# Recent Advances in the Antibacterial Activities of _Citrullus_ _Ianatus_ (Watermelon) By-Products
## 4 Antibacterial Activities of _Citrullus Ianatus_ By-Products
### Seeds
**} \\  & & & & **Value** & **Inhibition** & & \\  & & & & **(mg/mL)** & **(mm)** & \\ \hline \multirow{2}{*}{+} & _Streptococcus mutans_ & \multirow{2}{*}{Rind} & \multirow{2}{*}{Water} & \multirow{2}{*}{Maceration at RT} & n.a. & \multirow{2}{*}{35} & [99] \\ \cline{1-1} \cline{5-5  
the screening process did not yield any saponins in either the water-based or alcohol-based extracts. The strains of Gram-positive _S. aureus_ and Gram-negative _E. coli_, _P. aeruginosa_, and _Klebsiella pneumoniae_ underwent antibiotic susceptibility testing. The efficacy of the extracts against _S. aureus_, _E. coli_, and _P. aeruginosa_ was observed within the concentration range of 6.25 mg/mL to 50 mg/mL. The study revealed that _K. pneumoniae_ exhibited a significant level of resistance, specifically against the ethanolic extract, compared with other bacterial strains, requiring concentrations greater than 50 mg/mL of extract. Most bacteria required 6.25 mg/mL of extract, regardless of the extraction solvent. Only _E. coli_ required 12.5 mg/mL of either water or ethanolic extract. The concentration of the aqueous extract that exhibited the highest efficacy against _P. aeruginosa_ was determined to be 50 mg/mL. Specifically, this concentration led to the formation of a zone of inhibition with a diameter of 8 mm. In most cases, a higher concentration exhibited superior efficacy compared with a lower concentration, whereas the control substance ciprofloxacin demonstrated greater activity than either of the extracts. The results obtained from the determination of MIC and MBC suggest that the components present in the extract may possess bactericidal properties, possibly attributed to their proximity. The findings also suggest that the seeds of _C. lanatus_ possess bioactive compounds that have potential antibacterial properties, consistent with the rest of the plant. Consequently, these seeds hold potential for utilization in herbal formulations. Similarly, [PERSON] et al. [105] aimed to assess the antibacterial properties and chemical composition of the ethyl acetate extract derived from the seeds of _C. lanatus_ through the application of standard microbiological techniques. The seeds were macerated in ethyl acetate for 72 h and the extract was concentrated. The microorganisms targeted for evaluation included Gram-positive _S. aureus_, _B. subtilis_, and Gram-negative _E. coli_, _P. aeruginosa_. Analysis of the extract using GC-MS revealed that it contained oleic acid (31.22%), saturated fatty acids (23.85%), \(\gamma\)-tocopherol (8.79%), and other compounds with antibacterial activity, such as arcidine and methyl phthalate. The extract, which had a yield of 18.7%, had a MIC range of 0.313-2.5 mg/mL and a Maximum Bactericidal Concentration (MBC) range of 0.313-5 mg/mL, meaning that it was effective against all tested microorganisms. The inhibition zone diameters ranged from 24 to 26 mm. _P. aeruginosa_ and _S. aureus_ showed the greatest resistance, whereas _E. coli_ showed the lowest. This study revealed that pathogens typically associated with respiratory, gastrointestinal, and urinary tract infections could be inhibited using _C. lanatus_ seed extract. [PERSON] et al. [106] investigated the efficacy of 18 different cold-pressed cosmetic oils in terms of their ability to impede the proliferation of human pathogens. The antibacterial activity of cosmetic oils was assessed using the disc diffusion method. Bacteria such as Gram-positive _S. epidermidis_ and _S. aureus_ and Gram-negative bacteria such as _P. aeruginosa_ and _E. coli_ were the indicator microorganisms. The results showed that the efficacy of certain cosmetic oils in inhibiting indicator microorganisms exhibits variability in terms of their antagonistic effects. Among the various substances tested, it was found that tamanu seed oil had the highest efficacy in inhibiting bacterial growth; the oil showed a significant inhibitory effect on the growth of Gram-positive _S. aureus_, _S. epidermidis_ and Gram-negative _P. aeruginosa_. The growth of both _S. epidermidis_ and _P.