Cytotoxic and anti-inflammatory active phloroglucinol derivatives from Rhodomyrtus tomentosa

Potential applications of Rhodomyrtus tomentosa leaf extract as natural anti-staphylococcal additive in food systems: Efficacy and in vivo safety evaluation

This work aimed to explore the potential use of Rhodomyrtus tomentosa ethanol leaf extract (RTEL) as an alternative food preservative agent for controlling the growth of Staphylococcus aureus. Antibacterial activities against food-isolated S. aureus were performed using disc diffusion and broth microdilution assays, followed by evaluating in vivo subacute oral toxicity of the extract. Salad dressing was used as a food model to study bactericidal properties and consumer acceptability. RTEL remarkably inhibited S. aureus with minimum inhibitory concentrations (MICs) ranging from 7.81-62.5 µg/mL. Repeated oral doses (5, 50, and 300 mg/kg RTEL) for 28 days did not affect any of the measured toxicity parameters. The no-observed-adverse-effect-level (NOAEL) of RTEL was noted as more than 300 mg/kg body weight/day. The utilization of RTEL (12.5 mg/mL) in the vinaigrette salad dressing did not affect the consumer acceptability of the product, remarkably killed the pathogen within 3-9 h of exposure. The results indicated that RTEL is safe and effective as a natural anti-staphylococcal controlling agent that could be utilized in food systems. Further work is required on the effects of enterotoxin production, an important virulence factor of S. aureus responsible for food-borne disease.

Phloroglucinol Enhances Anagen Signaling and Alleviates H2O2-Induced Oxidative Stress in Human Dermal Papilla Cells

Phloroglucinol (PG) is one of the abundant isomeric benzenetriols in brown algae. Due to its polyphenolic structure, PG exhibits various biological activities. However, the impact of PG on anagen signaling and oxidative stress in human dermal papilla cells (HDPCs) is unknown. In this study, we investigated the therapeutic potential of PG for improving hair loss. A non-cytotoxic concentration of PG increased anagen-inductive genes and transcriptional activities of β-Catenin. Since several anagen-inductive genes are regulated by β-Catenin, further experiments were performed to elucidate the molecular mechanism by which PG upregulates anagen signaling. Various biochemical analyses revealed that PG upregulated β-Catenin signaling without affecting the expression of Wnt. In particular, PG elevated the phosphorylation of protein kinase B (AKT), leading to an increase in the inhibitory phosphorylation of glycogen synthase kinase 3 beta (GSK3β) at serine 9. Treatment with the selective phosphoinositide 3-kinase/AKT inhibitor, LY294002, restored the increased AKT/GSK3β/β-Catenin signaling and anagen-inductive proteins induced by PG. Moreover, conditioned medium from PG-treated HDPCs promoted the proliferation and migration of human epidermal keratinocytes via the AKT signaling pathway. Subsequently, we assessed the antioxidant activities of PG. PG ameliorated the elevated oxidative stress markers and improved the decreased anagen signaling in hydrogen peroxide (H2O2)-induced HDPCs. The senescence-associated β-galactosidase staining assay also demonstrated that the antioxidant abilities of PG effectively mitigated H2O2-induced senescence. Overall, these results indicate that PG potentially enhances anagen signaling and improves oxidative stress-induced cellular damage in HDPCs. Therefore, PG can be employed as a novel therapeutic component to ameliorate hair loss symptoms.

Rhodomyrtus tomentosa (Aiton) Hassk. (haramonting) protects against allethrin-exposed pulmo damage in rats: mechanistic interleukins

Inhaling Allethrin (C19H26O3) may induce oxidative stress in lung cells by causing the formation of free radi-cals. Interleukins (IL) are a group of secreted cytokines or proteins and signaling molecules initially produced as an immune response by leukocytes. Rhodomyrtus tomentosa (Aiton) Hassk. (haramonting) contains antioxidants that may prevent lung damage induced by allethrin-containing electric mosquito repellents. In this study, six groups of rats were exposed to allethrin via an electric mosquito repellent, including positive, negative, and comparison control groups and three groups were administered Rhodomyrtus tomentosa (Aiton) Hassk at 100 mg/kg BW, 200 mg/kg BW, and 300 mg/kg BW. After 30 days, the pulmonary tissue and the blood were taken for immunohisto-chemical and ELISA analysis. The accumulation of inflammatory cells causes the thickening of the alveolar wall structures. Injuries were more prevalent in the A+ group than in the other groups. The connection between the alveoli and blood capillaries, which can interfere with alveolar gas exchange, is not regulated, and the lu-minal morphology is aberrant, causing damage to the alveolar epithelial cells. Exposure to electric mosquito coils containing allethrin can increase the expression of interleukin-1, interleukin-8, interleukin-9, and interleu-kin-18 in blood serum and tissues while decreasing the expression of interleukin-6 and interleukin-10. Like the Vitamin C group, Rhodomyrtus tomentosa can increase alveolar histological alterations by decreasing the ex-pression of IL-1β, IL-8, IL-9, and IL-18 while increasing IL-6 and IL-10. So that this plant can be developed in the future as a drug to prevent lung harm from exposure.

Campomanesia lineatifolia Ruiz & Pavón (Myrtaceae): Isolation of major and minor compounds of phenolic-rich extract by high-speed countercurrent chromatography and anti-inflammatory evaluation

ETHNOPHARMACOLOGICAL RELEVANCE

Campomanesia lineatifolia Ruiz & Pavón (Myrtaceae), an edible species found in Brazilian Forest, possesses leaves that are traditionally used for the treatment of gastrointestinal disorders in Brazil. Extracts of C. lineatifolia are rich in phenolics and exhibit antioxidant, and gastric antiulcer properties. Furthermore, Campomanesia spp. have been described to possess anti-inflammatory properties, but studies related to chemical constituents of C. lineatifolia are scarce in the literature.

AIM OF THE STUDY

This work aims to identify the chemical composition of the phenolic-rich ethanol extract (PEE) from C. lineatifolia leaves and evaluate the anti-inflammatory activity that could be related to its ethnopharmacological use.

MATERIALS AND METHODS

The high-speed countercurrent chromatography (HSCCC), using an isocratic and a step gradient elution method, and NMR, HPLC-ESI-QTOF-MS/MS were used to isolate and identify the chemicals of PEE, respectively. Lipopolysaccharide-(LPS)-stimulated THP-1 cells were used to evaluate the anti-inflammatory activities from PEE and the two majority flavonoids isolated by measure TNF-α and NF-κB inhibition assays.

RESULTS

Fourteen compounds were isolated from the PEE, further identified by NMR and HPLC-ESI-QTOF-MS/MS, twelve of them are new compounds, and two others are already known for the species. The PEE, quercitrin and myricitrin promoted a concentration-dependent inhibition of TNF-α, and PEE promoted an inhibition of NF-κB pathway.

CONCLUSIONS

PEE from C. lineatifolia leaves demonstrated significant anti-inflammatory activity that may be related to the traditional use to treat gastrointestinal disorders.

Histological analysis of TGFβ1 and VEGFR expression in cervical carcinoma treated with Rhodomyrtus tomentosa

Cervical carcinoma is one of the most common malignant carcinomas around the world, including Indonesia. Rhodomyrtus tomentosa is an herbal medicine that is often used in Asia as a therapeutic agent to stop cancer metastases. The process of neoangiogenesis in cervical cancer depends on VEGFR activity. Increased TGFβ1 production is also linked to cervical cancer, suggesting that gene inactivation contributes to the emergence of cervical carcinoma.

Group C- was the control group, Group C+ was the cancer model group, CER100 was the group of rats with cancer + 100 mg/kg body weight (BW) of R. tomentosa, CER200 was the group of rats with cancer + 200 mg/kg BW of R. tomentosa, and CER400 was the group of rats with cancer + 400 mg/kg BWR. tomentosa. Rats were dissected after administration of R. tomentosa for 30 days. Immunohistochemical staining of the cervical tissue was performed with TGFβ1 and VEGFR antibodies. VEGFR expression was significantly different from TGFβ1 expression (p < 0.01). The highest expression was observed at the lowest dose of R. tomentosa (100 mg/kg BW), and the lowest expression was observed at 200 and 400 mg/kg BW. The administration of R. tomentosa can repair tissue damage and decrease the expression of TGFβ1 and VEGFR via histopathological parameters, indicating the importance of the activity of these proteins in the development of neoangiogenesis in cervical cancer.

PDGF-β and IL-18 Expressions on Carcinoma Cervical by Rhodomyrtus tomentosa

&lt;b&gt;Background and Objective:&lt;/b&gt; Cervical cancer, along with lung and breast cancer, is one of Indonesia's most aggressive gynaecological diseases. &lt;i&gt;Rhodomyrtus tomentosa&lt;/i&gt; has antioxidant and antiproliferative properties that could be developed into herbal medicines for molecular therapy. The IL-18 and PDGF-β are tumour-promoting agent proteins that may be therapeutic targets for a variety of cancers that were investigated in this study. &lt;b&gt;Materials and Methods:&lt;/b&gt; Rats were classified into five groups: Group C- is the control group, Group C+ is the cancer model group and Group RHO200 is the &lt;i&gt;Rhodomyrtus tomentosa&lt;/i&gt; 100 mg&lt;sup&gt;1&lt;/sup&gt; b.wt., rat group, Group RHO400 is the &lt;i&gt;Rhodomyrtus tomentosa&lt;/i&gt; 200 mg&lt;sup&gt;1&lt;/sup&gt; b.wt., rat group and Group RHO400 is the &lt;i&gt;Rhodomyrtus tomentosa&lt;/i&gt; 400 mg&lt;sup&gt;1&lt;/sup&gt; b.wt., rat group. The rats were dissected 30 days after receiving &lt;i&gt;Rhodomyrtus tomentosa&lt;/i&gt;. Immunohistochemistry is used to stain cervical tissues. &lt;b&gt;Results:&lt;/b&gt; The expression of IL-18 and PDGF-β was significantly different (p<0.01). The IL-18 and PDGF-β were most abundant at the lowest &lt;i&gt;Rhodomyrtus tomentosa&lt;/i&gt; doses (100-200 mg kg&lt;sup&gt;1&lt;/sup&gt; b.wt.), while they were least abundant at the 400 mg kg&lt;sup&gt;1&lt;/sup&gt; b.wt., doses. Histological analysis revealed that the highest dose of IL-18 and PDGF-β expression reduced abnormal tissue and the space between tumours, followed by several carcinoma cells that stopped growing. &lt;b&gt;Conclusion:&lt;/b&gt; &lt;i&gt;Rhodomyrtus tomentosa&lt;/i&gt; can be used as a herbal therapy to reduce the expression of PDGF-β and IL-18 (two cancer marker agents).

Phloroglucinol derivatives rhotomensones A-G from Rhodomyrtus tomentosa

Undescribed phloroglucinol derivatives, rhotomensones A-G, and a known derivative rhodomyrtosone B, were isolated from the leaves of Rhodomyrtus tomentosa. Rhotomensones A-D and G have unreported structural characteristics, in which rhotomensone A substitutes a benzene ring, rhotomensones B-D are bonded with a 2-methylbutanoyl group, and rhotomensone G has two fewer carbons. The structures of these compounds were determined by NMR spectroscopy, circular dichroism (CD) spectroscopy and X-ray crystallography. The inhibitory activities against α-glucosidase of rhotomensones E and F were evaluated in vitro, with IC₅₀ values of 0.50 ± 0.14 mg/mL and 0.07 ± 0.02 mg/mL. Moreover, rhodomyrtosone B showed significant antibacterial activity against some bacteria, with MIC values ranging from 0.50 to 16.00 μg/mL.

The Gene Regulatory Roles of Herbal Extracts on the Growth, Immune System, and Reproduction of Fish

The crucial need for safe and healthy aquatic animals obligates researchers in aquaculture to investigate alternative and beneficial additives. Medicinal herbals and their extracts are compromised with diverse effects on the performances of aquatic animals. These compounds can affect growth performance and stimulate the immune system when used in fish diet. In addition, the use of medicinal herbs and their extracts can reduce oxidative stress induced by several stressors during fish culture. Correspondingly, aquatic animals could gain increased resistance against infectious pathogens and environmental stressors. Nevertheless, the exact mode of action where these additives can affect aquatic animals' performances is still not well documented. Understanding the mechanistic role of herbal supplements and their derivatives is a vital tool to develop further the strategies and application of these additives for feasible and sustainable aquaculture. Gene-related studies have clarified the detailed information on the herbal supplements' mode of action when administered orally in aquafeed. Several review articles have presented the potential roles of medicinal herbs on the performances of aquatic animals. However, this review article discusses the outputs of studies conducted on aquatic animals fed dietary, medicinal herbs, focusing on the gene expression related to growth and immune performances. Furthermore, a particular focus is directed to the expected influence of herbal supplements on the reproduction of aquatic animals.

Potential of karamunting (Rhodomyrtus tomentosa) fraction against kidney damage in diabetic rats

Introduction: Karamunting (Rhodomyrtus tomentosa) is Indonesian native plant that contains high anti-oxidant compounds with the potential to suppress oxidative stress activity in cells. This study is the first research to specifically explore the role of the karamunting fraction in protecting kidney damage due to the formation of AGEs in the renal glomerulus in diabetes mellitus.

Objective: This study aims to assess the impact of karamunting on blood glucose profile, HbA1c, insulin profile and kidney condition (AGEs expression, TNF-α and kidney histology) in diabetic rats.

Methods: The karamunting extraction process was carried out by maceration with ethanol. Induction of diabetes mellitus was carried out using streptozotocin. Thirty male rats (Rattus norvegicus), Wistar strain weighing between 200–250 grams were the subject in this study. HbA1c, insulin, TNF-α, AGEs levels were evaluated in the kidney tissue. Histological assessment of the kidney was carried out.

Results: Karamunting can improve blood glucose levels in diabetic rats. This improvement in blood glucose levels causes an improvement in the level of HbA1c. Administration of karamunting fraction can prevent AGEs deposition in renal tissue, which in turn will inhibits the inflammation and prevents further damage of kidneys.

Conclusion: Karamunting fraction can improve blood glucose regulation so that it can prevent further damage and complications of kidney organs in diabetic rats.

Dimeric Acylphloroglucinol Derivatives with New Skeletons from Leptospermum scoparium

Leptosparones A-F (1-6), six new dimeric acylphloroglucinol derivatives with unprecedented skeletons, were isolated from Leptospermum scoparium. Compounds 1-3 and 5-6 are phenylpropanoyl-phloroglucinol dimers, while 4 is a phenylpropanoylphloroglucinol-isovalerylphloroglucinol hybrid. Structurally, these compounds represent the first examples of dimeric phloroglucinols with unprecedented C(7')-C(8) linkage between the phloroglucinol core and the acyl side chain. Their structures were elucidated by comprehensive analyses of spectroscopic data, single crystal X-ray diffraction and chemical calculations. In addition, all compounds showed inhibitory effects against α-glucosidase with IC₅₀ values ranging from 39.5 to 186.8 μM.

Asymmetric synthesis of 9-alkyl tetrahydroxanthenones via tandem asymmetric Michael/cyclization promoted by chiral phosphoric acid

A tandem asymmetric Michael-addition/cyclization of cyclic 1,3-dicarbonyl compounds to β,γ-unsaturated α-ketoesters catalyzed by chiral phosphoric acid is presented. This protocol provides a facile approach for the construction of enantioenriched 9-alkyl tetrahydroxanthenones, an ubiquitous framework found in a number of natural products and pharmaceutical molecules, in high yields with good to high enantioselectivities.

A biomimetic synthesis-enabled stereochemical assignment of rhodotomentones A and B, two unusual caryophyllene-derived meroterpenoids from Rhodomyrtus tomentosa

Rhodotomentones A and B (1 and 2), two unusual caryophyllene-derived meroterpenoids (CDMTs) featuring a rare 6/6/9/4/6/6 hexacyclic ring system, along with their biogenetically-related CDMTs 7 and 12–15, were isolated from Rhodomyrtus tomentosa.

The Biomimetic Total Syntheses of the Antiplasmodial Tomentosones A and B

The first biomimetic total syntheses of natural phloroglucinols tomentosones A and B and their analogues have been accomplished. The synthetic strategy primarily referred to the potential biosynthetic precursors and their possible sequence of segments assembly by chemological evolution of the structural entities and enabled rapid access of the titled compounds in a practical fashion.

Triketone-terpene meroterpenoids from the leaves of Rhodomyrtus tomentosa

Eight new meroterpenoids (1-8) featuring β-triketone-conjugated terpenoids, rtomentones A-H, were isolated from the leaves of Rhodomyrtus tomentosa. Structures of the isolates were unambiguously established by a combination of NMR and ECD spectroscopy and X-ray diffraction analysis. Rtomentone C (3) was the first example of aromadendrane-based meroterpenoid containing an oxa-spiro[5.6] ring. Rtomentone D (4) was obtained as a racemic mixture confirmed by chiral HPLC analysis. The cytotoxicity against MDA-MB-231, A549, and DLD-1 cells of all isolates was evaluated.

The First Racemic Total Syntheses of the Antiplasmodials Watsonianones A and B and Corymbone B

The first biomimetic total syntheses of three biologically meaningful acylphloroglucinols, watsonianones A and B and corymbone B, with potent antiplasmodial activity, were performed. Their total syntheses were carried out through a diversity-oriented synthetic strategy from congener 2,2,4,4-tetramethyl-6-(3-methylbutylidene)cyclohexane-1,3,5-trione with high step efficiency. The spontaneous enolization/air oxidation of the precursor 2,2,4,4-tetramethyl-6-(3-methylbutylidene)cyclohexane-1,3,5-trione through a singlet O₂-induced Diels-Alder reaction pathway to assemble the key biosynthetic peroxide intermediate is also discussed.

Meroterpene-Like α-Glucosidase Inhibitors Based on Biomimetic Reactions Starting from β-Caryophyllene

BACKGROUND

Natural meroterpenes derived from phloroglucinols and β-caryophyllene have shown high inhibitory activity against α-glucosidase or cancer cells, however, the chemical diversity of this type of skeletons in Nature is limited.

METHODS

To expand the chemical space and explore their inhibitory activities against α-glucosidase (EC 3.2.1.20), we employed β-caryophyllene and some natural moieties (4-hydroxycoumarins, lawsone or syncarpic acid) to synthesize new types of meroterpene-like skeletons. All the products (including side products) were isolated and characterized by NMR, HR-MS, and ECD.

RESULTS

In total, 17 products (representing seven scaffolds) were generated through a one-pot procedure. Most products (12 compounds) showed more potential activity (IC₅₀ < 25 μM) than the positive controls (acarbose and genistein, IC₅₀ 58.19, and 54.74 μM, respectively). Compound 7 exhibited the most potent inhibition of α-glucosidase (IC₅₀ 3.56 μM) in a mixed-type manner. The CD analysis indicated that compound 7 could bind to α-glucosidase and influence the enzyme's secondary structure.

CONCLUSIONS

Compound 7 could serve as a new type of template compound to develop α-glucosidase inhibitors. Full investigation of a biomimic reaction can be used as a concise strategy to explore diverse natural-like skeletons and search for novel lead compounds.

Callistemonols A and B, Potent Antimicrobial Acylphloroglucinol Derivatives with Unusual Carbon Skeletons from Callistemon viminalis

A phytochemical investigation on the leaves of Callistemon viminalis resulted in the isolation of two unusual compounds, callistemonols A (1) and B (2). Callistemonol A (1) possesses a novel skeleton of a furan ring fusing both an α,β-triketone and a phloroglucinol unit, while callistemonol B (2) is an acylphloroglucinol derivative featuring two methyl substituents on a five-membered ring and an isovaleryl side chain. Their structures were fully characterized on the basis of extensive spectroscopic analysis, including 1D and 2D NMR parameters, as well as the IR and HRESIMS data. Callistemonol A (1) represents an example of a natural dibenzofuran with two phenyl moieties, and a plausible biogenetic pathway to generate this novel dibenzofuran through a C-C bond-forming radical SAM enzyme is proposed. Moreover, antimicrobial assays, in conjunction with time-killing and biophysical studies, revealed that 1 and 2 exert potent bactericidal activities against a panel of methicillin-resistant pathogenic microbes.

Isolation and Synthesis of Novel Meroterpenoids from Rhodomyrtus tomentosa: Investigation of a Reactive Enetrione Intermediate

Rhodomyrtusials A-C, the first examples of triketone-sesquiterpene meroterpenoids featuring a unique 6/5/5/9/4 fused pentacyclic ring system were isolated from Rhodomyrtus tomentosa, along with several biogenetically-related dihydropyran isomers. Two bis-furans and one dihydropyran isomer showed acetylcholinesterase (AChE) inhibitory activity. Structures of the isolates were unambiguously established by a combination of spectroscopic data, ECD analysis, and total synthesis. Bioinspired total syntheses of six isolates were achieved in six steps utilizing a reactive enetrione intermediate generated in situ from a readily available hydroxy-endoperoxide precursor.

The Health Beneficial Properties of Rhodomyrtus tomentosa as Potential Functional Food

Rhodomyrtus tomentosa (Aiton) Hassk. is a flowering plant belonging to the family Myrtaceae, native to southern and southeastern Asia. It has been used in traditional Vietnamese, Chinese, and Malaysian medicine for a long time for the treatment of diarrhea, dysentery, gynecopathy, stomachache, and wound healing. Moreover, R. tomentosa is used to make various food products such as wine, tea, and jam. Notably, R. tomentosa has been known to contain structurally diverse and biologically active metabolites, thus serving as a potential resource for exploring novel functional agents. Up to now, numerous phenolic and terpenoid compounds from the leaves, root, or fruits of R. tomentosa have been identified, and their biological activities such as antioxidant, antibacterial, anti-inflammatory, and anticancer have been evidenced. In this contribution, an overview of R. tomentosa and its health beneficial properties was focused on and emphasized.

Structures and Bioactive Properties of Myrtucommulones and Related Acylphloroglucinols from Myrtaceae

Myrtaceae are a group of plants that include a number of renowned species used in ethnomedicine in many areas worldwide. Their valuable therapeutic properties have stimulated a fruitful research activity addressed to the identification of the bioactive components of their extracts yielding a great diversity of terpenes; polyphenols; and other exclusive products. Among the latter, starting with the discovery of myrtucommulone A from myrtle (Myrtus communis), a series of structurally-related acylphloroglucinol compounds have been characterized from several species that represent the basic active principles to be considered in view of possible drug development. Aspects concerning chemical and biological properties of these products are reviewed in the present paper.