Phytochemical Contents and Antioxidant Activity of Medicinal Plants from the Rubiaceae Family in Thailand

Several plants of the Rubiaceae family possess potential pharmacological properties, such as antioxidant activity, for subsequent drug development. We investigated the methanolic extracts from the bark and wood of five Rubiaceae species for phenolic and flavonoid contents and antioxidant activity. Regarding the phytochemical contents and antioxidant activity, Mitragyna diversifolia wood (437.57 ± 9.90 mg GAE g-1) and Haldina cordifolia wood (30.11 ± 0.20 mg QE g-1) displayed the highest total phenolic content (TPC) and total flavonoid content (TFC) respectively. Morinda coreia bark followed the highest antioxidant activities (IC50 = 360.58 ± 19.28 µg ml-1) in the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH), Catunaregam tomentosa bark (IC50 = 13.96 ± 5.32 µg ml-1) in the nitric oxide radical scavenging activity (NO), M. coreia wood (IC50 = 918.27 ± 0.16 µg ml-1) in the superoxide radical scavenging activity (SO) and M. coreia wood (IC50 = 236.65 ± 1.66 µg ml-1) in ferric reducing antioxidant power activity (FRAP). The TPC and TFC displayed strong correlations with DPPH in M. diversifolia wood and with FRAP in M. diversifolia bark and wood. We found high correlation between TFC and FRAP in all plant extracts except C. tomentosa wood, while no relation was detected between TFC and NO in all plant extracts. Comparing Rubiaceae species, the highest antioxidant potential were showed in C. tomentosa bark. Overall, it is worth mentioning that the Rubiaceae species exhibit potential as a promising source of natural antioxidants

GC-MS profiling, anti-oxidant and anti-diabetic assessments of extracts from microalgae Scenedesmus falcatus (KU.B1) and Chlorella sorokiniana (KU.B2)

Microalgae are a potentially valuable source in the food, pharmaceutical and nutraceutical sectors. While biological activities surveys have investigated the pharmaceutical properties of a few microalgae species, there are not many reports covering biological activity studies. This study was carried out to identify the metabolites by gas chromatography-mass spectrometry and evaluate the anti-oxidant, anti-diabetic properties of green algae extracts, Chlorella sorokiniana (KU.B2) and Scenedesmus falcatus (KU.B1). A total of 51 different chemical constituents were detected and tentatively identified. The primary compounds in both microalgae extracts included (R)-2-hexanol (38.67% in C. sorokiniana and 23.53% in S. falcatus), n-hexadecanoic acid (13.58% in C. sorokiniana and 18.94% in S. falcatus) and octadecanoic acid (22.30% in C. sorokiniana and 32.67% in S. falcatus). According to the profiling results, the C. sorokiniana extract exhibited greater anti-oxidant activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging (IC50 = 480.30 ±?14.85 µg ml-1), nitric oxide (NO) radical scavenging (562.73 ±?3.52 µg mL-1) and ferric reducing anti-oxidant power (FRAP) of 58.51 ± 2.42 mgTE g-1. Comparatively, the C. sorokiniana extract had higher contents of alpha-glucosidase and alpha-amylase (IC50 = 491.22 ± 78.41 and 2,817.00 ±143.04 µg mL-1, respectively) than the S. falcatus extract. This first report demonstrated anti-diabetic effect of both extracts on diabetic enzymes. The results confirm microalgae's anti-oxidant and anti-diabetic properties and suggest their potential benefits in cosmeceutical, nutraceutical and pharmaceutical applications

Inhibition of Proinflammatory Enzymes and Attenuation of IL-6 in LPS-Challenged RAW 264.7 Macrophages Substantiates the Ethnomedicinal Use of the Herbal Drug Homalium bhamoense Cubitt & W.W.Sm

Commonly used to treat skin injuries in Asia, several Homalium spp. have been found to promote skin regeneration and wound healing. While ethnobotanical surveys report the use of H. bhamoense trunk bark as a wound salve, there are no studies covering bioactive properties. As impaired cutaneous healing is characterized by excessive inflammation, a series of inflammatory mediators involved in wound healing were targeted with a methanol extract obtained from H. bhamoense trunk bark. Results showed concentration-dependent inhibition of hyaluronidase and 5-lipoxygenase upon exposure to the extract, with IC50 values of 396.9 ± 25.7 and 29.0 ± 2.3 µg mL−1, respectively. H. bhamoense trunk bark extract also exerted anti-inflammatory activity by significantly suppressing the overproduction of interleukin 6 (IL-6) in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages at concentrations ranging from 125 to 1000 µg mL−1, while leading to a biphasic effect on nitric oxide (NO) and tumor necrosis factor alpha (TNF-α) levels. The phenolic profile was elucidated by HPLC-DAD, being characterized by the occurrence of ellagic acid as the main constituent, in addition to a series of methylated derivatives, which might underlie the observed anti-inflammatory effects. Our findings provide in vitro data on anti-inflammatory ability of H. bhamoense trunk bark, disclosing also potential cutaneous toxicity as assessed in HaCaT keratinocytes

Kitul, a food plant with antidiabetic-like effects: Reduction of intracellular reactive species in glucose-stimulated RIN-5F pancreatic β-cells and mitigation of pro-inflammatory mediators in activated RAW 264.7 macrophages

Kitul (Caryota urens L.) inflorescences are broadly used for sweet sap production in Asian countries and Kitul food products are known as being suitable for diabetic patients. Considering the strong ability to inhibit α-glucosidase, we hypothesize that kitul antidiabetic properties might also involve the modulation of inflammatory pathways and hyperglycaemia-induced oxidative damage. Hence, the effects of an inflorescence’s methanol extract were investigated in glucose-stimulated pancreatic cells (RIN-5F) and LPS-stimulated RAW 264.7 macrophages. The extract reduced the overproduction of intracellular reactive species in pancreatic cells and also NO, L-citrulline and IL-6 levels in LPS-stimulated RAW 264.7 macrophages. Inhibition of 5-lipoxygenase (IC50 = 166.1 µg/mL) through an uncompetitive manner was also recorded upon treatment with C. urens inflorescences extract. The phenolic profile of the inflorescences was characterized by HPLC-DAD, six hydroxycinnamic acids being identified and quantified. Overall, our data provide additional evidence on the pleiotropic mechanisms of Kitul inflorescences as an antidiabetic agentCatarina Andrade thanks FCT/MCTES (Fundação para a Ciência e Tecnologia and Ministério da Ciência, Tecnologia e Ensino Superior) and ESF (European Social Fund) through NORTE 2020 (Programa Operacional Região Norte) for her PhD grant ref. SFRH/BD/131431/2017. Nelson Gomes thanks FCT (Fundação para a Ciência e Tecnologia) for funding through the Scientific Employment Stimulus - Individual Call (Ref. CEECIND/03037/2017)Peer reviewe

Valorisation of the industrial waste of Chukrasia tabularis A.Juss.: Characterization of the leaves phenolic constituents and antidiabetic-like effects

Chukrasia tabularis A.Juss. is a canopy tree widely distributed in Asia and commonly used for construction-grade timber. While the residues resulting from the timber exploration constitute the major source of waste, other parts of the plant remain underutilized. Therefore, aiming the valorisation of a major residue resulting from C. tabularis wood industry, the leaves were here investigated on their potential content in bioactive constituents, but also on their capacity to modulate mediators and enzymes engaged in metabolic disorders, particularly those involved on the development and progression of diabetes. HPLC–DAD–ESI/MS and UPLC-ESI-QTOF-MS characterization of a methanol extract obtained from the leaves, allowed the identification of 25 phenolic constituents, quercetin-3-O-rhamnoside being identified as the main bioactive. The leaf extract and the major flavonoid (quercetin-3-O-rhamnoside) were investigated on their impact towards a series of targets involved in the physiopathology of diabetes. The extract displayed significant scavenging properties against nitric oxide and superoxide radicals, inhibiting also lipid peroxidation and aldose reductase activity. While no noteworthy effects were noted on pancreatic lipase and α-amylase activity, the extract strongly inhibited α-glucosidase (IC = 21.14 µg/mL) and proved to be ca. 5 times more effective than the benchmark drug, acarbose. Moreover, the leaf extract significantly inhibited also 5-lipoxygenase (5-LOX) (IC = 13.12 µg/mL). Kinetic studies on α-glucosidase and 5-LOX activity disclosed a mixed type inhibition. Furthermore, C. tabularis extract reduced LPS-induced overproduction of NO, L-citrulline and IL-6 in activated RAW 264.7 macrophages. When individually assayed, quercetin-3-O-rhamnoside significantly contributed to the antiradical properties and inhibitory effects of the extract upon the enzymatic targets, but other phenolic bioactives appear also to underlie the recorded anti-inflammatory effects. Taken together, our results demonstrate that the leaves of C. tabularis are rich in phenolic constituents with a great potential to improve metabolic disorders. The evidenced bioactivity of this industrial product might feed R&D programs for the development of new drugs that might simultaneously improve glycaemic, oxidative and inflammatory benchmarks in diabetic patients.The work was supported through the project UIDB/50006/2020, funded by FCT (Fundação para a Ciência e Tecnologia) /MCTES (Ministério da Ciência, Tecnologia e Ensino Superior) through national funds. This work was also supported by the Bilateral Research Cooperation (BRC), Department of Botany, Faculty of Science, Kasetsart University, The Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission and Strengthening and Developing New Researcher Plan, in conformance with the Research and Innovation of Graduate study Strategy of the National Research Council of Thailand (NRCT) as of the fiscal year 2019. C. Andrade thanks FCT and ESF (European Social Fund) through POCH (Programa Operacional Capital Humano) for her PhD grant ref. SFRH/BD/131431/2017. N. Gomes is indebted to national funds through FCT, under the project CEECIND/03037/201

Phenolic profiling and biological potential of ficus curtipes corner leaves and stem bark: 5-Lipoxygenase inhibition and interference with NO levels in LPS-stimulated RAW 264.7 macrophages

The economic value of fig trees has been globally acknowledged due to their utilization in the food industry, being also frequently used in traditional medicine. While ubiquitously distributed in Southeast Asia, Ficus curtipes Corner remains uninvestigated concerning its biological properties and chemical profile. HPLC-DAD-ESI/MSn characterization of methanol extracts obtained from the stem bark and leaves allowed the identification and quantitation of 21 phenolic compounds for the first time; the stem bark was predominantly rich in flavan-3-ols and apigenin derivatives, while solely apigenin-di-glycosides have been identified and quantitated on the leaf extract. Both extracts inhibited 5-lipoxygenase (5-LOX) activity in a concentration-dependent manner, the one obtained from the stem bark being significantly more active (IC50 = 10.75 μg/mL). The effect of both extracts on lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages was evaluated, and while the stem bark extract did not lead to a noticeable interference on nitric oxide (NO) levels, the extract obtained from the leaves notably decreased NO and L-citrulline levels at concentrations ranging from 250 to 500 μg/mL. Herein, F. curtipes is valorized due to its modulatory effects on inflammatory mediators and also as a source of bioactive phenols, which may fuel further studies on the development of nutraceuticals.The work was supported by UID/QUI/50006/2019 with funding from FCT/MCTES through national funds, and by Programa de Cooperación Interreg V-A España—Portugal (POCTEP) 2014–2020 (project 0377_IBERPHENOL_6_E). This work was also supported by national funds through FCT—Fundação para Ciência e a Tecnologia, I.P., under the project CEECIND/03037/2017. C. Andrade thanks FCT—Fundação para Ciência e a Tecnologia, I.P. for the grant SFRH/BD/131431/2017.Peer reviewe

Valorisation of kitul, an overlooked food plant: Phenolic profiling of fruits and inflorescences and assessment of their effects on diabetes-related targets

Caryota urens L. has long been valued as a traditional food, the edible fruits being eaten raw and the inflorescences commonly used on sweet sap and flour production. In the current work, the phenolic profile of methanol extracts obtained from the inflorescences and fruits was unveiled for the first time, nine caffeic acid derivatives being identified and quantified. Since kitul products have been reported for their antidiabetic properties, extracts radical scavenging activity and α-amylase, α-glucosidase and aldose reductase inhibitory activity were assessed. The inflorescences’ extract was particularly active against yeast α-glucosidase (IC = 1.53 μg/mL), acting through a non-competitive inhibitory mechanism. This activity was also observed in enzyme-enriched homogenates obtained from human Caco-2 cells (IC = 64.75 µg/mL). Additionally, the extract obtained from the inflorescences showed no cytotoxicity on HepG2, AGS and Caco-2 cell lines. Our data suggest that C. urens inflorescences can support the development of new functional foods with α-glucosidase inhibitory activity.Acknowledgements The work was supported by UIDB/50006/2020 with funding from Fig. 5. Effects of C. urens INF methanolic extract on (A) AGS, (B) HepG2 and (C) Caco-2 cell viability. (D) INF methanolextract inhibition of human α-glucosidase inhibition obtained from Caco-2 cells homogenates. Data represent the mean ± SD of at least three independent experiments, performed in triplicate. F. Ferreres, et al. Food Chemistry 342 (2021) 128323 8 FCT/MCTES through national funds, and by Programa de Cooperación Interreg V-A España – Portugal (POCTEP) 2014–2020 (project 0377_IBERPHENOL_6_E). N. Gomes is indebted to national funds through FCT - Fundação para a Ciência e a Tecnologia, I.P., under the project CEECIND/03037/2017. C. Andrade thanks FCT - Fundação para Ciência e a Tecnologia, I.P. for the grant SFRH/BD/131431/201