Anti-inflammatory Activity of Ocimum gratissimum Leaf Extract in Carrageenan-Induced Paw Oedema in Rats

Inflammation underlies a broad spectrum of veterinary clinical conditions including mastitis, arthritis, and wound infections, and plant-based anti-inflammatory agents have long been used in traditional Nigerian animal husbandry. Ocimum gratissimum, locally referred to as scent leaf and widely cultivated across Nigeria, contains eugenol, thymol, and various flavonoids with putative anti-inflammatory properties. This study evaluated the anti-inflammatory activity of ethanolic leaf extract of Ocimum gratissimum using the carrageenan-induced paw oedema model in Wistar rats. Thirty-five male rats were assigned to five groups: normal saline control, indomethacin at 10 mg/kg, and extract at 100, 250, and 500 mg/kg. Paw volumes were measured plethysmometrically at baseline and at 1, 2, 3, 4, and 5 hours after subplantar injection of 0.1 mL of one percent carrageenan. The extract produced dose-dependent inhibition of paw oedema across all measurement time points. At 500 mg/kg, the extract achieved 65.4 percent inhibition at hour three, compared with 72.1 percent for indomethacin. Phytochemical screening confirmed flavonoids, tannins, alkaloids, and terpenoids in the extract. These results support the anti-inflammatory potential of Ocimum gratissimum leaf extract and indicate a mechanism consistent with inhibition of prostaglandin synthesis. The plant represents a potential source of low-cost anti-inflammatory agents suitable for field veterinary practice in rural Nigeria. Keywords: Ocimum gratissimum, anti-inflammatory, carrageenan, paw oedema, phytochemistry.