A new flavonoid from the stem bark of Acer tegmentosum

Estrogenic Activity of 4-Hydroxy-Benzoic Acid from Acer tegmentosum via Estrogen Receptor α-Dependent Signaling Pathways

Acer tegmentosum, a deciduous tree belonging to Aceraceae, has been used in traditional oriental medicine for treating hepatic disorders, such as hepatitis, cirrhosis, and liver cancer. We evaluated the estrogen-like effects of A. tegmentosum using an estrogen receptor (ER)-positive breast cancer cell line, namely MCF-7, to identify potential phytoestrogens and found that an aqueous extract of A. tegmentosum promoted cell proliferation in MCF-7 cells. Five phenolic compounds (1-5) were separated and identified from the active fraction using bioassay-guided fractionation of crude A. tegmentosum extract and phytochemical analysis. The chemical structures of the compounds were characterized as vanillic acid (1), 4-hydroxy-benzoic acid (2), syringic acid (3), isoscopoletin (4), and (E)-ferulic acid (5) based on the analysis of their nuclear magnetic resonance spectra and liquid chromatography-mass spectrometry data. All five compounds were evaluated using an E-screen assay for their estrogen-like effects on MCF-7 cells. Among the tested compounds, only 4-hydroxy-benzoic acid (2) promoted the proliferation of MCF-7 cells, which was mitigated by the ER antagonist, ICI 182,780. The mechanism underlying the estrogen-like effect of 4-hydroxy-benzoic acid (2) was evaluated via western blotting analysis to determine the expression levels of extracellular signal-regulated kinase (ERK), phosphoinositide 3-kinase (PI3K), serine/threonine kinase (AKT), and ERα. Our results demonstrated that 4-hydroxy-benzoic acid (2) induced the increase in the protein expression levels of p-ERK, p-AKT, p-PI3K, and p-Erα, concentration dependently. Collectively, these experimental results suggest that 4-hydroxy-benzoic acid (2) is responsible for the estrogen-like effects of A. tegmentosum and may potentially aid in the control of estrogenic effects during menopause.

Structural Characterization of the Acer ukurunduense Chloroplast Genome Relative to Related Species in the Acer Genus

Acer ukurunduense refers to a deciduous tree distributed in Northeast Asia and is a widely used landscaping tree species. Although several studies have been conducted on the species’ ecological and economic significance, limited information is available on its phylo-genomics. Our study newly constitutes the complete chloroplast genome of A. ukurunduense into a 156,645-bp circular DNA, which displayed a typical quadripartite structure. In addition, 133 genes were identified, containing 88 protein-coding genes, 37 tRNA genes, and eight rRNA genes. In total, 107 simple sequence repeats and 49 repetitive sequences were observed. Thirty-two codons indicated that biased usages were estimated across 20 protein-coding genes (CDS) in A. ukurunduense. Four hotspot regions (trnK-UUU/rps16, ndhF/rpl32, rpl32/trnL-UAG, and ycf1) were detected among the five analyzed Acer species. Those hotspot regions may be useful molecular markers and contribute to future population genetics studies. The phylogenetic analysis demonstrated that A. ukurunduense is most closely associated with the species of Sect. Palmata. A. ukurunduense and A. pubipetiolatum var. pingpienense diverged in 22.11 Mya. We selected one of the hypervariable regions (trnK-UUU/rps16) to develop a new molecular marker and designed primers and confirmed that the molecular markers could accurately discriminate five Acer species through Sanger sequencing. By sequencing the cp genome of A. ukurunduense and comparing it with the relative species of Acer, we can effectively address the phylogenetic problems of Acer at the species level and provide insights into future research on population genetics and genetic diversity.

Safety Assessment of Acer tegmentosum Maxim. Water Extract: General Toxicity Studies in Sprague-Dawley Rats and Beagle Dogs With Re-evaluation of Genotoxic Potentials

Acer tegmentosum Maxim., commonly known as Manchurian stripe maple, is a deciduous tree belonging to the family of Aceraceae and has been traditionally used in folk medicine for its remedial effects in liver diseases and traumatic bleedings. With a growing body of experimental evidence for its pharmacological efficacies, such as neuroprotective, hepatoprotective, antioxidant, and anti-inflammatory activities, A. tegmentosum has gradually gained popularity as a health supplement and functional food. However, the large part of essential toxicity information still remained lacking despite the possibility of mutagenic potentials as previously suggested, posing safety concerns for human consumption. In this study, we evaluated 90-day repeated oral toxicity of A. tegmentosum Maxim. water extract (ATWE) in SD rats with acute toxicity assessment in beagle dogs, and reevaluated genotoxicity using a combination of in vitro and in vivo assays. During the oral study period, ATWE did not cause toxicity-related clinical signs and mortality in rodents without adverse effects observed in the analysis of hematology, serum biochemistry, and histopathology, establishing >5,000 mg/kg BW as the NOAEL. In addition, doses up to 5,000 mg/kg BW did not cause acute toxicity in beagle dogs. When assessed for genotoxicity using bacterial reverse mutation, chromosome aberration, and micronucleus formation, ATWE showed lack of mutagenicity and clastogenicity. These results demonstrated that AWTE was safe in the present preclinical study for systemic toxicity and genotoxicity at the tested doses, providing a guideline for safe use in humans.

Phytochemical composition, antisnake venom and antibacterial activities of ethanolic extract of Aegiphila integrifolia (Jacq) Moldenke leaves

Snakebites are considered a major neglected tropical disease, resulting in around 100,000 deaths per year. The recommended treatment by the WHO is serotherapy, which has limited effectiveness against the toxins involved in local tissue damage. In some countries, patients use plants from folk medicines as antivenoms. Aegiphila species are common plants from the Brazilian Amazon and are used to treat snakebites. In this study, leaves from Aegiphila integrifolia (Jacq) Moldenke were collected from Roraima state, Brazil and its ethanolic extract was evaluated through in vitro and in vivo experiments to verify their antiophidic activity against Bothrops atrox crude venom. The isolated compounds from A. integrifolia were analyzed and the chemical structures were elucidated on the basis of infrared, ultraviolet, mass, ¹H and ¹³C NMR spectrometry data. Among the described compounds, lupeol (7), betulinic acid (1), β-sitosterol (6), stigmasterol (5), mannitol (4), and the flavonoids, pectolinarigenin (2) and hispidulin (3), were identified. The ethanolic extract and flavonoids (2 and 3) partially inhibited the proteolytic, phospholipase A2 and hyaluronidase activities of B. atrox venom, and the skin hemorrhage induced by this venom in mice. Antimicrobial activity against different bacteria was evaluated and the extract partially inhibited bacterial growth. Thus, taken together, A. integrifolia ethanolic extract has promising use as an antiophidic and antimicrobial.