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Gymnema inodorum (Lour.) Decne. (G. inodorum) is widely used in Northern Thai cuisine as local vegetables and commercial herb tea products. In the present study, G. inodorum extract (GIE) was evaluated for its antioxidant and anti-inflammatory effects in LPS plus IFN-γ-induced RAW264.7 cells. Major compounds in GIE were evaluated using GC-MS and found 16 volatile compounds presenting in the extract. GIE exhibited antioxidant activity by scavenging the intracellular reactive oxygen species (ROS) production and increasing superoxide dismutase 2 (SOD2) mRNA expression in LPS plus IFN-γ-induced RAW264.7 cells. GIE showed anti-inflammatory activity through suppressing nitric oxide (NO), proinflammatory cytokine production interleukin 6 (IL-6) and also downregulation of the expression of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and IL-6 mRNA levels in LPS plus IFN-γ-induced RAW264.7 cells. Mechanism studies showed that GIE suppressed the NF-κB p65 nuclear translocation and slightly decreased the phosphorylation of NF-κB p65 (p-NF-κB p65) protein. Our studies applied the synchrotron radiation-based FTIR microspectroscopy (SR-FTIR), supported by multivariate analysis, to identify the FTIR spectral changes based on macromolecule alterations occurring in RAW264.7 cells. SR-FTIR results demonstrated that the presence of LPS plus IFN-γ in RAW264.7 cells associated with the increase of amide I/amide II ratio (contributing to the alteration of secondary protein structure) and lipid content, whereas glycogen and other carbohydrate content were decreased. These findings lead us to believe that GIE may prevent oxidative damage by scavenging intracellular ROS production and activating the antioxidant gene, SOD2, expression. Therefore, it is possible that the antioxidant properties of GIE could modulate the inflammation process by regulating the ROS levels, which lead to the suppression of proinflammatory cytokines and genes. Therefore, GIE could be developed into a novel antioxidant and anti-inflammatory agent to treat and prevent diseases related to oxidative stress and inflammation.

The brown planthopper (BPH) Nilaparvata lugens (Stål) is a major insect pest of Oryza sativa that causes crop yield loss in tropical regions, including Thailand. In this study, the crude ethanolic extract of the leaves and branches of Combretum trifoliatum , its active isolated components, apigenin and camphor, and Finopril were tested for their ability to control the first to fifth instars of N. lugens. The C. trifoliatum crude extract and both allelochemicals showed insecticide potential (24 h-LC50 ~ 8.83–95.96 mg/L against each instar for crude extract), and their toxicity depended on the time of exposure. Camphor showed the higher efficacy (LD50 ~ 4.43 mg/L) and not different compared to Finopril. All plant compounds tested reduced carboxylesterase (CE) and glutathione-s-transferase (GST) activities. Camphor caused the greatest decreases in CE and GST activities after exposure, whereas apigenin induced a slight change in acetylcholinesterase activity. The results of the present study suggest that C. trifoliatum extract can be used as an insecticide to manage N. lugens populations.

Oroxylum indicum (L.) Kurz has been used as plant-based food and herbal medicine in many Asian countries. The aim of the present study was to examine the antioxidant and anti-inflammatory activities of O. indicum extract (O. indicum) in RAW264.7 cells activated by LPS plus IFN-γ. The phytochemical compounds in O. indicum were identified by GC-MS and LC-MS/MS. Five flavonoids (luteolin, apigenin, baicalein, oroxylin A, and quercetin) and 27 volatile compounds were found in O. indicum. O. indicum presented antioxidant activities, including reducing ability by FRAP assay and free radical scavenging activity by DPPH assay. Moreover, O. indicum also suppressed LPS plus IFN-γ-activated reactive oxygen species generation in RAW264.7 macrophages. It possessed the potent anti-inflammatory action through suppressing nitric oxide (NO) and IL-6 secretion, possibly due to its ability to scavenge intracellular ROS. The synchrotron radiation-based Fourier transform infrared (SR-FTIR) spectroscopy results showed the alteration of signal intensity and integrated areas relating to lipid and protein of the activated RAW264.7 macrophages compared to unactivated cells. This is the first report of an application of the SR-FTIR technique to evaluate biomolecular changes in activated RAW264.7 cells. Our results indicate that O. indicum may be used as a potential source of nutraceutical for the development of health food supplement or a novel anti-inflammatory herbal medicine.

Acne vulgaris is the most common dermatological problem among adolescents and young adults. Acne-associated pathogens, including Cutibacterium acnes and Staphylococcus epidermidis , and inflammation are among predominant etiologies of acne. Drugs targeting pathogens and inflammation response are an effective avenue to treat acne vulgaris. Rice bran has high pharmacological value, but its therapeutic potential for the treatment of acne remains unexplored. This study, therefore, aimed to purify and identify an anti-acne component from the ethanolic extract of Thai black rice ( Oryza sativa cv. Neow Dam 3) bran and to investigate its underlying mechanisms of action. Protocatechuic acid (PA) was purified by bio-guided extraction and identified by a nuclear magnetic resonance. The antibacterial action was elucidated by minimum inhibitory concentration (MIC) determination and electron microscopy. PA cytotoxicity in HaCaT keratinocytes was assessed by an MTT assay, expression of inflammatory-associated genes and proteins by RT-qPCR, western blotting, and ELISA, and the nuclear translocation of NF-κB by immunofluorescence. The MIC of PA against C. acnes DMST 14,916 and S. epidermidis ATCC 12,228 and DMST 14,932 was 2048 µg/mL, which was similar to ferulic acid. Scanning and transmission electron microscopy demonstrated C. acnes and S. epidermidis treated with PA had unambiguous membrane damage and abnormal morphology. C. acnes lysate induced the expression of IL-6 , IL-8 , IL-1β , iNOS , TNF-α , and COX-2 genes, increased phosphorylated NF-κB, IL-6, and TNF-α protein levels, and caused translocation of NF-κB into the nucleus, while noncytotoxic levels of PA suppressed these effects. In summary, PA had anti-acne activity by inhibiting acne-associated pathogens, possibly through cell membrane damage, and suppressed inflammation induced by C. acnes via the NF-κB pathway suggesting that it may have therapeutic use for treating acne in the future.

Skin damage and premature aging are predominantly driven by UV radiation through several mechanisms. The most common of these are by reactive oxygen species (ROS) generation, upregulation of matrix metalloproteinases (MMPs), and weakened antioxidant defenses. Moringa oleifera is a nutritionally valuable plant with diverse biological activities. This study optimized ethanol concentrations coupled with ultrasonic-assisted extraction to maximize the yield and efficacy of M. oleifera leaf extract (MOLE). We also elucidated the underlying mechanisms of MOLE in protecting against photooxidative damage and skin aging from UVB exposure in HaCaT keratinocytes. Extraction with 50% ethanol produced the highest total phenolic and flavonoid contents, aligning with the greatest antioxidant activity by ABTS and FRAP assays. MOLE showed no significant cytotoxicity up to 1000 µg/mL in the MTT assay. MOLE protected cells from detrimental UVB radiation by scavenging ROS; reducing cell damage and death; enhancing gene expression of superoxide dismutase (SOD-1), glutathione peroxidase (GPx), and catalase (CAT); and improving SOD activity. UVB exposure elevated MMP-1, MMP-3, and MMP-9 expression and decreased collagen type I (col-1) and elastin (ELN) expression, while these effects were ameliorated by MOLE. Our findings suggest that MOLE protected against UVB-induced photooxidative damage and premature aging in the HaCaT keratinocytes.

BackgroundPlant secondary metabolites or mixtures in extracts or essential oils are well known to enhance the activity in binary mixtures. The present study is the first to report that thymol synergistically or additively enhances the activity of P. ribesioides extracts and isolated compounds against S. exigua larvae at sublethal doses.ResultsThymol was synergistic when are mixed with hexane extract; however, if the hexane extract level was higher (LD30) than the thymol level (LD10), the reaction was antagonistic. CH2Cl2 extract and thymol were more toxic than the extract or thymol alone, and EtOAc extract was synergized by thymol if the components were combined at similar levels (1:1 thymol:EtOAc extract at the LD10 or LD30). MeOH extract individually had moderate insecticidal activity, but all combinations with thymol were synergistic as binary mixtures. Isolated compounds, piperine, phenethyl cinnamamide and cinnamic acid represented synergistic, additive, and antagonistic action after combining with thymol (1:1 at the LD10 or LD30). Detoxification enzymes after exposure of insects to treatments showed isolated compounds + thymol could inhibit CE, GST and AChE reaction of S. exigua exceptional being piperine + thymol, which induced detoxification enzyme activity.ConclusionThe synergistic activity was extract- and dose-specific. The impact on detoxification enzymes was variable and dependent on the composition of the extract and the doses of extract and thymol used in a binary mixture. In this metabolic model, the major insect compound in an extract may become detoxified, whereas a minor compound will act unimpeded, showing a lower LD50 than acting alone. This model suggests that thymol synergizes with extract components differently, which could depend on the specific metabolites in the extract and the dose applied. Such studies will help design effective insecticides based on natural plant mixtures and a synergistic compound.

Background Staphylococcus epidermidis is one of the most multiple resistances to antibiotics in the recent years. Therefore, practically-prescribed antibiotics in the treatment of these strains are not effective. Plant-derived antibacterial is one of the most interesting sources of new therapeutics. The present study was to investigate antibacterial, synergy and modes of action of quercetin and amoxicillin against amoxicillin-resistant Staphylococcus epidermidis (ARSE). Methods The MICs, checkerboard assay, viability curves, cytoplasmic membrane (CM) permeability, enzyme assay, transmission electron microscopy, confocal microscopy and FT-IR microspectroscopy measurement was performed. Results The MICs of amoxicillin, penicillin, quercetin and kaempferol against all ARSE strains were 16, 200, 256-384 and >1024 μg/mL respectively. Synergistic effects were exhibited on amoxicillin plus quercetin and penicillin plus kaempferol against these strains at FIC index 0.50 and <0.38 respectively. The synergistic activity of quercetin plus amoxicillin was confirmed by the viable count. This combination increased CM permeability, caused marked morphological, peptidoglycan and cytoplasmic membrane damage, increased protein amide I and II, but decreased fatty acid in bacterial cells. The quercetin had an inhibitory activity against β-lactamase. Conclusions So, these findings are the first report that quercetin has the synergistic effect with amoxicillin against ARSE via four modes of actions, inhibit peptidoglycan synthesis and β-lactamases activity, increase CM permeability and protein amide I and II but decrease fatty acid in bacterial cells. Of course, this flavonol has the dominant potential to develop a brand-new collateral phytochemical agent plus amoxicillin to treat ARSE. Future work should focus on the bioavailability, efficacy and toxicity in animal and human studies, as well as, the synergistic effect on blood and tissue should be evaluated and achieved.

Spodoptera litura Fabricius (Lepidoptera: Noctuidae) is one of the most destructive pests of various crops cultivated in Thailand. Spodoptera litura larvae, at early stages, attack the leaves and feed on every part of infested crops in later stages. Acorus calamus essential oil contains toxic asarones, which are generalistic cytotoxic compounds. However, the present study is the first attempt to look at safer metabolites from the rhizomes that could deter insect feeding. The objective was to use such compounds as safer residues on crops that would prevent the feeding of herbivorous lepidopterans. Accordingly, phenolic metabolites were isolated and evaluated to establish the feeding deterrence against polyphagous S. litura larvae. Methanol extract of A. calamus, chrysin, and 4-hydroxy acetophenone compounds were the most effective feeding deterrents with FD50 of 87.18, 10.33, and 70.77 µg/cm2, respectively, after 4 h of feeding on treated kale leaves in a no-choice leaf disc assay. Chrysin also reduced carboxylesterase activities (1.37-fold), whereas A. calamus methanol extract reduced glutathione-S-transferase activities (1.44-fold). Some larvae were also seen dead if they consumed the treated kale leaves. Feeding deterrent activity in the methanol extract of A. calamus was due to chrysin and 4-hydroxy acetophenone. The large-scale utilization of such compounds could help develop feeding deterrent strategies in the integrated pest management of lepidopterans. Graphical Abstract

Background Globally, staphylococci have developed resistance to many antibiotics. New approaches to chemotherapy are needed and one such approach could be to use plant derived actives with conventional antibiotics in a synergestic way. The purpose of this study was to isolate α-mangostin from the mangosteen ( Garcinia mangostana L.; GML) and investigate antibacterial activity and mechanisms of action when used singly and when combined with oxacillin against oxacillin-resistant Staphylococcus saprophyticus (ORSS) strains. The isolated α-mangostin was confirmed by HPLC chromatogram and NMR spectroscopy. The minimum inhibitory concentration (MIC), checkerboard and killing curve were determined. The modes of action of these compounds were also investigated by enzyme assay, transmission electron microscopy (TEM), confocal microscopic images, and cytoplasmic membrane (CM) permeabilization studies. Results The MICs of isolated α-mangostin and oxacillin against these strains were 8 and 128 μg/ml, respectively. Checkerboard assays showed the synergistic activity of isolated α-mangostin (2 μg/ml) plus oxacillin (16 μg/ml) at a fractional inhibitory concentration index (FICI) of 0.37. The kill curve assay confirmed that the viability of oxacillin-resistant Staphylococcus saprophyticus DMST 27055 (ORSS-27055) was dramatically reduced after exposure to isolated α-mangostin (2 μg/ml) plus oxacillin (16 μg/ml). Enzyme assays demonstrated that isolated α-mangostin had an inhibitory activity against β-lactamase in a dose-dependent manner. TEM results clearly showed that these ORSS-27055 cells treated with this combination caused peptidoglycan and cytoplasmic membrane damage, irregular cell shapes and average cell areas were significantly larger than the control. Clearly, confocal microscopic images confirmed that this combination caused considerable peptidoglycan damage and DNA leakage. In addition, the CM permeability of ORSS-27055 was also increased by this combination of actives. Conclusions These findings provide evidence that isolated α-mangostin alone has not only some activity but also shows the synergistic activity with oxacillin against ORSS-27055. The chromone and isoprenyl structures could play a significant role in its action. This synergistic activity may involve three mechanisms of action. Firstly, potential effects of cytoplasmic membrane disruption and increases permeability. Secondly, inhibit β-lactamase activity. Finally, also damage to the peptidoglycan structure. We proposes the potential to develop a novel adjunct phytopharmaceutical to oxacillin for the treatment of ORSS. Future studies require clinical trials to establish if the synergy reported can be translated to animals and humans.

Spodoptera litura Fabricius (Lepidoptera: Noctuidae) is one of the most destructive pests of various crops cultivated in Thailand. Spodoptera litura larvae, at early stages, attack the leaves and feed on every part of infested crops in later stages. Acorus calamus essential oil contains toxic asarones, which are generalistic cytotoxic compounds. However, the present study is the first attempt to look at safer metabolites from the rhizomes that could deter insect feeding. The objective was to use such compounds as safer residues on crops that would prevent the feeding of herbivorous lepidopterans. Accordingly, phenolic metabolites were isolated and evaluated to establish the feeding deterrence against polyphagous S. litura larvae. Methanol extract of A. calamus, chrysin, and 4-hydroxy acetophenone compounds were the most effective feeding deterrents with F[D.sub.50] of 87.18, 10.33, and 70.77 [micro]g/[cm.sup.2], respectively, after 4 h of feeding on treated kale leaves in a no-choice leaf disc assay. Chrysin also reduced carboxylesterase activities (1.37-fold), whereas A. calamus methanol extract reduced glutathione-S-transferase activities (1.44-fold). Some larvae were also seen dead if they consumed the treated kale leaves. Feeding deterrent activity in the methanol extract of A. calamus was due to chrysin and 4-hydroxy acetophenone. The large-scale utilization of such compounds could help develop feeding deterrent strategies in the integrated pest management of lepidopterans. Key words: Acorus calamus, chrysin, 4-hydroxy acetophenone, feeding deterrent, Spodoptera litura