The purpose of this study was to determine the phytochemical compositions and to evaluate the biological activity of the stem bark of Dialium cochinchinense. The phytochemical analysis showed the presence of steroids, terpenoids, anthraquinones, saponins, and phenolics in the stem bark of D. cochinchinense. The optimal extraction conditions were 70% ethanol at 30°C for 40min with a material/solvent ratio of 1/20. Under the optimal conditions, the corresponding predicted response value for the total phenolic content was 100.80 ± 0.40 mg GAE/g DW. The evaluation of antioxidant activity indicated that the polyphenol-rich extract was a good source of antioxidants as measured by the DPPH assay with the IC50 of 3.81 ± 0.58 μg mL-1. The extract also demonstrated a strong a-glucosidase inhibitory activity with the IC50 value of 2.14 ± 0.05 μg/mL. Therefore, D. cochinchinense could be useful as a potential preventive intervention for free radicals in mediated diseases as well as an antioxidant drug and a potential source in treating diabetes mellitus in the pharmaceutical industry.

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The extraction of oil from passion fruit seeds with acetone, ethanol, ethyl acetate, isopropanol, and hexane was studied. The effects of the variables, namely type of solvent, material to solvent ratio, temperature, and extraction time, were investigated. The highest extraction yield was 78.52%, which was obtained using ethyl acetate with a material to solvent ratio of 1/10 at room temperature (28oC) for 4h using a shaker. This yield was similar to that obtained when using hexane as a solvent. Our results indicate that ethyl acetate can replace the conventional hexane solvent in the extraction of oil from passion fruit seeds. The high content of polyunsaturated fatty acids in passion fruit seed oil suggests that this product has good potential for use in the human food, cosmetic, and pharmaceutical industries.

This study aimed to quantify the phenolic contents and the antioxidant capacities of leaf extract powders from three Myrtaceae plants, namely Cleistocalyx operculatus (Vietnamese name: Vối), Psidium guajava (Ổi), and Rhodomyrtus tomentosa (Sim), investigate their inhibitive activities on the growth of bacteria isolated from spoiled shrimps, and evaluate their values as preservative agents in the cold storage of Pacific whiteleg shrimps (Penaeus vannamei). The extract leaf powders from R. tomentosa, C. operculatus, and P. guajava had high phenolic contents of 281.25, 282.36, and 349.51 mg gallic acid equivalent/g leaf extract, respectively. Among the three plants, the extract powders of R. tomentosa and P. guajava leaves had the highest antioxidant capacities (about 4 mmol Trolox equivalent (TE)/g) followed by the one of C. operculatus (2.85 mmol TE/g). These three extract powders showed significant antibacterial activities against the seven bacteria isolated from cold-stored spoiled whiteleg shrimps with the inhibition zones ranging from 0.33 to 19.67mm depending on the extract concentration. Among the three leaf extracts, the one from P. guajava leaves showed the highest inhibitive activity. Aeromonas sp2 was the most sensible to Myrtaceae leaf extracts while Aeromonas sp4 was the least affected strain. All the extracts showed high inhibitive activities against melanosis, volatile nitrogen-containing compounds formation, lipid oxidation, and microbial growth in stored shrimps, thereby prolonging the shelf-life of the shrimps. The results suggested the potential application of these three Myrtaceae plants as sources of antioxidant and antimicrobial agents in the cold storage of shrimps.