Leishmania mexicana cell death achieved by Cleoserrata serrata (Jacq.) Iltis: Learning from Maya healers

ETHNOPHARMACOLOGICAL RELEVANCE

Aerial parts of Cleoserrata serrata (Jacq.) Iltis are widely used in South-Central Mexico to treat wounds and bacterial skin infections and in Panama by Kuna, Ngöbe-Buglé, and Teribe Indians for tropical warm baths and by Kunas in the form of "Ina kuamakalet" for snakebites.

AIMS OF THE STUDY

To evaluate the effect of Cleoserrata serrata extract on growth and viability of L. mexicana amastigotes and promastigotes in vitro, as well as on bacteria that usually co-infect skin ulcers.

MATERIALS AND METHODS

Cleoserrata serrata was collected in La Chontalpa, Tabasco, Mexico. The antiproliferative effect of the extract was tested on growth of Leishmania mexicana amastigotes and promastigotes in vitro, as well as on bacteria that usually co-infect skin ulcers.

RESULTS

Our data show that Cleoserrata serrata significantly inhibits parasite growth (which was more important in infective amastigotes) and additionally inhibits growth of the co-infective bacteria Staphylococcus aureus and Pseudomonas aeruginosa. Confocal microscopy showed a leishmanicidal effect.

CONCLUSION

We conclude that Cleoserrata serrata extract is potentially an optimal treatment alternative for patients with cutaneous leishmaniasis infected with Leishmania mexicana, since it controls both the parasite as well as bacterial co-infections. Furthermore, it can be applied topically. The precise metabolites responsible for the anti-Leishmania and anti-bacterial effects remain to be established.

Macrophage Activation by Ursolic and Oleanolic Acids during Mycobacterial Infection

Oleanolic (OA) and ursolic acids (UA) are triterpenes that are abundant in vegetables, fruits and medicinal plants. They have been described as active moieties in medicinal plants used for the treatment of tuberculosis. In this study, we analyzed the effects of these triterpenes on macrophages infected in vitro with Mycobacterium tuberculosis (MTB). We evaluated production of nitric oxide (NO), reactive oxygen species (ROS), and cytokines (TNF-α and TGF-β) as well as expression of cell membrane receptors (TGR5 and CD36) in MTB-infected macrophages following treatment with OA and UA. Triterpenes caused reduced MTB growth in macrophages, stimulated production of NO and ROS in the early phase, stimulated TNF-α, suppressed TGF-β and caused over-expression of CD36 and TGR5 receptors. Thus, our data suggest immunomodulatory properties of OA and UA on MTB infected macrophages. In conclusion, antimycobacterial effects induced by these triterpenes may be attributable to the conversion of macrophages from stage M2 (alternatively activated) to M1 (classically activated).

Ursolic and oleanolic acids as antimicrobial and immunomodulatory compounds for tuberculosis treatment

BACKGROUND

New alternatives for the treatment of Tuberculosis (TB) are urgently needed and medicinal plants represent a potential option. Chamaedora tepejilote and Lantana hispida are medicinal plants from Mexico and their hexanic extracts have shown antimycobacterial activity. Bioguided investigation of these extracts showed that the active compounds were ursolic acid (UA) and oleanolic acid (OA).

METHODS

The activity of UA and OA against Mycobacterium tuberculosis H37Rv, four monoresistant strains, and two drug-resistant clinical isolates were determined by MABA test. The intracellular activity of UA and OA against M. tuberculosis H37Rv and a MDR clinical isolate were evaluated in a macrophage cell line. Finally, the antitubercular activity of UA and OA was tested in BALB/c mice infected with M. tuberculosis H37Rv or a MDR strain, by determining pulmonary bacilli loads, tissue damage by automated histomorphometry, and expression of IFN-γ, TNF-α, and iNOS by quantitative RT-PCR.

RESULTS

The in vitro assay showed that the UA/OA mixture has synergistic activity. The intracellular activity of these compounds against M. tuberculosis H37Rv and a MDR clinical isolate in a macrophage cell line showed that both compounds, alone and in combination, were active against intracellular mycobacteria even at low doses. Moreover, when both compounds were used to treat BALB/c mice with TB induced by H37Rv or MDR bacilli, a significant reduction of bacterial loads and pneumonia were observed compared to the control. Interestingly, animals treated with UA and OA showed a higher expression of IFN-γ and TNF-α in their lungs, than control animals.

CONCLUSION

UA and OA showed antimicrobial activity plus an immune-stimulatory effect that permitted the control of experimental pulmonary TB.

Antiprotozoal and antimycobacterial activities of Persea americana seeds

Background

Persea americana seeds are widely used in traditional Mexican medicine to treat rheumatism, asthma, infectious processes as well as diarrhea and dysentery caused by intestinal parasites.

Methods

The chloroformic and ethanolic extracts of P. americana seeds were prepared by maceration and their amoebicidal, giardicidal and trichomonicidal activity was evaluated. These extracts were also tested against Mycobacterium tuberculosis H37Rv, four mono-resistant and two multidrug resistant strains of M. tuberculosis as well as five non tuberculosis mycobacterium strains by MABA assay.

Results

The chloroformic and ethanolic extracts of P. americana seeds showed significant activity against E. histolytica, G. lamblia and T. vaginalis (IC₅₀ <0.634 μg/ml). The chloroformic extract inhibited the growth of M. tuberculosis H37Rv, M. tuberculosis MDR SIN 4 isolate, three M. tuberculosis H37Rv mono-resistant reference strains and four non tuberculosis mycobacteria (M. fortuitum, M. avium, M. smegmatis and M. absessus) showing MIC values ≤50 μg/ml. Contrariwise, the ethanolic extract affected only the growth of two mono-resistant strains of M. tuberculosis H37Rv and M. smegmatis (MIC ≤50 μg/ml).

Conclusions

The CHCl₃ and EtOH seed extracts from P. americana showed amoebicidal and giardicidal activity. Importantly, the CHCl₃ extract inhibited the growth of a MDR M. tuberculosis isolate and three out of four mono-resistant reference strains of M. tuberculosis H37Rv, showing a MIC = 50 μg/ml. This extract was also active against the NTM strains, M. fortuitum, M. avium, M. smegmatis and M. abscessus, with MIC values <50 μg/ml.

The use of the microplate alamar blue assay (MABA) to assess the susceptibility of Mycobacterium lepraemurium to anti-leprosy and other drugs

Although murine leprosy is no longer a common illness, our understanding of the biology of this disease is incomplete. One particular example of this concerns the etiologic agent Mycobacterium lepraemurium (MLM). MLM is a fastidious microorganism that is difficult to grow in axenic media; in a way, this has hampered attempts to thoroughly study its physiological and metabolic characteristics. MLM is an obligate intracellular bacillus that invades macrophages and replicates profusely with a generation time that oscillates between 0.5 and 11 days. In the present study, we have successfully maintained MLM alive for more than 12 days in vitro, providing us with an opportunity to study its susceptibility to several anti-leprosy agents and other drugs. To achieve this, we used a fluorescence reduction assay of alamar blue (a resazurin) in a microplate format (microplate-alamar-blue-assay; MABA), which is a highly sensitive, practical, and inexpensive method for assaying cell viability. We found that MLM was highly susceptible to clofazimine and rifampicin and was less susceptible to streptomycin, thiacetazone, kanamycin, dapsone, and ethionamide, in that order. MLM was not susceptible to four plant triterpenoids (oleanolic acid, neolignan-c, sitosterol, and ursolic acid) for which bactericidal activity has been reported in M. tuberculosis. Because the MABA has high sensitivity, it can be used to monitor the activity of microorganisms that are difficult to cultivate (such as M. lepraemurium), in response to various drugs, thus offering a method to complement the study of murine leprosy, about which many questions remain unanswered.

Antimycobacterial triterpenoids from Lantana hispida (Verbenaceae)

As the Mycobacterium tuberculosis strains resistant to multiple drugs are increasing at an alarming rate, there is an urgent need for alternative anti-tuberculosis drugs. In a bioassay-guided search for antimycobacterial compounds obtained from higher plants, the study of the hexane extract from the aerial parts of Lantana hispida was performed and the biological activity of the plant products were tested against Mycobacterium tuberculosis H37Rv strain by microdilution alamar blue assay. Activity of the primary fractions led to the isolation of three pentacyclic triterpenoids with oleanane nucleous, together with beta-sitosterol. The molecular structures of the compounds were characterized as 3-acetoxy-22-(2'-methyl-2Z-butenyloxy)-12-oleanen-28-oic acid (1), 3-hydroxy-22 beta-(2'-methyl-2Z-butenoyloxy)-12-oleanen-28-oic acid (reduced lantadene A) (2) and oleanolic acid (3). MIC values for compounds 1 and 2 were 50 microg/ml, and for compound 3 the MIC=25 microg/ml.