Gas chromatography-mass spectrometry (GC-MS) analysis and in vitro evaluation of antioxidant and antimicrobial activities of various solvent extracts from Citrullus colocynthis (L.) roots to control pathogen and spoilage bacteria

Citrullus colocynthis (L.) schrad is an important medicinal plant belonging to the family of Cucurbitaceae. In the present study we evaluated in vitro the antimicrobial and the antioxidant properties of various solvent extracts from C. colocynthis roots as well as the latter phytochemical characterisation. Total phenolic and flavonoid contents were determined. The highest content of total phenolic was found in extracts obtained with ethyl acetate (205 mg GAE/g) followed by methanol (85 mg GAE/g). The major phenolic compounds in ethyl acetate extract were identified by gas chromatography-mass spectrometry (GC-MS). A total of 12 compounds were characterized including oleic acid, linoleic acid, caffeic acid, hexadecanoic acid and octadecanoic acids. The antioxidant activities were evaluated using 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) and lipid peroxidation methods. These tests showed that the ethyl acetate extract exhibited the best performance. The different extracts were also tested against a panel of pathogen, food-borne and spoilage bacteria and fungi in order to evaluate the antimicrobial properties of this plant. Among the tested extracts, only the ethyl acetate extract exhibited bactericidal and fungicidal activities. To our knowledge, this is the first report on the chemical composition, antioxidant and antimicrobial activities of phenolic extracts from C. colocynthis roots. The results of the present work indicate that C. colocynthis extracts could be used as natural antioxidant and antimicrobial agents in the food preservation and human health.Key words: Citrullus colocynthis, antibacterial activity, antifungal activity, antioxidant activity, phenolics composition

Antimicrobial, antioxidant and phytochemical investigation of Balanites aegyptiaca (L.) Del. edible fruit from Sudan

The methanol extract of the fruit (edible mesocarp) of Balanites aegyptiaca (L.) Del., a popular plant from Sudan, widely employed in Sudanese folk medicine was screened for antimicrobial, antioxidant and some active phytochemical compounds. The extract showed the presence of saponin, terpenoids, phenolic compounds and alkaloids. The methanolic extract of the fruits extracted from B. aegyptiaca exhibited a strong antioxidant activity in the DPPH assay and a potent capacity in preventing linoleic acid oxidation. Methanol extracts (50 and 100 mg/ml) were tested on several microbial strains using agar-well diffusion, minimum inhibitory concentration (MIC), minimum bacterial concentration (MBC) and minimum fungal concentration (MFC) methods. These experiments were performed on ten bacterial strains (five Gram-positives and five Gram-negatives) and four fungal strains. Methanol extracts, particularly at concentration of 100 mg/ml was found to be active against all bacterial and fungal strains and it was comparable to standard antibiotics Gentamicin and Amphotericin B. These findings support some of the traditional applications of the fruit of B. aegyptiaca against microbial aliments. It is therefore recommended that further studies regarding fractionation, separation and purification of these active antimicrobial compounds are required, in addition to toxicological evaluation in vivo.Key words: Balaneties aegyptiaca, antibacterial, antifungal, phytochemical, antioxidant, methanol extract

Evaluation of antimicrobial and antioxidant properties of leaves of Emex spinosa and fruits of Citrillus colocynthis from Saudi Arabia

The crude methanol extract of Citrullus colocynthis fruit and Emex spinosa leaves were examined for antimicrobial and antioxidant potentialities. The phytochemical analysis revealed presence of some bioactive principles, such as alkaloids, flavonoids and anthraquinones for E. spinosa and saponin, flavonoids, terpenoids and alkaloids for C. colocynthis. The antimicrobial activities were determined against seven bacterial strains (Proteus vulgaris NCTC 8196, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumonia ATCC 53651, Salmonella typhi NCTC 0650, Staphylococcus aureus ATCC 25923 and Bacillus cereus NCTC 8236) and one fungal strain (Candida albicans ATCC 7596). E. spinosa leaf methanol extract was most active against fungus, whileC. colocynthis fruit methanol extract was most active against bacteria, particularly E. coli ATCC 25922 and P. aeruginosa ATCC 27853. The antioxidant properties of extracts were investigated in vitro using1,1-diphenyl, 2-picryl hydrazyl (DPPH) radical scavenging assay and in vivo in rats using serological and enzymatic tests. Both plant extracts showed considerable antioxidant activities. The promising findings of this investigation could be used as a novel natural antimicrobial and antioxidant agents.Keywords: Emex spinosa, Citrillus colocynthis, antimicrobial, antioxidant activity.African Journal of Biotechnology Vol. 12(34), pp. 5308-531

Biopreservative effect of the tunisian halophyte lobularia maritima flavonoid fraction, used alone and in combination with linalool in stored minced beef meat

In the present study, Lobularia maritima (Lm) flavonoid extract (LmFV) was characterized by HPLC analyses and five compounds were detected. Further, to describe the chemical content of the matrix, GC-MS analyses after silylation were performed; the obtained results showed the presence of a large number of components belonging to several chemical classes, mostly sugar alcohols, sugars, fatty acids, and terpenes. Firstly, the antibacterial activities of this fraction and linalool (Lin) were evaluated against eight foodborne pathogenic strains with MIC values between 2.3 and 5.8 mg/mL and 0.23 and 0.7 mg/mL, respectively. Then, the antioxidant activity of both was evaluated by the DPPH antiradical test and the phosphomolybdenum test. Furthermore, the biopreservative effect of LmFV alone and in combination with Lin on minced beef stored at 4 C for 14 days was evaluated using microbiological and physiochemical tests. LmFV at 4.6% alone significantly reduced microbial spoilage in ground meat (p < 0.05). The combination of LmFV (4.6%) and Lin (0.46%) was more effective than LmFV alone in inhibiting bacterial contamination, reducing TBARS values and the risk of bacterial contamination, and reducing the accumulation of Met myoglobin (MetMb). This combination, therefore, extends the shelf life of the product by about 10 days. Based on these microbiological results and physicochemical parameters, it can be stated that the addition of Lin potentiates the flavonoid fraction of L. maritima more strongly against the deterioration of meat quality by significantly improving its biopreservative effect as a natural conservativ

Thiamine Demonstrates Bio-Preservative and Anti-Microbial Effects in Minced Beef Meat Storage and Lipopolysaccharide (LPS)-Stimulated RAW 264.7 Macrophages

This study assessed the anti-inflammatory effect of thiamine (TA) in lipopolysaccharide-stimulated RAW264.7 cells and also assessed the preservative properties of TA in minced beef. TA demonstrated a concentration-dependent antimicrobial effect on microbial contaminants. Inhibition zones and MIC from the effect of TA on the tested bacterial strains were respectively within the ranges 15–20 mm and 62.5–700 µg/mL. TA significantly (p < 0.05) decreased all the pro-inflammatory factors [(nitric oxide (NO), prostaglandin E2 (PGE2), TNF-α, IL-6, IL-1β, and nuclear factor-κB (NF-κB)] monitored relative to LPS-stimulated RAW264.7 cells. TA inhibited the expression of both iNOS and COX-2. In minced beef flesh, the growth of Listeria monocytogenes was inhibited by TA. TA improved physicochemical and microbiological parameters of stored minced beef meat compared to control. Principal component analyses and heat maps elucidate the quality of the tested meats

Chemical composition and evaluation of antioxidant and antimicrobial activities of Tunisian Thymelaea hirsuta with special reference to its mode of action

In the present study, we evaluated in vitro antimicrobial and antioxidant properties of Thymelaea hirsuta extracts as well as its phytochemical composition. Total phenolic and flavonoid contents were highest in acetone and ethyl acetate extracts respectively. The different extracts were tested against a panel of microorganisms, food-borne bacteria and spoilage fungi, in order to evaluate the antimicrobial properties of this plant. Among the tested extracts, only the ethyl acetate one exhibited antibacterial and antifungal activities. Acetone extract showed only an antibacterial activity. The investigation of the mode of action of the active ethyl acetate extract by the time-kill curve showed a drastic bactericidal effect after 5 min using a concentration of 624 μg/ml. Also, it appears that the ethyl acetate extract is an antifungal agent with a cellular target includes the pump H+-ATPase. The antioxidant activities of the different extract were evaluated using DPPH, lipid peroxidation and hydroxyl radical scavenging methods. From the obtained results it can be noticed that ethyl acetate and acetone extracts exhibited the best performance. The major phenolic compounds of the ethyl acetate extract of T. hirsuta were identified by Gas chromatography–mass spectrometry (GC–MS). A total of 16 compounds were characterized including p-hydroxybenzoic, p-coumaric, ferulic and caffeic acids known to have various biological activities.Tunisian “Ministry of Higher Education, Scientific Research and Technology

A Lobularia maritima LmSAP protein modulates gibberellic acid homeostasis via its A20 domain under abiotic stress conditions.

Stress-associated proteins (SAPs) are favorable targets to improve stress tolerance in plants, owing to their roles in developmental processes and stress responses. However, the role of SAPs and the molecular mechanisms by which they regulate plant stress responses remain poorly understood. Previously, it was reported that LmSAP expression was upregulated by various abiotic stressors in Lobularia maritima, and that transgenic tobacco lines with constitutively expressed LmSAPΔA20 and LmSAPΔA20-ΔAN1 showed dwarf phenotypes due to the deficiency of cell elongation under salt and osmotic stresses. In this study, we examined the function of A20 domain in the GA pathway in response to abiotic stresses. Transient expression of acGFP-LmSAPΔA20 and acGFP-LmSAPΔA20-ΔAN1 in onion epidermal cells demonstrated that these fused proteins were localized in the nucleo-cytoplasm. However, the truncated form acGFP-LmSAPΔAN1 was localized in the nucleus. Moreover, comparison of native and truncated LmSAP showed dramatic structural changes caused by the deletion of the A20 domain, leading to loss of function and localization. Interestingly, overexpression LmSAP and truncated LmSAPΔAN1 led to up-regulation of GA biosynthetic genes and increased total gibberellins (GAs) content, corresponding with accelerated development in transgenic tobacco plants. Moreover, the dwarf phenotype of the transgenic lines that express LmSAPΔA20 and LmSAPΔA20-ΔAN1 under stress conditions was fully restored by the application of exogenous GA3. These findings improve our understanding of the role of LmSAP in regulating GA homeostasis, which is important for regulating plant development under abiotic stress conditions

Identification of phenolic compounds by HPLC/MS and in vitro evaluation of the antioxidant and antimicrobial activities of Ceratonia siliqua leaves extracts

Ceratonia siliqua is a typical plant of the Mediterranean area, which is mainly used as animal and human food and in folk medicine for treating some diseases such as antidiarrheal and diuretic. The present study was planned to evaluate the potential of antimicrobial and antioxidant activities of C. siliqua leaves extract and the identification of bioactive compounds by high performance liquid chromatography/mass spectrometry (HPLC/MS) in the active extract. The antioxidant activities of the different organic extracts of C. siliqua were assayed by 2,2-diphenyl-l-picrylhydrazyl (DPPH) and β-carotene tests. Among the tested extracts, results showed that the ethyl acetate extract displayed the greatest DPPH scavenging ability with an IC50 of 1.8 µg/ml and a strong β-carotene bleaching inhibition after 120 min of incubation with an IC50 of 24.01 µg/ml. The investigation of the phenolic and flavonids content showed that the ethyl acetate extract of C. siliqua revealed the highest phenolic contents. Only the ethyl acetate extract of C. siliqua (EACs) showed antimicrobial activity with a broad-spectrum microbiocide with diameter inhibition zones ranging from 12 to 24 mm and MIC values of 0.312 to 1.25 mg/ml. The HPLC finger print of EACs active extract showed the presence of six phenolic compounds. They included (1) 1,6-Di-galloyl-glucose, (2) 1,2,6-Tri-galloyl-glucose, (3) Myricetin glucoside, (4) 1,2,3,6-Tetra-galloyl-glucose, (5) Myricetin rhamnoside and (6) Syringic acid. These results are a good agreement of the popular use and experimentally observed effects of C. siliqua and would promote the reasonable usage and exploitation of the biomolecules of this important plant