Chronic non-communicable diseases are responsible for a large majority of deaths worldwide. These include cardiovascular and respiratory diseases, diabetes and cancer. Inflammation has been reported to be involved in the initiation or progression of these conditions. Populations in developing or low to middle-income countries often rely on traditional medicine using locally available herbs and plants for their medical care. This study examined the anti-inflammatory potential of aqueous extracts of twelve medicinal plants used in Nigeria. The antioxidant activity was estimated using the total radical-trapping antioxidant parameter (TRAP) and ferric reducing ability (FRAP) assays. The abilities to inhibit nuclear factor kappa light chain enhancer of activated B cells (NfkB), a key regulator of the inflammatory response, and to activate nuclear factorE2 related factor 2 (Nrf2), a transcription factor that regulates cellular antioxidant defense systems, were determined using in vitro cell based assays. Extracts of Erythrina senegalensis (leaves), Sclerocarya birrea (bark), Boswellia dalzielli (leaves and bark), Pseudrocedrila kotschyi (bark), Sterculia setigera (stem bark), and Sarcocephalus esculentus (bark) contained the highest levels of antioxidant activity. Extracts that showed the greatest inhibition of NfkB were S. esculentus (bark), 91.8%; E. senegalensis (leaves), 81.4%; S. birrea (stem bark), 77.5%; and S. setigera (stem bark), 75.5%. B. dalzielli (leaves) and Xylopia aethiopica (leaves) gave 7.4 and 7.7 fold activation of Nrf2, respectively. These were comparable to activation by sulphorophane.

The folkloric use of Clerodendrum volubile P Beauv (Verbenaceae) for treatment of inflammatory conditions in the Southern part of Nigeria has been reported. The anti-inflammatory action of the ethanolic leaf extract on carrageenan-induced rat paw oedema, lipoxygenase and xanthine oxidase inhibitory effects, and membrane stabilizing potential were evaluated. The extract reduced carrageenan-induced rat paw oedema in a dose dependent manner compared to control group. C. volubile inhibited xanthine oxidase activity in a dose - dependent manner; at 0.5 mg/ml it exhibited maximum inhibitory activity of 95.48% while the standard drug, allopurinol exhibited 70 % inhibition. The extract significantly inhibited lipoxygenase activity, with highest activity at 0.4 mg/ml while Quercetin showed maximum inhibition of the enzyme at 0.1 mg/ml. The extract and Acetaminophen exhibited maximum membrane stabilizing activity of 91.85 ± 0.50% and 94.32 ± 0.32% at 2.5 mg/ml respectively. These findings provide justification for the traditional use of C. volubile in inflammatory conditions.