Apart from being well known to the world as herb-based sweetening additive, Stevia rebaudiana (S. rebaudiana) and its phenolic compounds are considered as a natural antidiabetic alternative to replace synthetic drugs that possess numbers of side effects. Therefore, this study was aimed to evaluate the solvent effects on the extraction of phenolic compounds and steviol glycoside identification associated with antidiabetic potential of the extracts. Total phenolic (TPC) and flavonoid (TFC) content of the extracts were quantified, while the antidiabetic activity of the extracts was determined byα-amylase andα-glucosidase inhibitory assay. As a matter of interest, TFC was found to be present at the highest concentration in ethanol extract (10.91 mg QE/g), while the presence of TPC showed no significant difference between water extract (6.65 mg GAE/g) and other organic solvents. HPLC analysis showed the abundant presence of steviol glycoside in the water extract, the principal compound suggested for treating diabetes. Furthermore, GC-MS analysis has shown the major compounds of 1-hepta-triacotanol, duvatrienediol, dihydroxanthin,β-amyrin, lupenone, phytol,γ-sitosterol, agatholic acid and fatty acids were present. In relation to the antidiabetic potential, the effects of the extracts in inhibitingα-amylase andα-glucosidase activity were investigated in vitro. Interestingly, among allS. rebaudiana extracts, water extract exhibited the most significantα-amylase inhibitory activity with IC50= 8.63μg/ml, comparable to the synthetic drug, acarbose IC50= 13.73μg/ml. These findings demonstrated that phenolic recovery was highly dependent on extraction solvent and the promising water extract as the bestα-amylase inhibitory potential with greatest steviol glycoside recovery.

Inhibition of cytochrome P450 (P450) enzymes (CYP) has been shown to lower the metabolism of drugs that are P450 substrates and to consequently alter their pharmacokinetic profiles. Curcumin (CUR), piperine (PIP), and capsaicin (CAP) are spice components (SC) that inhibit the activities of a range of P450 enzymes, but the selection of which SC to be prioritized for further development as an adjuvant will depend on the ranking order of the inhibitory potential of the SCs on specific P450 isozymes. We used common human recombinant enzyme platforms to provide a comparative evaluation of the inhibitory activities of CUR, PIP, and CAP on the principal drug-metabolizing P450 enzymes. SC-mediated inhibition of CYP3A4 was found to rank in the order of CAP (IC 1.84 ± 0.71 µM) ∼ PIP (2.12 ± 0.45 µM) > CUR (11.93 ± 3.49 µM), while CYP2C9 inhibition was in the order of CAP (11.95 ± 4.24 µM) ∼ CUR (14.58 ± 4.57 µM) > PIP (89.62 ± 9.17 µM). CAP and PIP were significantly more potent inhibitors of CYP1A2 (IC 2.14 ± 0.22 µM and 14.19 ± 4.15 µM, respectively) than CUR (IC > 100 µM), while all three SCs exhibited weak activity toward CYP2D6 (IC 95.42 ± 12.09 µM for CUR, 99.99 ± 5.88 µM for CAP, and 110.40 ± 3.23 µM for PIP). Of the three SCs, CAP thus has the strongest potential for further development into an inhibitor of multiple CYPs for use in the clinic. Data from this study are also useful for managing potential drug-SC interactions.

Background In the current literature, there are ongoing debates on the toxicity of graphene oxide (GO) that demonstrate contradictory findings regarding its toxicity profile. As a potential drug carrier, these findings are very concerning due to the safety concerns in humans, as well as the dramatic rise of GO being excreted into the environment. Therefore, there is an imperative need to mitigate the potential toxicity of GO to allow for a safer application in the future. Purpose The present study aims to address this issue by functionalizing GO with Pluronic F127 (PF) as a means to mitigate toxicity and resolve the biocompatibility of GO. Although results from previous studies generally indicated that Pluronic functionalized GO exhibits relatively low toxicity to living organisms, reports that emphasize on its toxicity, particularly during embryonic developmental stage, are still scarce. Methods In the present study, two different sizes of native GO samples, GO and NanoGO, as well as PF-functionalized GO, GO-PF and NanoGO-PF, were prepared and characterized using DLS, UV-Vis, Raman spectroscopy, FTIR, and FESEM analyses. Toxicological assessment of all GO samples (0–100 µg/mL) on zebrafish embryonic developmental stages (survival, hatching and heart rates, and morphological changes) was recorded daily for up to 96 hours post-fertilization (hpf). Results The toxicity effects of each GO sample were observed to be higher at increasing concentrations and upon prolonged exposure. NanoGO demonstrated lower toxicity effects compared to GO. GO-PF and NanoGO-PF were also found to have lower toxicity effects compared to native GO samples. GO-PF showed the lowest toxicity response on zebrafish embryo. Conclusion These findings highlight that toxicity is dependent on the concentration, size, and exposure period of GO. Functionalization of GO with PF through surface coating could potentially mitigate the toxicity effects of GO in embryonic developmental stages, but further investigation is warranted for broader future applications.

No abstract