No abstract

The research lends support to the ethnomedicinal use of the plant in combating microbial infections, leishmaniasis and malarial infections.

Malaria is a major public health disease affecting millions of people worldwide especially in sub-Saharan Africa, with annual deaths of over 4 million. The emergence of resistant strains of Plasmodium parasite to currently used drugs necessitates the search for newer and affordable cure for malaria from medicinal plants sources. Caesalpinia pulcherrima (L) Sw. is used in traditional medicine for the treatment of various diseases including malaria. Phytochemical, acute toxicity studies and antiplasmodial activities were carried out on the stem bark extracts of the plant. Fraction (HEEA) was fractionated over silica gel column to obtain pure compounds (characterized by IR, UV, 1D and 2D spectroscopy) which were subjected to antiplasmodial investigations. Phytochemical studies revealed the presence of saponins, flavonoids, phenols, terpenoids, tannins, and alkaloids. The LD50 was established at 5656.85 mg/kg body weight in Swiss albino mice. Of all the fractions, HEEA exhibited the highest antiplasmodial activities against both the D6 and W2 Plasmodium falciparum clones at IC50 3.7 and 5.3µg /mL, respectively. Two known compounds; Pulcherrin J (1) and 6β-cinnamoyloxy-7β-hydroxyvouacapen-5α-ol (2) were isolated from HEEA and investigated for antiplasmodial activities. They showed significant inhibition of parasites growth in the D6 and W2 clones with IC50 values 10.25-˃10.62 µM and 10.25-˃10.62 µM, for compound 1 and 2, respectively, as against those of the standard antimalarial drugs (Chloroquine and Artemisinin) with IC50 values <0.0937 and <0.1062, respectively. These findings revealed that C. pulcherrima stem bark possess significant antiplasmodial activities and could be a promising source of newer antiplasmodial agents.

Stachytarpheta jamaicensis (family Verbanaceae) commonly known as blue porterweed is widely used in folk medicine for the treatment of various diseases including diabetes mellitus. The present study investigated the blood glucose lowering effect and the antioxidant activity of the leaf extracts of Stachytarpheta jamaicensis. The phytochemical screening of the powdered leaf sample was done according to standard procedures. The antioxidant activity of the methanol and ethyl acetate extracts of the leaves were investigated using the 1,1-diphenyl-2-picrylhydrazine (DPPH) radical scavenging assay, the total phenolic and flavonoid contents were also evaluated following standard procedures. The hypoglycaemic effect of the extracts was evaluated using streptozotocin-induced diabetes in rats. Phytochemical screening shows the presence of carbohydrates, alkaloids, saponins, tannins, phenolic compounds, and flavonoids. The extracts demonstrated appreciable and concentration-dependent radical scavenging effect with IC50 values of 16.95 µg/mL and 33.12 µg/mL, for the methanol extract and ethyl acetate extract, respectively. Oral administration of the extracts at 200 mg/kg and 400 mg/kg daily dose significant lowers blood glucose levels in streptozotocin-induced diabetes in experimental rats compared to the control group (untreated diabetic animals). The present findings have therefore shown that S. jamaicensis leaves has hypoglycaemic and antioxidant effects and may therefore serve as a potential source of hypoglycaemic agent as well as antioxidant agents for the prevention and management of free radical induced metabolic diseases.