Ethiop. j. public health nutr. Broad-spectrum antimicrobials from the essential oil of Trachyspermum ammi Ashenif Tadele * , Negero Gemeda, Hirut Lemma, Biruktawit Girma, Birhanu Tesfaye, Asfaw Debella, Christina Haile, Aliyi Amano, Getachew Addis, Abiy Abebe, Bekesho Geleta, Worku Gemechu, Kidist Yersaw, Frehiwot Teka and Samuel Woldkidan Traditional and Modern Medicine Research Directorate, Ethiopian Public Health Institute, P.O.Box: 1242 Corresponding author: asheniftadele@gmail.com Abstract Background: Skin diseases the common causes of morbidity in rural and urban areas of developing countries with a high proportion of visits to health facilities. The development of antimicrobial drug resistances challenges the management of skin infections. These prompted the search for new antimicrobials from plants for the management of skin infections. Objective: To develop effective topical anti-microbial formulations from Trachyspermum ammi essential oil. Method: The essential oil obtained by hydro distillation, subjected for GC-MS analysis and antimicrobial activity test. The essential oil was formulated into five different semisolid vehicles. The inhibition zones of the essential oil and the formulated products were determined by using agar dilution and well diffusion method. The skin sensitization potential of the formulations were evaluated by guinea pig maximization. Results: The major constituents of the Trachyspermum ammi oil were γ-Terpinene (39.8%), thymole (34.1%) and p-cymene (24.8 %), and showed broad spectrum antimicrobial with MIC 0.125 to 1.25 µg/ml. The formulations showed inhibition against the growth of microorganisms starting at a concentration of 0.5% (v/w). Bioactive compounds were released better from the hydrophilic preparations than from the hydrophobic ones. The release from macrogol blend was particularly better. The hydrophilic ointment formulation of the oil showed a mild skin sensitization potential while macrogol blend ointment was devoid of sensitization. Conclusion: Trachyspermum ammi essential oil is potential medicinal plant source of broad-spectrum antimicrobial used for the management of skin infections. Therefore, it is suggested that the topical formulation of these oils can be used as alternative drugs for the treatment of skin disease. It is further recommended that, clinical trial study of the topical formulations must be performed before utilized as treatment of dermatological disorders. Keywords: Trachyspermum ammi, antimicrobial activity, topical formulation, zone of inhibition, Guinea pig maximization test Introduction Skin diseases are amongst the most common causes of morbidity in rural and urban areas of developing countries accounting for a high proportion of visits to healthcare centers. In Ethiopia, skin diseases are among the ten top leading causes of morbidity; it ranges 2.4 - 4.6 % of the general population, 2.8 - 4% of females and 3.0 - 4.2% of children less than 5 years of age visited hospitals due to skin diseases (FDRE/MoH 2015). In the rural community of southwestern parts of Ethiopia, more than half of all the households and 80% of the selected children have manifested one or more skin diseases (Figueroa et al. 1996; Figueroa et al. 1998). The prominent skin diseases are bacterial infections include cellulitis, impetigo, Methicillin -resistant Staphylococcus aureus infections; dermatophyte related fungal infections of the hair, skin, nails, feet and groin (Dagnew and Erwin 1991; Figueroa et al. 1996; Figueroa et al. 1998; Hiletework 1998; Shibeshi 2000). Skin Wounds, resulting from microbial infection are the most common public health problems. The common wound pathogens include Streptococcus pyogens, Staphylococcus aureus, Pseudomonas aeuruginosa and fungal infections such as the dermatophytoses (ring worm, tinea), ptyriasis versicolor and candidiasis (Rezaei et al. 2011). There are different conventional treatments for dermatological disorders. However, these medications are with adverse effects (such as hepatotoxicity, neurotoxicity, nephrotoxicity, hematologic reactions and Stevens-Johnson syndrome), and development of antimicrobial resistance. For example, resistance is reported for fluconazole (Fichtenbaum et al. 2000; Gupta and Cooper 2008) and for C. albicans (Maenza et al. 1997; Martins et al. 1997). S. pyogenes and S. aureus which commonly cause skin and soft tissue infections developed resistance for penicillin G; Klebsiella spp. (100%) ; Pseudomonas spp. (93.3%); and Escherichia coli (91.5%) for for ampicillin; and Enterococcus spp. (3.3%); S. aureus (4.0%); and Streptococcus spp. (16.7%) for vancomycin (Ten Hove et al. 2017). Due to the above mentioned reasons, treatment of dermatological infections is time consuming, costy and time consuming. Researchers due attention for evaluating the efficacy and safety of medicinal plants, to promote their Volume 2 Issue 2 ISSN 2709-1341 1 https://ejphn.ephi.gov.et/