## 4 Discussion  
The plant extracts are known for their various phytocomplexes, some of which have been proven to have the ability to reduce metal salts to metal nanoparticles [18]. For instance, for metal nanoparticles, mostly silver and gold, it has been discovered that terpenoids [19], protein [20], flavonoid [21], functional groups like carbonyl, amino, and sulfhydryl [22], and polyols [23] from different plants play a role in gold nanoparticle surface capping and reduction of both gold and silver ions. Metal nanoparticles have been synthesized using plant extracts such as rosmeary [24], olives [25], and green tea to name a few, and have been found to have antibacterial activity [26]. In this study, _P. americana_ Mill. seed husk extract was used. The seed on its own contains compounds such as flavonoids, tannins, saponins, phenolic, and alkaloids which are known to be present in most plants [27]. We were specifically interested in whether hydronium jarosite nanoparticles can be reproduced using only the seed husk instead of the avocado seed and its potential application as an antibacterial agent.  
Metal-based nanoparticles are currently being investigated for different applications. Among these metal-based nanoparticles, iron oxides have been synthesized and have been shown to possess antimicrobial activity [28] when they were tested against _E. coli_, _S. aureus_, _Pseudomonas_, and _Klebsiella pneumonia_. It was found that particle size and concentration had an effect [29]. Jerosite ((H\({}_{3}\)O)Fe\({}_{3}\) + 3(SO\({}_{4}\))\({}_{2}\)(OH)) has been found to possess significant antibacterial properties. A study conducted by [PERSON] et al. (2018) demonstrated that jarosite nanoparticles exhibited a dose-dependent antibacterial effect against two bacterial strains, namely _E. coli_ and _S. aureus_. The study further revealed that jarosite nanoparticles caused cell membrane damage, which ultimately resulted in bacterial death. These findings suggest that jarosite has potential applications as an antibacterial agent in various fields, including medicine and agriculture. However, the present study did not show any effect on the bacteria tested [12]. The micro-plate dilution essay result corroborated the agar well diffusion assay and revealed that the _E. coli_, _S. aureus_, and MRSA tested were not susceptible to the hydronium jarosite NPs at the highest concentration \(\leq\)1000 ug/mL. This clearly shows that the material has no antimicrobial activity.  
Several studies have investigated the cytotoxicity of jarosite on various cell types, including human cell lines and aquatic organisms. One study conducted by [PERSON] et al. (2016) evaluated the cytotoxicity of jarosite on human hepatoma HepG2 cells. The results showed that jarosite exposure induced dose-dependent cytotoxicity, leading to increased levels of reactive oxygen species and apoptosis in the cells. The study suggested that jarosite exposure may cause oxidative stress and apoptosis in human hepatoma cells [30]. Another study by [PERSON] et al. (2019) investigated the cytotoxicity of jarosite on the aquatic organism _Daphnia magna_. The results showed that jarosite exposure resulted in decreased survival and reproduction of the organisms, as well as increased levels of oxidative stress and DNA damage. Overall, these studies suggest that jarosite can have cytotoxic effects on various cell types and organisms. In this study, we used hydronium jarosite which showed concentration-dependent cytotoxicity from \(\geq\)100 ug/mL at 24 h and \(\geq\)50 ug/mL for 48 and 72 h. On the other hand, the cytotoxicity effect observed for hydronium jarosite nanomaterials can support its potential application as an anticancer agent [31]. Further studies are needed to fully understand the mechanisms of jarosite toxicity and the potential risks it may pose to human health and the environment [32].