In Vitro Antioxidant and Anti-inflammatory Potential of the Optimized Combinations of Essential Oils from Three Cameroon Grew Ocimum L

In the best of our knowledge, there is no report on the antioxidant and anti-inflammatory effect of the combination of essential oils from Ocimum genus. In our previous report, the combinations of Ocimum basilicum/Ocimum gratissimum, Ocimum basilicum/Ocimum urticaefolium and Ocimum gratissimum/Ocimum urticaefolium were optimized for their antifungal effect. The present report presents the spectral profile and antioxidant and anti-inflammatory effects of those optimized combinations. The optimized combinations were prepared following our previously described approach and analyzed by Fourier Transformed infrared spectroscopy for fingerprinting of essential oils involved in the combination. The radical scavenging activity was evaluated on diphenyl-picryl-hydrazyle (DPPH) and ferric reducing antioxidant power (FRAP). The antioxidant activity was determined using the protective model of Linseed oil accelerated oxidation. The anti-inflammatory activity was assayed using cyclooxygenase (COX) 1 and 2. The results indicated that the fingerprints of the combination are different from those in the essential oil analyzed alone. This denotes the physical expression of different hydrogen bonds in the mixture. Overall, the optimized combinations exerted a maximum reduction (OD = 4) effect on the ferric ion. As well, they scavenged the DPPH efficiently (90% inhibition). These combinations also successfully inhibited the auto-oxidation of flaxseed oil by reduction of cis double bonds, aldehyde and hydroxyl. The optimized combination of Ocimum basilicum and Ocimum gratissimum showed a lower inhibitory effect in comparison to the control consisting of enzyme without inhibitor. Of note, Ocimum gratissimum alone exerted an inhibitory effect on both isoform of cyclooxygenase with IC50 = 0.23 μL/mL and 0.27 μL/mL for cyclooxygenase 1 and 2 respectively. Also, the essential oil of Ocimum basilicum exhibited a better effect on cyclooxygenase 2 (IC50 = 0.22 μL/mL) but showed less action on cyclooxygenase 1 (IC50 = 0.55 μL/mL). The essential oil of Ocimum urticaefolium presented the best effect on cyclooxygenase 1 (IC50 = 0.06 μL/mL) but appeared to be nonactive on cyclooxygenase 2. Globally, the optimized combinations inhibited efficiently all the isoforms of cyclooxygenase with percentage inhibition of ≥ 67% for cyclooxygenase 2 and ≥ 98% for cyclooxygenase 1.