Explore the vast range of titles available.

Rhodomyrtus tomentosa fruits, endemic to the Western Ghats were analyzed for its free, bound and esterified phenolics by Ultra High Performance Liquid Chromatography–Mass Spectrometry. Overall, twenty-nine phenolic compounds were identified, amongst them 18 were detected in this fruit for the first time. Gallic acid (80.44 ± 8.74 mg/100 g) and ellagic acid (107.47 ± 7.28 mg/100 g) were the most prominent ones found in the bound phenolic fraction and gallic acid (103.76 ± 6.34 mg/100 g) in the esterified phenolic fraction of the fruit, respectively. Total Phenolic content was found to be highest in bound phenolics (7.09 ± 0.17 mg Gallic acid equivalent/g). The antioxidant and antimicrobial activities of the three extracts namely free, bound and esterified phenolic fruit fractions have been analyzed. Bound phenolics exhibited the highest antioxidant potential (DPPH-15.63 ± 0.86; ABTS-34.73 ± 0.07; FRAP-17.89 ± 0.27 mg/g Ascorbic acid equivalent). The bound phenolics showed good antimicrobial activity against Bacillus cereus, Staphylococcus aureus and Escherichia coli with a MIC of 0.156, 0.625 and 1.25 mg/mL respectively. The exploration of phenolic compounds in Indian variety of Rhodomyrtus tomentosa fruits may provide useful insights on its utilization as a functional food ingredient.

Extraction of polysaccharides from Rhodomyrtus tomentosa berry (RTP) is essential for understanding their bioactive ingredients and developing functional foods and pharmaceuticals. This study aimed to evaluate the effects of ultrasonic-assisted enzymatic extraction (UAE) and microwave-assisted enzymatic extraction (MAE) on the yield, physicochemical properties, and antioxidant activity of RTP. The results revealed that the optimal conditions for RTP extraction using the UAE were as follows: liquid-solid ratio 35 ml/g; ultrasonic time of 11 min, ultrasonic power of 240 W, and complex enzyme dosage of 2.5%. Under these conditions, the extraction yield was 35.67 ± 0.32%. The FTIR results indicated that the two extraction methods did not affect the functional groups of the polysaccharides. The scanning electron microscopy results indicated that the surface of the UAE-extracted samples showed folds, fibrous structures, and a large number of small pores, which may be more effective in releasing the polysaccharides. Whereas the sample surface was smoother after MAE treatment. The ABTS radical scavenging ability of UAE was significantly higher than that of MAE. This study demonstrated that the UAE method is a promising method for extracting high-quality RTP based on its high yield, high efficiency, and outstanding antioxidant activity.

Rhodomyrtus tomentosa leaf (RT)-incorporated transferosomes were developed with lecithin and cholesterol blends with edge activators at different ratios. RT-transferosomes were characterized and employed in transferosomal gel formulations for the management of skin and soft-tissue infections. The optimized formulation entrapped up to 81.90 ± 0.31% of RT with spherical vesicles (405.3 ± 2.0 nm), polydispersity index value of 0.16 ± 0.08, and zeta potential of − 61.62 ± 0.86 mV. Total phenolic and flavonoid contents of RT-transferosomes were 15.65 ± 0.04 μg GAE/g extract and 43.13 ± 0.91 μg QE/g extract, respectively. RT-transferosomes demonstrated minimum inhibitory and minimum bactericidal concentrations at 8–256 and 64–1024 μg/mL, respectively. Free radical scavenging assay showed RT-transferosomes with high scavenging activity against DPPH and ABTS radicals. Moreover, RT-transferosomes demonstrated moderate activity against mushroom tyrosinase, with IC50 values of 245.32 ± 1.32 μg/mL. The biocompatibility results against L929 fibroblast and Vero cells demonstrated IC50 at 7.05 ± 0.17 and 4.73 ± 0.13 μg/mL, respectively. In addition, nitric oxide production significantly decreased by 6.78–88.25% following the treatment with 31.2–500 ng/mL RT-transferosomes (p < 0.001). Furthermore, the freeze–thaw stability study displayed no significant change in stability in the sedimentation and pH of gel fortified with RT-transferosomes. The results suggested that RT-transferosome formulation can be effectively employed as natural biomedicines for scar prevention and the management of skin soft-tissue infections.

Purpose: Water hyacinth (WH) is an aquatic weed that has negatively impacted aquatic ecosystems. WH can be easily composted and used as a soil ameliorant to improve plant growth. In this study, the effects of WH compost on the growth of Rhodomyrtus tomentosa were evaluated. Methods: Native R. tomentosa seedlings were cultivated with WH compost in two different systems: a pot cultivation with soil: WH compost mixed in ratios ranging from 10:0 to 7:3 and an open field cultivation with 1 to 3 parts of WH added to the topsoil. Plant growth characteristics and rhodomyrtone yield were also investigated. Results: Plant height and numbers of stems were not significantly different between the two cultivation methods (p>0.05). Plants treated with WH compost had more leaves than those not treated with WH compost (p<0.05). Growing the plants with WH compost resulted in significant increases in leaf biomass, especially, rhodomyrtone content in both cultivation systems. In the pot cultivation system, the highest rhodomyrtone yield (0.99 mg/mL) was obtained from R. tomentosa leaf from plants growing in a soil and coconut coir medium enriched with 1 part of WH compost by volume. In the field cultivation system, the highest rhodomyrtone yield (0.86 mg/mL) was obtained from R. tomentosa leaf sampling from plants growing in soil with 1 part of WH  added to the soil at the planting period and once every month. Conclusion: WH compost demonstrated its potential for sustainable cultivation of R. tomentosa that can be fruitfully propagated for commercial purposes. 

Rhodomyrtus tomentosa fruits serve as both functional food and medicinal resources due to their rich bioactive constituents and manifold pharmacological effects. Phytochemical exploration of the R. tomentosa fruits led to the identification of eight new polymethylated phloroglucinols, designated as rhodotomentodione F ( 1 ) and rhodotomentodimers H‒N ( 2 ‒ 8 ), along with six previously described congeners ( 9 ‒ 14 ). Based on the detailed inspection of comprehensive spectroscopic data, electronic circular dichroism (ECD) simulations, and nuclear magnetic resonance (NMR) calculations, and DP4+ analyses, the structures of phloroglucinols 1 ‒ 8 were determined. Heterodimeric phloroglucinols 3 ‒ 14 exhibited human acetylcholinesterase ( h AChE) inhibitory activities, with 13 exhibiting the highest potency (IC 50  = 1.04 μM). Moreover, molecular docking analysis clarified the potential binding interactions between the most active phloroglucinol 13 with h AChE. In addition, phloroglucinols 11 and 12 displayed significant anti-VRE (vancomycin-resistant Enterococci ) activities, with MIC values reaching as low as 1 μg/mL. Graphical Abstract

ObjectiveSilver nanoparticles synthesized using Rhodomyrtus tomentosa leaf extract and silk sericin were used to functionalize carbopol 940 gel for topical applications.ResultsUV–vis spectra presented surface plasmon resonance at 426 nm, transmission electron microscopy revealed that nanoparticles were spherical with an average size of 25–50 nm. X-ray diffraction presented crystalline silver nanoparticles with zeta potential of ≈ − 30 mV. FTIR spectra showed a reduction of silver nitrate indicated by the shift in –OH at 2958 cm–1. The silver nanoparticle demonstrated broad-spectrum antimicrobial activity against Gram-positive, Gram-negative and fungi with MIC ranging between 0.26 and 2.10 μg mL−1, respectively. MIC of hydrogel ranged between 1.05–2.10 μg mL−1 with cell viability of 89%. Spreadability and extrudability of gel were 9.3 ± 0.85 s and 19.85 ± 0.03%, respectively with first order of fickian diffusion.ConclusionsThe silver nanoparticle gel exhibited an effective antimicrobial property, hence can be exploited for topical applications.

Rhodomyrtus tomentosa fruit (RTF) has been known as a food source with multiple health-care components. In this work, nutrition characteristics, free and bound phenolic profiles, antioxidant properties in vitro and digestive enzymes inhibitory activities of un-fully mature RTF (UM-RTF) and fully mature RTF (FM-RTF) were evaluated for the first time. Results verified that high levels of energy, ascorbic acid, organic acids and total phenolics were observed in FM-RTF. Moreover, FM-RTF had significant higher total phenolic content (TPC), but significantly lower total flavonoid content (TFC) than UM-RTF. In addition, twenty phenolic compounds in RTF were identified by high performance liquid chromatography–electrospray ionization–quadrupole time-of-flight tandem mass spectrometry (HPLC-ESI-qTOF-MS/MS) method. Quantitative analysis results indicated that gallic acid, ellagic acid and astragalin were the predominant free phenolics, while gallic acid and syringetin-3-O-glucoside were dominant in bound phenolic fractions. In contrast, higher contents of phenolics were observed in FM-RTF. The results also confirmed that FM-RTF exhibited higher antioxidant activities and digestive enzymes inhibitory activities than UM-RTF. Strong inhibitory ability on α-glucosidase was found in RTF, while bound phenolics showed a stronger α-amylase inhibitory effect than free phenolics. Moreover, the interaction between the main phenolic compounds and α-glucosidase/α-amylase was preliminary explored by molecular docking analysis. The results provided valuable data about the chemical compositions and biological potential of R. tomentosa fruits in both maturation stages studied.

The invasive rust Puccinia psidii (myrtle rust) was detected in Australia in 2010 and is now established along the east coast from southern New South Wales to far north Queensland. Prior to reaching Australia, severe damage from P. psidii was mainly restricted to exotic eucalypt plantations in South America, guava plantations in Brazil, allspice plantations in Jamaica, and exotic Myrtaceous tree species in the USA; the only previous record of widespread damage in native environments is of endangered Eugenia koolauensis in Hawai’i. Using two rainforest tree species as indicators of the impact of P. psidii, we report for the first time severe damage to endemic Myrtaceae in native forests in Australia, after only 4 years’ exposure to P. psidii. A 3-year disease exclusion trial in a natural stand of Rhodamnia rubescens unequivocally showed that repeated, severe infection leads to gradual crown loss and ultimately tree mortality; trees were killed in less than 4 years. Significant (p < 0.001) correlations were found between both incidence (r = 0.36) and severity (r = 0.38) of P. psidii and subsequent crown loss (crown transparency). This provided supporting evidence to conclude a causal association between P. psidii and crown loss and tree mortality in our field assessments of R. rubescens and Rhodomyrtus psidioides across their native range. Assessments revealed high levels of damage by P. psidii to immature leaves, shoots and tree crowns—averaging 76 % (R. rubescens) and 95 % (R. psidioides) crown transparency—as well as tree mortality. For R. psidioides, we saw exceptionally high levels of tree mortality, with over half the trees surveyed dead and 40 % of stands with greater than 50 % tree mortality, including two stands where all trees were dead. Tree mortality was less prevalent for R. rubescens, with only 12 % of trees surveyed dead and two sites with greater than 50 % mortality. Any alternative causal agents for this tree mortality have been discounted. The ecological implications of this are unclear, but our work clearly illustrates the potential for P. psidii to negatively affect Australia’s biodiversity.

The acylphloroglucinol rhodomyrtone is a promising new antibiotic isolated from the rose myrtle Rhodomyrtus tomentosa, a plant used in Asian traditional medicine. While many studies have demonstrated its antibacterial potential in a variety of clinical applications, very little is known about the mechanism of action of rhodomyrtone. Preceding studies have been focused on intracellular targets, but no specific intracellular protein could be confirmed as main target. Using live cell, high-resolution, and electron microscopy we demonstrate that rhodomyrtone causes large membrane invaginations with a dramatic increase in fluidity, which attract a broad range of membrane proteins. Invaginations then form intracellular vesicles, thereby trapping these proteins. Aberrant protein localization impairs several cellular functions, including the respiratory chain and the ATP synthase complex. Being uncharged and devoid of a particular amphipathic structure, rhodomyrtone did not seem to be a typical membrane-inserting molecule. In fact, molecular dynamics simulations showed that instead of inserting into the bilayer, rhodomyrtone transiently binds to phospholipid head groups and causes distortion of lipid packing, providing explanations for membrane fluidization and induction of membrane curvature. Both its transient binding mode and its ability to form protein-trapping membrane vesicles are unique, making it an attractive new antibiotic candidate with a novel mechanism of action.

Background Rose myrtle ( Rhodomyrtus tomentosa (Ait.) Hassk), is an evergreen shrub species belonging to the family Myrtaceae, which is enriched with bioactive volatiles (α-pinene and β-caryophyllene) with medicinal and industrial applications. However, the mechanism underlying the volatile accumulation in the rose myrtle is still unclear. Results Here, we present a chromosome-level genomic assembly of rose myrtle (genome size = 466 Mb, scaffold N50 = 43.7 Mb) with 35,554 protein-coding genes predicted. Through comparative genomic analysis, we found that gene expansion and duplication had a potential contribution to the accumulation of volatile substances. We proposed that the action of positive selection was significantly involved in volatile accumulation. We identified 43 TPS genes in R. tomentosa . Further transcriptomic and TPS gene family analyses demonstrated that the distinct gene subgroups of TPS may contribute greatly to the biosynthesis and accumulation of different volatiles in the Myrtle family of shrubs and trees. The results suggested that the diversity of TPS-a subgroups led to the accumulation of special sesquiterpenes in different plants of the Myrtaceae family. Conclusions The high quality chromosome-level rose myrtle genome and the comparative analysis of TPS gene family open new avenues for obtaining a higher commercial value of essential oils in medical plants.