Bioactives and Optimized Modeling of Antimicrobial Activity in Modified Jatropha curcas–Black Soap (Preprint)

BACKGROUND Urinary tract infections (UTIs), the second most common type of infection in humans, remain a major public health concern due to their high prevalence and associated morbidity. Although several antibiotics are available for their treatment, the emergence and re-emergence of antimicrobial-resistant strains continue to limit therapeutic effectiveness. The formulation of combined therapeutic agents may enhance antimicrobial efficacy by producing synergistic effects that improve activity against resistant strains. OBJECTIVE To investigate the bioactives, antimicrobial activity, and response surface–modeled optimization of a modified Jatropha curcas–Abuwe soap formulation against clinically relevant uropathogens. METHODS GC–MS analysis identified phytochemical constituents. The stem juice was extracted using mechanical press method, modified with traditional black soap, diluted and tested against four microorganisms (Staphylococcus aureus, Escherichia coli, klebsiella pneumonia and Proteus species) isolated from urinary tract infections (UTIs) using agar diffusion and minimum inhibitory concentration of (MIC). Response surface methodology (RSM) using a three-level factorial design modeled inhibition zones as a function of extract concentration (C) and water content (CW) using Design-Expert software version 6.0.8. RESULTS GC–MS analysis identified α-linolenic acid (42.49%) and palmitic acid (32.53%) as the dominant constituents, while stearic acid (8.27%), ethyl iso-allocholate (4.17%), squalene (4.18%), palmitic acid methyl ester (3.35%), and other hexadecanoic acid derivatives (2.00%) constituted the remaining components of the unmodified J. curcas. In the modified J. curcas formulation, tetradecanoic acid (69.84%) and n-hexadecanoic acid (21.03%) were identified as the predominant constituents, whereas oleic acid (3.66%), dodecanoic acid derivatives (2.76%), and hexanoic acid (2.71%) were present as minor components. The modified J. curcas formulation demonstrated consistently higher inhibitory activity against all tested organisms (S. aureus: 2.67 ± 1.48 mm, P = .01; E. coli: 3.69 ± 2.15 mm, P = .002; Proteus sp.: 4.53 ± 2.48 mm, P = .01) compared with the unmodified extract. However, against Klebsiella sp. (4.88 ± 1.98 mm), the inhibitory effect of the modified formulation was statistically comparable to that of the unmodified J. curcas extract (P = .11). Modified Jatropha curcas formulation demonstrated enhanced antimicrobial activity (97.24 mg/mL ≤ MIC ≤ 125.00 mg/mL) against all tested bacterial pathogens, whereas the unmodified extract required substantially higher concentrations (187.50 mg/mL ≤ MIC ≤ 250.00 mg/mL) to achieve inhibition, with the most pronounced effect observed against Staphylococcus aureus. Response surface modeling produced well-fitted second-order polynomial models for each organism as a function of concentration and water content. CONCLUSIONS The integration of Jatropha curcas extract into Abuwe soap significantly enhanced antimicrobial efficacy at lower concentrations. This modified formulation shows promise as an alternative antimicrobial approach for managing uropathogenic infections and warrants further investigation