaysian medicinal plants, namely Asplenium nidus L. and Phaleria macrocarpa  (Scheff.) Boerl. as sources of anti-herpes simplex virus type-1 (HSV-1). The paper examines the various extracts and fractions from these plants for their phytochemicals, in vitro cytotoxicity and antiviral activity. The variability in phytochemical profiles is addressed and correlated with the mode of antiviral action in infected host cells. Asplenium nidus root aqueous extract contains alkaloids, flavone aglycone, terpenoids, saponin, tannin and steroids. Asplenium nidus extracts/fractions are considered as non-cytotoxic, with the 50% cytotoxic concentration (CC50) in the range of 0.78+0.15 to 47.01+1.56 mg/mL. The effective concentration (EC50) of extracts/fractions toward the virus was within 0.056+0.007 to 0.743+0.39 mg/mL and the selective indices (SI) were within 14 to 63.25 which exceed 10, suggesting promising antiviral properties. P. macrocarpa fruit extracts/fractions are considered as non-cytotoxic, with the CC50 in the range of 0.40+0.02 to 1450 ± 2.0 mg/mL. The EC50   values were within 0.10+0.02 to 18 ± 1.2 mg/mL. As for the SI values were within 8 to 80.6 mg/mL with only three fraction/extracts worthy as antiviral agents, including P. macrocarpa fruit aqueous extract, fruit methanol extract and, aqueous protein extract P. macrocarpa fruit. The aqueous protein extract P. macrocarpa fruit contains proteins, sugar, flavonoid, polyphenol, and xanthone. Asplenium nidus root aqueous extract and aqueous protein extract P. macrocarpa fruit both exhibit multiple modes of action indicated by virus inhibition percentage exceeding 50% supported by statistical analysis with p<0.05. These include preventing virus attachment and penetration into cells, virucidal activity and reducing viral progeny to inhibit reinfection. These findings underscore the potential of tropical medicinal plants in contributing to the development of novel antiviral therapeutics.