Objective: The present study was carried out to investigate the antinociceptive activity of the aqueous extract of Muntingia calabura (MCAE) leaves and to determine the effect of temperature and the involvement of the opioid receptor on the said activity using the abdominal constriction test (ACT) and hot-plate test (HPT) in mice. Materials and Methods: The extract was prepared by soaking the dried powdered leaves of M. calabura in distilled water (dH₂O) overnight, and the supernatant obtained was considered as a stock solution with 100% concentration. The stock solution was diluted to 1, 5, 10, 50 and 100% and used to determine the antinociceptive activity of MCAE. A further experiment was done with 50% concentration to determine the effect of temperature and naloxone involvement of the opioid receptor system in MCAE antinociceptive activity. Results: At the various concentrations MCAE showed significant antinociceptive activity in both tests. However, the concentration-dependent activity was observed only in the ACT but not in the HPT. The 50% concentration of MCAEs were also stable against the effect of various temperatures as indicated by the presence of activity in both tests. The temperatures (40, 60 and 100°C) also showed an enhanced extract activity only in the HPT. Pre-treatment with naloxone (2 and 10 mg/kg) blocked the extract activity in both tests, indicating the involvement of the opioid receptor system in MCAE antinociceptive activity. Conclusion: Our data indicate that M. calabura leaves possess antinociceptive activity against chemically and thermally induced noxious stimuli. The bioactive compound(s) responsible for its antinociceptive activity is/are heat-stable and work partly via the opioid receptor system.

Nanofibrillated cellulose (NFC) can be used for reinforcer to silicone polymer to expect enhancement of its mechanical strength. However, NFC is a hydrophilic material, which typically poor-dispersed characteristic in non-polar polymer matrices. To overcome this bothersome characteristic, surface modification of NFC has been studied to tailor the interfacial interactions between NFC and matrices for fiber dispersibility in matrices. In this work, NFC was treated with some acids to modify a functional group in NFC. The acid treatment approaches successfully introduced the functional groups onto NFC surface, which confirmed by FT-IR, TGA, and SEM-EDS analyses. Moreover, the XRD analysis revealed that this treated NFC was the cellulose type I and acid treatments did not vary it. The TGA results showed lower thermal degradation of all treated NFC as compared to control NFC. Additionally, the effects of treated NFC as nanofiller in the silicone elastomer were evaluated the mechanical properties. The treated NFC also showed a good dispersibility in silicone composite, and no agglomeration was observed. Moreover, the tensile strength and elongation of silicone composite with treated NFC as nanofiller showed high performance compare to silicone composite with pristine NFC.The highest tensile value was recorded at 3.4 MPa in silicone/NFC-P samples using phosphoric acid-treated NFC. Therefore, a low concentration of acid treatments has the potential to be an effective method as a surface modification of NFC.

Dried hybrid fillers comprised of silica/CNF were successfully synthesized in ethanol/water mixed solvents at room temperature without the usage of any precursor. The as-prepared fillers were incorporated with polypropylene (PP) as a polymer matrix through a twin-screw extruder. From surface morphology analysis, the agglomeration of the silica/CNF hybrid fillers was prevented in the PP matrix and they exhibited moderate transparency, around 17.9% and 44.6% T at 660 nm. Further, the chemical structures of the polymer composites were identified by Fourier transform infrared (FT-IR) analysis. According to thermogravimetric analysis (TGA), the insertion of silica as a co-filler to the PP matrix resulted in an increase in its degradation onset temperature and also thermal stability. In addition, the mechanical properties of the PP composites also increased after the blending process with the hybrid fillers. Overall, sample PP-SS/CNF exhibited the highest tensile strength, which was 36.8 MPa, or around 73.55% compared to the pristine PP. The improvements in tensile strength were attributed to good dispersion and enhanced efficiency of the stress transfer mechanism between the silica and the cellulose within the PP matrix. However, elongation of the sample was reduced sharply due to the stiffening effect of the filler.

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