Browsing by Author "O. Bakr, Riham"

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Antioxidant and anti-listerial activities of selected Egyptian medicinal plants
(African Journal of Microbiology Research, 2013) O. Bakr, Riham; A. Omer, E.; A. Abdel-Razik, K.; S. M. Abuelnaga, A.; N. Danial, Enas; G. Elgindy, A.
This work investigates the phenolic, antioxidant capacity of crude extracts of eight Egyptian medicinal plants (Syrian oregano, marjoram, rosemary, lemongrass, thyme, yarrow, marigold and sweet wormwood) and estimates their activity against Listeria monocytogenes, one of the most virulent food borne pathogens. Antioxidant activity of Rosemary (70.6±1.65%) and thyme (70.8±1.72%) based on TBA assay was significantly higher compared to other plants and ascorbic acid. Rosemary was found to possess the best antilisterial activity with lowest MBC (8 µl/ml); while its total phenolic content (TPC) represented 69.73 ± 0.47 mg/g GAE. Thyme showed MBC of 46 µl/ml with TPC 96.85±0.56 mg/g GAE. Lemon grass and marigold showed considerable antilisterial activity (MBC 31, 46 µl/ml respectively), although they had lower phenolic contents and low thiobarbituric acid inhibition. Sweet wormwood, marjoram and yarrow were inactive against listeria. Rosemary and thyme appeared as possible alternatives for synthetic food additives and preservatives.
In vitro Comparison of the Antimicrobial Activity of Five Herbal Extracts, and Selected Mouthwashes Marketed in Egypt against Cariogenic Streptococcus Mutans
(The Egyptian Society of Medical Microbiology, 2014) M. Helmy, Mai; O. Bakr, Riham
Dental caries is a multifactorial human disease that has widely affected many populations all over the world. Streptococcus mutans plays a major role in dental caries development. Few of mouthwashes, however, have undergone rigorous testing and lack the quality of an ideal agent as evidenced by the limited amount of information on their safety and efficacy in the literature. Thus presently the antibacterial activity of herbal agents is being extensively studied. The present study aims to compare the antimicrobial effects of 70% aqueous ethanol extract obtained from traditional Egyptian plants with the most common Egyptian mouthwashes brands against S.mutans. S.mutans isolated on Mitis Salivarius Agar (MSA) and confirmed by API 20 Strep C. 70% aqueous ethanol extracts of Achillea fragrantissima Sch.Bip (No 5), Euphorbia hirta L. (No 2), Nymphaea alba L. (No 1), Thymus vulgaris L.(No 4 ) and Plectranthus amboinicus L (No 3) were prepared.The susceptibility pattern of 25 S. mutans bacterial isolates obtained from 82 dental plaque samples of patients having dental caries to the selected mouthwashes and plant extracts was determined using the agar well diffusion method. The zones of inhibition produced by the mouthwashes and herbal extracts against the bacterial isolates were measured compared with chlorhexidine positive control. Chlorhexidine formulations listermix and jase were the most effective mouthwash preparations, while chlorhexidine free formulation betadine was the least effective preparation against S.mutans. Extracts No 1 and 2 exhibited the highest antimicrobial effect, while extract No 4 showed the least one. Chlorhexidine formulations Jase and listermix are considered to be the most effective mouthwash anticaris. N. alba, E. hirta plant extracts have the greatest antibacterial activity against S.mutans. If similar results are confirmed in clinical trials, these plant extracts can be used alone or in combination to produce new, useful and economic antimicrobial mouthwashes alternative to commonly known mouthwashes with less side effects.
Nymphaea alba and Liver Protection
(Academic Press, 2019) O. Bakr, Riham
This chapter highlights the importance of Nymphaea alba as a promising hepatoprotective candidate. It starts by its description as an aquatic plant with a long history in traditional medicine, presenting its folk uses. Flavonoids and hydrolyzable tannins were the major identified classes of active constituents in the flower, leaf, and rhizome. A variety of biological activities have been described, but the focus was on studies that could contribute to the hepatoprotective activity. Studies performed in intoxicated animal models showed amelioration in the liver markers, restoration of the antioxidant defense system, and a prominent effect on inflammatory mediators. The correlation between the phenolics identified, especially tannins, and the antihepatotoxic effect is discussed.
Production of Flavonoids and Phenolic Compounds by Elicitation of Iphiona mucronata (Forssk.) Asch. & Schweinf (Asteraceae) Callus and Suspension Cultures
(International Journal of Pharmacognosy and Phytochemistry, 2015) A. Al-Gendy, Amal; O. Bakr, Riham; D. El-Gindi, Omayma
Callus and suspension cultures of Iphiona mucronata grown on Murashige and Skoog medium, supplemented with 0.1 mg/l kinetin (Kn), 0.1 mg/l naphthalene acetic acid (NAA) and 5 mg/l ascorbic acid were elicited with different elicitors. Total flavonoids and phenolics were determined by aluminum chloride - potassium acetate and Folin-Ciocalteu colorimetric methods respectively. When callus and suspension cultures elicited with 10 mg/l yeast extract (Y), it showed an increase of 2.8 and 3.7 folds for flavonoids production respectively. When callus cultures treated with 0.001 mM phenyl alanine (Ph), a slight increase in flavonoids content reached 1.17 folds, while treated suspension reached maximum level after 60 hours. Methyl jasmonate (MJ; 150 µM) increased flavonoids concentration 4 times for callus and 2.3 times for suspension. Determination of phenolics for elicited suspension showed an increase of 2.3 (Y), 2.5 (Ph) and 1.3 (MJ) times. The obtained results favored the use of yeast extract for high productivity and viability of cell lines.
Somatic embryogenesis and plant regeneration from callus and suspension cultures of Iphiona mucronata (Forssk)
(European Scientific Journal, 2013) A. Al-Gendy, Amal; O. Bakr, Riham; D. El-gindi, Omayma
A protocol was designed for plant regeneration of Iphiona mucronata from embryogenic callus via somatic embryogenesis to enable micro propagation of this endangered plant. The embryogenic callus was induced using seedling cultured for nine months on Murashig and Skoog medium (MS) supplemented with 0.1 mg l-1 naphthalene acetic acid (NAA), 0.1 mg l1 kinetin (Kn) and 5 mg l-1 ascorbic acid and incubated in the dark followed by growing on hormone free medium. Transfer of developed embryos to MS medium supplemented with 0.5 mg l-1 kinetin induced shoot formation. Four treatments were further tried for plant development by using indole acetic acid (IAA) or indole butyric acid (IBA) alone or in combination with kinetin. The results showed that 2 mg l-1 IAA was the best for in vitro plantlet regeneration. Embryogenic suspension was induced by transfer of embryogenic callus to liquid medium having the same composition followed by hormone free medium where different stages of embryos were monitored. Shoots were developed upon transfer to liquid medium supplemented with 0.5 mg l-1 Kn. However, no further development appeared upon transfer to semi solid medium containing different phytohormones. Embryogenic callus showed the highest phenolic contents when compared with embryogenic suspension, regenerated plantlets and the parent plant while flavonoids were detected only in embryogenic callus.