This study is the first to identify 1'ACA from A. malaccensis. The crude or purified compound could potentially be developed as antimicrobials.

Objective: This study aimed at determining the antibacterial activity of the underutilized plants of Sri Lanka, “Kottamba” (Terminalia catappa), “Purpurata” (Alpinia purpurata) and “Harankaha” (Curcuma zedoaria), against food-borne pathogens. Chemical composition and in vitro cytotxicity of the most active antibacterial plant extract(s) were examined.Methods: Crude rhizome extracts were obtained for all plants whereas in respect of T. catappa, the red pericarp of the fruit was used. The antibacterial activity was determined using the agar disc diffusion and broth dilution assays. Total phenol content, Gas Chromatograph-Mass Spectrometry analysis and cytotoxicity assay were conducted only with the plant which showed the most effective antibacterial activity.Results: T. catappa extract showed significantly (p<0.05) high DIZ (19.6±0.47 mm) against S. aureus 113. A. purpurata showed DIZ (16.3±0.94, 15.0±1.00, 14.3±0.57 mm) against L. monocytogenes V7 (1/2a), S. aureus 25925 and S. aureus MSSASS 25D. The MIC of T. catappa ethanol extract was 10 mg/ml, while MBC was 80 mg/ml for S. aureus 113. The phenolic content of T. catappa ethanol extract was 81.54±1.28 mg GAE/g dry sample and the major compound (31.86 %) was 2, 5-Furandione, 3 methyl. The No-Observed Adverse Effect Concentration (NOAEC) of this extract for COS7 cells was 100 µg/ml whereas for 3T3 it was 300 µg/ml. This indicates that the extract is cytotoxic only at a very high concentration, suggesting that at lower concentrations the extract could be used as a food preservative.Conclusion: The results indicate that T. catappa has potential antibacterial activity as a safe bio-preservative.

The objective of the study was to evaluate the potential toxicity of crude n-hexane extract of Alpinia malaccensis rhizome. The in vivo acute oral toxicity was evaluated by administering a single oral dose of the extract at 0, 300, or 2000 mg/kg body weight to female Wistar rats according to modified OECD Test Guideline 423. For the in vitro cytotoxicity study, A549, HepG2, 3T3, and COS-7 cell lines were exposed to different doses of A. malaccensis extract and cell viability was assessed adopting MTT assay followed by AO/EB staining, Hoechst staining, and comet assay with a view to compare the cellular and molecular mechanisms underlying the toxicity, if any. It was found that administration of 2000 mg/kg bw dose in in vivo oral acute toxicity study did not produce significant toxicity or mortality. No significant ( p < 0.05 ) differences were observed for body weight and hematological and biochemical parameters compared to control after 14 days of treatment. No changes in behavior, body weight, hematological and biochemical parameters, and aspects of histopathology were observed when compared to the control. Thus, the possible oral lethal dose for A. malaccensis extract is above 2000 mg/kg body weight. The in vitro cytotoxicity analysis showed nontoxicity concentrations of the extract to be 2, 1.4, 30, and 1.4 µg/mL for A549, HepG2, 3T3, and COS-7 cells, respectively, where no apoptotic/necrotic cell death and DNA damage were observed. In conclusion, the extract of rhizome of A. malaccensis did not produce apparent cytotoxicity or acute oral toxicity, confirming the scope to use A. malaccensis as a safe food preservative and a natural therapeutic product after further subacute and chronic toxicity studies.

The combined antibacterial activity of Alpinia malaccensis and Terminalia catappa, was tested for Listeria monocytogenes, Staphylococcus aureus and spoilage bacteria in vacuum packed ready‐to‐cook (RTC) chicken. The 10 g of chicken pieces were inoculated with each bacterium and marinated with 0.5 ml of the mixture of 5 mg/ml A. malaccensis and 20 mg/ml T. catappa. The chicken was vacuum packed after adding 1 ml extract mixture and stored at 4 or 8 °C for 12 days. Every three‐day intervals microbial count, lipid oxidation, pH, and the color was determined. Combination of plant extracts significantly (p < .05) inhibited the growth of S. aureus bacteria with 1.80, 2.13, 2.36, and 2.97 log CFU/g reduction over 3, 6, 9, and 12 days stored at 8 °C. Similarly, L. monocytogenes was significantly (p < .05) inhibited at 6, 9, 12 days with 1.22, 1.60, and 1.55 log CFU/g reduction compared to control at 4 °C. Lipid oxidation significantly reduced (p < .05) in treated chicken 1.39 MDA mg/kg and 2.43 MDA mg/kg at day 12 at 4 and 8 °C, respectively. Total plate count of treated chicken showed 6.59 ± 0.10 log CFU/g at 6 days of storage at 4 °C and 6.66 ± 0.36 CFU/g during 9 days of storage at 8 °C allowing safe for human consumption. Practical applications The shelf‐life of RTC marinated vacuum packed fresh chicken samples stored at 4 and 8 °C were significantly extended for 6 and 9 days, respectively. Plant extracts combination showed a significant inhibition of L. monocytogenes or S. aureus and spoilage bacteria and reduced lipid oxidation. Therefore, two plants extract combinations act as antimicrobials and antioxidants which could stabilize lipid oxidation, color, and microbial growth thus extending the shelf‐life of ready to cook fresh chicken meat products. Therefore, marinated RTC chicken is economically important for the food industry.