Haplophyllum tuberculatum (Forssk.) A. Juss Essential Oils: Seasonal Contents Variation, Bioactivity of the Traditionally-favored, High-yield and Frequent-use Summer Season Oil

Haplophyllum tuberculatum (Forssk.) A.Juss. volatile oils were obtained by distillation of the aerial parts of the plant growing in Libya during the summer and spring seasons. A yield and componential analysis revealed that the summer season oil, which is frequently used in traditional medicaments by North African communities, was high in yield (0.858%) compared to the spring season oil (0.47%), and distinguished by the presence of major and various diverse constituents, some of which are considered chemical markers. Owing to the traditional and high incidence of use of the summer-produced essential oil for the treatment of several disorders, including hepatic diseases, and fatigue, the oil was pharmacologically investigated for its varied bioactivities of anti-microbial, in vivo anti-oxidant, and in vitro anti-cancer properties. Thirty- three compounds were identified and represented 96.2% of the peaks in the GC-chromatogram of the summer oil, in which the major volatile constituents were delta-3-carene (21.5%), bornyl acetate (16.9%), and limonene aldehyde (15.2%). The summer-based essential oil of the plant demonstrated moderate anti-bacterial activity against Gram-positive bacteria and a relatively strong antibacterial effect against Gram- negative bacteria as compared to the positive antibacterial controls, ampicillin and gentamicin, respectively. Also, antifungal activity against Aspergillus sp. was observed. The summer-produced oil also exhibited in vivo antioxidant and in vitro anti-cancer activities.