Ocimum gratissimum leaf flavonoid-rich fraction induces apoptosis in macrophages and ameliorates lipopolysaccharides-induced neutrophil activation and inflammatory response in rats

[Speaker] Abayomi M. Ajayi:1
[Co-author] Benneth Ben-Azu:1, Anthony Eduviere:2, Ruberlei De Oliveira:3, Olusegun G. Ademowo:1
1:Department of Pharmacology & Therapeutics, Faculty of Basic Medical Sciences, University of Ibadan, Nigeria, 2:Department of Pharmacology & Therapeutics, University of Medical Sciences, Ondo, Nigeria, 3:Department of Basic Health Sciences, Faculty of Medicine, Federal University of Mato Grosso (UFMT), Mato Grosso, Brazil

Background: Ocimum gratissimum L. leaves have attracted considerable attention from researchers because of its medicinal value that exhibited anti-inflammatory, analgesic, antimicrobial and antioxidant activities. In this study, we examined the effect of flavonoid-rich ethylacetate fraction on apoptosis induction in activated macrophages and neutrophil activation and inflammatory response in LPS-induced air pouch in rats.

Methods: In vitro apoptotic effect of the fraction in LPS-stimulated RAW 264.7 cells were analysed by flow cytometry after staining with annexin-V and 7-aminoactinomycin D (7-AAD). Furthermore, six day old subcutaneous air pouch was formed under ketamine (100 mg/kg, i.p) anaesthesia in rats. Sterile saline (0.9%) or LPS (100 ng/mL) was injected into the air pouch after the 6th day of pouch induction and three days of pretreatment with EAFOg (25, 50 and 100 mg/kg). Rectal body temperature was taken before and hourly for five hours after LPS induction. Thereafter pouch lavage was recovered, neutrophil count, nitrite, TNF-α, PGE2, and myeloperoxidase activity were determined.

Results: Flavonoid-rich fraction of Ocimum gratissimum leaf (10, 30 and 100 µg/mL) dose- dependently induced apoptosis of LPS-stimulated RAW 264.7 macrophages within 24 h. EAFOg (25, 50 and 100 mg/kg) significantly reduced LPS-induced hyperthermia (54.0, 48.7 and 68.2%) in rats. The fraction reduced neutrophil counts (20.7, 55.2 and 53.8%) and myeloperoxidase enzyme activity (38.6, 52.8 and 72.3%), and as well reduced TNF-α (12.6, 23.4 and 30.2%), and PGE2 (7.7, 22.4 and 31.7%) in LPS-induced air pouch.
Conclusion: Ocimum gratissimum leaf demonstrates ability to induce apoptosis in activated macrophages and as well inhibit neutrophil activation and inflammatory response via reduction in TNF-α and PGE2 production. The pro-apoptotic and anti-inflammatory effects reinforce the beneficial therapeutic potential of Ocimum gratissimum in the treatment of conditions associated inflammation.
Keywords: Apoptosis, Inflammation, Ocimum gratissimum, flavonoid
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