The anticoagulant activity

in vitro

of three different sample isolated from the leech

Hirudinaria manillensis

with three different extracting methods was studied

and utilized the optimal extracting process

the anti-thrombin bioactivity of five species of leeches were analyzed

and compared the anti-thrombin bioactivity of three species of wild

H. manillensis

from different geographical distribution and two species of cultured

H

.

manillensis

reared with different diets. The results showed that among them

the extracts produced by acetone precipitation had the highest yield

and also displayed the stronger anticoagulant activity tested than others (

P

<

0.05). The test displayed three species of non-bloodsucking leeches (

Whitmania pigra

Whitmania acranulata

and

Whitmania laevis

) had no or lower anti-thrombin activity

and the two species of blood-sucking leeches (

H

.

manillensis

and

Hirudo nipponia

) had higher anti-thrombin activity

and that the anti-thrombin activity of

H. manillensis

was higher than

Hirudo nipponia

significantly (

P

<

0.01). There was no significant difference of inhibitory activity to thrombin between wild and cultured

H. manillensis

(

P

>

0.05). In conclusion

the leech of

H. manillensis

had high anti-thrombin bioactivity in vitro

and the artificial breeding had no adverse effect on its quality and anticoagulant activity.