Ta-Chen Lin

Antiherpes simplex virus type 2 activity of casuarinin from the bark of Terminalia arjuna Linn.

Casuarinin, a hydrolyzable tannin isolated from the bark of Terminalia arjuna Linn. (Combretaceae), was investigated for its antiviral activity on herpes simplex type 2 (HSV-2) in vitro. Results showed that the IC(50) of casuarinin in XTT and plaque reduction assays were 3.6+/-0.9 and 1.5+/-0.2 microM, respectively. The 50% cytotoxic concentration for cell growth (CC(50)) was 89+/-1 microM. Thus, the selectivity index (SI) (ratio of CC(50) to IC(50)) of casuarinin was 25 and 59 for XTT and plaque reduction assays, respectively. Casuarinin continued to exhibit antiviral activity even added 12 h after infection. During the attachment assay, casuarinin was shown to prevent the attachment of HSV-2 to cells. Furthermore, casuarinin also exhibited an activity in inhibiting the viral penetration. Interestingly, casuarinin was virucidal at a concentration of 25 microM, reducing viral titers up to 100,000-fold. This study concludes that casuarinin possesses anti-herpesvirus activity in inhibiting viral attachment and penetration, and also disturbing the late event(s) of infection.

Antiviral properties of prodelphinidin B-2 3'-O-gallate from green tea leaf

Prodelphinidin B-2 3′-O-gallate, a proanthocyanidin gallate isolated from green tea leaf, was investigated for its anti-herpes simplex virus type 2 properties in vitro. Prodelphinidin B-2 3′-O-gallate exhibited antiviral activity with IC50 of 5.0 ± 1.0 μM and 1.6 ± 0.3 μM for XTT and plaque reduction (PRA) assays, respectively. Cytotoxicity assay had shown that prodelphinidin B-2 3′-O-gallate possessed cytotoxic effect toward Vero cell at concentration higher than its IC50. The 50% cytotoxic concentration for cell growth (CC50) was 33.3 ± 3.7 μM. Thus, the selectivity index (SI) (ratio of IC50 to CC50) for XTT assay and PRA was 6.7 and 20.8, respectively. Prodelphinidin B-2 3′-O-gallate significantly reduced viral infectivity at concentrations 10 μM or more. Result of time-of-addition studies suggested that prodelphinidin B-2 3′-O-gallate affected the late stage of HSV-2 infection. In addition, it was also shown to inhibit the virus from attaching and penetrating into the cell. Thus, prodelphinidin B-2 3′-O-gallate was concluded to possess antiviral activity with mechanism of inhibiting viral attachment and penetration, and disturbing the late stage of viral infection.

EUPHORBIA THYMIFOLIA SUPPRESSES HERPES SIMPLEX VIRUS-2 INFECTION BY DIRECTLY INACTIVATING VIRUS INFECTIVITY

1. The ethyl acetate (EtOAc) extract and 3‐O‐galloyl‐4,6‐(S)‐hexahydroxydiphenoyl‐d‐glucose (3OG46HG) of Euphorbia thymifolia Linnea have been shown to exhibit anti‐herpes simplex virus (HSV)‐2 activity in vitro. In the present study, we investigated the mode of action of these two compounds in suppressing HSV‐2 multiplication.