Cloning, characterization, and inhibition studies of a ß-carbonic anhydrase from Leishmania donovani chagasi, the protozoan parasite responsible for leishmaniasis.

Leishmaniasis is an infection provoked by protozoans belonging to the genus Leishmania. Among the many species and subsepecies of such protozoa, Leishmania donovani chagasi causes visceral leishmaniasis. A ß-carbonic anhydrase (CA, EC 4.2.1.1) was cloned and characterized from this organism, denominated here LdcCA. LdcCA possesses effective catalytic activity for the CO2 hydration reaction, with kcat of 9.35 × 10(5) s(-1) and kcat/KM of 5.9 × 10(7) M(-1) s(-1). A large number of aromatic/heterocyclic sulfonamides and 5-mercapto-1,3,4-thiadiazoles were investigated as LdcCA inhibitors. The sulfonamides were medium potency to weak inhibitors (KI values of 50.2 nM-9.25 µM), whereas some heterocyclic thiols inhibited the enzyme with KIs in the range of 13.4-152 nM. Some of the investigated thiols efficiently inhibited the in vivo growth of Leishmania chagasi and Leishmania amazonensis promastigotes, by impairing the flagellar pocket and movement of the parasites and causing their death. The ß-CA from Leishmania spp. is proposed here as a new antileishmanial drug target.

Conventional therapy and promising plant-derived compounds against trypanosomatid parasites.

Leishmaniasis and trypanosomiasis are two neglected and potentially lethal diseases that affect mostly the poor and marginal populations of developing countries around the world and consequently have an important impact on public health. Clinical manifestations such as cutaneous, mucocutaneous, and visceral disorders are the most frequent forms of leishmaniasis, a group of diseases caused by several Leishmania spp. American trypanosomiasis, or Chagas disease, is caused by Trypanosoma cruzi, a parasite that causes progressive damage to different organs, particularly the heart, esophagus, and lower intestine. African trypanosomiasis, or sleeping sickness, is caused by Trypanosoma brucei and is characterized by first presenting as an acute form that affects blood clotting and then becoming a chronic meningoencephalitis. The limited number, low efficacy, and side effects of conventional anti-leishmania and anti-trypanosomal drugs and the resistance developed by parasites are the major factors responsible for the growth in mortality rates. Recent research focused on plants has shown an ingenious way to obtain a solid and potentially rich source of drug candidates against various infectious diseases. Bioactive phytocompounds present in the crude extracts and essential oils of medicinal plants are components of an important strategy linked to the discovery of new medicines. These compounds have proven to be a good source of therapeutic agents for the treatment of leishmaniasis and trypanosomiasis. This work highlights some chemotherapeutic agents while emphasizing the importance of plants as a source of new and powerful drugs against these widespread diseases.

A new experimental culture medium for cultivation of Leishmania amazonensis: its efficacy for the continuous in vitro growth and differentiation of infective promastigote forms.

Parasites from the genus Leishmania cause a variety of disease states in humans and other mammals in tropical and subtropical regions, which include cutaneous, mucocutaneous and visceral leishmaniasis. The elaboration of a culture medium for the in vitro cultivation of Leishmania spp., which promotes the growth and differentiation of the parasites, is an important tool for diagnosis, biochemical, biological and immunological studies in the genus. Herein, we have reported the development of a rapid, inexpensive and reliable monophasic culture medium. The novel medium, designated PBHIL, promoted an excellent parasite growth, generating high quantities of promastigotes with long-term viability, and was able to induce cellular differentiation of L. amazonensis promastigotes to the amastigote-like forms (93%). Additionally, we reported the influence of this novel medium on the biochemical characteristics of L. amazonensis and on the interaction of this parasite parasites with mammalian macrophages.