Highlights Tangerine, pomegranate and banana processing system. Physicochemical and microbiological characteristics of tangerine, pomegranate and banana peels. Different uses of tangerine, pomegranate and banana peels. Tangerine, pomegranate and banana peels valorisation methods.

This study investigated the chemical composition, antioxidant and antimicrobial activity of essential oil extracted from Artemisia aragonensis Lam. (EOA). Hydrodistillation was employed to extract EOA. Gas chromatography with flame ionization detection (GC-FID) and gas chromatography-mass spectrometry analyses (GC-MS) were used to determine the phytochemical composition of EOA. Antioxidant potential was examined in vitro by use of three tests: 2.2-diphenyl-1-picrilhidrazil (DPPH), ferric reducing activity power (FRAP) and total antioxidant capacity assay (TAC). Agar diffusion and microdilution bioassays were used to assess antimicrobial activity. GC/MS and GC-FID detected 34 constituents in the studied EOA. The major component was Camphor (24.97%) followed by Borneol (13.20%), 1,8 Cineol (10.88%), and Artemisia alcohol (10.20%). EOA exhibited significant antioxidant activity as measured by DPPH and FRAP assays, with IC50 and EC50 values of 0.034 ± 0.004 and 0.118 ± 0.008 mg/mL, respectively. EOA exhibited total antioxidant capacity of 7.299 ± 1.774 mg EAA/g. EOA exhibited potent antibacterial activity as judged by the low minimum inhibitory concentration (MIC) values against selected clinically-important pathogenic bacteria. MIC values of 6.568 ± 1.033, 5.971 ± 1.033, 7.164 ± 0.0 and 5.375 ± 0.0 μg/mL were observed against S. aureus, B. subtills, E. coli 97 and E. coli 57, respectively. EOA displayed significant antifungal activity against four strains of fungi: F. oxysporum, C. albicans, A. flavus and A. niger with values of 21.50 ± 0.43, 5.31 ± 0.10, 21.50 ± 0.46 and 5.30 ± 0.036 μg/mL, respectively. The results of the current study highlight the importance of EOA as an alternative source of natural antioxidant and antibacterial drugs to combat antibiotic-resistant microbes and free radicals implicated in the inflammatory responses accompanying microbial infection.

Candida albicans an opportunistic pathogenic fungus causes many infections in humans. Whereas Aspergillus niger is a fungus that can produce ochratoxins, a group of extremely dangerous secondary metabolites that are classified as potentially carcinogenic to humans and also causing deterioration in grapes, strawberries, etc. The purpose of the current study is to isolate, purify, identify and characterize new microorganisms associated with solid green household waste for the control of C. albicans and A. niger. The antifungal activity of bacterial isolates was carried out in vitro by the agar plug diffusion method, the disk and well diffusion method. The isolate that showed promising activity has been identified by those macroscopic, microscopic and biochemical characteristics. The results obtained in the course of this study showed the isolation of an isolate named Gn-A11-18, which was shown to have significant inhibitory activity with a 42.66% inhibition percentage against A. niger and a 44.66 mm inhibition diameter against C. albicans compared to the controls. The identification of Gn-A11-18 isolate has shown that this isolate belongs to the genus Bacillus with a similarity to Bacillus subtilis and Bacillus tequilensis. In the light of the results of this study, we can suggest that the bioactive compound of Bacillus sp. Gn-A11-18 could become a biological alternate that could have an important role to fight against C. albicans and A. niger.

The chemical composition and antibacterial, insecticidal, and antioxidant properties of the essential oil from Mentha pulegium L. (M. pulegium) growing in Morocco were investigated in this work. To achieve this goal, the oils were obtained by using hydrodistillation before being characterized by GC-MS. The antibacterial and antifungal activities were conducted against pathogenic strains using the disc diffusion and MICS bioassays. The insecticidal activity was carried out versus C. maculatus using contact and inhalation tests. The antioxidant activity was performed by using DPPH and total antioxidant capacity bioassays. The chemical analysis of the oil showed that 20 compounds were identified, which represented 98.91% of the total oil. In the oil, the main components detected were R-(+)-pulegone (76.35%), carvone (5.84%), dihydrocarvone (5.09%), and octanol-3 (2.25%). The essential oil has moderate-to-strong broad-spectrum antibacterial and antifungal properties; the results showed that B. subtilis was the most sensitive strain to M. pulegium oil, with the largest inhibition diameter (25 ± 0.33). For the antifungal activity, the results obtained indicated that Aspergillus niger was the most sensitive fungal strain to M. pulegium oil with an inhibition percentage up to 100%. Regarding the insecticidal activity, the inhalation test showed a high efficacy (100% mortality), and a lethal concentration of LC50 = 1.41 + 0.48 μL/L air was obtained after 24 hours of exposure. Moreover, the contact test showed that a total reduction in fertility and emergence was obtained with a dose of 20 μL/mL of acetone. Regarding the antioxidant activity, the sample concentration necessary to inhibit 50% of HE radicals (IC50) was 7.659 mg/mL (DPPH) and 583.066 57.05 mg EAA/g EO (TAC).

The antioxidant, antibacterial and antifungal properties of essential oils (EOs) of Juniperus thurifera L., a plant utilized in traditional, herbal medicine, were investigated. The EOs were extracted by use of a Clevenger apparatus and phytochemicals identified by gas chromatography coupled with mass spectrometry (GC/MS/MS). The antioxidant capacity of EOs of J. thurifera was determined by 2,2-diphenyl-1-picrylhydrazil (DPPH), total antioxidant capacity (TAC), and ferric reducing antioxidant power (FRAP). Antimicrobial activity of EOs of J. thurifera was determined against four fungal strains, Candida albicans; ATCC 10231, Aspergillus niger; MTCC 282, Aspergillus flavus; MTCC 9606 and Fusarium oxysporum; MTCC 9913 and four bacterial strains, Staphylococcus aureus; ATCC 6633, Escherichia coli; K12, Bacillus subtilis; DSM 6333, and Pseudomonas aeruginosa; CIP A22, by use of the disk diffusion method, and microdilution method used to determine the minimum inhibitory concentration (MIC). EOs of J. thurifera consisted of 31 compounds and were dominated by α-thujene (25%), elemol (12%) and muurolol (12%). Antioxidant activity recorded an IC50 of 24 ± 0.71 µg/mL (DPPF), EC50 of 0.19 ± 0.01 mg/mL (FRAP), and 9.3 × 102 ± 38 mg EAA/g (TAC). The EOs of J. thurifera exhibited significant antibacterial activity against all bacterial strains under investigation, especially P. aeruginosa; CIP A22 with an inhibition diameter of 28 ± 1.5 mm and MIC of 4.8 × 10 −2 ± 0. 001 µg/mL. EOs of J. thurifera also exhibited significant antifungal activity against C. albicans; ATCC 10231 and F. oxysporum; MTCC 9913 with an activity of 21 ± 2.1 mm, 32 ± 2.3%, and MIC of 9.5 × 10 −2 ± 0.001 Bioactive molecules found in EOs of J. thurifera could be used as an alternative solution to antibiotics available on the market to combat microbial resistance.