## 3 Results and Discussion
### In Vitro Dissolution Kinetics Study  
In vitro dissolution kinetics of the tablets are given in Figure 5. The kinetics of dissolution follow a rapid evolution; after 8 h of dissolution, the majority of bioactive compounds were dissolved from the cellulosic matrix of the _Atriplex halimus_ tablets.  
It is noted that all the tablets showed a very rapid increase in dissolution rate during the first two hours of dissolution at pH = 1.2; then, dissolution rates continued to increase but with a lower rate at pH = 6 and pH = 7.2. This kinetics can be explained by the nature of the matrix used: the tablets consist only of plant powder, which is mainly composed of cellulosic fibers. Indeed, cellulose is a hydrophilic polymer but insoluble in water; this biopolymer can be hydrolyzed to a better acid like the stomach (pH = 1.2).  
The use of digestive enzymes in the in vitro dissolution kinetics study showed that the maximum dissolution rate was expected after 3 h of dissolution (CP1 ENZ, CP2 ENZ, CP3 ENZ, and CP4 ENZ), whereas in the absence of enzymes, the maximum dissolution exceeds 5 h (CP1, CP2, CP3, and CP4). Improvement of this dissolution kinetics is due to two types  
Figure 5: In vitro dissolution kinetics of tablets without digestive enzymes (CP1, CP2, CP3, and CP4) and with digestive enzymes (CP1 ENZ, CP2 ENZ, CP3 ENZ, and CP4 ENZ).  
of enzymes. The first type is enzymes produced naturally by rats that have been treated for a week with plant powder; these enzymes are usually responsible for degradation of certain proteins or glycoproteins contained in plant matrix. The second type of enzyme is those produced by intestinal flora of rats; intestinal bacteria have the ability to produce enzymes capable of degrading cellulose into low-molecular-weight polysaccharides and sugars capable of being absorbed by the intestine.  
Mathematical modeling of in vitro dissolution kinetics in the presence or absence of digestive enzymes was performed for all tablets, and the different parameters of the mathematical models, as well as the correlation coefficients, are given in Table 9. Among the mathematical models used, [PERSON]'s model is the one that represents all the dissolution kinetics in the best way. Correlation coefficients for the Higuchi model vary between 0.63 and 0.73.  
Although the [PERSON] model showed the best fit among the classical kinetic models tested, with R\({}^{2}\) values ranging from 0.63 to 0.73, these coefficients remain relatively low and highlight the limited predictive power of the applied models. The Higuchi model, which assumes drug diffusion from a homogeneous matrix, may not be appropriate for describing the release behavior of our plant-based tablets.  
These formulations contain whole or ground plant particles, whose fibrous and heterogeneous structures may significantly affect the release mechanism. We suggest that the release process may involve a two-step kinetic mechanism:  
* An initial interparticulate diffusion of the dissolution medium between the compressed plant particles, followed by
* An intraparticulate diffusion of bioactive compounds through the internal cellular matrix of the plant materials.  
This complexity is not fully captured by standard models, which are generally designed for simpler pharmaceutical systems. To better describe such release behavior, future studies should consider more flexible and descriptive models. For example, the Weibull model has been widely used to fit a broad range of release profiles, including those not governed by a single kinetic process [43]. In addition, biphasic or multilayer models may offer better insight into systems involving sequential diffusion steps or multiple structural domains within the matrix [44]. These approaches could improve the mechanistic understanding of bioactive release from complex plant-based formulations and support further development of predictive modeling for such systems.