# Recent Advances in the Antibacterial Activities of _Citrullus_ _Ianatus_ (Watermelon) By-Products
## 4 Antibacterial Activities of _Citrullus Ianatus_ By-Products
### Seeds
In addition, all other bacteria did not show any inhibition zone at any concentration of the extract. This study holds significant promise in the quest for novel biologically active compounds that show efficacy against multi-drug-resistant strains and diminish the side effects associated with antibiotics. Another interesting study was conducted by [PERSON] et al. [109], who evaluated the antibacterial efficacy of the aqueous extract derived from _C. lanatus_ seeds and investigated the concentration-effect relationship through time-kill studies. The crude powdered seeds of _C. lanatus_ were subjected to extraction through the process of maceration using water as the solvent. The antibacterial activity of the aqueous extracts was assessed against Gram-positive bacteria like _B. subtilis_ and _S. aureus_ along with Gram-negative bacteria _E. coli_ and _P. aeruginosa_ through the application of established microbiological techniques. The time-kill studies were conducted using a baseline of 10\({}^{6}\) CFU/mL for each test strain. Concentrations at the MIC, twice the MIC, and four times the MIC were employed for a duration of 24 h. The aqueous extract showed moderate antibacterial activity, as evidenced by inhibition growth zone diameters ranging from 15 to 17 mm and a MIC range of 2.5 to 20 mg/mL. The findings from time-kill studies revealed that the antibacterial activity observed was bacteriostatic and not dependent on the concentration of the antibacterial agent. Additionally, all tested strains showed a distinct pattern of regrowth. The aqueous extract of _C. lanatus_ seeds had antibacterial activity against test bacterial strains, exerting a bacteriostatic effect that was not dependent on the concentration of the extract. The extract displayed enhanced bactericidal activity against Gram-positive bacteria, specifically _Staphylococcus_ and _Bacillus_ species, as evidenced by a steep pharmacodynamic time-kill curve at 4 times the MIC. Conversely, a decreased inhibitory effect was observed against Gram-negative _E. coli_, with intermittent periods of bacterial regrowth observed in the presence of _P. aeruginosa_. Additional research is necessary to isolate and purify the antibacterial compounds present in the aqueous extract of _C. lanatus_ seed. This investigation holds promise for the development of a novel antibiotic that could be utilized in the treatment of bacterial infections. In a previously reported study from [PERSON] et al. [96], the results indicated that the oven-dried seed contained all of the phytochemicals. The air-dried seeds did not contain cardiac glycosides or flavonoids, whereas the sun-dried seeds did not contain phenols and phytates. The results of the antibacterial screening showed that the oven-dried seeds exhibited efficacy against all tested bacteria compared with the sun-dried and air-dried samples. The seeds that underwent oven drying exhibited notable activity against Gram-positive bacteria such as _S. aureus_, with an inhibition zone measuring 4.81 mm. It also demonstrated activity comparable to the sun-dried extract against _B. cereus_, with an inhibition zone of 3.91 mm. Conversely, the sun-dried extract displayed superior activity against four other Gram-negative bacteria: _P. aeruginosa_ (3.81 mm), _P. florescens_ (3.71 mm), _E. coli_ (5.81 mm), and _S. typhimurium_ (6.53 mm). In contrast, the sun-dried samples exhibited greater antibacterial properties compared with their air-dried counterparts. The most optimal method for drying watermelon seeds in preparation for analysis was found to be through the use of an oven. The samples that underwent oven drying exhibited the highest phytochemical composition and demonstrated superior antibacterial activity. The phenomenon could be attributed to the relatively brief drying period in comparison to exposure to sunlight, during which ultraviolet radiation leads to the depletion of plant constituents.