Antioxidant, phenolic and antifungal profiles of Acanthus mollis (Acanthaceae)

Bee Bread: A Promising Source of Bioactive Compounds with Antioxidant Properties-First Report on Some Antimicrobial Features

Bee bread has received attention due to its high nutritional value, especially its phenolic composition, which enhances life quality. The present study aimed to evaluate the chemical and antimicrobial properties of bee bread (BB) samples from Romania. Initially, the bee bread alcoholic extracts (BBEs) were obtained from BB collected and prepared by Apis mellifera carpatica bees. The chemical composition of the BBE was characterized by Fourier Transform Infrared Spectroscopy (FTIR) and the total phenols and flavonoid contents were determined. Also, a UHPLC-DAD-ESI/MS analysis of phenolic compounds (PCs) and antioxidant activity were evaluated. Furthermore, the antimicrobial activity of BBEs was evaluated by qualitative and quantitative assessments. The BBs studied in this paper are provided from 31 families of plant species, with the total phenols content and total flavonoid content varying between 7.10 and 18.30 mg gallic acid equivalents/g BB and between 0.45 and 1.86 mg quercetin equivalents/g BB, respectively. Chromatographic analysis revealed these samples had a significant content of phenolic compounds, with flavonoids in much higher quantities than phenolic acids. All the BBEs presented antimicrobial activity against all clinical and standard pathogenic strains tested. Salmonella typhi, Candida glabrata, Candida albicans, and Candida kefyr strains were the most sensitive, while BBEs' antifungal activity on C. krusei and C. kefyr was not investigated in any prior research. In addition, this study reports the BBEs' inhibitory activity on microbial (bacterial and fungi) adhesion capacity to the inert substratum for the first time.

Oxidative stress promotes cytotoxicity in human cancer cell lines exposed to Escallonia spp. extracts

BACKGROUND

Standard cancer treatments show a lack of selectivity that has led to the search for new strategies against cancer. The selective elimination of cancer cells modulating the redox environment, known as "selective oxycution", has emerged as a viable alternative. This research focuses on characterizing the unexplored Escallonia genus plant extracts and evaluating their potential effects on cancer's redox balance, cytotoxicity, and activation of death pathways.

METHODS

36 plant extracts were obtained from 4 different species of the Escallonia genus (E. illinita C. Presl, E. rubra (Ruiz & Pav.) Pers., E. revoluta (Ruiz & Pav.) Pers., and E. pulverulenta (Ruiz & Pav.) Pers.), which were posteriorly analyzed by their phytoconstituents, antioxidant capacity, and GC-MS. Further, redox balance assays (antioxidant enzymes, oxidative damage, and transcription factors) and cytotoxic effects (SRB, ∆Ψmt, and caspases actives) of those plant extracts were analyzed on four cell lines (HEK-293T, MCF-7, HT-29, and PC-3).

RESULTS

36 plant extracts were obtained, and their phytoconstituents and antioxidant capacity were established. Further, only six extracts had EC50 values < 10 µg*mL- 1, indicating high toxicity against the tested cells. From those, two plant extracts were selective against different cancer cell lines: the hexane extract of E. pulverulenta´s stem was selective for HT-29, and the ethyl acetate extract of E. rubra´s stem was selective for PC-3. Both extracts showed unbalanced redox effects and promoted selective cell death.

CONCLUSIONS

This is the first study proving "selective oxycution" induced by Chilean native plant extracts.

Phytochemical Analysis and Anti-Inflammatory Potential of Acanthus mollis L. Rhizome Hexane Extract

The rhizomes of Acanthus mollis have traditionally been used for the treatment of several ailments involving inflammation. However, to the best of our knowledge, their chemical composition and pharmacological properties have not been studied until now. As a first approach, this study analyses the A. mollis rhizome hexane extract phytochemistry and its anti-inflammatory and antioxidant capacities in HepG2 and RAW 264.7 cell culture assays. Chemical profiling was performed with gas chromatography mass spectrometry without the modification of native molecules. Free phytosterols (such as β-sitosterol) account for 70% of detected compounds. The anti-inflammatory capacity of the rhizome extract of A. mollis is mediated by the decrease in the NO production in RAW 264.7 that has previously been stimulated with lipopolysaccharide in a dose-dependent manner. Furthermore, HepG2 pre-treatment with the rhizome extract prevents any damage being caused by oxidative stress, both through ROS scavenge and through the antioxidant cellular enzyme system. In this respect, the extract reduced the activity of glutathione peroxidase and reductase, which were stimulated under oxidative stress conditions. Our results suggest that the extract from the rhizomes of A. mollis may constitute a potential source of natural products with anti-inflammatory activity and could validate the traditional use of A. mollis.

Comparative transcriptome analysis on the mangrove Acanthus ilicifolius and its two terrestrial relatives provides insights into adaptation to intertidal habitats

Acanthus is a unique genus covering both mangroves and terrestrial species, and thus is an ideal system to comparatively analyze the mechanisms of mangrove adaptation to intertidal habitats. We performed RNA sequencing of the mangrove plant Acanthus ilicifolius and its two terrestrial relatives, Acanthus leucostachyus and Acanthus mollis. A total of 91,125, 118,290, and 141,640 unigenes were obtained. Simple sequence repeats (SSR) analysis showed that A. ilicifolius had more SSRs, the highest frequency of distribution, and higher in polymorphism potential compared to the two terrestrial relatives. Phylogenetic analyses suggested a relatively recent split between A. ilicifolius and A. leucostachyus, i.e., about 16.76 million years ago (Mya), after their ancestor divergence with A. mollis (32.11 Mya), indicating that speciation of three Acanthus species occurred in the Early to Middle Miocene. Gene Ontology (GO) enrichment revealed that the unique unigenes in A. ilicifolius are predominantly related to rhythmic process, reproductive process and response to stimuli. The accelerated evolution and positive selection analyses indicated that the genus Acanthus migrated from terrestrial to intertidal habitats, where 311 pairs may be under positive selection. Functional enrichment analysis revealed that these genes associated with essential metabolism and biosynthetic pathways such as oxidative phosphorylation, plant hormone signal transduction, photosynthetic carbon fixation and arginine and proline metabolism, are related to the adaptation of A. ilicifolius to intertidal habitats, which are characterized by high salinity and hypoxia. Our results indicate the evolutionary processes and the mechanisms underlying the adaptability of Acanthus to various harsh environments from the arid terrestrial to intertidal habitats.

A review of the ethnomedicinal uses, chemistry, and pharmacological properties of the genus Acanthus (Acanthaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

The Acanthus genus belongs to the Acanthaceae family, and its species are distributed in all continents, mainly in tropical and subtropical regions. Several traditional applications are referred to, but few scientific studies validate them. Despite this, studies in animal models corroborate some of its uses in folk medicine, such as anticancer, antidiabetic, anti-inflammatory, and antinociceptive, which encourages the research on plants of this genus.

AIM OF THE REVIEW

To our knowledge, this document is the first comprehensive review study that provides information on the geographic distribution, botanical characteristics, ethnomedicinal uses, phytochemicals, and pharmacological activities of some Acanthus species to understand the correlation between traditional uses, phytochemical, and pharmacological activities, providing perspectives for future studies.

RESULTS

In traditional medicine, Acanthus species are mainly used for diseases of respiratory, nervous and reproductive system, gastrointestinal and urinary tract, and skin illness. The most used species are A. montanus, A. ilicifolius, and A. ebracteatus. Chemical compounds (125) from different chemical classes were isolated and identified in seven species, mainly from A. ilicifolius, about 80, followed by A. ebracteatus and A. montanus, appearing with a slightly lower number with fewer phytochemical profile studies. Isolated phytoconstituents have been mainly alkaloids, phenylpropanoid glycosides, and phenylethanoids. In addition, aliphatic glycosides, flavonoids, lignan glycosides, megastigmane derivatives, triterpenoids, steroids, fatty acids, alcohols, hydroxybenzoic acids, simple phenols were also cited. Scientific studies from Acanthus species extracts and their phytoconstituents support their ethnomedical uses. Antimicrobial activity that is the most studied, followed by the antioxidant, anti-inflammatory, and anticancer properties, underlie many Acanthus species activities. A. dioscoridis, A. ebracteatus, A. hirsutus, A. ilicifolius, A. mollis, A. montanus, and A. polystachyus have studies on these activities, A. ilicifolius being the one with the most publications. Most studies were essentially performed in vitro. However, the anticancer, antidiabetic, anti-inflammatory and antinociceptive properties have been studied in vivo.

CONCLUSION

Acanthus species have remarkable phytoconstituents with different biological activities, such as antioxidant, antimicrobial, anti-inflammatory, antinociceptive, hepatoprotective, and leishmanicidal, supporting traditional uses of some species. However, many others remain unexplored. Future studies should focus on these species, especially pharmacological properties, toxicity, and action mechanisms. This review provides a comprehensive report on Acanthus genus plants, evidencing their therapeutic potential and prospects for discovering new safe and effective drugs from Acanthus species.

Ethnopharmacology, phytochemistry, chemical ecology and invasion biology of Acanthus mollis L

ETHNOPHARMACOLOGICAL RELEVANCE

Acanthus mollis L. (Bear's Breeches) is a wide-spread medicinal and ornamental plant and is particularly suited to exemplarily illustrate the diverse aspects of invasion biology by neophytes. Since ancient times, it has been a popular Mediterranean ornamental plant in horticulture and served as model for the decoration of column capitals in architecture.

AIM OF THE STUDY

In the present review, we aimed to give an overview about ethnopharmacology, phytochemistry, chemical ecology, and invasion biology of A. mollis. Thus, the importance of plantation cultivation in the presence of ecologically problematic species and environmental protection were emphasized.

MATERIALS AND METHODS

We conducted an extensive literature search via screening PubMed, Scopus, and Web of Science, in order to compile the data about A. mollis and its role on invasion biology and thereby attracting attention to the prominence of the horticultural and agricultural cultivation of plant species with a special focus on A. mollis as a model.

RESULTS AND CONCLUSION

Phytochemical analyses revealed secondary metabolites from the classes of flavonoids, phenols, phenylpropanoids, anthraquinones arylnaphthalene lignans, phytosterols and others. Extracts of A. mollis and isolated phytochemicals not only exert assorted activities including antioxidant, anti-inflammatory and neuroprotective in murine and human experimental models, but also act against plant parasites (bacteria, insects, mollusks, fungi), protecting the plant from microbial attack and herbivorous predators. A. mollis has been used in traditional medicine to treat dermatological ailments, gastrointestinal diseases, ulcers and even tumors. Nevertheless, the robustness and rapid growth of A. mollis as well as the global horticultural trade facilitated its invasion into fragile ecosystems of Australia, New Zealand, and several other spots around the globe in Northern Europe (Great Britain), Asia (China, India), South Africa, and South America (Argentina). The release of A. mollis from gardens into the wild represents a considerable danger as invasive species are threatening biodiversity and leading to the extinction of domestic plants in the long run. Likewise, the likelihood of other medicinal plants in terms of invasion biology are needed to be fully recognized and discussed.

Neuroprotective Potential of Verbascoside Isolated from Acanthus mollis L. Leaves through Its Enzymatic Inhibition and Free Radical Scavenging Ability

The phenomenon of today’s ageing population has increased interest in the search for new active substances that delay the onset and development of neurodegenerative diseases. In this respect, the search for natural compounds, mainly phenolic compounds, with neuroprotective activity has become the focus of growing interest. Verbascoside is a phenylethanoid that has already presented several pharmacological activities. The purpose of this study is to isolate and identify verbascoside from Acanthus mollis leaves. Consequently, its neuroprotective ability through enzymatic inhibition and free radical scavenging ability has been analyzed both in vitro and in cell culture assays. The antioxidant capacity of verbascoside was evaluated in vitro through total antioxidant capacity, DPPH^•, ^•OH, and O₂^•—scavenging activity assays. The effect of verbascoside on intracellular reactive oxygen species (ROS) levels of HepG2 and SH-SY5Y cell lines was studied in normal culture and under induced oxidative stress. The inhibitory ability of the phenylethanoid against several enzymes implied in neurodegenerative diseases (tyrosinase, MAO-A, and AChE) was analyzed in vitro. Verbascoside neuroprotective activity is at least in part related to its free radical scavenging ability. The effect of verbascoside on ROS production suggests its potential in the prevention of harmful cell redox changes and in boosting neuroprotection.

Degradation of antifungal anthraquinone compounds is a probable physiological role of DyP secreted by Bjerkandera adusta

Alizarin is an anti-fungal compound produced by the plant, Rubia tinctorum. The parasitic fungus Bjerkandera adusta Dec 1 was cultured in potato dextrose (PD) medium with or without alizarin. Alizarin was a good substrate for the dye-decolorizing peroxidase (DyP) from B. adusta Dec 1 and hampered B. adusta growth at the early stage of plate culture. During liquid shaking culture, DyP activity in cultures supplemented with 100 μM alizarin was greater than that in controls cultured without alizarin. In particular, DyP activity per dry cell mass increased approximately 3.5-, 3.1-, and 2.9-fold at 24, 30, and 36 h after inoculation, respectively, compared with control cultures. These data suggest that alizarin stimulates the expression of DyP. Interestingly, alizarin rapidly decomposed at an early stage in culture (24–42 h) in PD medium supplemented with 100 μM alizarin. Thus, alizarin appears to induce DyP expression in B. adusta Dec 1, and this DyP, in turn, rapidly degrades alizarin. Collectively, our findings suggest that the physiological role of DyP is to degrade antifungal compounds produced by plants.

In vitro antioxidant and antiproliferative effect of the extracts of Ephedra chilensis K Presl aerial parts

BACKGROUND

Ephedra chilensis K Presl, known locally as pingo-pingo, is a Chilean endemic plant used in traditional medicine as an anti-inflammatory and used in other treatments. However, unlike for the other Ephedra species, there have been no reports on the antioxidant and cytotoxic effects of this plant. The present study aims to explore the potential applications of E. chilensis extract as a cytotoxic agent against in vitro cancer cell lines and to explore the relationship between this extract and antioxidant activity.

METHODS

Total anthraquinone, flavonoid, and phenolic contents, as well as antioxidant activity (DPPH, FRAP, and TRAP assays) and cytotoxic effect on several cancer cell lines (MCF-7, PC-3, DU-145, and HT-29) were measured for the hexane, dichloromethane and ethanol extracts of E. chilensis. In addition, several correlations among the phytochemical content, antioxidant activity, and cytotoxic effect were evaluated. Finally, GC-MS analyses of the most active extracts were carried out to identify their major components and to relate these components to the cytotoxic effect.

RESULTS

Antioxidant activity was found in the EtOH extracts of Ephedra, and the results were correlated with the phenolic content. For the cytotoxic activity, the non-polar extracts of E. chilensis had the highest antiproliferative effect for the MCF-7 and PC-3 cancer lines; the extract was shown to be up to three times more selective than doxorubicin. However, the cytotoxic effect was not correlated with the antioxidant activity. Lastly, the GC-MS analysis showed a high concentration of saturated fatty acids (mainly n-hexadecanoic acid) and terpenoids (mainly 4-(hydroxy-ethyl)-γ-butanolactone).

CONCLUSION

The cytotoxic activity and selectivity of the non-polar extracts of E. chilensis for the MCF-7 and PC-3 cell lines could be related to the terpenic compounds and fatty acids of the extracts or to the synergistic effect of all of the compounds in the extracts. These non-polar extracts can be used for the development of new drugs against breast and prostate cancer.