Antioxidant phenolic compounds from the leaves of Erica Arborea (Ericaceae)

Triterpenoid and Steroid Content of Lipophilic Extracts of Selected Medicinal Plants of the Mediterranean Region

The available phytochemical characteristics of the medicinal plants and derived herbal material often lack data concerning the content of steroids (including phytosterols) and triterpenoids, that can be responsible for various beneficial properties and therapeutic effects, either directly, or as a result of synergistic action with other bioactive constituents. The aim of the present work was the analysis of the content of these compounds in herbal material (leaves, aerial parts) derived from selected medicinal plants (Cistus ladanifer, Cistus monspeliensis, Erica arborea, Globularia alypum, Pistacia lentiscus, Rhamnus alaternus), widely used in folk medicine in the Mediterranean region. Results obtained by gas chromatography-mass spectrometry (GC-MS)-targeted profiling revealed the diversity in the profiles and contents of steroids and triterpenoids in the analyzed plant material, ranging from 5.7% d.w. in E. arborea to 0.1% in G. alypum. The obtained results supplement the existing phytochemical data of the investigated medicinal plants, pointing to the E. arborea aerial parts and P. lentiscus leaves as valuable resources of phytosterols and bioactive triterpenoids.

Preliminary Characterization of Phytochemicals and Polysaccharides in Diverse Coffee Cascara Samples: Identification, Quantification and Discovery of Novel Compounds

Coffee cascara is the first and most significant by-product of the coffee processing industry, whose valorization has become an urgent priority to reduce harmful environmental impacts. This work aimed to provide an improved understanding of phytochemicals and polysaccharides in coffee cascara in order to offer information for the better evaluation of potential applications. Phytochemicals in 20 different coffee cascara samples were ultrasonically extracted and analyzed by HPLC-UV and HPLC-MS/MS. Four novel compounds were isolated for the first time from coffee cascara, including two still unknown tautomers (337 Da), and two dihydroflavonol glycosides (dihydromyricetin glycoside and dihydromyricetin rhamnosylglycoside). Their presence can contribute to the design of new value-added applications of coffee cascara. Chemical characterization of two polysaccharides from two of the coffee cascara pulp samples showed that they were mainly composed of homogalacturonan, with rhamnose and arabinose as minor neutral sugars. In addition, principal component analysis results indicated that coffee cultivar and/or country significantly impacted the phytochemical composition of coffee cascara, although differences may be reduced by the external environment and processing method. It is suggested that processing method should be carefully designed when generating coffee cascara from the same cultivar and country/farm.

Phenolic Compounds as Unambiguous Chemical Markers for the Identification of Keystone Plant Species in the Bale Mountains, Ethiopia

: Despite the fact that the vegetation pattern and history of the Bale Mountains in Ethiopia were reconstructed using pollen, little is known about the former extent of Erica species. The main objective of the present study is to identify unambiguous chemical proxies from plant-derived phenolic compounds to characterize Erica and other keystone species. Mild alkaline CuO oxidation has been used to extract sixteen phenolic compounds. After removal of undesired impurities, individual phenols were separated by gas chromatography and were detected by mass spectrometry. While conventional phenol ratios such as syringyl vs. vanillyl and cinnamyl vs. vanillyl and hierarchical cluster analysis of phenols failed for unambiguous Erica identification, the relative abundance of coumaryl phenols (>0.20) and benzoic acids (0.05-0.12) can be used as a proxy to distinguish Erica from other plant species. Moreover, a Random Forest decision tree based on syringyl phenols, benzoic acids (>0.06), coumaryl phenols (<0.21), hydroxybenzoic acids, and vanillyl phenols (>0.3) could be established for unambiguous Erica identification. In conclusion, serious caution should be given before interpreting this calibration study in paleovegetation reconstruction in respect of degradation and underground inputs of soil organic matter.

Challenges of traditional herbal teas: plant infusions and their mixtures with bioactive properties

Five traditional and medicinal plants have been individually characterized and analyzed in terms of bioactivities to determine how these characteristics are modified when preparing blends.

Dihydromyricetin enhances glucose uptake by inhibition of MEK/ERK pathway and consequent down-regulation of phosphorylation of PPARγ in 3T3-L1 cells

Accumulating evidence suggests that inhibition of mitogen-activated protein kinase signalling can reduce phosphorylation of peroxisome proliferator-activated receptor γ (PPARγ) at serine 273, which mitigates obesity-associated insulin resistance and might be a promising treatment for type 2 diabetes. Dihydromyricetin (DHM) is a flavonoid that has many beneficial pharmacological properties. In this study, mouse fibroblast 3T3-L1 cells were used to investigate whether DHM alleviates insulin resistance by inhibiting PPARγ phosphorylation at serine 273 via the MEK/ERK pathway. 3T3-L1 pre-adipocytes were differentiated, and the effects of DHM on adipogenesis and glucose uptake in the resulting adipocytes were examined. DHM was found to dose dependently increase glucose uptake and decrease adipogenesis. Insulin resistance was then induced in adipocytes using dexamethasone, and DHM was shown to dose and time dependently promote glucose uptake in the dexamethasone-treated adipocytes. DHM also inhibited phosphorylation of PPARγ and ERK. Inhibition of PPARγ activity with GW9662 potently blocked DHM-induced glucose uptake and adiponectin secretion. Interestingly, DHM showed similar effects to PD98059, an inhibitor of the MEK/ERK pathway. DHM acted synergistically with PD98059 to improve glucose uptake and adiponectin secretion in dexamethasone-treated adipocytes. In conclusion, our findings indicate that DHM improves glucose uptake in adipocytes by inhibiting ERK-induced phosphorylation of PPARγ at serine 273.

Dihydromyricetin delays the onset of hyperglycemia and ameliorates insulin resistance without excessive weight gain in Zucker diabetic fatty rats

Many flavonoids are reported to be partial agonists of PPARγ and exert antidiabetic effects with fewer side effects compared with full agonists. Here, we assessed the effects of flavonoid dihydromyricetin (DHM) on glucose homeostasis in male Zucker diabetic fatty rats. Animals were treated with DHM (50-200  mg kg^-1) or rosiglitazone (4  mg kg^-1) once a day for 8 weeks. We found that DHM reduced fasting blood glucose and delayed the onset of hyperglycemia by 4 weeks. Furthermore, DHM preserved pancreatic β-cell mass, elevated adiponectin and improved lipid profile more vigorously than rosiglitazone. Notably, DHM decreased body weight gain and fat accumulation in both liver and adipose tissue, while rosiglitazone caused a significant increase of body weight and fat accumulation. DHM inhibited phosphorylation of PPARγ at serine 273 more efficiently than rosiglitazone. These results suggest that DHM exerts antidiabetic effects without causing excessive body weight gain via inhibition of PPARγ phosphorylation.

Digestibility and Bioavailability of the Active Components of Erica australis L. Aqueous Extracts and Their Therapeutic Potential as Acetylcholinesterase Inhibitors

Erica australis L. (Ericaceae) is used in traditional medicine to treat many free-radical related ailments. In the present work, the stability and biological activity of the plant aqueous extracts submitted to an in vitro digestive process were investigated. Chemical stability was monitored by HPLC-DAD and LC-MS/MS, while the bioactivities were evaluated through the inhibition of acetylcholinesterase (AChE) and DPPH radical scavenging activity. Both extracts, whose main components were flavonol glycosides, inhibited AChE, showing IC₅₀ values of 257.9 ± 6.2 µg/mL and 296.8 ± 8.8 µg/mL for the decoction and for the infusion, respectively. Significant radical scavenging activities were also revealed by both extracts, as denoted by the IC₅₀ values for the decoction, 6.7 ± 0.1 µg/mL, and for the infusion, 10.5 ± 0.3 µg/mL. After submission to gastric and pancreatic juices, no remarkable alterations in the composition or in the bioactivities were observed, suggesting that the extracts may pass through the gastrointestinal tract, keeping their composition and therefore their biological properties. Moreover, the bioavailability of the components of both extracts, as studied in a Caco-2 cell model, showed that compounds can permeate the membrane, which is a condition to exert their biological activities. Our results add further support to the potential of E. australis for its antioxidant and neuroprotective properties.

Geno/cytotoxicty and Apoptotic Properties of Phenolic Compounds from the Seeds of Dorema Glabrum Fisch. C.A

Introduction: Dorema glabrum (Apiaceae) is a rare and monocarpic species distributed in Transcaucasia and North West of Iran. We aimed to explore anti-cancer potency of bioactive compounds from the seeds of Dorma glabrum.

Methods: Methanol extract was subjected to phytochemical investigation using normal phase Sep-pak and reversed-phase HPLC, and cytotoxic effect of isolated compounds on CAOV-4 cell line was evaluated. Furthermore, Annexin V/PI staining and comet assay were used to study genotoxicity of compounds.

Results: Diglucosyl caffeoyl ester (1), Glucopyranosylcaffeic acid (2) and skimmin (3), were identified. MTT cytotoxicity assay showed growth inhibition of CAOV-4 cells due to treatment with compunds (1), (2) and (3) with an IC₅₀ of 99.7, 87.3 and 70.03 μg/ml at 48 h, respectively. Annexin V-FITC/PI staining showed occurrence of early/late apoptosis in the (1)-treated cells, while (2)-and (3)-treated cells necrosis/late apoptosis was dominant event. Single/double strands DNA breakages were observed by comet assay in all treatments.

Conclusion: This work provides sufficient information about anti-cancer properties of the diglucosyl caffeoyl ester from the seeds of D. glabrum.

Evaluating Antiproliferative and Antioxidant Activity of Marrubium crassidens

PURPOSE

Naturally occurring substances as novel drugs in cancer therapy, at all times, represent a challenge to science since medicinal plants are proving to be brilliant sources of new chemopreventive agents.

METHODS

In the present study, methanol extract from aerial parts of Marrubium crassidens was assessed for its antiproliferative activity in the breast cancer cell line MCF-7 through MTT bioassay using cell viability and cytotoxicity indices. The antioxidant property of M. crassidens extract together with its phenolic and flavonoids content were evaluated, as well.

RESULTS

According to data obtained in the study, M. crassidens exhibited antiproliferative activity with a gradual rise in cytotoxicty effect setting out on 240µg/mL concentration of the extract. Moreover, the RC50 value for antioxidant activity of the extract was determined as 40µg/mL and values for the total phenolic and flavonoids were calculated as 512.64mg gallic acid equivalent and 212.73mg quercetin equivalent per 100g of dry plant material.

CONCLUSION

Generally, the observed antiproliferative and antioxidant properties of M. crassidens could be certified to the high amounts of phenolic and flavonoid content detected in the extract.

Dihydromyricetin promotes hepatocellular carcinoma regression via a p53 activation-dependent mechanism

The development of antitumor chemotherapy drugs remains a key goal for oncologists, and natural products provide a vast resource for anti-cancer drug discovery. In the current study, we found that the flavonoid dihydromyricetin (DHM) exhibited antitumor activity against liver cancer cells, including primary cells obtained from hepatocellular carcinoma (HCC) patients. In contrast, DHM was not cytotoxic to immortalized normal liver cells. Furthermore, DHM treatment resulted in the growth inhibition and remission of xenotransplanted tumors in nude mice. Our results further demonstrated that this antitumor activity was caused by the activation of the p53-dependent apoptosis pathway via p53 phosphorylation at serine (15Ser). Moreover, our results showed that DHM plays a dual role in the induction of cell death when administered in combination with cisplatin, a common clinical drug that kills primary hepatoma cells but not normal liver cells.

Antioxidant activity of phenolics in leaves of three red pepper (Capsicum annuum) cultivars

The antioxidant properties and phenolic profiles were first investigated in this paper on the leaves of three red pepper cultivars, Blackcuban (BCPL), Hongjinju (HPL), and Yeokgang-hongjanggun (YHPL). Of the ethanol extract of the three cultivars, BCPL showed potent antioxidant activities against the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and the 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical. Nine antioxidative compounds from the red pepper leaves were isolated and identified as one polyamine phenolic conjugate, N-caffeoylputrescine (1); three chlorogenic acid derivatives, 5-O-caffeoylquinic acid (2), 5-O-caffeoylquinic acid methyl ester (4), and 5-O-caffeoylquinic acid butyl ester (9); one anthocyanin, delphinidin-3-[4-trans-coumaroyl-l-rhamnosyl(1→6)glucopyranoside]-5-O-glucopyranoside (3); and four flavone glycosides, luteolin-7-O-apiofuranosyl(1→2)glucopyranoside (5), luteolin-7-O-glucopyranoside (6), apigenin 7-O-apiofuranosyl(1→2)glucopyranoside (7), apigenin-7-O-glucopyranoside (8). 1 and 3 had the greatest potential for radical-scavenging activity and HepG2 cells protecting effect against oxidative stress. BCPL exhibited the highest content of 1 and 3. Of the three cultivars BCPL may be considered a good source of antioxidants.

Antiproliferative activity of Marrubium persicum extract in the MCF-7 human breast cancer cell line

AIM

Developing antitumor drugs from natural products is receiving increasing interest worldwide due to limitations and side effects of therapy strategies for the second leading cause of disease related mortality, cancer.

METHODS

The antiproliferative activity of a methanolic extract from the aerial parts of Marrubium persicum extract was assessed with the MCF-7 breast cancer cell line using the MTT test for cell viability and cytotoxicity indices. In addition, antioxidant properties of the extract were evaluated by measuring its ability to scavenge free DPPH radicals. Moreover, the total phenolic and flavonoid content of the extract was determined based on Folin-Ciocalteu and colorimetric aluminum chloride methods.

RESULTS

The findings of the study for the antiproliferative activity of the methanolic extract of M. persicum showed that growth of MCF-7 cells was inhibited by the extract in a dose and time dependent manner, where a gradual increase of cytotoxicity effect has been achieved setting out on 200 μg/mL concentration of the plant extract. The antioxidant assay revealed that the extract was a strong scavenger of DPPH radicals with an RC50 value of 52 μg/mL. The total phenolic and flavonoids content of the plant extract was 409.3 mg gallic acid equivalent and 168.9 mg quercetin equivalent per 100g of dry plant material.

CONCLUSION

Overall, M. persicum possesses potential antiproliferative and antioxidant activities on the malignant MCF-7 cell line that could be attributed to the high content of phenolics and flavonoids, and therefore warrants further exploration.

Isolation of natural products by low-pressure column chromatography

This chapter describes the isolation of natural products using low-pressure column chromatography (LPLC) and provides a brief summary of the adsorption and size exclusion processes involved in LPLC. Different types of stationary phases used in both adsorption and size exclusion LPLC are also presented with specific examples. Various operational parameters in relation to column packing (both wet and dry), column equilibration, sample application, and column development, and a summary of generic procedures for adsorption and size exclusion LPLC are also incorporated in this chapter. Throughout the chapter, several specific examples of the application of LPLC for the isolation of various natural products including alkaloids, coumarins, flavones, and saponins from various plants are given. Many of these examples include a combination of adsorption and size exclusion chromatography to obtain specific compounds.

Phytochemical Analysis and Antioxidant Capacity of BM-21, a Bioactive Extract Rich in Polyphenolic Metabolites from the Sea Grass Thalassia testudinum

The aqueous ethanol extract of Thalassia testudinum leaves (BM-21) is now being developed in Cuba as an herbal medicine due to its promising pharmacological properties. Although some interesting biological activities of BM-21 have already been reported, its chemical composition remains mostly unknown. Thus, we now describe the qualitative and quantitative analyzes of BM-21 using standard phytochemical screening techniques, including colorimetric quantification, TLC and HPLC analyses. Phytochemical investigation of BM-21 resulted in the isolation and identification of a new phenolic sulfate ester (1), along with ten previously described phenolic derivatives (2-11), seven of which have never been previously reported from the genus Thalassia. The structures of these compounds were established by analysis of their spectroscopic (1D and 2D NMR) and spectrometric (HRMS) data, as well as by comparison of these with those reported in the literature. Furthermore, BM-21 was found to exhibit strong antioxidant activity in four different free radical scavenging assays (HO•, RO2•, O2-• and DPPH•). Consequently, this is the first study which highlights the phytochemical composition of BM-21 and demonstrates that this product is a rich source of natural antioxidants with potential applications in pharmaceutical, cosmetic and food industries.

A RP-HPLC-DAD-APCI/MSD method for the characterisation of medicinal Ericaceae used by the Eeyou Istchee Cree First Nations

INTRODUCTION

Ericaceae medicinal plants are traditionally used by the Eeyou Istchee Cree and other northern peoples of North America to treat type 2 diabetic symptoms. Because of the importance of phenolics as potential cures for degenerative diseases including type 2 diabetes, an analytical method was developed to detect them in the leaf extracts of 14 Ericaceae plants.

OBJECTIVE

To develop an optimised method which is applicable to a relatively large number of Ericaceae plants using their leaf extracts. For this purpose phenolics with a wide range of polarity, including a glucosylated benzoquinone, two phenolic acids, three flavanols, a flavanone, a flavone and five flavonols, were included in this study.

METHODOLOGY

Characterisation of phytochemicals in extracts was undertaken by automated matching to the UV spectra to those of an in house library of plant secondary metabolites and the authentication of their identity was achieved by reversed phase-high-performance chromatography-diode array detection-atmospheric pressure chemical ionisation/mass selective detection.

RESULTS

Twenty-six phenolics were characterised within 26 min of chromatographic separation in 80% ethanol extracts of 14 Ericaceae plants. The calibration curves were linear within 0.5-880 microg/g dry mass of the plant with regression values better than 0.995. The limits of detection ranged from 0.3 for microg/mL for (+)-catechin to 2.6 microg/mL for chlorogenic acid. This is a first study dealing with relatively large number of Ericaceae extracts and is applicable to other plants of same family.