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The presented work deals with the titanium dioxide semiconductor-based dye-sensitized solar cell (DSSC) performance analysis. The DSSC is sensitized with natural dye extracted from Carissa spinarum fruit with iodide-Tri-iodide as an electrolyte and graphite coated transparent conducting oxide as back electrode. The dye characteristics were investigated by Fourier transform infrared, ultraviolet-visible, and photoluminescence spectroscopy to study the associated functional groups, optical band gap, and emission, respectively. The understudied dye showed an absorption edge at 530nm with an optical band gap around 2.2eV and a broad emission band from 630 to 820nm and with a sharp peak at 741nm. Cyclic voltammograms were employed to estimate the energy levels of the understudy sensitizer. This well-characterized dye has been successfully used in DSSC, and its photovoltaic response was studied under-stimulated AM 1.5 solar illumination using 100mWcm-2 light intensity. For this cell, the short circuit current density (JSC) was 4.17mAcm-2 and the open circuit voltage was 0.423V leading to the power conversion efficiency of 0.956%. Furthermore, this device was also subjected to an open-circuit voltage decay study. We also calculated the lifetime of decay, series resistance (RS), saturation current (IS), shunt resistance (RSh), and the ideality factor (n). Also, an in-depth investigation related to recombination phenomena and how these associated parameters influence the cell's photovoltaic (PV) properties was carried out. The PV performance was also tested in different wavelengths (red, green, blue, etc.) and various useful parameters were calculated.

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Background: The root bark of Carissa spinarum Linn. (Apocynaceae) is claimed to be used for the management of depression in Ethiopian folkloric medicine, and the crude extract has been reported to possess antidepressant-like activity in rodents. Objective: This study aimed to evaluate the antidepressant-like effect of different fractions of the root bark in rodents and the possible underlying mechanisms in rats. Methods: A 70% ethanol extract of the root bark was successively fractionated with n-butanol, ethyl acetate, and water. Animals of both sexes received 2% Tween 80, imipramine (30 mg/kg), or various doses (50, 100, 200 mg/kg) of the fractions. Duration of immobility was determined using the tail suspension test and the forced swim test. Locomotor activity was evaluated in the open field test. Serum corticosterone levels, total phenols, flavonoids, and alkaloids were determined. Preliminary mechanistic studies were also performed to explore possible mechanisms of action of the active fraction. Results: All fractions but the aqueous fraction significantly (p<0.001) decreased the duration of immobility in both tests, with the ethyl acetate fraction being the most active. The locomotor test revealed that the activity was not due to non-specific psycho-stimulant effects. Serum corticosterone levels were reduced by both fractions, with the ethyl acetate fraction again being the most effective. Mechanistic studies showed the involvement of multiple neurotransmission systems, including adrenergic, dopaminergic and cholinergic as well as L-Arginine-NO-cGMP pathway. Higher contents of phenols (42.42 vs 29.8 mgGAE/g), flavonoids (12.43 vs 2.07 mgQE/g), and alkaloids (0.17 vs 0.07 mgATE/g) were found in the ethyl acetate than in the n-butanol fraction. Conclusion: The present findings collectively indicate that the ethyl acetate and n-butanol fractions are endowed with antidepressant-like activity due to the presence of phenols, flavonoids, and alkaloids, which are medium polar in nature.

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Background: Among many traditionally used medicinal plants, Carissa spinarum (Agam) is a well-known indigenous plant in Ethiopia. It is used in its raw form to treat different diseases in different parts of the country. Therefore, the aim of this study is to investigate extraction, isolation, and determination of the antibacterial properties of the solvent leaf extract of Carissa spinarum. Methods: In this study, 800 g of powdered leaves of Carissa spinarum were macerated with 2500 mL of methanol and yielded 58 g (7.25%, w/w) of gummy material. The extract was then further partitioned by using ethyl acetate and chloroform. The extracts were subjected to phytochemical screening test. The antibacterial activity of the three solvent leaf extracts of Carissa spinarum were evaluated using disc diffusion method. The methanol extract was subjected to column chromatography silica gel (60-200 mesh) by mixing methanol:petroleum ether (4:1). Then fractions were collected and investigated by TLC and finally identified using spectroscopy. Results: The three extracts (methanol, ethyl acetate, and chloroform) of Carissa spinarum were presented to antimicrobial activity by disc diffusion method against four bacterial species using gentamycin and ampicillin discs as positive controls and DMSO as a negative control. All extracts had a relatively antibacterial effect with different extent zones of inhibition. However, the methanol extract showed superior antibacterial activity compared with DMSO and ethyl acetate and chloroform extracts. These could due to variation of the phytoconstituents. The most probable structure of the compound isolated was 5-(2',3',4',6'-tetrahydroxy-5'-methoxycyclohexyloxy)-2,3,4 trihydroxypentanoic acid. Conclusion: Data obtained from this study collectively indicated that the three solvent extracts of Carissa spinarum have a promising antimicrobial activity which supports the traditional claim of the plant for treatment of infection.

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Carissa spinarum Linn. has been utilized both in the food industry and as a traditional medicine for various ailments, while the responsible chemical components and action mechanisms of its antioxidative and hepatoprotective activities remain unclear. In this work, at least 17 quinic acid derivatives as potential ligands for the superoxide dismutase (SOD) enzyme from Carissa spinarum L. were screened out using the bio-affinity ultrafiltration with liquid chromatography mass spectrometry (UF-LC/MS), and 12 of them (1-12), including, three new ones (1-3), were further isolated by phytochemical methods and identified by high resolution electrospray ionization mass spectrometry (HR-ESI-MS) and extensive nuclear magnetic resonance (NMR) spectroscopic analysis. All of these isolated compounds were evaluated for their antioxidant activities by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric-reducing antioxidant power (FRAP) methods. As a result, compounds 4 and 6-11 displayed similar or better antioxidant activities compared to vitamin C, which is in good agreement with the bio-affinity ultrafiltration with SOD enzyme. Then, these compounds, 4 and 6-11, with better antioxidant activity were further explored to protect the L02 cells from H2O2-induced oxidative injury by reducing the reactive oxygen species (ROS) and Malondialdehyde (MDA) production and activating the SOD enzyme. To the best of our knowledge, this is the first report to use an efficient ultrafiltration approach with SOD for the rapid screening and identification of the SOD ligands directly from a complex crude extract of Carissa spinarum, and to reveal its corresponding active compounds with good antioxidative and hepatoprotective activities.

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The low stability of anthocyanins is a constraint in the food industry. The present work has been carried out to overcome this low stability by encapsulating fruit concentrate of underutilized plant Carissa spinarum (CS) with polyphenols in microemulsions (CSME) and nanoemulsions (CSNE). Increasing the amount of CS reduced the particle size from 1154 to 70-300 nm whereas addition of Tween 80 reduced it optimally to 5-25 nm. Degradation of anthocyanins in control and ME/NE proceeded with zero- and first-order reaction rates, respectively, at 28 °C (half-life 6, 25 and 40 days, respectively). The degradation kinetics of phenolics-flavonoids were also studied. CSNE exhibited higher anti-quorum sensing (QS) activity than CSME against Chromobacterium violaceum (73.7%); it inhibited biofilm formation by 70.1 and 64.4% in Pseudomonas aeruginosa, and Yersinia enterocolitica, respectively. This is the first report of using the more stable ME/NE to study anti-QS activity, an alternative to conventional antibiotics.

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Carissa spinarum has been traditionally used for the treatment of various diseases due to its different pharmacological activities. However, the active compounds responsible for its potentially specific activities have rarely been explored. To this end, the ethyl acetate (EA) fraction was screened out and selected for further phytochemical isolation because of its promising activities in preliminary 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and COX-2 inhibition assays. As a result, 10 compounds (1-10), including a new one (5), were isolated, with eight of these being identified as phenolic compounds, as expected. Compound 9 possessed an IC50 value of 16.5 ± 1.2 µM, which was lower than that of positive control (vitamin C, 25.5 ± 0.3 µM) in the DPPH assay, and compounds 2, 6, 7 and 9 showed better total antioxidant capacity than vitamin C in the FRAP assay. Meanwhile, compounds 1-6 and 9 also had IC50 values of less than 1.0 µM, which was even better than the positive control indomethacin in the COX-2 inhibition assay. In this context, compounds 2 and 9 were further evaluated to exhibit clear hepatoprotective activities by improving the L02 cell viability and reducing ROS production using a H2O2-induced L02 cell injury model. This study provides initial evidence revealing the most potent phenolic compounds from the root bark of C. spinarum responsible for its antioxidant, anti-inflammatory and hepatoprotective activities.

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Carissa spinarum L. (Apocynaceae) is used traditionally, in Africa, to treat many diseases such as malaria, sickle cell anemia, epilepsy, helminthoses, and sexual weakness. The aim of this study is to investigate the cytotoxicity on Artemia salina, the acute and subacute (28 days) oral toxicity of C. spinarum hydroalcoholic root extract on Wistar rats. The cytotoxicity was performed on A. salina larvae. The acute and subacute toxicity was performed using Organization of Economic Cooperation and Development guideline. Malondiadehyde as lipoperoxidation marker was evaluated and expressed according to tissue proteins. The cytotoxicity has shown that the lethal concentration 50 (LC50) was 0.9 mg/mL. The limit test dose of 5000 mg/kg did not provoke death or toxicity signs. For the subacute toxicity, no signs of toxicity or mortality were observed during the experiment. Results of biochemical and hematological parameters have not shown any treatment-related abnormalities, except a significant decrease of alkaline phosphatase at 1000 mg/kg (P < .05) and an increase of chloride ion level at 500 mg/kg (P < .01). There was no significant difference between the treated group and the control group concerning the malondialdehyde concentration, the body weight, and the organs relative weight (P < .05), except for testis at 500 mg/kg (P < .05). According to our results, the hydroalcoholic extract of C. spinarum roots is safe when administrated at 500 mg and 1000 mg/kg to Wistar rats for 28 days.

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Carissa spinarum is a well-known medicinal plant which has been reported for its anthelmintic, antipyretic, antiviral, antimicrobial and antitumour activities. In this study, a reverse-phase high-performance liquid chromatographic method was developed for the simultaneous estimation of betulinic acid (BA) and ursolic acid (UA) in the methanol extract of C. spinarum root. The method was further validated for linearity, limit of detection (LOD = 3.3σ/S), limit of quantification (LOQ = 10σ/S), precision, accuracy and ruggedness. The linear response was obtained using the equation, y = 511.5x+17603 (r(2) = 0.9920) and y = 2886x+6821 (r(2) = 0.9935) for BA and UA, respectively. The LOD and LOQ were found to be 0.268 ± 0.520 µg mL(-1), 0.878 ± 0.183 µg mL(-1) for BA (0.58% w/w) and 3.140 ± 0.36 µg mL(-1), 8.820 ± 0.85 µg mL(-1) for UA (1.09% w/w), respectively. The %RSD of precision and recovery of BA and UA was < 2.0%. The proposed method was simple, accurate, specific, precise and reproducible.

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