Cytotoxic and Antibacterial Prenylated Acylphloroglucinols from Hypericum olympicum L.

Two new bicyclo[3.3.1]nonane type bicyclic polyprenylated acylphloroglucinol derivatives (BPAPs), olympiforin A and B as well as three known prenylated phloroglucinols, were isolated from the aerial parts of Hypericum olympicum L. The structures of the isolated compounds were established by means of spectral techniques (HRESIMS and 1D and 2D NMR). All compounds were tested on a panel of human tumor (MDA-MB-231, EJ, K-562, HL-60 and HL-60/DOX) and non- tumorigenic (HEK-293 and EA.hy926) cell lines using the MTT assay. All tested compounds exerted significant in vitro cytotoxicity with IC50 values ranging from 1.2 to 24.9 µM and from 0.9 to 34 µM on tumor and non-cancerous cell lines, respectively. Most of the compounds had good selectivity and were more cytotoxic to the tumor cell lines than to the normal ones. A degradation of the precursor caspase 9 for some of the compounds was observed; therefore, the intrinsic pathway of apoptosis is the most likely mechanism of cytotoxic activity. The BPAPs were examined for antibacterial and antibiofilm activity through the broth microdilution method and the protocol of Stepanovic. They showed a moderate effect against Enterococcus faecalis and Streptococcus pyogenes but a very profound activity against Staphylococcus aureus with minimum inhibitory concentrations (MIC) in the range of 0.78-2 mg/L. Olympiforin B also had a great effect against methicillin-resistant S. aureus (MRSA) with an MIC value of 1 mg/L and a very significant antibiofilm activity on that strain with a minimum biofilm inhibition concentration (MBIC) value of 0.5 mg/L. The structures of the isolated compounds were in silico evaluated using ADME and drug likeness tests.

Anticancer Podophyllotoxin Recovery from Juniper Leaves at Atmospheric and High Pressure Using Eco-Friendly Solvents.

Podophyllotoxin (PPT) is a precursor for the synthesis of drugs against cancer and other diseases. The present sources of PPT (Sinopodophyllum hexandrum and Podophyllum peltatum) are endangered species, with PPT production highly dependent on their growing conditions. In connection with the identification of new sources of PPT, the present study aimed to recover PPT from Juniperus virginiana leaves via atmospheric or high pressure extraction methods with a focus on using eco-friendly solvents. PPT quantification was determined by UHPLC/HRMS/MS. A thorough study of conventional extraction was carried out to reveal the optimal conditions (solvent ethyl acetate at room temperature and a duration of 1 h) for maximizing the PPT recovery (about 30 mg/g of dry extract and 3 mg/g of dry initial plant material). Peleg's equation was applied for process kinetics modeling. The best PPT content in the final dry extract (42-45 mg/g of dry extract) was obtained by high pressure methods under supercritical (scCO2 with ethanol or ethyl acetate, 30 MPa, 50 °C and 100 min) or accelerated solvent extraction conditions (solvent ethyl acetate, 10.35 MPa, 20 °C and 3 cycles for 15 min). Seasonal stability and storage stability of the raw material were also determined. The present results have potential applications in the pharmacy for the delivery of PPT from juniper leaves.

Outstanding Antibacterial Activity of Hypericum rochelii-Comparison of the Antimicrobial Effects of Extracts and Fractions from Four Hypericum Species Growing in Bulgaria with a Focus on Prenylated Phloroglucinols.

Microbial infections are by no means a health problem from a past era due to the increasing antimicrobial resistance of infectious strains. Medicine is in constant need of new drugs and, recently, plant products have had a deserved renaissance and garnered scientific recognition. The aim of this work was to assess the antimicrobial activity of ten active ingredients from four Hypericum species growing in Bulgaria, as well as to obtain preliminary data on the phytochemical composition of the most promising samples. Extracts and fractions from H. rochelii Griseb. ex Schenk, H. hirsutum L., H. barbatum Jacq. and H. rumeliacum Boiss. obtained with conventional or supercritical CO2 extraction were tested on a panel of pathogenic microorganisms using broth microdilution, agar plates, dehydrogenase activity and biofilm assays. The panel of samples showed from weak to extraordinary antibacterial effects. Three of them (from H. rochelii and H. hirsutum) had minimum inhibitory concentrations as low as 0.625-78 mg/L and minimum bactericidal concentrations of 19.5-625 mg/L against Staphylococcus aureus and other Gram-positive bacteria. These values placed these samples among the best antibacterial extracts from the Hypericum genus. Some of the agents also demonstrated very high antibiofilm activity against methicillin-resistant S. aureus. Ultra-high-performance liquid chromatography-high-resolution mass spectrometry revealed the three most potent samples as rich sources of biologically active phloroglucinols. They were shown to be good drug or nutraceutical candidates, presumably without some of the side effects of conventional antibiotics.

In Vitro Study of the Biological Potential of Wastewater Obtained after the Distillation of Four Bulgarian Oil-Bearing Roses.

The wastewater after rose oil distillation is usually discharged into the drainage systems and it represents a serious environmental problem. While being rich in polyphenols, which have beneficial biological activity and application in the pharmaceutical industry, limited research has been carried out about the biological activity of the specific wastewaters per se. Wastewaters after distillation of the four Bulgarian oil-bearing roses Rosa damascena Mill., R. alba L., R. centifolia L., and R. gallica L. exerted significant antioxidant activity and good antiherpes simplex virus type-1 (HSV-1) activity while maintaining a good toxicological safety profile (low cytotoxic effect) towards normal cell lines. More precisely, the non-tumorigenic cells were a human (HEK-293 embryonic kidney cells) and a mouse cell line (CCL-1 fibroblasts, which are recommended as a standard for cytotoxicity evaluation in Annex C of ISO 10993-5). The concentrations that achieved antioxidant and radical scavenging effects (0.04-0.92% v/v) were much lower than most of the maximum tolerated concentrations for the tissue culture cells (0.2-3.4% v/v). The wastewaters had a weak antiproliferative effect against Staphylococcus aureus. None of the wastewaters had activity against Gram-negative bacteria or a bactericidal or antifungal effect. We can conclude that these four species, which are the most preferred species worldwide for producing high-quality rose oil, have the potential to be developed as promising antioxidant and antiherpesvirus nutraceuticals.

Redox-Modulating Capacity and Antineoplastic Activity of Wastewater Obtained from the Distillation of the Essential Oils of Four Bulgarian Oil-Bearing Roses.

The wastewater from the distillation of rose oils is discharged directly into the soil because it has a limited potential for future applications. The aim of the present study was to determine in vitro the chromatographic profile, redox-modulating capacity, and antineoplastic activity of wastewater obtained by distillation of essential oils from the Bulgarian Rosa alba L., Rosa damascena Mill., Rosa gallica L., and Rosa centifolia L. We applied UHPLC-HRMS for chromatographic analysis of rose wastewaters, studied their metal-chelating and Fe(III)-reducing ability, and performed MTT assay for the evaluation of cytotoxic potential against three tumorigenic (HEPG2-hepatocellular adenocarcinoma, A-375-malignant melanoma, A-431-non-melanoma epidermoid squamous skin carcinoma) and one non-tumorigenic human cell lines (HaCaT-immortalized keratinocytes). The median inhibitory concentrations (IC50) were calculated with nonlinear modeling using the MAPLE® platform. The potential of the wastewaters to induce apoptosis was also examined. Mono-, di-, and acylated glycosides of quercetin and kaempferol, ellagic acid and its derivatives as main chemical components, and gallic acid and its derivatives-such as catechin and epicatechin-were identified. The redox-modulating capacity of the samples (TPTZ test) showed that all four wastewaters exhibited the properties of excellent heavy metal cleaners, but did not exert very strong cytotoxic effects. The lowest IC50 rate was provided in wastewater from R. centifolia (34-35 µg/mL of gallic acid equivalents after a 72 h period for all cell lines). At 24 and 48 hours, the most resistant cell line was HEPG2, followed by HaCaT. After 72 h of exposure, the IC50 values were similar for tumor and normal cells. Still, R. damascena had a selectivity index over 2.0 regarding A-431 non-melanoma skin cancer cells, showing a good toxicological safety profile in addition to moderate activity-IC50 of 35 µg/mL polyphenols. The obtained results related to wastewaters acquired after the distillation of essential oils from the Bulgarian R. alba, R. damascena, R. gallica, and R. centifolia direct our attention to further studies for in-depth elucidation of their application as detoxifying agents under oxidative damage conditions in other experimental datasets.

Junipers of Various Origins as Potential Sources of the Anticancer Drug Precursor Podophyllotoxin.

Juniper representatives are natural sources of plenty of bioactive metabolites and have been used since ancient times as folk remedies against tapeworms, warts, cancer, etc. The antiproliferative activities of junipers are attributed to podophyllotoxin (PPT), which is a precursor for the synthesis of efficient anticancer drugs. However, the natural sources of PPT, Sinopodophyllum hexandrum (Royle) T. S. Ying and Podophyllum peltatum L., are already endangered species because of their intensive industrial exploitation. Therefore, identification of other sources of PPT is necessary. This study is a broad comparative investigation of junipers, for which original sources have been accessed from different continents of the world. The present research is aimed at the identification of species, producing PPT and other lignans at concentrations that are sufficient for the high antiproliferative activity of the corresponding extracts. Cytotoxic juniper leaf extracts demonstrated a broad spectrum of activity on a panel of cancer cell lines. The antiproliferative properties of junipers were attributed to the combined activity of great diversity of lignans (podophyllotoxin, deoxypodophyllotoxin, ß-peltatin, yatein, matairesinol, anhydropodorhizol, etc.), detected by UHPLC-HRMS and LC-ESI-MS/MS in the corresponding extracts. Several species of the genus Juniperus L. were outlined as perspective sources of drug precursors with potential pharmaceutical applications.

UHPLC-HRMS based flavonoid profiling of the aerial parts of Chenopodium foliosum Asch. (Amaranthaceae).

Chenopodium foliosum Asch. has been recognised by Bulgarian legislation as a medicinal plant. The decoction of its aerial parts has been used for treatment of cancer, as an immunostimulant and antioxidant drug. An UHPLC-HRMS profiling method was used for a comprehensive study of flavonoid composition of C. foliosum. Fourty flavonoid glycosides with nine aglycones (patuletin, gomphrenol, spinacetin, 6-methoxykaempferol, kaempferol, quercetin, isorhamnetin, 3,5,3',4'-tetrahydroxy-6,7-methylenedioxyflavone and 3,5,4'-trihydroxy-3'-methoxy-6,7-methylenedioxyflavone) were detected. Kaempferol, quercetin and isorhamnetin glycosides were identified as minor components. A pseudo MS3 experiment aided at discriminating 6-methoxykaempferol and isorhamnetin glycosides. Flavonoid composition dominated by di-, triglycosides and acylated flavonoids. Acid hydrolysis and GS-MS analysis confirmed the presence of D-glucose, D-apiose and L-rhamnose. Ten flavonoids were reported here for the first time.

Ultra-high-performance liquid chromatography - high-resolution mass spectrometry profiling and hepatoprotective activity of purified saponin and flavonoid fractions from the aerial parts of wild spinach (Chenopodium bonus-henricus L.).

An ultra-high-performance liquid chromatography - high-resolution mass spectrometry profiling method was used for a comprehensive study of flavonoid and saponin-rich fractions from the aerial parts of wild spinach (Chenopodium bonus-henricus L.). Thirty-six compounds, respectively, 22 saponins of eight sapogenins (phytolaccagenin, bayogenin, medicagenic acid, 2ß-hydroxygypsogenin, 2ß-hydroxyoleanoic acid, 2-hydroxy-30-nor-gypsogenin, 2-hydroxyakebonic acid, and akebonic acid) together with 12 flavonoid glycosides of 6-methoxykaempferol, isorhamnetin, patuletin, spinacetin as well as two ecdysteroids (20-hydroxyecdysone and polypodine B) were detected. The occurrence of sapogenins 2-hydroxy-30-nor-gypsogenin, 2-hydroxyakebonic acid, and akebonic acid in the Chenopodium genus is reported here for the first time. The flavonoid and saponin-rich fractions showed in vitro hepatoprotective and antioxidant activity comparable to those of flavonoid complex silymarin (60 µg/mL) in a model of metabolic bioactivation, induced by CCl4. All tested fractions, compared to silymarin, significantly reduced the cellular damage caused by CCl4 in rat hepatocytes, preserved cell viability and GSH level, decreased LDH leakage, and reduced lipid damage. The results showed that saponin-rich fractions F3A and F3B possessed better hepatoprotective activity than flavonoid-rich fractions (F2A and F2B). The most active was fraction F3B and this is probably due to the synergism between the saponins and some acylated flavonol glycosides found there.

Neuroprotective, anti-α-glucosidase and prolipase active flavonoids from Good King Henry (Chenopodium bonus-henricus L.).

Nine glycosides of patuletin, 6-methoxykaempferol and spinacetin from Good King Henry (Chenopodium bonus-henricus L.) were investigated for neuroprotective, anti-α-glucosidase and lipase activities. All tested flavonoids (100 µM) showed statistically significant neuroprotective activities on isolated rat brain synaptosomes using 6-hydroxydopamine in vitro model. They preserved synaptosome viability as well as the reduced glutathione level. 6-Methoxykaempferol glycoside 9 possessed the most prominent neuroprotective and antioxidant effects, within the same range as silibinin (100 µM). Anti-α-glucosidase and lipase activities of the tested compounds were established by measuring the levels of the released 4-nitrophenol using LC-MS here for the first time. Patuletin glycosides 2 and 7 possessed similar activity to acarbose with IC50 210, 249 and 206 µM, respectively. All flavonoids exhibited prolipase activity and could be used in the treatment of cachexia. The most active were flavonoids, which contain esterified ferulic acid.

Three new prenyloxy chromanones from aerial parts of Hypericum aucheri.

Three new prenyloxy chromanone derivatives, aucherine A-C (6, 7 and 9) as well as six known prenylated phloroglucinols (1-5 and 8) were isolated from the aerial parts of Hypericum aucheri Jaub. Et Spach. The structures of the isolated compounds were established by means of spectral techniques (HRESIMS, 1D and 2D NMR). The new compounds were tested on а panel of human tumor cell line using MTT assay. All tested compounds exerted moderate cytotoxicity with IC50 values ranging from 19.6 to 57.8 µM. The influence of the new compounds on some key signaling molecules (procaspase-9 and Bcl-xL), implicated in the regulation of programmed cell death was assessed by Western blot analysis.

Hepatoprotective activity of a purified methanol extract and saponins from the roots of Chenopodium bonus-henricus L.

An ultra-high-performance liquid chromatography-high-resolution mass spectrometry based profiling of a purified MeOH extract (PME) from the roots of Chenopodium bonus-henricus L. (Amaranthaceae) tentatively identified 15 saponins of six sapogenins. The PME exerts hepatoprotective and antioxidant activities comparable to those of flavonoid complex silymarin in in vitro (1 and 10 µg/mL) and in vivo (200 mg/kg/daily for 7 days) models of hepatotoxicity, induced by CCl4. The main constituents of PME, respectively saponins bonushenricoside A (1), 3-O-ß-D-glucuronopyranosyl-bayogenin-28-O-ß-D-glucopyranosyl ester (2), 3-O-ß-D-glucuronopyranosyl-medicagenic acid-28-O-ß-D-xylopyranosyl (1→4)-α-L-rhamnopyranosyl(1→2)-α-L-arabinopyranosyl ester (3), 3-O-ß-D-glucuronopyranosyl-2ß-hydroxygypsogenin-28-O-ß-D-glucopyranosyl ester (4), 3-O-α-L-rabinopyranosyl-bayogenin-28-O-ß-D-glucopyranosyl ester (6) and bonushenricoside B (8) (3 µg/mL each), compared to silymarin (5 and 50 µg/mL), significantly reduced the cellular damage caused by CCl4 in rat hepatocytes, preserved cell viability and glutathione level, decreased lactate dehydrogenase leakage and reduced lipid damage. The experimental data suggest that the glycosides of phytolaccagenin, bayogenin, medicagenic acid, 2ß-hydroxygypsogenin, 2ß-hydroxyoleanoic acid and oleanoic acid are a promising and safe class of hepatoprotective agents.

Saponins from the roots of Chenopodium bonus-henricus L.

Two new glycosides of phytolaccagenin and 2ß-hydroxyoleanoic acid, namely bonushenricoside A (3) and bonushenricoside B (5) together with four known saponins, respectively compounds 3-O-L-α-arabinopyranosyl-bayogenin-28-O-ß-glucopyranosyl ester (1), 3-O-ß-glucuronopyranosyl-2ß-hydroxygypsogenin-28-O-ß-glucopyranosyl ester (2), 3-O-ß-glucuronopyranosyl-bayogenin-28-O-ß-glucopyranosyl ester (4) and 3-O-ß-glucuronopyranosyl-medicagenic acid-28-ß-xylopyranosyl(1→4)-α-rhamnopyranosyl(1→2)-α-arabinopyranosyl ester (6) were isolated from the roots of Chenopodium bonus-henricus L. The structures of the compounds were determined by means of spectroscopic methods (1D and 2D NMR, IR and HRMS). The MeOH extract and compounds were tested for cytotoxic activity on five leukemic cell lines (HL-60, SKW-3, Jurkat E6-1, BV-173 and K-562). In addition, the ability of metanolic extract and saponins to modulate the interleukin-2 production in PHA/PMA stimulated Jurkat E6-1 cells was investigated as well.

Cytotoxic prenylated acylphloroglucinols from Hypericum annulatum.

A phytochemical investigation of the aerial parts of Hypericum annulatum Moris led to the isolation of five new prenylated acylphloroglucinol derivatives hyperannulatins A-E (1-3, 5 and 7) in addition to the known hypercalyxone A (4) and 3-geranyl-1-(2'-methylpropanoyl)phloroglucinol (6). The structures were determined by 1D and 2D NMR and MS spectroscopic techniques. Compounds 1 and 2 have in their structure evgenyl group, a rare hydrocarbon side chain. The cytotoxicity of isolated compounds was established on a panel of tumor cell lines (HL-60, HL-60/DOX, MDA-MB, SKW-3 and K-562) and was determined using MTT based assays. The compounds 1 and 2 showed to be the most potent cytotoxic agents, whose IC50 values against the chemosensitive cell lines ranged 3.42-5.87 µM and 1.48-8.21 µM, respectively. Noteworthy, albeit all tested compounds were less potent than podophyllotoxin their IC50 values were comparable to that of the other reference drug etoposide. In some of the cell lines compounds 1 and 2 even outclassed the cytotoxicity of etoposide.

Chenopodium bonus-henricus L. - A source of hepatoprotective flavonoids.

Three new flavonoid glycosides (7-9) named patuletin-3-O-(5″'-О-Е-feruloyl)-ß-d-apiofuranosyl(1→2)[ß-d-glucopyranosyl (1→6)]-ß-d-glucopyranoside (7), spinacetin-3-O-(5″'-О-Е-feruloyl)-ß-d-apiofuranosyl (1→2)[ß-d-glucopyranosyl(1→6)]-ß-d-glucopyranoside (8) and 6-methoxykaempferol-3-O-(5″'-О-Е-feruloyl)-ß-d-apiofuranosyl(1→2)[ß-d-glucopyranosyl (1→6)]-ß-d-glucopyranoside (9) together with six known flavonoid glycosides of patuletin, spinacetin and 6-methoxykaempferol (1-6) were isolated from the aerial parts of C. bonus-henricus and identified with spectroscopic methods (1D and 2D NMR, UV, IR, HRESIMS). The MeOH extract exerts hepatoprotective and antioxidant activities comparable to those of flavonoid complex silymarin in in vitro (60µg/mL) and in vivo (100mg/kg/daily for 7days) models of hepatotoxicity, induced by CCl4. Flavonoids (1-9) (100µM), compared to silybin, significantly reduced the cellular damage caused by CCl4 in rat hepatocytes, preserved cell viability and GSH level, decreased LDH leakage and reduced lipid damage. High concentrations of compounds (1-9) showed marginal or no cytotoxicity on HepG2 cell line. The experiment data suggest that the glycosides of 6-methoxykaempferol, spinacetin and patuletin are a promising and safe class of hepatoprotective agents.

Polyprenylated Phloroglucinols from Hypericum maculatum.

A detailed phytochemical investigation of the dichloromethane extract of the aerial parts of Hypericum maculatum Crantz. led to the isolation of four new (2-5) and six known (1a/b, 6-10) polyprenylated phloroglucinol derivatives. The new compounds were identified by means of spectral methods (MS, NMR, IR, UV) as (E)-4-(3,7-dimethylocta-2,6-dien-1-yl)-5-hydroxy-2-(3-methylbut-2-en-1-yl)-3,6-dioxocyclohexa-1,4-dien-1-yl isobutyrate (2), (E)-2-(3,7-dimethylocta-2,6-dien-1-yl)-5-hydroxy-4-(3-methylbut-2-en-1-yl)-3,6-dioxocyclohexa-1,4-dien-1-yl isobutyrate (3), (E)-4-(3,7-dimethylocta-2,6-dien-1-yl)-5-hydroxy-2-(3-methylbut-2-en-1-yl)-3,6-dioxocyclohexa-1,4-dien-1-yl 2-methylbutanoate (4) and (E)-2-(3,7-dimethylocta-2,6-dien-1-yl)-5-hydroxy-4-(3-methylbut-2-en-1-yl)-3,6-dioxocyclohexa-1,4-dien-1-yl 2-methylbutanoate (5). The known compounds have been identified as hyperpolyphyllirin/hyperibine J (1a/b), erectquione A (6), (E)-1-(3-(3,7-dimethylocta-2,6-dien--yl)-2,4,6-trihydroxyphenyl)-2-methylpropan-1-one (7), (E)-1-(3-(3,7-dimethylocta-2,6-dien-1-yl)- 2,4,6-trihydroxyphenyl)-2-methylbutan-1-one (8), 1-(5,7-dihydroxy-2-methyl-2-(4-methylpent-3-en-1-yl)chroman-8-yl)-2-methylpropan-1-one (9) and 1-(6,8-dihydroxy-1,1,4a-trimethyl-2,3,4,4a,9,9a-hexahydro-1H-xanthen-5-yl)-2-methylpropan-1-one (10). The stereochemistry of 1a is described for the first time. The cytotoxicity of 1-6 on SKW-3, BV-173 and K-562 tumor cell lines was determined using MTT based assays.

30-normedicagenic acid glycosides from Chenopodium foliosum.

Two new glycosides of 30-normedicagenic acid, namely 3-O-[beta-D-glucuronopyranosyl methyl ester]-2beta,3beta-dihydroxy-30-noroleane-12,20(29)-diene-23,28-dioic acid 28-O-beta-D-glucopyranosyl ester, and 3-O-beta-D-glucopyranosyl-2beta,3beta-dihydroxy-30-noroleane- 12,20(29)-diene-23,28-dioic acid, together with the known 3-O-beta-glucopyranosyl-2beta,3beta-dihydroxy-30-noroleane-12,20(29)-diene-23 ,28-dioic acid 28-O-beta-glucopyranosyl ester, and 3-O-beta-glucuronopyranosyl-2beta,3beta-dihydroxy-30-noroleane-12,20(29)-diene-23,28-dioic acid 28-O-beta-glucopyranosyl ester were isolated from the aerial parts of Chenopodium foliosum Asch. The structures of the compounds were determined by means of spectroscopic methods (1D and 2D NMR, UV, IR) and HRMS-ESI. The compounds were tested for cytotoxicity on three leukemic cell lines (BV-173, SKW-3, HL-60). In addition, the saponins showed moderate stimulatory effects on interleukin-2 production in PHA/PMA stimulated Jurkat E6.1 cells.