Uncommon Trimethoxylated Flavonol Obtained from Rubus rosaefolius Leaves and Its Antiproliferative Activity

A novel flavonoid and other constituents from Rubus rosifolius S.Vidal (Rosaceae)

Various reports revealed that chemical constituents from many species of Rubus exhibit diverse biological activities. In this study, a novel flavonoid with a 2-(phenanthren-9-yl)-4H-chromen-4-one structure (1), a 5-phenylthiophene-2-carbaldehyde derivative (5) first isolated from a natural source, together with five known compounds including three polyketides (2-4) and two sesquiterpenoids (6-7) were isolated from a traditional Chinese medicine Rubus rosifolius S.Vidal (Rosaceae). The structures of new compounds were elucidated by detailed spectroscopic analysis including NMR and X-ray single-crystal diffraction. The bioassays results indicated that, compound 1 displayed significant cytotoxicity against human colon cancer cell line HCT116 with IC50 value of 8.6 ± 1.9 μM, and compound 5 exhibited moderate cytotoxicity against human breast cancer cell line MDA-MB-435 with IC50 value of 24.1 ± 0.8 μM.

Chromosome-scale genome, together with transcriptome and metabolome, provides insights into the evolution and anthocyanin biosynthesis of Rubus rosaefolius Sm. (Rosaceae)

Rubus rosaefolius is a kind of red raspberry possessing high nutritional and pharmaceutical value. Here we present a chromosome-level draft genome of R. rosaefolius. Of the total 131 assembled scaffolds, 70 with a total size of 219.02 Mb, accounting for 99.33% of the estimated genome size, were anchored to seven pseudochromosomes. We traced a whole-genome duplication (WGD) event shared among members of the Rosaceae family, from which were derived 5090 currently detectable duplicated gene pairs (dgps). Of the WGD-dgps 75.09% underwent purifying selection, and approximately three-quarters of informative WGD-dgps expressed their two paralogs with significant differences. We detected a wide variety of anthocyanins in the berries of R. rosaefolius, and their total concentration remained relatively stable during berry development but increased rapidly during the ripening stage, mainly because of the contributions of pelargonidin-3-O-glucoside and pelargonidin-3-O-(6″-O-malonyl)glucoside. We identified many structural genes that encode enzymes, such as RrDFR, RrF3H, RrANS, and RrBZ1, and play key roles in anthocyanin biosynthesis. The expression of some of these genes significantly increased or decreased with the accumulation of pelargonidin-3-O-glucoside and pelargonidin-3-O-(6″-O-malonyl)glucoside. We also identified some transcription factors and specific methylase-encoding genes that may play a role in regulating anthocyanin biosynthesis by targeting structural genes. In conclusion, our findings provide deeper insights into the genomic evolution and molecular mechanisms underlying anthocyanin biosynthesis in berries of R. rosaefolius. This knowledge may significantly contribute to the targeted domestication and breeding of Rubus species.

Preussiate, a new urease inhibitory chalcone from Dioscorea preussii Pax

The phytochemical investigation of the aqueous methanolic extract of the aerial parts of Dioscorea preussii, led to the isolation of a new chalcone preussiate (1) along with 10 other compounds including xanthomicrol (2), cholestan-3-one (3), arjunolic acid (4), tormentic acid (5), ursolic acid (6), betulin (7), lupeol (8), p-hydroxybenzoic acid (9), isovanillin (10) and vanillic acid (11), being reported for the first time from this plant. Their structures were established by spectroscopic techniques including 2D NMR spectroscopy. All the isolates were subjected to the biological screening but only showed antioxidant and urease inhibitory properties. The compounds 1,8 and 11 displayed the most potent urease inhibitory properties with IC50 values, 22.4, 33.3 and 35.7 µM, respectively, while 3 was moderately active. The compound 11 showed potent antioxidant activity among all the tested isolates with an IC50 value of 45.3 µM.

Cytogenotoxic evaluations of leaves and stems extracts of Rubus rosifolius in primary metabolically noncompetent cells

Plants with medicinal potential may also produce adverse effects in humans. This seems to be the case for the species Rubus rosifolius, where preliminary studies demonstrated genotoxic effects attributed to extracts obtained from leaves and stems of this plant using on HepG2/C3A human hepatoma cells as a model. Considering the beneficial properties of this plant as an antidiarrheal, analgesic, antimicrobial, and antihypertensive and its effects in the treatment of gastrointestinal diseases, the present study was developed with the aim of determining the cytotoxic and genotoxic potential of extracts of leaves and stems of R. rosifolius in primary without metabolic competence in human peripheral blood mononuclear cells (PBMC). Cell viability analyses at concentrations of between 0.01 and 100 µg/ml of both extracts did not markedly affect cell viability. In contrast, assessment of the genotoxic potential using the comet assay demonstrated significant damage to DNA within PBMC from a concentration of 10 µg/ml in the stem extract, and a clastogenic/aneugenic response without cytokinesis-block proliferation index (CBPI) alterations at concentrations of 10, 20, or 100 µg/ml for both extracts. Under our experimental conditions, the data obtained demonstrated genotoxic and mutagenic effects attributed to extracts from leaves and stems of R. rosifolius in cells in the absence of hepatic metabolism.

Two triterpenoids from Rubus fraxinifolius leaves and their tyrosinase and elastase inhibitory activities

Numerous therapeutic compounds have been isolated from naturally abundant organic resources, which may offer economical and sustainable sources of compounds with safe and efficacious biological activities. In the cosmetics industry, natural compounds with anti-aging activities are eagerly sought. Thus, we prepared various extracts from Rubus fraxinifolius leaves and used enzyme inhibition assays to isolate compounds with protective effects against skin aging. Two triterpenoids were isolated from Rubus fraxinifolius Poir. leaves. The structures were characterized by spectroscopic analyses (LC-ESI-MS, 1D/2D NMR) and comparison to reported data. Compound 1 and 2 were determined as 2,3-O-ethyleneglycol, 19-hydroxyurs-12-en-23,28-dioic acid and 2,3-O-propanediol,19-hydroxyurs-12-en-28-oic acid. Methanol extract and isolates were assessed for their inhibitory effects on elastase and tyrosinase. Compounds 1 and 2 inhibited elastase with IC₅₀ 122.199 µg/mL and 98.22 µg/mL, and also inhibited tyrosinase with IC₅₀ 207.79 µg/mL and 221.51 µg/mL, respectively. The molecular docking proved that both compounds have affinities toward the enzymes.

Inhibition of pancreatic elastase in silico and in vitro by Rubus rosifolius leaves extract and its constituents

Objective:

Elastases are protease enzymes, which mainly hydrolyze proteins of the connective tissue, so they have a significant impact on human disease. Rubus rosifolius is one of the Rubus species found in Indonesian mountains, and it has potential as an elastase inhibitor. The objective of this research was to examine the in vitro elastase inhibitor activity of R. rosifolius leaves and to dock different ligands of its constituents against target protein of Porcine Pancreatic Elastase (PPE) receptor.

Method:

Dried leaves powder of R. rosifolius was extracted using Soxhlet apparatus with n-hexane, ethyl acetate, and methanol. The extract was evaporated, and in vitro elastase inhibitor activity was determined using PPE with the quercetin used as control positive. Selected nine constituents of R. rosifolius were evaluated on the docking behavior of elastase receptor using Protein–Ligand ANT System (PLANTS) computational software with PPE enzyme with Protein Data Bank (PDB) file 1BRU.

Result:

The methanol extract showed significantly inhibited elastase with IC50 186.13 μg/mL, but ethyl acetate extract showed weak activity, and n-hexane extract did not show any activity. Docking studies and binding free energy calculations and hydrogen bonding with some amino acids revealed that ellagic acid showed the least binding energy for the target enzyme.

Conclusion:

This research has opened new insights into understanding that constituents of R. rosifolius methanol extract are potential inhibitors against elastase, and suggested the active compound is ellagic acid.

Risk assessment via genotoxicity, metabolism, apoptosis, and cell growth effects in a HepG2/C3A cell line upon treatment with Rubus rosifolius (Rosaceae) leaves extract

Sm. (Rosaceae) is a plant traditionally used in Brazil and some other countries to treat diarrhea, stomach diseases, and as an analgesic, antimicrobial, antihypertensive, and as well as other pharmacological properties. The aim of this study was to examine cytotoxic and genotoxic effects of R. rosifolius leaves extract on HepG2/C3A cells and correlate these findings with the expression of mRNA to underlying mechanisms of action. At concentrations between 0.01 and 100 µg/ml, cytotoxic effects were not detected by the MTT assay. This was confirmed by mRNA induction of the CYP3A4 gene (by RT-qPCR assay). However, genotoxic effects occurred at treatments from 1 µg/ml extract (comet and micronucleus test). An increase in the number of cells in S phase was observed at 100 µg/ml, and an elevation in apoptotic cell number was found for all tested concentrations (10, 20, or 100 µg/ml) (cell cycle and apoptosis analysis by flow cytometry). The genotoxicity induced by the extract was the main cause of the rise in the number of cells undergoing apoptosis, as indicated by rise in mRNA of CASP7 gene, and elevation of cells in the S phase of the cell cycle at the higher tested concentrations, as an attempt to repair genetic damage that occurred. These observations suggest that, despite its pharmacological potential, the use of R. rosifolius leaves extract may pose a risk to the integrity of the genetic material of human cells.

Caucasian endemic medicinal and nutraceutical plants: in-vitro antioxidant and cytotoxic activities and bioactive compounds

OBJECTIVES

In order to assess traditional claims about the therapeutic potential of Caucasian endemic medicinal plants and to select plants for phytochemical research, nine plant species were selected and assessed for their in-vitro antioxidant and cytotoxic activities. The metabolite profiles of some priority plants were analysed.

METHODS

Antioxidant effects were assessed using the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) system, lipid peroxidation and Folin-Ciocalteu methods. Cytotoxic activities were examined against human liver cancer cells (HepG2) using the Alamar Blue assay. Terpenoids of selected species were analysed by GC and GC-MS. Polyphenols were separated by HPLC.

KEY FINDINGS

Thymus transcaucasicus, Heracleum transcaucasicum, Ribes armenum, Crataegus armena showed most promising antioxidant activity in ABTS model system. Moreover, Rubus takhtadjanii, C. armena, T. transcaucasicus showed a high level of antioxidant activity by inhibiting lipid peroxidation. C. armena and T. transcaucasicus expressed high-to-moderate cytotoxicity against HepG2 cells. The main terpenoids and polyphenols of Centaurea hajastana, C. armena and T. transcaucasicus were quantified.

CONCLUSIONS

This study provides in-vitro data relevant for assessing the use of Caucasian endemic medicinal plants, most importantly C. armena and T. transcaucasicus as traditional antioxidant supplements and potential anticancer remedies. Metabolite profiles of some lead plants showed the nature of bioactive compounds of medical interest.

Extraction Optimization of 5,7-Dihydroxy-6,8,4′-trimethoxyflavonol, a Bioactive Flavonoid from Rubus rosifolius (Rosaceae) Leaves

Recently, it has been demonstrated that a rare flavonoid, 5,7-dihydroxy-6,8,4′-trimethoxyflavonol (1), isolated from the leaves of Rubus rosifolius showed significant antiproliferative activity against different cancer cell lines and had a diuretic effect. This study aimed to determine the best extraction method evaluating dynamic maceration extraction (DME), ultrasonic assisted extraction (UAE), and microwave assisted extraction (MAE). In addition, level optimization for different factors was focused using Design of Experiments. The flavonoid content was estimated by high performance liquid chromatography (HPLC). The results indicated that UAE provided the highest content with the shortest extraction time. For optimization, response surface methodology (RSM) was used, applying a Box-Behnken Design (BBD) with three factors at three levels. It was possible to observe that the flavonoid content significantly increased with the increase of temperature (max. 70°C). The time had little influence on the extraction and, for this reason, was set at 25 min. With regard to the drug/solvent ratio, it was observed that this had an impact on yield with a ratio of 3.5%. A model was built and a determination coefficient of 0.98 was obtained. After validation, an optimized method was developed, able to extract 1 with a lower time, lower solvent consumption, and affording higher contents.