Fadia S. Youssef

Medicinal Plants with Potential Antidiabetic Activity and their Assessment

Objective: Diabetes mellitus is a clinical syndrome characterized by a deficiency in insulin production or resistance to insulin action. Consequently, it leads to inappropriate hyperglycemia. Prolonged hyperglycemia can cause severe complications that probably affect every system of the body and every drug taken by the patient. This study highlights the most popular medicinal plants with potential antidiabetic significance, their modes of action together with the method used for their assessment. Key findings: Through antidiabetic evaluation conducted on different medicinal herbs since centuries revealed the presence of potent antidiabetic activity. Moreover, the candidates from natural source with diverse structures of secondary metabolites. This indicates various sites of action within the human body. Conclusions: Further investigations are required, and more attention should be drawn to explore the biological activity of hundreds of traditionally used medicinal plants both in vitro and in vivo to assess the claimed activity with the aim of finding potent antidiabetic candidates from the natural resources.

Antihyperglycaemic activity of the methanol extract from leaves of Eremophila maculata (Scrophulariaceae) in streptozotocin‐induced diabetic rats

This study was designed to evaluate the antihyperglycaemic activity of the methanol leaf extract of Eremophila maculata (EMM) both in vitro and in vivo.

Chemical profiling of Phlomis thapsoides (Lamiaceae) and in vitro testing of its biological activities

A phytochemical study of Phlomis thapsoides (Lamiaceae) resulted in the isolation of one new compound, 6,10,17-trimethyl-2-octadecanone, and three known compounds (sitosterol-3-O-β-glucoside, and the iridoid glucosides ipolamiide and lamiide). The structures of the isolated compounds were elucidated using mass spectrometry, 1D/2D NMR spectroscopy experiments in comparison with published data. The chemical composition of the essential oil obtained from aerial parts of P. thapsoides was determined by gas liquid chromatography and gas liquid chromatography-mass spectroscopy. The main volatile constituents were phenylethyl alcohol (6.81 %), trans-3-hexenol (5.55 %), 1-octen-3-ol (5.10 %), α-cadinol (4.92 %), and α-muurolol (4.67 %). The antioxidant activity of the extracts was evaluated by three methods: 1,1-diphenyl-2-picrylhydrazyl free radical scavenging activity, 2,2′-azinobis-[3-ethylbenzthiazoline-6-sulfonic acid] and ferric reducing antioxidant power assay along with the determination of total phenolic content. Although the ethyl acetate extract contained 362.06 mg of gallic acid equivalents, the antioxidant activities, as revealed by 1,1-diphenyl-2-picrylhydrazyl, 2,2′-azinobis-[3-ethylbenzthiazoline-6-sulfonic acid] and ferric reducing antioxidant power assays, were of medium strength (IC50 of 73.08 ± 3.18, 9.48 ± 0.71 µg/mL and 9.33 ± 0.17 mM of FeSO4 equivalents, respectively). Only lamiide inhibited soybean 5-lipoxygenase with an IC50 value of 72.92 µg/mL in vitro. In-silico molecular modeling studies on 5-lipoxygenase and human 5-lipoxygenase-activating protein were used to evaluate the potential anti-inflammatory activity. Sitosterol-3-O-β-glucoside followed by the iridoid glucoside lamiide exhibited the highest inhibition of 5-lipoxygenase whereas the new compound 6,10,17-trimethyl-2-octadecanone and sitosterol-3-O-β-glucoside exhibited the highest inhibition of 5-lipoxygenase-activating protein as evidenced from their higher fitting scores. The cytotoxicity of the plant extracts and lamiide against Caco2 and HepG-2 cancer cells resulted in IC50 values of >100 µg/mL indicating a low cytotoxicity.

The genus Eremophila (Scrophulariaceae): an ethnobotanical, biological and phytochemical review.

Eremophila (Scrophulariaceae) is an endemic Australian genus with 214 species, which is commonly known as Fuchsia bush, Emu bush or Poverty bush. Plants of this genus played an important role for the Australian Aborigines who used them widely for medicinal and ceremonial purposes. Many studies have been carried out on many species of this genus and have generated immense data about the chemical composition and corresponding biological activity of extracts and isolated secondary metabolites.

Inhibition of cytochrome P450 (CYP3A4) activity by extracts from 57 plants used in traditional chinese medicine (TCM)

Background: Herbal medicine is widely used all over the world for treating various health disorders. It is employed either alone or in combination with synthetic drugs or plants to be more effective. Objective: The assessment of the effect of both water and methanol extracts of 57 widely used plants from Traditional Chinese Medicine (TCM) against the main phase I metabolizing enzyme CYP3A4 in vitro for the first time. Materials and Methods: The inhibition of cytochrome P450 activity was evaluated using a luminescence assay. The principal component analysis (PCA) was used to correlate the inhibitory activity with the main secondary metabolites present in the plant extracts. Molecular modeling studies on CYP3A4 (PDB ID 4NY4) were carried out with 38 major compounds present in the most active plant extracts to validate the observed inhibitory effect. Results: Aqueous extracts of Acacia catechu, Andrographis paniculata, Arctium lappa, Areca catechu, Bupleurum marginatum, Chrysanthemum indicum, Dysosma versipellis, and Spatholobus suberectus inhibited CYP3A4 is more than 85% (at a dose of 100 μg/mL). The corresponding methanol extracts of A. catechu, A. paniculata, A. catechu, Mahonia bealei, and Sanguisorba officinalis inhibited the enzyme by more than 50%. Molecular modeling studies revealed that two polyphenols, namely hesperidin and rutin, revealed the highest fitting scores in the active sites of the CYP3A4 with binding energies equal to -74.09 and -71.34 kcal/mol, respectively. Conclusion: These results provide evidence that many TCM plants can inhibit CYP3A4, which might cause a potential interference with the metabolism of other concomitantly administered herbs or drugs. Abbreviation used: CHARMm: Chemistry at HARvard Macromolecular Mechanics, CYP: Cytochrome P450, DMSO: Dimethyl Sulfoxide, PCA: Principal Component Analysis, PDB: Protein Data Bank, TCM: Traditional Chinese Medicine

Chemical Profiling of the Essential Oils of Syzygium aqueum, Syzygium samarangense and Eugenia uniflora and Their Discrimination Using Chemometric Analysis.

The essential oil compositions of the leaves of three related Myrtaceae species, namely Syzygium aqueum, Syzygium samarangense and Eugenia uniflora, were investigated using GLC/MS and GLC/FID. Altogether, 125 compounds were identified: α‐Selinene (13.85%), β‐caryophyllene (12.72%) and β‐selinene constitute the most abundant constituents in S. aqueum. Germacrene D (21.62%) represents the major compound in S. samarangense whereas in E. uniflora, spathulenol (15.80%) represents the predominant component. Multivariate chemometric analyses were used to discriminate the essential oils using hierarchical cluster analysis (HCA) and principal component analysis (PCA) based on the chromatographic results. The antimicrobial activity of the popularly used E. uniflora essential oil was assessed using broth microdilution method against six Gram‐positive, three Gram‐negative bacteria and two fungi. The oil showed moderate antimicrobial activity against Bacillus licheniformis exhibiting MIC and MMC of 0.63 mg/ml. The cytotoxic activity of E. uniflora essential oil was investigated against Trypanosoma brucei brucei (T. b. brucei) and MCF‐7 cancer cell line using MTT assay. It showed moderate activity against MCF‐7 cells with an IC50 value of 76.40 μg/ml. On the other hand, T. brucei was highly susceptible to E. uniflora essential oil with IC50 of 11.20 μg/ml, and a selectivity index of 6.82.

Volatile Oils from the Aerial Parts of Eremophila maculata and Their Antimicrobial Activity

The essential oils isolated from the fresh flowers, fresh leaves, and both fresh and air‐dried stems of Eremophila maculata (Scrophulariaceae) were characterized by GC‐FID and GC/MS analyses. Sabinene was the major component in most of the oils, followed by limonene, α‐pinene, benzaldehyde, (Z)‐β‐ocimene, and spathulenol. The leaf and flower essential oils showed antibacterial and antifungal activity against five Gram‐positive and four Gram‐negative bacterial strains, multi‐resistant clinical isolates from patients, i.e., methicillin‐resistant Staphylococcus aureus (MRSA), as well as two yeasts. Minimum inhibitory concentrations (MICs) and minimum microbicidal concentrations (MMCs) were between 0.25 and 4 mg/ml.

Chemical Composition of Pinus roxburghii Bark Volatile Oil and Validation of Its Anti-Inflammatory Activity Using Molecular Modelling and Bleomycin-Induced Inflammation in Albino Mice

The chemical composition of Pinus roxburghii bark essential oil (PRO) was qualitatively and quantitatively determined using GC/FID and GC/MS. The anti-inflammatory activity was assessed in vitro by evaluating the binding percentages on the cannabinoids and opioids receptors. Bleomycin (BLM)-induced pulmonary inflammation in albino mice was adopted to assess PRO anti-inflammatory efficacy in vivo. In silico molecular modelling of its major components was performed on human glucocorticoids receptor (GR). Seventy-five components were identified in which longifolene (33.13%) and palmitic acid (9.34%) constituted the predominant components. No binding was observed on cannabinoid receptor type 1 (CB1), whereas mild binding was observed on cannabinoid receptor type 2 (CB2), delta, kappa, and mu receptors accounting for 2.9%, 6.9%, 10.9% and 22% binding. A significant in vivo activity was evidenced by reduction of the elevated malondialdehyde (MDA), nitric oxide (NO), myeloperoxidase (MPO), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) levels by 55.56%, 55.66%, 64.64%, 58.85% and 77.78% with concomitant elevation of superoxide dismutase (SOD) and catalase (CAT) activities comparable to BLM-treated group at 100 mg/kg body weight. In silico studies showed that palmitic acid exerted the fittest binding. PRO could serve as a potent anti-inflammatory natural candidate that should be supported by further clinical trials.

Synergistic Hepatoprotective and Antioxidant Effect of Artichoke, Fig, Blackberry Herbal Mixture on HepG2 Cells and Their Metabolic Profiling Using NMR Coupled with Chemometrics

The edible plants have long been reported to possess a lot of biological activities. Herein, the hepatoprotective and the antioxidant activities of the aqueous infusion of the edible parts of Cynara cardunculus, Ficus carica, and Morus nigra and their herbal mixture (CFM) was investigated in vitro using CCl4 induced damage in HepG2 cells. The highest amelioration was observed via the consumption of CFM at 1 mg/ml showing 47.00% and 37.09% decline in aspartate transaminase and alanine transaminase and 77.32% and 101.02% increase in reduced glutathione and superoxide dismutase comparable to CCl4 treated cells. Metabolic profiling of their aqueous infusions was done using nuclear magnetic resonance spectroscopic experiments coupled with chemometrics particularly hierarchical cluster analysis (HCA) and principal component analysis (PCA). The structural closeness of the various metabolites existing in black berry and the mixture as reflected in the PCA score plot and HCA processed from the 1H‐NMR spectral data could eventually explained the close values in their biological behavior. For fig and artichoke, the existence of different phenolic metabolites that act synergistically could greatly interpret their potent biological behavior. Thus, it can be concluded that a herbal mixture composed of black berry, artichoke, and fig could afford an excellent natural candidate to combat oxidative stress and counteract hepatic toxins owing to its phenolic compounds.

Volatile constituents of Dietes bicolor (Iridaceae) and their antimicrobial activity

Abstract Volatile oils from the leaves, flowers and rhizomes of Dietes bicolor (Steud.) Sweet ex Klatt (Iridaceae) were analyzed using GLC/FID and GLC/MS. A total of 84 compounds were identified accounting for 94.65, 95.63 and 87.09% in the hydrodistilled oils from flowers, leaves and rhizomes, respectively. Spathulenol (48.44%) represented the major component in the leaf oil, followed by dihydro-edulan I (6.25%), cubenol (6.00%) and τ-cadinol (5.90%). For the flower and rhizome oils, fatty acids, their esters, aliphatic hydrocarbons and their derivatives predominate. The antimicrobial activity of both leaf and flower oils was investigated against four bacteria in addition to four fungi using the micro-broth dilution method. The leaf oil showed a more potent antimicrobial activity as compared to the flower oil against most of the assessed bacteria and fungi, with higher activities against Gram- positive organisms showing MIC values of 115 and 460 μg/ml for Bacillus subtilis and Streptococcus pneumonia, respectively. Gram-negative bacteria were generally less susceptible (MIC > 2 mg/ml for both oils against Escherichia coli) and being completely ineffective against Pseudomonas aeruginosa. A relevant antifungal potency of the leaf oil against Geotrichum candidum and Syncephalastrum racemosum was also observed with MIC values of 115 and 920 μg/ml, respectively.