IN-VITRO ANTIGIARDIASIC ACTIVITY OF PLANT-EXTRACTS

Objective: To investigate antigiardiasic activity in plants used in Me xico as antidiarrheics and/or antiparasitics. Materials and methods. F ourteen species were evaluated. The antigiardiasic activity was measur ed in vitro in a blinded fashion using trophozoites of Giardia duodena lis incubated with plant extracts. The viability of trophozoites was a scertained using MTT (3-[4,5-dimethylthiazol-2-il]-2, 5-diphenyl tetra zolium bromide) which is reduced to MTT-formazan by the activity of li ve trophozoites. The reduced MTT was extracted with an acidified alcoh ol (2-propanol with HCl 0.04 M) and measured in a spectrophotometer at 570 nm. Negative (trophozoites without extract) and positive controls (incubated with tinadazol) were included. Results. The scientific and trivial names of the plants are given (trivials in Spanish marked by an asterisk). They had the following trophozoite mortality (mean +/- S D in percent): Justicia spicigera (muicle) = 91 +/- 0.5; Lipia berian dieri (oregano) = 90 +/- 0.6; Psidium guajava (guava) = 87 +/- 1.0; po sitive control of tinidazol = 79 +/- 1.9; Punica granutus (granado) = 78 +/- 1.3; Magnifera indica (mango) = 77 +/- 1.0; Plantago major (la nte) = 76 +/- 1.2; Cupressus semperbirens (cipres) = 73 +/- 1.2; Cast ella tormentosa (chaparro amargoso) = 70 +/- 0.7; Hematoxilon campech anum (palo de Campeche) = 67 +/- 1.2. Without or with a low mean acti vity were Prosopis juliflora (mezquite) and Rizophora mangle (mangle* ) with 0%, Oriza sativa (rice) with 5%, Capsicum annum (pimiento) wit h 21% and Persea americana (avocado) with 23%. There were no associati ons of the antigiardiasic effect with concentration or osmolality of t he extracts. Conclusions. A clear in vitro antigiardiasic effects was seen in nine species. Three of them were superior to tinidazol which i s a drug of common use in the treatment of giardiasis.