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Introduction: Hymenosporum flavum (Hook.) F. Muell. is the sole species within the genus Hymenosporum is known for its antimicrobial activity. The current study aims to examine the prospective activity of H. flavum as a safe supporter of sorafenib (as a reference standard) against hepatocellular carcinoma (HCC). Methods: Isolation and identification of compounds were made by chromatographic and spectroscopic methods. A fingerprint for the plant extract was done using HPLC-MS/MS spectrometric analysis. The total plant extract was examined in vitro for HCC activity. The isolated flavonoids were examined for their cytotoxic activities using molecular docking studies against both RAF-1 and ERK-2, and the promising compounds were further examined in vitro using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Results: Two new flavonols were isolated from the leaf extract of H. flavum (Hook.) F. Muell., quercetin-3-O-(glucopyranosyl 1→2 ribopyranoside) (1) and kaempferol-3-O-(glucopyranosyl 1→2 ribopyranoside) (2), accompanying other six known flavonoids (3-8), and identified via spectroscopic analysis. Moreover, HPLC- PDA/MS/MS spectrometric analysis revealed the presence of seventy phenolic metabolites. The cytotoxic activity of the plant extract confirmed its potential action on HepG2 cells indicated by the production level of lactate dehydrogenase (LDH) upon treatment compared with the normal cells. The isolated flavonoids were examined for their cytotoxic activity using molecular docking studies against both RAF-1 and ERK-2 as proposed mechanisms of their anticancer activities. Furthermore, compounds 1 and 3, which showed the best in silico results, were further examined in vitro using qRT-PCR. They exhibited promising inhibitory activities against both RAF-1 and ERK-2 gene expression. Moreover, they showed promising cytotoxic activities indicated by the MTT assay. Also, both of them improved the efficiency of sorafenib in targeting both RAF-1 and ERK-2 pathways suggesting synergistic combinations. Conclusion: Our findings showed the potential cytotoxic activity of H. flavum extract on HepG2 cells. Some isolated compounds (1 & 3) exhibited promising inhibitory activities against both RAF-1 and ERK-2 gene expression giving a lead future study for these compounds to be used in pharmaceutical preparations either alone or in combination with sorafenib.

Background:Myrtus species are characterized by the presence of phenolic acids, flavonoids, tannins, volatile oils and fatty acids. They are remedies for variety of ailments. This study therefore investigated medicinal effects of Myrtus communis L.Methods:Bioactivity studies of Myrtus communis L. leaves were carried out on volatile oil, 7% methanol and aqueous extracts and the isolated compounds myricetin 3-O-β-glucopyranoside, myricetin 3-O-∝–rhamnopyranoside and gallic acid.Results:Determination of the median lethal dose (LD50) revealed that the volatile oil, alcoholic and aqueous extracts were practically nontoxic and highly safe as no lethality was observed. The tested materials (volatile oil, alcoholic and aqueous extracts, myricetin 3-O-β-glucopyranoside, myricetin 3-O-∝–rhamnopyranoside and gallic acid) showed significant antihyperglycemic, anti-inflammatory and antinociceptive effects as compared with control groups and reference drugs.Conclusion:Administration of extracts of M. communis leaves could be safe at the dose used in this study.

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