"COMPARATIVE ISOCONVERSIONAL THERMAL ANALYSIS AND DEGRADATION KINETICS OF SALVIA SPINOSA (KANOCHA) SEED HYDROGEL AND ITS ACETATES: A POTENTIAL MATRIX FOR SUSTAINED DRUG RELEASE"

Abstract

The present study deals with the isolation and modification of Salvia spinosa hydrogel (SSH) to investigate its thermal degradation profile. The SSH was modified chemically to its acetylated derivative (ASSH-1–4) with DS 1.05-2.79. After characterization by Fourier transform infrared (FTIR) and solid-state CP/MAS 13C-NMR spectroscopic techniques, both SSH and ASSH-4 were subjected to thermogravimetric analyses (TG) by the isoconversional method, i.e., the Flynn-Waal-Ozawa (FWO) and the Kissinger methods. TG curves showed that both SSH and ASSH-4 exhibited two-step degradation. The energy of activation (Ea) for each degradation step was calculated by fitting thermal degradation data to the FWO method, revealing greater stability of ASSH-4 than that of SSH. Analysis by Kissinger’s method revealed the second and one and a half order of thermal degradation (n) for SSH and ASSH-4, which also evidenced that ASSH-4 is more stable than SSH. The values of the thermodynamic triplet (ΔH, ΔG and ΔS) were calculated from thermal data. Positive values were found for ΔG, which showed the non-spontaneous nature of thermal degradation of SSH and ASSH-4. The values of integral procedural decomposition temperature (IPDT) and intrinsic thermal stability (ITS) for SSH and ASSH-4 were found comparatively greater than those of many other commercially available materials of the same kind, which revealed the higher stability of both materials. SSH, as a benign polysaccharide-based material, was also assessed for its utility in drug release studies, taking caffeine as a model drug. The SSH matrix-based tablet formulation (SSHC) showed a sustained release behavior of the drug in preliminary studies.