Green synthesis and characterisation of natural antiseptic soaps from the oils of underutilised tropical seed

The maintenance of beautiful skin and hair is the desire of many people all over the world, thus, the application of safe cosmetic products is inevitable. Natural cosmetics containing bioactive phytochemical compounds offer great deal of beauty and pharmacological effect with less toxicity to users and the environment. The principle of green chemistry was adopted for the preparation of herbal antiseptic soaps which were plant-based, biodegradable and free of artificial colourings/preservatives. Underutilised tropical seeds of Daniellia oliveri, Elaeis guineensis and Vitellaria paradoxa (Shea butter) were used as sources of oil or fat for the saponification processes while Moringa oleifera seed oil and leave extract served as sources of antimicrobial agents. Ocimum basilicum also served as source of fragrance as well as antiseptic agent. The oils were mixed at different ratio to obtain soaps with different properties. Physicochemical parameters which include colour, acid value, free fatty acid values, saponification values, hardness, pH, colour and foaming ability of the oil and soaps were determined as applicable. The fatty acids methyl esters of the oils were prepared via transesterification and subjected to GC–MS analysis to obtain the fatty acid composition of the oils. Daniellia oliveri oil contains 57% linolelaidic acid as the major fatty acid, while oleic acid (46%) and lauric acid (44%) were the most prominent in Shea butter and palm kernel oil respectively. The antimicrobial activity of the soaps determined using agar diffusion method indicated that the soaps made from the oil of Daniellia oliveri and Shea butter inhibited the growth Streptococcus aureus, Klebsiella granulomatis and Aspergillus niger. Shea butter soap has the highest activity against Klebsiella granulomatis (42mm), while soaps made from blend of palm kernel oil and Shea butter had highest activity against Aspergillus niger (7.0). The production was highly cost effective when compared to selected commercial soaps. Therefore, the adoption of these natural resources for the preparation of eco-friendly herbal soaps would save the environment of the daily introduction of many hazardous synthetic chemical products whilst also finding utility for non-conventional seed oils and at the same time improving the economic status of the community.