Herpes simplex viruses (HSV) are ubiquitous agents which cause a variety of diseases ranging in severity from mild to severe, and in certain cases, they may became lifethreatening, especially in immunocompromised patients. After primary infection, HSV will persist in the host for the latter's entire lifetime, and HSV infection is thus considered as lifelong infection. Nucleoside analogues such as acyclovir (ACV), penciclovir etc., are the only officially approved drugs for the therapy of HSV infection.1,2) They are usually effective in treatment of primary or recurrent HSV infection. However, the widespread use of nucleoside-based drugs has lead to the emergence of HSV strain resistant to those related drugs, especially among immunocompromised patients. According to the previous surveys, the incidence of ACV-resistant strain among immunocompromised patients is around 5% and reaches 14% among bone marrow transplant recipients. [3][4][5] The high prevalence of ACV-resistant HSV among these populations suggests that new medication is needed.Adenoviruses (ADV) are other ubiquitous agents. They are associated with a wide range of illnesses, including ocular, respiratory, gastrointestinal and urinary infections. ADV infection is usually mild and always heals without the need of any special therapy. However, severe ADV infection has been reported in immunocompromised patients, including patients with leukemia, 6) AIDS, 7) or organ transplantation. 8) Furthermore, ADV cause pneumonia have been reported to have considerable mortality rate especially in children of age below 2 years old.9,10) 5-Iodo-2Ј-deoxyuridine (IDU), ganciclovir, cidafovir and several cysteine protease inhibitors are reported to inhibit ADV infection, and some of them have been used for ADV infection. [11][12][13][14] These agents, however, are either too toxic for use or not approved by governmental agencies for the therapy of ADV infection. In addition, the development of resistance of ADV to related drugs has also been reported in literature.15) Thus, new and more effective antiviral agents for future therapy in ADV infection are desired.In our continuous efforts to search for novel antiviral agents from traditional medicinal plants, twelve traditionally used medicinal plants in Taiwan were extracted with hot water (HW) and then investigated for their in vitro anti-HSV and anti-ADV activities. This is the first report on the anti-HSV and ADV activities of the HW extract of the related twelve medicinal plants. Preparation of the Extracts Hot water (HW) extract of the medicinal plants was prepared according to the procedures as described previously by Chang and Yeung with minor modifications.
MATERIALS AND METHODS
Plant Materials16) Briefly, different parts of the medicinal plants were boiled with 1000 ml of distilled water for 1 h. The aqueous was collected and the residual was extracted again with another 1000 ml of distilled water. The resulting aqueous extracts were collected, combined, filtered by gauze, concentrated under reduced pressure and ...