TABLE 2.
Half-maximal inhibitory concentration (IC50) and minimum inhibitory concentration (MIC) of nano-encapsulated naphthoquinones against bacteria of clinical interest.
| Sample | IC50 and MIC (mg/mL) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Staphylococcus aureus (ATCC 14458) | Staphylococcus epidermidis (ATCC 12228) | Staphylococcus aureus (ATCC 29213) | Streptococcus pyogenes (ATCC 19615) | Pseudomonas aeruginosa (ATCC 15442)* | ||||||
| CNP | NI | NI | NI | NI | NI | NI | NI | NI | NI | NI |
| NQ1 | 0.4 | 1.2 | 0.1 | 0.3 | 0.03 | 0.2 | 0.3 | 0.3 | 1.04 | 2.5 |
| NQ2 | 0.2 | 1.2 | 0.04 | 0.6 | 0.04 | 0.3 | 0.3 | 0.6 | 1.4 | 2.5 |
| CNP-NQ1 | 1.3 | 2.5 | 1.3 | 2.5 | 1.1 | 2.5 | 4.4 | >5.0 | 4.7 | >5.0 |
| CNP-NQ2 | 1.1 | 2.5 | 1.5 | >5.0 | >5.0 | >5.0 | >5.0 | >5.0 | >5.0 | >5.0 |
NI, No inhibition up to 5 mg/mL. Antimicrobial activities evaluated as IC50 were estimated by the microdilution method using resazurin as the viability indicator to construct a concentration vs. proliferation inhibition curve. Experiments were performed in triplicate and IC50 values were estimated from inhibition curves using the GraphPad Prism v.8 software. The minimum inhibitory concentration (MIC) was determined as the lowest sample concentration at which no microbial growth was observed. NQ1—3-chloromethylene-menadione, NQ2—2,3-dichloro-1, 4-naphthoquinone; CNP, chitosan nanocapsules; CNP, chitosan nanocapsules, and NQ1 or NQ2-loaded chitosan nancoapsules (CNP-NQs). *Asterisk indicates that P. aeruginosa is a resistant pathogen to various commercial germicides.