Evaluation of anti-HSV-2 activities of Barleria lupulina and Clinacanthus nutans

Barleria lupulina Lindl. and Clinacanthus nutans (Burm. f.) Lindau, both belonging to the family Acantaceae, are well-known medicinal plants used in Thai folklore medicine. Virucidal effects of organic extracts of these two plants against herpes simplex virus type 2 strain G, HSV-2 (G), the standard HSV-2 strain were noted. The extracts were assessed for intracellular activities against HSV-2 (G) and five clinical HSV-2 isolates. B. lupulina extract exhibited activity against all five isolates but not the standard strain while that of C. nutans did not show any activity against these viruses as determined by plaque inhibition assay. When the activities were verified by yield reduction assay, anti-HSV-2 activities of B. lupulina extract were observed against HSV-2 (G) as well. The results suggest a therapeutic potential of B. lupulina but not C. nutans against HSV-2.