Protective role of arzanol against lipid peroxidation in biological systems

Protective Effect of Arzanol against H2O2-Induced Oxidative Stress Damage in Differentiated and Undifferentiated SH-SY5Y Cells

Oxidative stress can damage neuronal cells, greatly contributing to neurodegenerative diseases (NDs). In this study, the protective activity of arzanol, a natural prenylated α-pyrone-phloroglucinol heterodimer, was evaluated against the H2O2-induced oxidative damage in trans-retinoic acid-differentiated (neuron-like) human SH-SY5Y cells, widely used as a neuronal cell model of neurological disorders. The pre-incubation (for 2 and 24 h) with arzanol (5, 10, and 25 μM) significantly preserved differentiated SH-SY5Y cells from cytotoxicity (MTT assay) and morphological changes induced by 0.25 and 0.5 mM H2O2. Arzanol reduced the generation of reactive oxygen species (ROS) induced by 2 h oxidation with H2O2 0.5 mM, established by 2',7'-dichlorodihydrofluorescein diacetate assay. The 2 h incubation of differentiated SH-SY5Y cells with H2O2 determined a significant increase in the number of apoptotic cells versus control cells, evaluated by propidium iodide fluorescence assay (red fluorescence) and NucView® 488 assay (green fluorescence). Arzanol pre-treatment (2 h) exerted a noteworthy significant protective effect against apoptosis. In addition, arzanol was tested, for comparison, in undifferentiated SH-SY5Y cells for cytotoxicity and its ability to protect against H2O2-induced oxidative stress. Furthermore, the PubChem database and freely accessible web tools SwissADME and pkCSM-pharmacokinetics were used to assess the physicochemical and pharmacokinetic properties of arzanol. Our results qualify arzanol as an antioxidant agent with potential neuroprotective effects against neuronal oxidative stress implicated in NDs.

Arzanol, a natural phloroglucinol α-pyrone, protects HaCaT keratinocytes against H2O2-induced oxidative stress, counteracting cytotoxicity, reactive oxygen species generation, apoptosis, and mitochondrial depolarization

Skin oxidative stress results in structural damage, leading to premature senescence, and pathological conditions such as inflammation and cancer. The plant-derived prenylated pyrone-phloroglucinol heterodimer arzanol, isolated from Helichrysum italicum ssp. microphyllum (Willd.) Nyman aerial parts, exhibits anti-inflammatory, anticancer, antimicrobial, and antioxidant activities. This study explored the arzanol protection against hydrogen peroxide (H2O2) induced oxidative damage in HaCaT human keratinocytes in terms of its ability to counteract cytotoxicity, reactive oxygen species (ROS) generation, apoptosis, and mitochondrial membrane depolarization. Arzanol safety on HaCaT cells was preliminarily examined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and microscopic observation. The arzanol pre-incubation (5-100 μM, for 24 h) did not induce cytotoxicity and morphological alterations. The phloroglucinol, at 50 μM, significantly protected keratinocytes against cytotoxicity induced by 2 h-incubation with 2.5 and 5 mM H2O2, decreased cell ROS production induced by 1 h-exposure to all tested H2O2 concentrations (0.5-5 mM), as determined by the 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA) assay, and lipid peroxidation (thiobarbituric acid reactive substances [TBARS] method). The 2-h incubation of keratinocytes with H2O2 determined a significant increase of apoptotic cells versus control cells, evaluated by NucView® 488 assay, from the dose of 2.5 mM. Moreover, an evident mitochondrial membrane potential depolarization, monitored by fluorescent mitochondrial dye MitoView™ 633, was assessed at 5 mM H2O2. Arzanol pre-treatment (50 μM) exerted a strong significant protective effect against apoptosis, preserving the mitochondrial membrane potential of HaCaT cells at the highest H2O2 concentrations. Our results validate arzanol as an antioxidant agent for the prevention/treatment of skin oxidative-related disorders, qualifying its potential use for cosmeceutical and pharmaceutical applications.

HPLC Analysis and In Vitro and In Silico Evaluation of the Biological Activity of Polyphenolic Components Separated with Solvents of Various Polarities from Helichrysum italicum

Helichrysum italicum has piqued the interest of many researchers in recent years, mostly for its essential oil, but increasingly for its polyphenolic content as well. In the current study, we examine the polyphenolic composition of H. italicum grown in Bulgaria. The polyphenolic complex was fractionated with solvents of various polarities, including hexane, chloroform, ethyl acetate, and butanol, in order to assess the biological impact of the components. HPLC-PDA and UHPLC-MS/MS were used to examine all fractions. The green coffee fingerprint profile was employed as a "surrogate standard" in the polyphenolic components detection approach. From the UHPLC-MS/MS analysis, we identified 60 components of the polyphenolic complex such as quercetin 3-O-glucuronide, quercetin acetyl-glycoside, isorhamnetin acetyl-glycoside, isorhamnetin caffeoyl-glycoside, quercetin caffeoyl-malonyl-glycoside, isorhamnetin coumaroyl-glycoside, coumaroyl-caffeoylquinic acid, and diCQA-acetyl-derivative were first reported in the composition of H. italicum. The biological activity of the fractions was evaluated in vitro and in silico, which included the fight against oxidative stress (hydrogen peroxide scavenging activity (HPSA), hydroxyl radical scavenging activity (HRSA), metal-chelating activity (MChA)) and nitrosative (nitric oxide scavenging activity) (NOSA)), in vitro anti-inflammatory, and anti-arthritic activity. Results are presented as IC50 ± SD μg/mL. The analysis showed that the EtOAc fraction was characterized by highest HPSA (57.12 ± 1.14 μg/mL), HRSA (92.23 ± 1.10 μg/mL), MChA (5.60 ± 0.17 μg/mL), and NOSA (89.81 ± 2.09 μg/mL), while the hexane and chloroform fractions showed significantly higher in vitro anti-inflammatory activity (30.48 ± 2.33 μg/mL, 62.50 ± 1.69 μg/mL) compared to the standard ibuprofen. All three fractions showed potential anti-arthritic activity (102.93 ± 8.62 μg/mL, 108.92 ± 4.42 μg/mL, 84.19 ± 3.89 μg/mL).

Helichrysum italicum: From Extraction, Distillation, and Encapsulation Techniques to Beneficial Health Effects

Helichrysum italicum (family Asteraceae), due to its various beneficial health effects, represents an important plant in the traditional medicine of Mediterranean countries. Currently, there is a renewed interest in this medicinal plant, especially in investigations involving the isolation and identification of its bioactive compounds from extracts and essential oils, as well as in experimental validation of their pharmacological activities. In this paper, we review the current knowledge on the beneficial health effects of Helichrysum italicum extracts, essential oils, and their major bioactive polyphenolic compounds, ranging from antioxidative, anti-inflammatory, and anticarcinogenic activities to their antiviral, antimicrobial, insecticidal, and antiparasitic effects. This review also provides an overview of the most promising extraction and distillation techniques for obtaining high-quality extracts and essential oils from Helichrysum italicum, as well as methods for determining their antioxidative, antimicrobial, anti-inflammatory, and anticarcinogenic activities. Finally, new ideas for in silico studies of molecular mechanisms of bioactive polyphenols from Helichrysum italicum, together with novel suggestions for their improved bioavailability through diverse encapsulation techniques, are introduced.

Towards a modern approach to traditional use of Helichrysum italicum in dermatological conditions: In vivo testing supercritical extract on artificially irritated skin

ETHNOPHARMACOLOGICAL RELEVANCE

Helichrysum italicum has been widely used in traditional medicine to treat allergies, colds, cough, skin, liver and gallbladder disorders, inflammation, infections, and sleeplessness. Furthermore, it possesses considerable wound healing and skin protective properties, documented by several in vivo studies performed on animals. However, there is a lack of experimental evidence supporting its potential as a topical agent tested by human clinical trials.

AIM OF THE STUDY

The study aimed to investigate the skin protective activity of cotton gauze and polypropylene non-woven fabric, impregnated with H. italicum extract by the integrated supercritical CO₂ extraction-supercritical solvent impregnation process.

MATERIALS AND METHODS

The integrated process of supercritical CO₂ extraction of H. italicum and the impregnation of cotton gauze and polypropylene non-woven fabric was performed under 350 bar and 40 °C with and without the addition of ethanol as a cosolvent. Impregnated textile materials were tested in vivo for their bioactivity on irritated human skin. Randomized in vivo studies performed involved assays of both safety and efficacy of the impregnated textiles. The effects were evaluated using the in vivo non-invasive biophysical measurements of the following skin parameters: electrical capacitance, transepidermal water loss, melanin index, erythema index, and skin pH.

RESULTS

Both cotton gauze and polypropylene non-woven fabric were impregnated with H. italicum extracts under supercritical conditions with considerable values of the impregnation yield (1.97%-4.25%). The addition of ethanol as a cosolvent during the process caused significant changes in the incorporated extracts' impregnation yield and chemical profile. Both impregnated textile materials were safe, evaluated by their testing on the human skin with no cause of any irritation and redness. However, efficacy studies revealed that polypropylene non-woven fabric impregnated with H. italicum extract with ethanol as a cosolvent, possessed significantly greater potential for skin protection than the other investigated samples.

CONCLUSIONS

The present study demonstrated the feasibility of the combined supercritical extraction and impregnation process in developing materials for topical application based on H. italicum extract. The results of in vivo studies performed on human volunteers confirmed the suitability of H. italicum active components to be a part of human skin protective preparations because of their ability to maintain the skin unimpaired. Traditionally claimed applications as a medicinal plant capable of regenerating skin have been scientifically proven, in addition to employing green technology in obtaining the impregnated materials with a broad spectrum of utilization.

Involvement of NO/cGMP Signaling Pathway, Ca2+ and K+ Channels on Spasmolytic Effect of Everlasting Flower Polyphenolic Extract (Helichrysum stoechas (L.) Moench)

Functional gastrointestinal diseases (FGID) are worldwide prevalent conditions. Pharmacological treatments can be ineffective, leading the population to turn to herbal or traditional remedies. Helichrysum stoechas (L.) Moench is a medicinal plant traditionally used in the Iberian Peninsula to treat digestive disorders, but its effects on gastrointestinal motility have not been scientifically demonstrated. The aim of this work was to evaluate the antispasmodic effect of a polyphenolic extract of H. stoechas (HSM), its mechanism of action and its antioxidant activity. Isometric myography studies were performed in rat ileum, and malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA) levels were measured in rat jejunum. HSM reduced the integrated mechanical activity of spontaneous contractions. In Ca²⁺-free medium, HSM reduced the concentration-response curve of CaCl₂ similarly to verapamil. Pre-incubation with the extract blocked the contraction induced by Bay K8644, KCl and carbachol. L-NAME, ODQ, Rp-8-Br-PET-cGMPS, KT-5823, apamin, TRAM-34 and charybdotoxin reduced the relaxant effect of the extract on spontaneous contractions. MDA+4-HDA levels in LPS-treated tissue were reduced by the extract, showing antioxidant activity. In conclusion, HSM showed antispasmodic activity through inhibition of Ca²⁺ influx, activation of the NO/PKG/cGMP pathway and opening of Ca²⁺-activated K⁺ channels. The results suggest that H. stoechas could help in the prevention or treatment of FGIDs.

Cell-Based Antioxidant Properties and Synergistic Effects of Natural Plant and Algal Extracts Pre and Post Intestinal Barrier Transport

In this work, both direct and indirect cell-based antioxidant profiles were established for 27 plant extracts and 1 algal extract. To evaluate the direct antioxidant effects, fluorescent AOP1 cell assay was utilized, which measures the ability of different samples to neutralize intracellular free radicals produced by a cell-based photo-induction process. As the intestinal barrier is the first cell line crossed by the product, dose response curves obtained from Caco-2 cells were used to establish EC50 values for 26 out of the 28 natural extracts. Among them, 11 extracts from Vitis, Hamamelis, Syzygium, Helichrysum, Ilex and Ribes genera showed remarkable EC50s in the range of 10 µg/mL. In addition to this, a synergistic effect was found when combinations of the most potent extracts (S. aromaticum, H. italicum, H. virginiana, V. vinifera) were utilized compared to extracts alone. Indirect antioxidant activities (i.e., the ability of cells to trigger antioxidant defenses) were studied using the ARE/Nrf2 luminescence reporter-gene assay in HepG2 cells, as liver is the first organ crossed by an edible ingredient once it enters in the bloodstream. Twelve extracts were subjected to an intestinal epithelial barrier passage in order to partially mimic intestinal absorption and show whether basolateral compartments could maintain direct or indirect antioxidant properties. Using postepithelial barrier samples and HepG2 cells as a target model, we demonstrate that indirect antioxidant activities are maintained for three extracts, S. aromaticum, H. virginiana and H. italicum. Our experimental work also confirms the synergistic effects of combinations of post-intestinal barrier compartments issued from apical treatment with these three extracts. By combining cell-based assays together with an intestinal absorption process, this study demonstrates the power of cell systems to address the issue of antioxidant effects in humans.

A Review and Evaluation of the Data Supporting Internal Use of Helichrysum italicum

Helichrysum italicum is a Mediterranean plant with various pharmacological activities. Despite extensive reports on the bioactivity of the plant, its clinically studied applications have not yet been reviewed. The aim of our study was to gather information on the internal use of H. italicum and its bioactive constituents to determine its efficacy and safety for human use. We reviewed research articles that have not been previously presented in this context and analyzed relevant clinical studies with H. italicum. Cochranelibrary.com revealed six eligible clinical trials with H. italicum that examined indications for pain management, cough, and mental exhaustion. Although the efficacy of H. italicum has been demonstrated both in in vitro tests and in humans, it is difficult to attribute results from clinical trials to H. italicum alone, as it has usually not been tested as the sole component. On the other hand, clinical trials provide positive information on the safety profile since no adverse effects have been reported. We conclude that H. italicum is safe to use internally, while new clinical studies with H. italicum as a single component are needed to prove its efficacy. Based on the recent trend in H. italicum research, further studies are to be expected.

Helichrysum italicum ssp. italicum Infusion Promotes Fat Oxidation in Hepatocytes and Stimulates Energy Expenditure and Fat Oxidation after Acute Ingestion in Humans: A Pilot Study

Helichrysum italicum is an aromatic plant with promising pharmacological activities. Bioactive compounds found in plants represent an important alternative treatment for weight loss and an infusion of H. italicum contains compounds which could have such effect. Our aim was, therefore, to investigate its acute effects on resting energy expenditure (REE) and possible differences in substrate oxidation in a pilot study. A dried, ground plant material of H. italicum ssp. italicum was infused with hot water and chemically characterized with HPLC-MS analysis. Sensory evaluation of herbal tea was performed. A randomized, crossover, controlled pilot study was then conducted on eleven healthy male subjects. The REE and substrate oxidation were measured by indirect calorimetry at baseline and 30 and 120 min after ingestion of infusion or hot water. The expression of genes involved in lipid metabolism was examined in H. italicum infusion-treated hepatocytes. Several phenolic classes were identified in the infusion, caffeoylquinic acids were the most abundant, followed by pyrones and flavonols. A single ingestion of H. italicum infusion significantly increased REE by 4% and fat oxidation by 12% compared to hot water ingestion. A significant 2-fold up-regulation of β-oxidation-related genes in HepG2 cells, exposed to H. italicum infusion, was detected. This pilot study suggests that H. italicum infusion possesses bioactive substances with potential application in obesity prevention, which could, with additional studies, become an economically interesting novel application of the plant. Clinical trial registration number: NCT04818905

A Comparative Study of the Antioxidative Effects of Helichrysum italicum and Helichrysum arenarium Infusions

Helichrysum arenarium (L.) Moench (abbrev. as HA) has a long tradition in European ethnomedicine and its inflorescences are approved as a herbal medicinal product. In the Mediterranean part of Europe, Helichrysum italicum (Roth) G. Don (abbrev. as HI) is more common. Since infusions from both plants are traditionally used, we aimed to compare their antioxidative potential using in vitro assays. Two morphologically distinct HI plants, HIa and HIb, were compared to a commercially available HA product. Genetic analysis using microsatellites confirmed a clear differentiation between HI and HA and suggested that HIb was a hybrid resulting from spontaneous hybridization from unknown HI subspecies. High-performance liquid chromatography-mass spectrometry analysis showed the highest amounts of hydroxycinnamic acids and total arzanol derivatives in HIa, whereas HIb was richest in monohydroxybenzoic acids, caffeic acids, and coumarins, and HA contained the highest amounts of flavonoids, especially flavanones. HIa exhibited the highest radical scavenging activity; it was more efficient in protecting different cell lines from induced oxidative stress and in inducing oxidative stress-related genes superoxide dismutase 1, catalase, and glutathione reductase 1. The antioxidative potential of HI was not only dependent on the morphological type of the plant but also on the harvest date, revealing important information for obtaining the best possible product. Considering the superior properties of HI compared to HA, the evaluation of HI as a medicinal plant could be recommended.

So Uncommon and so Singular, but Underexplored: An Updated Overview on Ethnobotanical Uses, Biological Properties and Phytoconstituents of Sardinian Endemic Plants

The last decades have recorded an increase of plant-based drug discovery processes. Indeed, natural products possess a superior chemical diversity as compared to synthetic ones, leading to a renewal in searching for new therapeutic agents from the plant kingdom. In particular, since the structural variety of natural compounds reflects the biodiversity of their source organisms, regions of the world with high biodiversity and endemism deserve particular interest. In this context, Sardinia Island (Italy), with 290 endemic taxa (12% of the total flora), is expected to provide unique and structurally diverse phytochemicals for drug development. Several research groups built up a large program dedicated to the analysis of Sardinian endemic species, highlighting their peculiar features, both in respect of phytochemical and biological profiles. On this basis, the aim of this review is to provide an up-to-date and comprehensive overview on ethnobotanical uses, biological properties and phytoconstituents of Sardinian endemic plants in order to support their beneficial potential and to provide input for future investigations. We documented 152 articles published from 1965 to June 2020 in which a broad range of biological activities and the identification of previously undescribed compounds have been reported, supporting their great value as sources of therapeutic agents.

Composition, Antioxidant Potential, and Antimicrobial Activity of Helichrysum plicatum DC. Various Extracts

Helichrysum plicatum DC. is widely used in folk medicine in treating a variety of health disorders. The aim of this study was to examine the influence of different extraction solvents on the chemical composition, antioxidant potential, and antimicrobial activities of H. plicatum. Aerial parts were separately extracted with ethanol, dichloromethane, and sunflower oil. The oil extract (OE) was re-extracted with acetonitrile. A total of 142 compounds were tentatively identified in ethanolic (EE), dichloromethane (DCME), and acetonitrile (ACNE) extracts using HPLC-DAD/ESI-ToF-MS. The dominant compound class in all extracts were α-pyrones, alongside flavonoids in EE, terpenoids in DCME and ACNE, and phloroglucinols in DCME. The antioxidant potential of the extracts was assessed by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) assay. EE and DCME possessed the most potent radical scavenging capacity. Antimicrobial activity was investigated on eight bacterial, two yeast, and one fungal species. All extracts exhibited high antifungal and notable antibacterial activities compared to control substances, with DCME being the most potent. DCME exhibited stronger antimicrobial activity against P. aeruginosa than the standard chloramphenicol.

Complexes of arzanol with a Cu2+ ion: a DFT study

Arzanol (C₂₂H₂₆O₇) is a naturally occurring acylphloroglucinol largely responsible for the anti-inflammatory, anti-oxidant, antibiotic and antiviral activities of Helichrysum italicum. Like all acylphloroglucinols, the molecule contains a carboxylic substituent (-COR group); for arzanol, this is a -COCH₃ group. The molecule is further characterized by the presence of an α-pyrone ring bonded in meta to -COR through a methylene bridge, and of a prenyl chain bonded to the other meta position. The molecule can form up to three intramolecular hydrogen bonds (IHB) simultaneously, and their presence and patterns are the major stabilizing factors. This work considers complexes of representative conformers of arzanol with a Cu²⁺ ion, taking into account the different possibilities for the binding of the Cu²⁺ ion to the electron-density rich sites of the molecule and including simultaneous coordination to two geometrically suitable sites. Calculations were performed at the DFT/B3LYP level, using the 6-31+G(d,p) basis set for the C, O and H atoms and the LANL2DZ pseudopotential for the Cu²⁺ ion. Interaction energies show preference for simultaneous binding of Cu²⁺ to two sites. Simultaneous binding to the O of a phenol OH neighboring the prenyl chain and to the π bond of the prenyl chain appears to be the most favorable option, followed by simultaneous binding to the sp² O of the α-pyrone ring and the O of the phenol OH ortho to -COR on the side of the α-pyrone ring. The charge of the Cu²⁺ ion is reduced to +1 or slightly less in the complexes, which is consistent with the molecules' antioxidant (reducing) ability. Graphical abstract The copper ion prefers to attach to two sites of the arzanol molecule simultaneously. The arzanol molecule reduces the charge of the copper ion from +2 to +1 by transferring an electron to it; it becomes a radical molecular cation. The distribution of the unpaired electron in the molecule (as highlighted by the spin density maps) depends on the site/s to which the Cu²⁺ ion binds and on the molecule's conformer.

Intramolecular Hydrogen Bonding and Conformational Preferences of Arzanol-An Antioxidant Acylphloroglucinol

Arzanol is a naturally-occurring prenylated acylphloroglucinol isolated from Helichrysum italicum and exhibiting anti-oxidant, antibiotic and antiviral activities. The molecule contains an α-pyrone moiety attached to the phloroglucinol moiety through a methylene bridge. The presence of several hydrogen bond donor or acceptor sites makes intramolecular hydrogen bonding patterns the dominant stabilising factor. Conformers with all the possible different hydrogen bonding patterns were calculated at the HF/6-31G(d,p) and DFT/B3LYP/6-31+G(d,p) levels with fully relaxed geometry in vacuo and in three solvents—chloroform, acetonitrile and water (these levels being chosen to enable comparisons with previous studies on acylphloroglucinols). Calculations in solution were performed with the Polarisable Continuum Model. The results show that the lowest energy conformers have the highest number of stronger intramolecular hydrogen bonds. The influence of intramolecular hydrogen bonding patterns on the other molecular properties is also analysed.

Separation of phytochemicals from Helichrysum italicum: An analysis of different isolation techniques and biological activity of prepared extracts

Helichrysum italicum presents a valuable source of natural bioactive compounds. In this work, a literature review of terpenes, phenolic compounds, and other less common phytochemicals from H. italicum with regard to application of different separation methods is presented. Data including extraction/separation methods and experimental conditions applied, obtained yields, number of identified compounds, content of different compound groups, and analytical techniques applied are shown as corresponding tables. Numerous biological activities of both isolates and individual compounds are emphasized. In addition, the data reported are discussed, and the directions for further investigations are proposed.

New insights into the antioxidant activity and cytotoxicity of arzanol and effect of methylation on its biological properties

The heterodimeric phloroglucinyl pyrone arzanol (Arz) has raised considerable interest because of its antiviral, anti-inflammatory, and antioxidant activity. We have investigated the effect of methylation of the pyrone moiety on the antioxidant activity and cytotoxicity of Arz. This manoeuvre, that left the polyphenolic moiety unscathed, was nevertheless detrimental for antioxidant activity in both the cholesterol thermal degradation- and the Cu²⁺-induced liposome oxidation assays, providing evidence of structure-activity relationships that go beyond the preservation of the polyphenolic pharmacophore. The antioxidant activity of Arz was retained also in the Fe-NTA model of in vivo oxidative stress, with protective effect on the oxidative degradation of plasmatic lipids, unsaturated fatty acids and cholesterol. Both Arz and methylarzanol (Me-Arz) were devoid of toxic effect on colonic differentiated Caco-2 cells up to 100μM, but significantly reduced cancer Caco-2 cell viability at lower dosages. Arz could also selectively reduce viability of other cancer cell lines, [murine melanoma cells (B16F10 cells), human cervical carcinoma cells (HeLa cells)], suggesting that it can act as a selective modulator of cell processes typical of cancer cells. Taken together, our results qualify Arz as a lead structure for further in vivo investigation of its pharmacological potential.

Arzanol, a potent mPGES-1 inhibitor: novel anti-inflammatory agent

Arzanol is a novel phloroglucinol α-pyrone, isolated from a Mediterranean plant Helichrysum italicum (Roth) Don ssp. microphyllum which belongs to the family Asteraceae. Arzanol has been reported to possess a variety of pharmacological activities. However, anti-inflammatory, anti-HIV, and antioxidant activities have been studied in some detail. Arzanol has been reported to inhibit inflammatory transcription factor NFκB activation, HIV replication in T cells, releases of IL-1β, IL-6, IL-8, and TNF-α, and biosynthesis of PGE₂ by potentially inhibiting mPGES-1 enzyme. Diversity of mechanisms of actions of arzanol may be useful in treatment of disease involving these inflammatory mediators such as autoimmune diseases and cancer. This review presents comprehensive information on the chemistry, structure-activity relationship, and pharmacological activities of arzanol. In addition this review discusses recent developments and the scope for future research in these aspects.

Antimicrobial phenolics and unusual glycerides from Helichrysum italicum subsp. microphyllum

During a large-scale isolation campaign for the heterodimeric phloroglucinyl pyrone arzanol (1a) from Helichrysum italicum subsp. microphyllum, several new phenolics as well as an unusual class of lipids named santinols (5a-c, 6-8) have been characterized. Santinols are angeloylated glycerides characterized by the presence of branched acyl- or keto-acyl chains and represent a hitherto unreported class of plant lipids. The antibacterial activity of arzanol and of a selection of Helichrysum phenolics that includes coumarates, benzofurans, pyrones, and heterodimeric phloroglucinols was evaluated, showing that only the heterodimers showed potent antibacterial action against multidrug-resistant Staphylococcus aureus isolates. These observations validate the topical use of Helichrysum extracts to prevent wound infections, a practice firmly established in the traditional medicine of the Mediterranean area.