# Plant Organic Acids as Natural Inhibitors of Foodborne Pathogens
## 3 Results
### In Silico Bioavailability and Toxicity Prediction  
For the tested organic acids, predicted LD50 ranges from 48 to 5000 mg/kg. The predicted toxicity class for most is between 3 and 5, with an LD50 > 50 mg/kg, indicating that they are toxic or harmful if swallowed, except for acetic acid, which is class 1, and oleic acid, which is class 2. Acetic, benzoic, capric, formic, oxalic, and valeric acids demonstrate high gastrointestinal tract absorption and are highly bioavailable orally. They generally also exhibit the lowest predicted LD50 values (<1000 mg/kg), indicating higher acute toxicity. High gastrointestinal tract absorption and high oral bioavailability are also demonstrated by aminoacetic, fumaric, glutamic, malic, nicotinic, salicylic, and succinic acids. However, their LD50 levels are above 1000 mg/kg, suggesting they are relatively safer. Chlorogenic and rosmarinic acids appear to be the safest, as they have low gastrointestinal absorption and oral bioavailability, coupled with high predicted LD50 values reaching 5000 mg/kg. None of the tested compounds have carcinogenic properties. Based on the available data, they do not pose a risk of causing cancer. All the presented acids can lead to skin sensitization and/or eye irritation. Among the 21 acids listed, a total of 11, including benzoic, chlorogenic, formic, fumaric, malic, nicotinic, oxalic, rosmarinic, succinic, tannic, and tartaric acids, exhibit nephrotoxic effects. Nicotinic and salicylic acids may also act neurotoxically and hepatotoxicity. Additionally, benzoic acid demonstrates hepatotoxicity. This means that the consumption of organic acids in large quantities can be toxic and lead to various complications. The obtained results for the bioavailability and toxicity prediction of the studied organic acids are presented in Table 4.  
Figure 1: Example images of 96-well plates showing the results of minimal inhibitory concentration (MIC) testing against _Penicillium candidium_ (100 to 1.25 mg/mL). Staining was performed using 2,3,5-triphenyltetrazolzolium chloride (TTC). Legends: 1—acetic acid, 2—valeric acid, 3—formic acid, 4—caproic acid, 5—citric acid, 6—aminoacetic acid, 7—tannic acid, 8—ascorbic acid, 9—oxalic acid, 11—glutamic acid, 12—tartaric acid, 13—malic acid, 14—benzoic acid, 15—succinic acid, 16—nicotinic acid, 17—palmitic acid, 18—salicylic acid, 20—oleic acid, 21—tramaric acid, 22—rosmarinic acid, and 23—chlorogenic acid. Those marked 10, 19, and 24 are acids not presented in this study. It is also important to consider the relationship between MIC values and LD50, especially given that they are expressed in different units. Table 5 presents the conversion of MIC values to mg/kg and their comparison with LD50. Chlorogenic acid and rosmarinic acid stand out as both safe and effective food preservatives against bacteria and fungi, with their MIC values being lower (1344-4398 mg/kg for chlorogenic acid and 1213-4168 mg/kg for rosmarinic acid) than their LD50 values (5000 mg/kg). This makes them suitable and safe candidates for food preservation. Some acids, such as ascorbic, malic, nicotinic, salicylic, succinic, tannic, and tartaric acids, show safety for use against bacteria but not fungi. Their MIC values for bacteria are lower than their LD50 values (MIC \(<\) LD50), indicating safety for human consumption when used as antibacterial preservatives. Unfortunately, their higher MIC values for fungi than LD50 suggest that it is necessary to choose between limited antifungal effectiveness or potential toxicity. Many of the studied organic acids, including acetic, aminoacetic, benzoic, caproic, citric, formic, fumaric, glutamic, oleic, oxalic, palmitic, and valeric acids, exhibit MIC values that exceed their LD50 values, indicating potential toxicity to humans. These acids are therefore not safe for use as food preservatives, indicating a risk of human toxicity at effective concentrations. The selection of organic acids as food preservatives requires careful evaluation of both their antimicrobial effectiveness and their safety profiles.