Amel M. Kamal

Discovery, Optimization, and Pharmacophore Modeling of Oleanolic Acid and Analogues as Breast Cancer Cell Migration and Invasion Inhibitors Through Targeting Brk/Paxillin/Rac1 Axis

Bioassay‐guided fractionation of Terminalia bentzoe L. leaves methanol extract identified the known triterpene oleanolic acid (1) as its major breast cancer cell migration inhibitor. Further chemical optimization afforded five new (9–12 and 15) and seven known (4–8, 13, and 14) semisynthetic analogues. All compounds were tested for their ability to inhibit human breast cancer MDA‐MB‐231 cells migration, proliferation, and invasion. The results revealed that 3‐O‐[N‐(3′‐chlorobenzenesulfonyl)‐carbamoyl]‐oleanolic acid (11) and 3‐O‐[N‐(5′‐fluorobenzenesulfonyl)‐carbamoyl]‐oleanolic acid (12) were the most active hits at low μm concentration. Western blot analysis indicated the activity of 1, 11, and 12 might be related, at least in part, to the suppression of Brk/Paxillin/Rac1 signaling pathway. Pharmacophore modeling study was conducted to better understand the common structural binding epitopes important for the antimigratory activity. The sulfonyl carbamoyl moiety with an optimal bulkiness electron‐deficient phenyl ring is associated with improved activity. This study is the first to discover the antimigratory and anti‐invasive activities of oleanolic acid and analogues through targeting the Brk/Paxillin/Rac1 axis.

Antioxidant and cytotoxic activity of polyphenolic compounds isolated from the leaves of Leucenia leucocephala

Context: Cancer is a serious clinical problem to the health care system. Anticancer drugs have been extracted from plants containing phenolic compounds. Leucenia species (Fabaceae) contain a variety of bioactive components of numerous biological and pharmacological properties. Objective: This study explored the constitutive polyphenols of Leucenia leucocephala Lam. growing in Egypt and evaluated the antioxidant and cytotoxic activity. Materials and methods: Chemical structures of the isolated compounds from the leaves of L. leucocephala were established by spectral techniques (UV, 1H, and 13C NMR, MS). Results: Chromatographic separation of 80% MeOH extract of the leaves of L. leucocephala have resulted in a novel flavonoid-galloyl glycoside [myricetin 3-O-(2′,3′4′-tri-O-galloyl)-α-l-rhamnopyranoside] with three known polyphenolic compounds isolated for the first time from this species (apigenin 7-O-β-d-glucuronopyranoside methyl ester, luteolin 7-O-β-d-glucuronopyranoside methyl ester, and 1,3,6-tri-O-galloyl-β-d-glucopyranose) and seven known previously isolated compounds. Also, 80% methanol extract exhibited high antioxidant activity (SC50 = 3.94 µg/ml), which is correlated with its phenolic content. The extract also showed cytotoxic activity against Hep G2 (IC50 value 1.41 µg/ml) confirming its anticancer activity against hepatocellular carcinoma. Among the tested compounds (4–8) for antioxidant property, compound 7 was the most active compound (SC50 = 2.49 µg/ml). Also compounds 7 and 8 exhibited high cytotoxic activity (IC50 = 2.41 and 2.81 µg/ml, respectively). Discussion and conclusion: These findings demonstrate that the leaves of L. leucocephala contain a considerable amount of polyphenolic compounds with high antioxidant properties, thus it has great potential as a source for natural health products.

3-O-[N-(p-fluorobenzenesulfonyl)-carbamoyl]-oleanolic acid, a semisynthetic analog of oleanolic acid, induces apoptosis in breast cancer cells.

Oleanolic acid (OA), a pentacyclic triterpene acid widely distributed in food and traditional herbal remedies, exhibits diverse therapeutic effects. OA has been subjected to various chemical modifications to optimize its anticancer effect. Among other analogs, 3-O-[N-(p-fluorobenzenesulfonyl)-carbamoyl]-oleanolic acid (PFOA) was semisynthesized from OA. This study evaluates the cytotoxic effects of PFOA on MDA-MB-231, MCF-7, BT-474, and T-47D human breast cancer cells. Acute treatment of PFOA inhibited breast cancer cell viability in a dose-dependent manner. Treatment of PFOA at cytotoxic doses significantly induced apoptosis in cancer cells as shown by flow cytometry analysis. Activation of apoptosis in MCF-7 and BT-474 cells seemed to be initiated through induction of Fas ligand, which resulted in activation of caspase-8 and PARP-1, whereas apoptosis in MDA-MB-231 cells was initiated by the activation of caspase-9, caspase-3 and PARP-1. The mechanism of apoptosis induction in T-47D involves activation of PARP-1. PFOA decreased the expression of EGFR, HER-2, MET and ERα in human breast cancer cell lines. These findings suggest that PFOA inhibits cell growth, activates apoptosis, and decreases the expression of key proteins involved in progression of breast cancer.

Bioassay-guided isolation and POM analyses of a new immunomodulatory polyphenolic constituent from Callistemon viridiflorus

Chromatographic separation of 80% EtOH extract of Callistemon viridiflorus leaves led to the isolation of six known constituents (1–6) along with a new polyphenolic compound 7 identified as apigenin 4′-O-β-d-glucopyranosyl-(1″′ → 4″)-O-β-d-glucopyranoside. The ethanolic extract of C. viridiflorus leaves and isolated compounds were evaluated for in vitro immunomodulatory activity by means of RAW 264.7 macrophages proliferation (MTT) assay. Ethanolic extract of leaves and compounds 1, 3, 4, 6 and 7 caused a significant increase in macrophage proliferation; these findings may suggest that this medicinal plant could be utilised as an excellent source of compounds for immunomodulatory activity.

Rutin as A Novel c-Met Inhibitory Lead for The Control of Triple Negative Breast Malignancies

ABSTRACT Triple negative breast cancer (TNBC) has high metastatic and mortality potential and lacks effective and selective therapeutic options. Aberrant dysregulation of the receptor tyrosine kinase c-Met promotes TNBC progression, motility and survival and therefore considered a valid therapeutic target. Among various identified anticancer agents, plant polyphenols (PPs) including flavonoids, have been shown to be safe and proven for their antitumor activity through modulating diverse macromolecular targets. This study reports the bioassay-guided identification of the common flavonol glycoside rutin as breast cancer cell proliferation, migration and invasion inhibitor. The cell free Z′-LYTE kinase assay, Western blot and in silico docking experiments uncovered, for the first time, c-Met kinase as a potential mechanistic target for rutin-mediated anticancer effects on TNBC cell lines. Likewise, the intraperitoneal injection of rutin at 30 mg/kg, 3X/week, significantly reduced the growth of the TNBC MDA-MB-231/GFP orthotopic xenograft in nude mouse model. These results clearly designate the functional dietary flavonoid rutin as a potential lead for the prevention and control of c-Met-dependent breast malignancies.

Lipoidal Matter and Essential Oil Contents of Leaves and Fowers of Callistemon viridiflorus and their Antimicrobial Activity

Abstract Comparative investigation of hydro-distilled essential oils from leaves and flowers of Callistemon viridiflorous Sims (family Myrtaceae) grown in Egypt was carried out including their chemical composition and some of their bioactivities. The obtained oils revealed the presence of 19 and 22 identified constituents in the leaves and flowers, respectively. The oils were dominated by oxygenated compounds of 96.1 and 98.5 % in leaves and flowers of C. viridiflorous respectively. Methyl eugenol was found to be the main component in leaves (89.1 %) and flowers (95.1 %). Hydrocarbon contents in both leaves and flowers were 3.9 and 1.5 %, respectively. The unsaponifiable fraction of the fixed oil obtained by extracting the leaves of C. viridiflorous with petroleum ether was analyzed by GLC. The percentage of hydrocarbons and sterols were found to be 76.9 and 2.9 %, respectively. Nonane (12.0 %), octadecane (11.0 %) and hexane (9.1 %) were found as the major hydrocarbon constituents. Stigmasterol (1.3 %), β-sitosterol (0.9 %) and cholesterol (0.7 %) were the major phytosterol constituents. Analysis of methylated fatty acid fraction of C. viridiflorous leaves extract by GLC revealed that the percentage of saturated fatty acids was higher than that of unsaturated fatty acids being 84.5 and 14.9 %, respectively. Arachidic (42.4 %) and palmitic (37.0 %) acids were the major identified saturated fatty acid while oleic acid (5.5 %) was the major identified unsaturated fatty acid. The oils of leaves and flowers of C. viridiflorus exhibited broad spectrum antimicrobial activity against both gram- positive and gram-negative bacteria as well as Candida albicans yeast.