Formulation,characterization and in vivo and in vitro evaluation of aloe-emodin-loaded solid dispersions for dissolution enhancement

OBJECTIVE:To prepare aloe-emodin solid dispersion(AE-SD)and determine the metabolic process of AE and AE-SD in vivo.METHODS:AE-SD was prepared via solvent evaporation or solvent melting using PEG-6000 and PVP-K30 as carriers.Thermogravimetric analysis,X-ray diffraction spectroscopy,differential scanning calorimetry,Fourier transform infrared spectroscopy and scanning electron microscopy were used to identify the physical state of AESD.Optimal prescriptions were screened via the dissolution degree determination method.Using Phoenix software,AE suspension and AE-SD were subjected to a pharmacokinetic comparison study analyzing the alteration of behavior in vivo after AE was prepared as a solid dispersion.Acute toxicity was assessed in mice,and the physiological toxicity was used as the determination criterion for toxicity.RESULTS:AE-SD showed that AE existed in the carrier in an amorphous state.Compared with polyethylene glycol,polyvinylpyrrolidone(PVP)inhibited AE crystallization,causing the drug to transform from a dense crystalline state to an amorphous form and increasing the degree of drug dispersion.Therefore,it was more suitable as a carrier material for AE-SD.The addition of poloxamer(POL)was more beneficial to the stability of solid dispersions and could reduce the amount of PVP.The dissolution test confirmed that the optimal ratio of AE to the composite vector AE-PVP-POL was 1:2:2,and its dissolution effect was also optimal.Based on the pharmacokinetic comparison,the drug absorption was faster and quickly reached the peak of blood drug concentration in AE-SD compared to AE,the Cmax of AE-SD was greater than that of AE,and t1/2 and mean residence time of AE-SD were less than AE.The results showed that the drug metabolism in AE-SD was better,and the residence time was shorter.The toxicology study showed that both AE and AE-SD had no toxicity.CONCLUSION:This paper established that the solubility of the drug could be increased after preparing a solid dispersion,as demonstrated by in vitro dissolution experiments.In vivo pharmacokinetics studies confirmed that AE-SD could improve the bioavailability of AE in vivo,providing a new concept for the research and development of AE preparations.

Advanced Oxidation Protein Products Regulate the Pharmacokinetics of Aloe-emodin,Emodin,Rhein,and Chrysophanol in Chronic Kidney Disease Rats

Background:As accelerators and products of the progression of chronic kidney disease(CKD),advanced oxidation protein products(AOPPs)affect the function of the liver.Huang Gan granules(HGGs)are commonly used to prevent the progression of CKD,but the pharmacokinetics of aloe-emodin,emodin,rhein,and chrysophanol in HGGs in CKD remain unknown.Objective:To investigate the influence and its molecular mechanism of AOPPs on the in vivo pharmacokinetics of aloe-emodin,emodin,rhein,and chrysophanol in HGGs.Methods:We constructed 5/6 nephrectomised(5/6 nx),adenine-induced(adenine)and AOPP-treated rat models.After oral administration of HGG,the concentrations of aloe-emodin,emodin,rhein,and chrysophanol in the plasma samples were detected by high-performance liquid chromatography(HPLC),and their pharmacokinetics were analysed with the PKSolver software.The plasma concentrations of IL-6 and TNF-αare detected by enzyme linked immunosorbent assay(ELISA).The RT-PCR was performed in the HepG2 cells to explore the effect of TNF-αand IL-6 on the mRNA expression of CYP1A2 and CYP3A4.Result:The results showed that the method was suitable for the quantification of four anthraquinones in plasma and excreta samples with satisfactory linear(R R^(2)>0.9931),precision(<9.4%)and accuracy(±10%).In 5/6 nx,adenine and AOPPs-treated rats,the concentrations of TNF-αand IL-6 were increased.In 5/6 nx and adenine rats,the pharmacokinetic parameters(t_(1/2),MRT_(0-∞)and AUC_(0-∞))of aloe-emodin,emodin,rhein,and chryso-phanol were,respectively,significantly increased and correlated with the concentration of AOPPs.In AOPPs-treated rats,the concentration of AOPPs was significantly increased and the pharmacokinetic parameters of four anthraquinones were also increased.Conclusion:In summary,inflammatory cytokine production may be one of the important causes in AOPPs’regulat-ing the pharmacokinetic of aloe-emodin,emodin,rhein,and chrysophanol in the CKD rats.Studies of aloe-emodin,emodin,rhein,and chrysophanol in CKD facilitate the appropriate prescription of HGGs in the clinical.

Effect of aloe-emodin on expression of proliferating cell nuclear antigen of vascular smooth muscle cells in culture after arterial injury

Objective To observe the effect of aloe-emodin on the expression of proliferating cell nuclear antigen (PCNA) in smooth muscle cells (SMCs) after arterial injury and study the molecular mechanism of inhibition of aloe-emodin on SMC proliferation.Methods Deendothelialization was performed at the abdominal aorta in Japanese white rabbits using a 3F Fogarty arterial embolectomy catheter. 48 hours later, the medium of abdominal aorta was isolated and primary SMCs culture was performed. Cells were synchronized to G0 by serum starvation, then aloe-emodin at a concentration of 20?μg/ml was added to the culture medium containing 10%［v/v］ fetal calf serum. Vehicle was also added to the medium as a control. After 18 hours, the expression of PCNA at the level of mRNA and protein were examined using techniques of RT/PCR, Western blotting and inmmunocytochemistry respectively. Results Compared with the control group, the expression of PCNA mRNA and protein was prominently decreased after addition of aloe-emodin. Conclusion The inhibition of aloe-emodin on SMCs proliferation may be caused by inhibiting the expression of the PCNA gene.

Comparison of microwave-assisted extraction of aloe-emodin in aloe with Soxhlet extraction and ultrasound-assisted extraction

This paper reports the extraction of aloe-emodin from aloe by microwave-assisted extraction. The effects of various factors, including the solvent, the ratio （mL/g） of the solvent to the sample, microwave irradiation time and microwave power, were discussed in the experiments. The yield of aloe-emodin was determined by HPLC. The optimized conditions for micro- wave-assisted extraction of aloe-emodin were concluded as follows： the solvent is 80% ethanol （V/V） solution, microwave ir- radiation time is 3 rain and microwave power is 340 W. Additionally, HPLC fingerprint was developed for consistency evalua- tion of aloe. The similarities of 3 aloe samples obtained by microwave-assisted extraction, ultrasound-assisted extraction and Soxhlet extraction were more than 0.9, indicating that 3 aloe samples were consistent. Compared with Soxhlet extraction and ultrasound-assisted extraction, microwave extraction is a rapid method with higher yield and less solvent consumption. Aloe samples treated by microwave-assisted extraction, ultrasound-assisted extraction and Soxhlet extraction were observed using transmission electronic microscopy. The micrographs provide evidence of more breakage of chloroplasts treated by micro- wave-assisted extraction as compared to Soxhlet extraction and ultrasound-assisted extraction.

Study on the adsorptive catalytic voltammetry of aloe-emodin at a carbon paste electrode

A new catalytic voltammetric method for the determination of anthraqunone medi-cines at a carbon paste electrode (CPE) was described for the first time. The mechanism of the catalytic reaction was investigated by using linear sweep voltammetry, cyclic voltammetry, con-stant potential electrolysis and so on. The experiment results indicate that aloe-emodin was effi-ciently accumulated at a CPE by adsorption. In the following potential scan, aloe-emodin was reduced to homologous anthrahydroquinone compound, then the compound was immediately oxidized to aloe-emodin by the dissolved oxygen, and the aloe-emodin was again reduced at the CPE. As a result, a cyclic catalytic reaction was established. But a reversible redox reaction of aloe-emodin can only be observed at a mercury electrode, no catalytic reaction occurs there. A sensitive catalytic voltammetric peak of aloe-emodin was obtained at about ?0.60 V (vs. SCE) in 0.56 mol/L NH3-NH4Cl buffer (pH 8.9). The proposed method was applied to the determination of aloe-emodin in the Radix Rhei with satisfactory results. The determination results were in good agreement with reference values obtained by the HPLC. The adsorptive catalytic voltammetry for the determination of organic compound at CPE, chemically modified electrode and other solid electrodes could be significant in the studies on pharmacology, pharmacodynamics, toxicity of medicine, clinical medicine and biochemistry.

Valorization of Aloe barbadensis Miller. (Aloe vera) Processing Waste

Aloe vera plant is known worldwide for its medicinal properties and application in gel-based products such as shampoo,soap,and sunscreen.However,the demand for these gel-based products has led to a surplus production of Aloe vera processing waste.An Aloe vera gel processing facility could generate up to 4000 kg of Aloe vera waste per month.Currently the Aloe vera waste is being disposed to the landfill or used as fertilizer.A sustainable management system for the Aloe vera processing waste should be considered,due to the negative societal and environmental impacts of the currents waste disposal methods.Therefore,this review focuses on various approaches that can be used to valorize Aloe vera waste into value-added products,such as animal and aquaculture feeds,biosorbents,biofuel and natural polymers.Researchers have reported Aloe vera waste for environmental applications biosorbents used for wastewater treatment of various pollutants.Several studies have also reported on the valorization of Aloe vera waste for production of biofuels such as bioethanol,mixed alcohol fuels,biogas and syngas.Aloe vera waste could also be valorized through isolation and synthesis of natural polymers for application in wound dressing,tissue engineering and drug delivery systems.Aloe vera waste valorization was also reviewed through extraction of value-added bioactive compounds such as aloe-emodin,aloin and aloeresin.These value-added bioactive compounds have various applications in the cosmetics(non-steroidal anti-inflammatory,tyrosinase inhibitors)and pharmaceutical(anticancer agent and COVID 19 inhibitors)industry.

Simultaneous determination of four active compounds in Dangguilonghui tablet by high-performance liquid chromatography

A high-performance liquid chromatography （HPLC） method has been developed for the first time to simultaneously quantify the four active ingredients, namely aloha, baicalein, aloe-emodin and wogonin, in Dangguilonghui tablet. The marker compotmds were separated on the Diamonsil C18 column at a flow rate of 1.0 mL/min with a mobile phase of methanol-acetonitrile-0.3% aqueous phosphoric acid （220： 4： 200, v/v/v） and while the detection wavelength was set at 225 nm. The assay was linear over the range of 1.450 - 29.00 ug/mL （r = 0.9992） for aloin, 0.4050 - 8.100ug/mL （r = 0.9994） for baicalein, 0.1100 - 2.200 ug/mL （r = 0.9997） for aloe-emodin, 0.2160 - 4.320 ug/mL （r = 0.9991） for wogonin, respectively. The average sample recoveries at three concentration levels were 100.7% （RSD = 0.88%）, 101.0% （RSD = 0.89%）, 100.0% （RSD = 1.3%） and 100.1% （RSD = 1.1%） for these constituents, respectively. This method is suitable for the quality control of Dangguilonghui tablet.

Inhibitory effect of schisandrin B on gastric cancer cells in vitro

AIM： To investigate the inhibitory effect and possible mechanism of action of schisandrin B in SC-B on gastric cancer cells in vitro.METHODS： SC-B consisted of schisandrin B, aloeemodin, and Astragalus polysaccharides. Exponentially growing human gastric cancer SGO7901 cells were divided into six treatment groups： （1） control group （RPMI 1640 medium）; （2） negative control group （2% DMSO）; （3） positive control group （50 mg/L 5-Fluorouracil, 5-FU）; （4） low-dose group （LSC, final concentration of schisandrin B, 25 mg/L）, （5） moderate-dose group （MSC, final concentration of schisandrin B, 50 mg/L）; （6） highdose group （HSC, final concentration of schisandrin B, 100 mg/L）. Follow-up was done at 12-48 h. An MTT （Methylthiazolyldiphenyl-tetrazolium bromide） assay was used to examine the inhibitory effect of SOB on gastric cancer cells. The mitosis index was assessed using an inverted microscope. Flow cytometry was used to visualize the cell cycle. An RT-PCR （Reverse transcription-Polymerase chain reaction） -based assay was used to detect mRNA expression for cyclin D1 and glyceraldehyde-3-phosphate dehydrogenase （GAPDH）.RESULTS： The MTT assay showed that the number of living cells in the LSC, MSC and HSC groups was significantly smaller than that in the DMSO-treated group （P 〈 0.05） at 12-48 h. The inhibitory rate （IR） of the LSC group was 41.15% ± 3.86%, 59.24% ± 5.34% and 69.93% ± 7.81% at 12, 24 and 48 h, respectively. The IR of the MSC group was 42.82% ± 4.94%, 62.68% ± 7.58% and 71.79% ± 8.12% at 12, 24 and 48 h, respectively. The IR of the HSC group was 37.50% ± 3.21%, 40.34% ± 2.98% and 61.99% ± 4.88% at 12, 24 and 48 h, respectively. These results suggested that a moderate dosage had the most obvious inhibitory efficacy at 48 h. Compared to the DMSO group, the mitosis index of the LSC, MSC, HSC groups was greatly decreased （P 〈 0.05） at all time points. Any dose of SC-B suppressed mitosis within 12-48 h. Compared to the DMSO group, the percentage of cells in the G0/G1 phase of the MSC group was greatly increased, and that of the S ＋ G2M phase was greatly decreased, while the percentage of cell inhibition （PCI） in the MSC group was greatly increased （P 〈 0.05）. This suggested that SC-B could exclusively arrest cells in the G0/G1 phase. Cyclin D1 mRNA expression was lower in the MSC group than that in the DMSO group （P 〈 0.05）.CONCLUSION： SC-B can inhibit the proliferation and aberrant mitosis of human gastric cancer SCG-7901 cells /n v/tro, This inhibitory effect may be due to the down- regulation of cyclin D1 mRNA expression, which causes cell cycle arrest of gastric cancer cells.

Thermal Characterization and Decomposition Kinetics of Free Anthraquinones from Rhubarb

The thermal behaviour of aloe-emodin, chrysophanol and physcion and their kinetics have been investigated under non-isothermal conditions by means of differential thermal analysis （DTA） and thermogravimetry （TG）. The thermal characteristics have been determined using the DTA and TG-DTG curves. The non-isothermal kinetic data were analyzed by means of the Achar method and the Madhusudanan-Krishnan-Ninan （MKN） method. The possible reaction mechanisms have been investigated by comparing the kinetic parameters. The kinetic equation for aloe-emodin, chrysophanol and physcion can be expressed as dα/dt=Aexp（-E/RT）1/3（1-α）[-In（1-α]2. The activation energy E （kJ mol^-1） of the three free anthraquinones are 78.09, 89.54, and 107.5 and their InA/s^-1 are 22.98, 36.85 and 43.60, respectively.