Bio-lubricant Synthesis from Ocimum lamiifolium and Lactic Acid: A Study on Its Anti-microbial Activities

Abstract

Plant oils, which contain high amount of bioactive constituents, were perceived to be a viable alternatives for bio lubricant applications due to their biodegradability and high antimicrobial efficacy. They can also be used to formulate biodegradable lubricants for skin care applications. The present study was to extract, optimize extraction parameters, characterize Ocimum lamiifolium leaves oil, synthesize bio lubricant, and study antimicrobial activities for application of human skin. The extraction was carried out using Soxhlet method by using hexane as a solvent and separated by a rotary evaporator. Experimental analysis was performed by RSM box-Behnken method with 17 runs. The primary and interaction effects of the process parameters (temperature, extraction time, and particle size) and the optimum conditions were examined using design expert software. In the investigation, all the main factors had a significant effect, but no significant interaction effects of the parameters had shown on the oil yield. The model adequacy was also investigated by normal probability plot of residuals and plot of residuals versus predicted value. Both plots have shown that the model was acceptable. Finally, the optimum conditions of the process parameters for the extraction were optimized. The average optimum yield of the essential oil in percentage from 100 g of plant materials was 12.4% (w/w) and extracted at an extraction time of 4.5 hrs., solute to solvent ration ratio1.38 g/mL, and <1mm particle size of plant materials. The oil and synthesized bio lubricant for proximate analysis and instrumental analysis result found to be 15%, 25%, 4.2-5.91, 0.92g/ml, 11.5%, 19.7gKOH, 8.9mg/KOH, 35.3gL, 23.7gcm/sec,1160cp and 95% respectively to moisture content, the volatile component of lubricant, p H , specific gravity, ash value, saponification value, acid value, iodine value, spreadability, a viscosity of lubricant and diffusion. Instrumental analysis was carried out to characterize functional group present in, identify bioactive compound present in O. lamiifolium oil, and analyze absorption ability of the compound found in the product using FTIR, GC-MS, and UV-Vis analytical techniques, respectively. UV-Vis spectrophotometer analysis result shows the characteristic peaks in the range (200-700 nm), which supports the absorption of the results for UV-Vis light and colors. The FTIR analysis spectrum confirmed the presence of phenolic and alcoholic compounds that shows a shifting of peaks due to the interaction of lactic acid with O. lamiifolium during in situ polycondensation reaction, which was responsible for the characteristic change. The GC/MS analysis results of O. lamiifolium plant extract provide different peaks depicting the presence of 32 phytochemical compounds. The major 7 phytoconstituents were (phenol, Isocaryophyllene, Elemicin, methyl ester, methyl linolenate, Eicosyne, and squalene). Crude extract and synthesized bio-lubricant were screened for antibacterial activities against Staphylococcus aureus, bacillus subillitls, Salmonella typhi, and Escherichia coli (E.coli). The plant extracts of O. lamiifolium and synthesized bio lubricant showed maximum activity against 2 pathogens, Staphylococcus aureus, Escherichia coli, and moderate to a minimum against Salmonella typhi and bacillus subillitls. The results obtained in the present study suggest that the extracts of O. lamiifolium revealed a significant scope to develop a novel antibacterial herbal formulation/bio lubricant