Study of Antimicrobial, Antioxidant and Cytotoxicity Properties of Selected Plant Extracts for Food Preservative Applications

Abstract

An attempt has been made to evaluate antimicrobial, antioxidant and cytotoxicity properties of extracts from onion (Allium cepa L.), garlic (Allium sativum), leaves of guava (Psidium guajava), papaya (Carica papaya), tea (Camellia sinensis), baen (Avicennia alba) and keora (Sonneratia apetala), respectively to apply as natural preservatives for tomatoes. The air-dried plant materials of the respective plant species were subjected to ethanol-methanol extraction, concentrated and stored at 4 °C before use. The extracts were dissolved in 95% ethanol for analysis of antioxidant and antimicrobial properties. Of the extracts tested, tea extracts showed the highest zone of inhibition against several pathogenic bacteria (E. coli 35.0±3.2 mm; P. aeruginosa 29.3±2.6 mm; S. typhi 28.4±2.1 mm and S. pyogenes 27.7±3.7 mm) using the disc diffusion method. In regard to DPPH free radical scavenging assay, keora and guava extracts showed the highest percentage of radical scavenging activity with the values of 89.64± 0.18 and 89.39± 0.88, respectively, which were in agreement with higher total antioxidant capacity (TAC) of these extracts obtained by the phosphomolybdenum method. Brine shrimp lethality bioassay for cytotoxicity assessment showed LC50 of 132.54 ± 18.99 µg/mL for the leaf extract of keora which was found to be most toxic among all studied extracts. The initial results indicated that the extracts could be used for food preservative applications based on the antimicrobial, antioxidant and cytotoxicity properties of the tested extracts. However, efficacy, stability and safety issues need to be addressed with both in vitro and in vivo studies.

Effects of Neem, Moringa, and Synthesized Silver Nanoparticles Coating on Postharvest Shelf Life and Quality Retention of Tomato (Solanum lycopersicum L.)

“…The effectiveness of neem and moringa aqueous leaf extracts in reducing tomato decay observed in this study suggests that it could be a viable alternative for combating pathogen-related decay in tomatoes. This observation aligns with a study reported by [23], who reported that treating various kinds of fruits with chitosan and guava leaf extract significantly increased the shelf life of the fruits. Similarly, our findings are consistent with the report of [24], who highlighted the effectiveness of extracts from medicinal plants like Allium sativum, Azadirachta indica, Mentha arvensis, and Psoralia corlylifolia in preserving fruits from pathogenic and environmental factors.…”

Freeze drying and spray drying for the retention of the active components, L‐theanine and caffeine, and antioxidant activity of tea‐based ingredients

“…Similar to Islam et al . (2021), ascorbic acid was used as a positive control. Ascorbic acid methanolic solution (10 mg mL −1 ) was prepared and serially diluted.…”

“…Briefly, 1 mg mL À1 freeze-dried and spray-dried tea solutions in HPLC-grade water were separately prepared and vortexed. According to Islam et al (2021), with modifications, 0.004% (W/V%) methanolic solution of DPPH (2,2-diphenyl-1-picrylhydrazyl; Sigma-Aldrich) was freshly prepared. After shaking, 1 mL of the DPPH solution was added to 3 mL of the freeze-dried and spray-dried tea aqueous solutions, and the undried tea infusion and the samples were shaken.…”

“…Subsequently, the absorbance of each sample and the control (DPPH methanolic solution without tea sample) was recorded in triplicate at 515 nm using a UV/visible spectrophotometer (Ultrospec 2100 pro) similar to the procedure by Mimica-Dukic et al (2004) and Afroz Bakht et al (2019). Similar to Islam et al (2021), ascorbic acid was used as a positive control. Ascorbic acid methanolic solution (10 mg mL À1 ) was prepared and serially diluted.…”