Sub-acute and chronic toxicity profiles of Markhamia tomentosa ethanolic leaf extract in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Markhamia tomentosa (Benth.) K. Schum Ex Engl. (Bignoniaceae) is used in traditional African medicine for the treatment of diarrhoea, oedema, pain and malaria. The leaf extract was reported to show no visible sign of toxicity on acute exposure. This present study investigates the sub-acute and chronic toxicity effects of Markhamia tomentosa in rats.

MATERIALS AND METHODS

The animals (n=6/group) were treated daily with the extract at doses of 40, 200 and 1000mg/kg orally for 28 and 90 days. Control rats received distilled water and all animals were weighed at 7 days interval. The haematological, biochemical and histological parameters were determined.

RESULTS

The extract showed non-significant changes in body weight gain of treated compared to control rats in both studies. Extract significantly decreased red blood cell (RBC), mean cell haemoglobin concentration and increased mean corpuscular volume (MCV) parameters after the 28 day study. In the 90 day study, a significant increase in white blood cell, RBC, platelets and decrease in MCV and mean cell haemoglobin (MCH) parameters were observed. Biochemical parameters were significantly changed in both studies; triglycerides, total protein, alanine transaminase, aspartate transaminase and albumin showed significant increase while creatinine, blood urea nitrogen and uric acid levels showed significant decrease. Significant increase in liver weight with no treatment-related histological changes was observed in all harvested vital organs.

CONCLUSION

Markhamia tomentosa extract elicited non-toxic effect in the liver and kidney function parameters in rats. Thus, the extract is safe when administered orally.

Phytochemical screening and in vivo antimalarial activity of extracts from three medicinal plants used in malaria treatment in Nigeria

The use of plant to meet health-care needs has greatly increased worldwide in the recent times. The search for new plant-derived bioactive agents that can be explored for the treatment of drug-resistant malaria infection is urgently needed. Thus, we evaluated the antimalarial activity of three medicinal plants used in Nigerian folklore for the treatment of malaria infection. A modified Peter's 4-day suppressive test was used to evaluate the antimalarial activity of the plant extracts in a mouse model of chloroquine-resistant Plasmodium berghei ANKA strain. Animals were treated with 250, 500, or 800 mg/kg of aqueous extract. It was observed that of all the three plants studied, Markhamia tomentosa showed the highest chemosuppression of parasites of 73 % followed by Polyalthia longifolia (53 %) at day 4. All the doses tested were well tolerated. Percentage suppression of parasite growth on day 4 post-infection ranged from 1 to 73 % in mice infected with P. berghei and treated with extracts when compared with chloroquine diphosphate, the standard reference drug which had a chemosuppression of 90 %. The percentage survival of mice that received extract ranged from 0 to 60 % (increased as the dose increases to 800 mg/kg). Phytochemical analysis revealed the presence of tannins, saponins, and phenolic compounds in all the three plants tested.

Antiulcer activity of the ethanolic extract and ethyl acetate fraction of the leaves of Markhamia tomentosa in rats

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves of Markhamia tomentosa (Benth.) K. Schum. Ex Engl. (Bignoniaceae) are used traditionally in the treatment of skin afflictions, sores, ulcers and inflammation. The aim of the study was to investigate the antiulcer activity of the crude ethanolic extract from the leaves of Markhamia tomentosa, determine the active fraction(s) of the extract and identify the chemical constituents in the active fraction by LC-MS.

MATERIALS AND METHODS

The antiulcer activity of the crude extract (50, 100 and 150mg/kg, p.o.) was evaluated in ethanol and indomethacin-induced models while the solvent fractions (150mg/kg) were screened using ethanol-induced gastric lesions in rats. Furthermore, anti-ulcer activity of the active fraction (50, 100 and 150mg/kg, p.o.) was performed using indomethacin and pylorus ligation models. Parameters such as gastric volume, pH and acidity were determined in the pylorus ligation model. LC-ESI-MS analysis was used to identify the components in the active fraction.

RESULTS

The extract at the dose of 50, 100 and 150mg/kg caused a significant (p<0.05) dose-dependent inhibition of ulcer in the ethanol and indomethacin-induced ulcer models, respectively. The ethyl acetate (EtOAc) fraction showed the most potent antiulcer activity from all the fractions tested. This fraction produced 72% and 92% inhibition of indomethacin and pylorus-induced ulcer at a dose of 150mg/kg respectively. Acteoside, luteolin, luteolin-7-rutinoside, Luteolin-3',7-di-O-glucoside, carnosol, dilapachone, tormentic acid, oxo-pomolic acid and ajugol were detected in the EtOAc fraction.

CONCLUSION

Our data provide a rational base for the folkloric use of Markhamia tormentosa in the treatment of ulcers.

Antiproliferative and apoptosis inducing activity of Markhamia tomentosa leaf extract on HeLa cells

ETHNOPHARMACOLOGICAL RELEVANCE

Markhamia tomentosa (Benth) K. Schum ex. Engl. (Bignoniaceae), a tree widely dispersed in West Tropical Africa, is used traditionally to treat various diseases as it possesses antimicrobial, antioxidant, analgesic, anticancer and anti-inflammatory activities.

MATERIALS AND METHODS

This study evaluates the cytotoxic effect and underlying mechanisms of the ethanolic extract of Markhamia tomentosa on HeLa and MCF-7 cancer cell lines and non-cancerous Vero cell line. Brine shrimp lethality test was used for preliminary screening. Cytotoxicity was determined using the MTT assay and IC50 was calculated. Effect of Markhamia tomentosa on the cell cycle was monitored by flow cytometry and the apoptosis-induction capability confirmed by exposure of phosphatidylserine to the outer leaflet of the plasma membrane. Loss of mitochondrial membrane potential was analysed by flow cytometry using JC-1.

RESULTS

Markhamia tomentosa was toxic to brine shrimps with LD50 of 31.62µg/ml. Cell viability and growth of HeLa cells was inhibited by the extract with an IC50 of 189.1±1.76µg/ml at 24h post treatment. However, no cytotoxic effect was observed in MCF-7 and Vero cell lines. The extract induced cell cycle arrest in HeLa cells in the G0/G1 phase resulting in cell death after 24h exposure. Induction of apoptosis in HeLa cells was substantiated by Annexin V-FITC/PI double staining showing phosphatidylserine translocation and depolarisation of the mitochondrial membrane potential by flow cytometry of JC-1 stained cells.

CONCLUSION

The ethanolic extract of Markhamia tomentosa induces G0/G1 in HeLa cells followed by induction of the intrinsic pathway of apoptosis.

Anti-inflammatory activity of Markhamia tomentosa (Benth.) K. Schum. Ex Engl. ethanolic leaf extract

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves of Markhamia tomentosa (Benth.) K. Schum (Bignoniaceae) are used traditionally for the treatment of oedema and rheumatoid arthritis in Nigeria.

AIM OF THE STUDY

The aim of the work was to investigate the anti-inflammatory activity of the ethanolic leaf extract of Markhamia tomentosa.

MATERIALS AND METHODS

The extract was screened using the carrageenan-induced paw oedema in rats, xylene-induced oedema in mice and the formalin-induced oedema in mice at 50, 100, 200mg/kg doses p.o respectively. The mechanism by which the extract mediated the anti-inflammatory activity was assessed using the histamine-induced rat paw oedema and serotonin-induced rat paw oedema at the highest dose (200mg/kg).

RESULTS

The results showed that the extract produced a significant dose-dependent inhibition in carrageenan-induced, xylene-induced and the formalin tests. The extract exerted a significant inhibition of 54.55% (P<0.0001) and 42.11% (P<0.01) at 90 min in the histamine-induced and serotonin-induced rat paw oedema models respectively.

CONCLUSIONS

These findings suggest that the ethanolic leaf extract of Markhamia tomentosa possesses anti-inflammatory activity possibly mediated by histamine. The results justify the use of the plant in the preparation of ethno medicines used in the treatment of ailments associated with inflammation.