Immunomodulatory and anti-SARS activities of Houttuynia cordata.
BACKGROUND
Severe acute respiratory syndrome (SARS) is a life-threatening form of pneumonia caused by SARS coronavirus (SARS-CoV). From late 2002 to mid 2003, it infected more than 8000 people worldwide, of which a majority of cases were found in China. Owing to the absence of definitive therapeutic Western medicines, Houttuynia cordata Thunb. (Saururaceae)(HC) was shortlisted by Chinese scientists to tackle SARS problem as it is conventionally used to treat pneumonia.


OBJECTIVE
The present study aimed to explore the SARS-preventing mechanisms of HC in the immunological and anti-viral aspects.


RESULTS
Results showed that HC water extract could stimulate the proliferation of mouse splenic lymphocytes significantly and dose-dependently. By flow cytometry, it was revealed that HC increased the proportion of CD4(+) and CD8(+) T cells. Moreover, it caused a significant increase in the secretion of IL-2 and IL-10 by mouse splenic lymphocytes. In the anti-viral aspect, HC exhibited significant inhibitory effects on SARS-CoV 3C-like protease (3CL(pro)) and RNA-dependent RNA polymerase (RdRp). On the other hand, oral acute toxicity test demonstrated that HC was non-toxic to laboratory animals following oral administration at 16 g/kg.


CONCLUSIONS
The results of this study provided scientific data to support the efficient and safe use of HC to combat SARS.
Lau
Kit-Man
KM
Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
Lee
Kin-Ming
KM
Koon
Chi-Man
CM
Cheung
Crystal Sao-Fong
CS
Lau
Ching-Po
CP
Ho
Hei-Ming
HM
Lee
Mavis Yuk-Ha
MY
Au
Shannon Wing-Ngor
SW
Cheng
Christopher Hon-Ki
CH
Lau
Clara Bik-San
CB
Tsui
Stephen Kwok-Wing
SK
Wan
David Chi-Cheong
DC
Waye
Mary Miu-Yee
MM
Wong
Kam-Bo
KB
Wong
Chun-Kwok
CK
Lam
Christopher Wai-Kei
CW
Leung
Ping-Chung
PC
Fung
Kwok-Pui
KP
D000284:Administration, Oral; D000818:Animals; D000998:Antiviral Agents / Q000008:administration & dosage* / Q000302:isolation & purification / Q000633:toxicity; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D002681:China; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal / Q000008:administration & dosage* / Q000633:toxicity; D005260:Female; D005434:Flow Cytometry; D052859:Houttuynia; D051379:Mice; D008807:Mice, Inbred BALB C; D045473:Severe acute respiratory syndrome-related coronavirus / Q000187:drug effects*; D045169:Severe Acute Respiratory Syndrome / Q000188:drug therapy*; D013154:Spleen / Q000166:cytology; D023382:Toxicity Tests, Acute
D000998:Antiviral Agents; D004365:Drugs, Chinese Herbal; C442781:Houttuynia cordata extract