The Useful Medicinal Properties of the Root-Bark Extract of Alstonia boonei (Apocynaceae) May Be Connected to Antioxidant Activity

Markhamia lutea leaves aqueous and ethanolic extract with curative anti-inflammatory activity attenuates paclitaxel toxicity in rat's intestine

OBJECTIVES

Markhamia lutea (M. lutea, Bignoniaceae) is mainly found in tropical/neotropical regions of America, Africa and Asia. The plant's leaves, stems or roots are used to treat anaemia, bloody diarrhoea, parasitic and microbial infections. This study evaluates anti-inflammatory properties (in vitro) of Markhamia lutea and their curative effects on paclitaxel-induced intestinal toxicity (in vivo).

METHODS

The anti-inflammatory potential of Markhamia lutea was tested over cytokines (TNF-alpha, IL-6, IL-1β, IL-10), reactive oxygen species (ROS) and enzymes (cyclooxygenase and 5-lipoxygenase). While in vivo, intestinal toxicity was induced for 10 days by oral administration of paclitaxel (3 mg/kg, 0.05 mL). Animals in each group were further treated with aqueous (300 mg/kg) and ethanolic (300 mg/kg) leaves extracts of Markhamia lutea during 7 days and clinical symptoms were recorded, hematological, biochemical and histological analysis were subsequently performed.

RESULTS

In vitro, aqueous (250 μg/mL) and ethanolic (250 μg/mL) extracts of Markhamia lutea inhibited the activities of cyclooxygenase 1 (56.67 % and 69.38 %), cyclooxygenase 2 (50.67 % and 62.81 %) and 5-lipoxygenase (77.33 % and 86.00 %). These extracts inhibited the production of intracellular ROS, extracellular ROS and cell proliferation with maximum IC50 of 30.83 μg/mL, 38.67 μg/mL and 19.05 μg/mL respectively for the aqueous extract, then 25.46 μg/mL, 27.64 μg/mL and 7.34 μg/mL respectively for the ethanolic extract. The extracts also inhibited the production of proinflammatory cytokines (TNFα, IL-1β and IL-6) and stimulated the production of anti-inflammatory cytokines (IL-10). In vivo, after administration of paclitaxel, the aqueous and ethanolic extracts of Markhamia lutea significantly reduced the weight loss, the diarrheal stools and the mass/length intestines ratio of the treated animals compared to the animals of the negative control group. Biochemically, the extracts lead to a significant drop in serum creatinine and alanine aminotransferase levels, followed by a significant increase in alkaline phosphatase. In addition to bringing the haematological parameters back to normal values after disturbance by paclitaxel, the extracts caused tissue regeneration in the treated animals.

CONCLUSIONS

In vitro, aqueous and ethanolic extracts of Markhamia lutea showed anti-inflammatory properties (inhibition of COX1, COX2, 5-LOX activities, inhibition of ROS production and cell proliferation); in vivo, the same extracts showed curative properties against intestinal toxicity caused by paclitaxel.

Effects of Aqueous and Methanolic Extracts of Stem Bark of Alstonia boonei De Wild. (Apocynaceae) on Dextran Sodium Sulfate-Induced Ulcerative Colitis in Wistar Rats

Among the most exploited species in Cameroon, Alstonia boonei is widely used in African medicine for the relief of several pathologies including gastrointestinal disorders. This study was conducted in order to assess the effects of aqueous and methanol stem-bark extracts of Alstonia boonei on DSS- (dextran sodium sulfate-) induced intestinal colitis and to determine its antioxidant potential. The classes of secondary metabolites present in these extracts were determined by chemical screening. The production of TNF-α, IL-6, IL-1β, and PGE2 was performed by in vitro ELISA analysis. Anticolitis effects were determined using an in vivo model of ulcerative colitis induced by DSS. The colitis was induced with a double dose of DSS (3% and 1%), and the aqueous and methanol extracts were administered orally from the 6^th day after commencement of induction. The phytochemical screening revealed the presence of six classes of secondary metabolites in these crude extracts: tannins, saponins, alkaloids, steroids, flavonoids, and phenols. Methanol and aqueous extracts of Alstonia boonei significantly (P < 0.001) inhibited TNF-α, IL-6, IL-1β, and PGE2 production stimulated by LPS. Both extracts at all doses significantly reduced (P < 0.01, P < 0.001) the signs of DSS-induced colitis in the Wistar rats by decreasing inflammation and chronic colon damage. In addition, the extracts significantly (P < 0.001) reduced malondialdehyde and nitric oxide levels in the colon and significantly (P < 0.01) increased superoxide dismutase and catalase and reduced glutathione (P < 0.05). Both extracts showed greater activity than the reference substance (prednisolone 4 mg/kg) used in this study. This study has demonstrated that aqueous and methanol extracts of Alstonia boonei stem bark have healing properties against colitis experimentally induced by DSS in rats.

Bio-efficacy of medicinal plants used for the management of diabetes mellitus in Gabon: An ethnopharmacological approach

BACKGROUND/AIM

People suffering of diabetes increased significantly worldwide. Population, in Sub-Saharan Africa and mainly in Gabon, rely on medicinal plants to manage diabetes, as well in rural as in urban areas. This study aimed to survey a wide range of Gabonese plants for their antidiabetic activity.

MATERIALS AND METHODS

This study focused on the identification of medicinal plants used in the local treatment of diabetes mellitus. Ethnobotanical investigations were carried out in rural and urban areas of three provinces of Gabon using a semi-structured interview.

RESULTS

About 50 plant species belonging to 31 families and 50 genera were recorded, a majority of which have been documented previously to have medicinal properties. Most have documented antidiabetic properties with characterized therapeutic chemical compounds. Of the plant parts used for treatment, stem barks were employed most frequently (50%), followed by leaves (26%); the remaining 24% comprised roots, fibers, fruit, bulbs, flowers, rhizom, skin, and stem. Regarding the mode of preparation, decoction was the most widely used (58%), followed by maceration (18%) and infusion (14%). Almost all the plant products were administered orally (98%).

CONCLUSIONS

Taken in concert, this study highlights the possibility of exploiting traditional knowledge of specific medicinal plants for the inexpensive treatment and management of diabetes.