# Recent Advances in the Antibacterial Activities of _Citrullus_ _Ianatus_ (Watermelon) By-Products
## 4 Antibacterial Activities of _Citrullus Ianatus_ By-Products
### Seeds  
[PERSON] et al. (2012) investigated and compared the active compounds present in two different watermelon varieties. The comparison was conducted through a qualitative phytochemical analysis of methanolic seed extracts. Fine seed powder was extracted through maceration in methanol for seven days at RT. Both extracts underwent a thorough antibacterial investigation and were subsequently compared. The inhibitory effects of the methanolic extract derived from red watermelon seeds were evaluated against Gram-positive bacteria like _Streptococcus pyogenes_ and _S. aureus_. The results demonstrated inhibition zones of the above bacteria ranging from 7-20 mm and 7-10 mm, respectively, at concentrations ranging from 250-1000 \(\mathrm{\SIUnitSymbolMicro m}\)/mL. On the other hand, the methanolic extract of red watermelon seeds did not exhibit any zone of inhibition against the Gram-negative bacteria _E. coli_ or _P. aeruginosa_. No zones of inhibition were observed for any of the tested organisms when utilizing a methanolic extract derived from yellow watermelon seeds. The data in this study provided evidence for additional research on the potential antibacterial properties of a methanolic extract derived from red watermelon seeds, specifically in relation to its impact on Gram-positive bacteria. In addition, the objective of the study conducted by [PERSON] et al. (2013) was to identify the extraction technique that resulted in the greatest concentration of antibacterial compounds from the seeds of _C. lanatus_. The solvents employed in this study were chloroform, methanol, and distilled water. Two different extraction methods were utilized: cold extraction and Soxhlet extraction, which was referred to as hot extraction in this particular investigation. Cold extraction required 72 h of orbital shaking, whereas Soxhlet extraction required 6 h of extraction, with both extracts being evaporated to dryness. The antibacterial properties of the seed extracts were assessed through the utilization of the agar well diffusion method using clinical isolates of Gram-positive _Staphylococcus_ spp. and Gram-negative _E. coli_, _Proteus_ spp., _Klebsiella_ spp., and _P. aeruginosa_. The results of the study demonstrated that the zones of inhibition ranged from 0-9 mm, 0.5-7 mm, 0-2 mm, 0-2.5 mm, and 0-8.5 mm for the above bacteria, respectively. _Staphylococcus_ spp. exhibited the highest level of inhibition when exposed to cold methanol extracts, followed by hot methanol extracts, and lastly, cold chloroform extracts. Significant antibacterial potentials (\(p<0.05\)) were observed only in the hot methanol and chloroform extracts when tested in the presence of _P. aeruginosa_. Saponins, which have been associated with antibacterial properties, were also identified in the hot methanol extracts at moderate concentrations and in the cold methanol extracts at high concentrations. The present study determined that the effectiveness of the extract against specific test organisms was influenced by both the solvent employed and the extraction conditions, namely cold maceration and Soxhlet extraction. Furthermore, it is possible that the observed significant zone of inhibition exhibited by the cold and hot methanol extracts against certain test organisms could be attributed to the presence of saponins. [PERSON] et al. (2014) investigated the phytochemical composition and antibacterial efficacy of _C. lanatus_ seeds against various bacterial strains. A cold maceration method took place for the extraction of watermelon seeds, with fine seed powder mixed with water or ethanol in a liquid-to-solid ratio of 8:1 for 24 h at RT, with the filtrate finally dried in an oven. The extracts contained alkaloids, flavonoids, glycosylides, tannins, and saponins. Interestingly,  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Gram**} & **Strain of Bacteria** & \multirow{2}{*}{**By-Product**} & \multirow{2}{*}{**Solvent**} & **Extraction Conditions** & **MIC** & **Zone of** & \multirow{2}{*}{**Ref.