Abstract

THE ANTIHYPERTENSIVE PROPERTIES OF METHANOLIC EXTRACT OF NEWBOULDIA LAEVIS LEAVES ON ANAESTHETIZED CAT

Ezeabikwa Juliet, Godwin Odey Olim*

ABSTRACT

Background: Hypertension remains a major cardiovascular health problem, and medicinal plants continue to be investigated as potential sources of antihypertensive agents. Newbouldia laevis is traditionally used for the management of hypertension, but further experimental evidence is required to support its use. Objective: This study investigated the antihypertensive properties of the methanolic leaf extract of Newbouldia laevis in an anaesthetized cat. Methods: Leaves of N. laevis were collected, identified, air-dried, powdered and extracted using a methanolic extraction procedure. The cardiovascular effect of the extract was evaluated in a cannulated anaesthetized cat preparation, with adrenaline and acetylcholine used as reference drugs. The extract was administered at doses of 10, 20, 40, 80 and 100 µg, and the peak effect and duration/width of response were recorded. Phytochemical screening was also performed. Acute toxicity was assessed in mice using Lorke's method at doses ranging from 10 to 5000 mg/kg. Results: The extract produced a negative peak response at all tested doses in both experimental states. In State One, the peak effect increased from −2.8 mm at 10 µg to −4.1 mm at 100 µg, while in State Two it increased from −3.3 mm to −4.1 mm over the same dose range. Alkaloids, tannins and flavonoids were strongly detected, while carbohydrates, reducing sugars, resins, proteins, oils and acidic compounds were also present. No mortality was observed at doses up to 5000 mg/kg. Conclusion: The methanolic leaf extract of N. laevis demonstrated a dose-related depressor response in the anaesthetized cat, suggesting potential antihypertensive activity. Further studies are required to establish its mechanism of action, active constituents and long-term safety.

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