Carissa carandas, commonly known in Thai as 'nham-daeng', has a long history in alternative medicine in Thailand. Ethanolic extracts of fresh leaves, unripe fruits and fully-ripe fruits were investigated for their antioxidant activity, total phenolic content, total anthocyanins, anthocyanin identification, vitamin C content and cytotoxicity. Results showed that the leaf extract exhibited the highest antioxidant activity, FRAP value and total phenolic content. The antioxidant activities of leaf, unripe and fully-ripe fruit extracts were 65.24±0.69, 0.85±0.03 and 2.42±0.41 mg AAE/g, respectively. Total phenolic contents were 24.91±0.22, 1.29±0.16 and 4.67±0.41 mg GAE/g and total anthocyanins were 0, 0.33±0.04 and 54.80±6.07 mg/l, respectively. The fully-ripe fruit extract, which showed low antioxidant activity and total phenolic contents, exhibited the highest total anthocyanins and cyanidin-3-galactoside levels. The unripe fruit extract showed the highest content of vitamin C (300.75±57 mg/100g). The major anthocyanin of all samples was cyanidin-3-galactoside. At a concentration of 200 µg/ml, treatment with the leaf extract caused the greatest reduction in HepG2 viability among the three extracts. These results indicated that the amounts of total phenolics and antioxidant activity could be correlated with cytotoxicity on HepG2 cells for the leaf sample.

ABSTRACT

Agaricus bisporus is easily perishable and subject to microbial contamination. The present study aspires to follow antioxidant activities and chemical changes of Agaricus bisporus after being exposed to gamma radiation. Powder samples were irradiated at 2.5, 5, 7.5 and 10 kGy. Subsequently, antioxidant activities, total protein content and total soluble polysaccharide content of irradiated samples were evaluated. Result showed that gamma irradiation up to 10 kGy did not significantly affect antioxidant activities. 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity assay (DPPH) of non-irradiated and irradiated samples ranged from 2.07 ± 0.09 to 2.19 ± 0.14 mgAAE/g, whereas ferric reducing antioxidant power (FRAP) of irradiated samples varied from 32.74 ± 0.39 to 34.52 ± 1.45 μmol FeSO4/g. Total phenolic contents were between 7.24 ± 0.38 and 7.65 ± 0.53 mgGAE/g. In terms of chemical properties, gamma radiation at 10 kGy showed no significant differences in total protein content and total water soluble polysaccharide content. Total protein contents were found from 42.46 ± 0.28 to 43.18 ± 0.13 %w/w. Amount of total water soluble polysaccharide content in non-irradiated and irradiated samples varied from 5.49 ± 0.15 to 5.72 ± 0.14 %w/w.

Gamma irradiation has been known for its great effect for inactivating microorganisms in various foods and it has been a safe method for food decontamination. In this present study, the dried lotus pollen was conducted to determine the effect of using gamma irradiation on the microbial load and antioxidant properties. The dried pollen lotus samples were irradiated with gamma irradiation at doses of 5 and 10 kGy and the total plate count (TPC) and total yeast and mold (Y&M) were determined. The study revealed that high microbial level of TPC and Y&M were found in non-irradiated. At dose of 5 kGy showed that gamma radiation was able to reduce the microorganism contamination in dried lotus pollen. The result permitted to accomplish the satisfactory microbial content for Thai community product standard of dried herb number 480/2547. In part of the antioxidant property, there was no any significant difference among the non-irradiated and irradiated samples in 60% ethanol extract. Surprisingly, total phenolic content and DPPH were increased by gamma radiation in hot water extract. Therefore gamma irradiation at 5 kGy could be a potential method for microbial decontamination of dried pollen lotus to improve hygienic quality.

Mushrooms are easily susceptible to microorganism spoilage and insect damage. Thus, the process of preservation is necessary for extending mushroom shelf-life. The objective of this study was to investigate the effects of gamma radiation on microbial analysis, antioxidant activities and chemical constituents of dried shiitake mushrooms. The shiitake powder was irradiated with gamma radiation at doses of 2.5, 5.0, 7.5 and 10 kGy. The irradiated samples were extracted with distilled water using ultrasonic bath. The extract was examined for microbial load, antioxidant activities by means of DPPH, FRAP and total phenolic content. Chemical properties were analyzed for total protein content and β-D-glucan content. The result showed that the total bacterial count was eliminated at a dose of 5 kGy and 2.5 kGy for yeast and mold, respectively. Pertaining to antioxidant activities; Increasing gamma irradiation dose, decreasing DPPH, FRAP and total phenolic content of shiitake powder were observed. At the dose of 10 kGy, the lowest DPPH value 2.07 ± 0.02 mgAAE/g, was achieved. The non-irradiated sample showed the highest value (3.16 ± 0.11 mgAAE/g). The FRAP values of irradiated samples ranged from 40.24 ± 0.41 to 3.16 ± 0.11 µmolFeSO 4 /g. At the dose of 2.5, 5.0, 7.5 and 10 kGy significantly reduced total phenolic acid content (9