This work studied the effects of drying temperature on the quality and drying kinetics of betel leaves (Piper betle L.). As the drying process applies heat on the product, this might lead to the degradation and decomposition of valuable phytochemicals within the herbs. In this study, the effect of drying temperature on the quality of dried leaves was studied by analyzing the change of major phytochemicals found in the leaves, which are hydroxychavicol and eugenol. The results indicate that the content of major compounds increased with temperature from 40 to 70°C but underwent decomposition when the leaves dried at 80°C. Besides that, the drying kinetics for different drying temperatures also studied. The kinetics results show that the increase of drying temperature shortened the total drying time. Five thin-layer models were selected in describing the drying process of betel leaves. The logarithmic model was found to be the most suitable one.

This work investigated the effects of extraction temperature on the quality of extract and the kinetics of solid‐liquid extraction of betel leaves. In this study, the effects of extraction temperature on the quality of extract were evaluated by comparing the concentration of its active compounds, including hydroxychavicol (HC) and eugenol (EU). The results indicate that the increase of extraction temperature led to the increase of the concentration of HC. EU concentration was decreased when temperatures higher than 60C were used. The kinetics data show that the extraction process reached equilibrium in a short time – about 40 min. Two models, namely equilibrium‐dependent solid‐liquid extraction (EDSLE) model and diffusion‐dependent solid‐liquid extraction model were applied to describe the extraction process. By comparing the values of correlation coefficients, the EDSLE model was found to be more suitable in describing the extraction process as it provided a better fit to the experimental data. PRACTICAL APPLICATIONS Betel leaves is one of the invaluable medicinal plants that has multiple useful bioactivities found in Malaysia. In this work, the effect of extraction temperature on the quality of the extract of betel leaves was investigated by quantifying the change of two active compounds, namely hydroxychavicol and eugenol. This is because the bioactivities depend on the content of the phytochemicals within the plant. The critical extraction temperature was determined based on the findings. Aside from this, the kinetics of the extraction process was also studied. Two mathematical models including equilibrium‐dependent solid‐liquid extraction (EDSLE) model and diffusion‐dependent solid‐liquid extraction model were used to predict the extraction process. EDSLE, which is simple and easy to be solved, was applicable in simulating the extraction process. The findings from this study are useful in understanding and optimizing the solid‐liquid extraction process of betel leaves.

BACKGROUND Papaya is widely grown in Malaysia and normally only the fruits are consumed. Other parts of the plant such as leaves, roots, bark, peel, seeds and pulp are also known to have medicinal properties and have been used to treat various diseases. Papaya leaves also contain flavonoids, alkaloids phenolic compounds and cynogenetic compounds, and are also reported to be able to treat dengue fever. RESULTS Studies were carried out on drying of papaya leaves using hot air (60, 70 and 80 °C), shade and freeze drying. Effective diffusivities were estimated ranging from 2.09 × 10−12 to 2.18 × 10−12 m2 s−1 from hot air drying, which are within the order of magnitudes reported for most agricultural and food products. The activation energy to initiate drying showed a relatively low value (2.11 kJ mol−1) as a result of the thin leave layer that eased moisture diffusion. In terms of total polyphenols content and antioxidant activities, freeze‐dried sample showed a significantly higher (P < 0.05) total polyphenols content [2158 mg gallic acid equivalent 100 g dry weight−1] and antioxidant activities [2,2'‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS) = 571 mg TE 100 g DW−1 and 2,2'‐diphenyl‐1‐picrylhydrazyl (DPPH) = 215 μg mg−1] compared to hot air and shade dried samples. CONCLUSION Freeze dried sample retained the most total polyphenols content and showed the highest antioxidant activities in both ABTS and DPPH antioxidant assays. Hot air and shade drying are not conducive with repect to preserving the antioxidants as a result of possible thermal degradation at elevated temperatures and oxidations under prolonged drying condition. © 2020 Society of Chemical Industry

Abstract:Objective: The combination effect of Piper betle (PB) and 5-fluorouracil (5-FU) in enhancing the cytotoxic potential of 5-FU in inhibiting the growth of colon cancer cells was investigated. Methods: HT29 and HCT116 cells were subjected to 5-FU or PB treatment. 5-FU and PB were then combined and their effects on both cell lines were observed after 24 h of treatment. PB-5-FU interaction was elucidated by isobologram analysis. Apoptosis features of the treated cells were revealed by annexin V/PI stain. High-performance liquid chromatography (HPLC) was performed to exclude any possible chemical interaction between the compounds. Results: In the presence of PB extract, the cytotoxicity of 5-FU was observed at a lower dose (IC 50 12.5 µmol/L) and a shorter time (24 h) in both cell lines. Both cell lines treated with 5-FU or PB alone induced a greater apoptosis effect compared with the combination treatment. Isobologram analysis indicated that PB and 5-FU interacted synergistically and antagonistically in inhibiting the growth of HT29 and HCT116 cells, respectively. Conclusions: In the presence of PB, a lower dosage of 5-FU is required to achieve the maximum drug effect in inhibiting the growth of HT29 cells. However, PB did not significantly reduce 5-FU dosage in HCT116 cells. Our result showed that this interaction may not solely contribute to the apoptosis pathway.

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