Aucubin, An Active Ingredient in Aucuba japonica, Prevents N-methyl-N-nitrosourea-induced Retinal Degeneration in Mice

Extraction and Purification of Aucubin from Eucommia ulmoides Seed Draff in Natural Deep Eutectic Solvents Using Macroporous Resins

Aucubin (AU) is an active ingredient that exerts strong antioxidant and anti-inflammatory effects in the treatment of several diseases. In order to improve the efficiency of resource utilization of traditional biomass waste, Eucommia ulmoides seed-draff (EUSD) waste biomass was used as the raw material, and a series of deep eutectic solvents were selected to evaluate the extraction efficiency of aucubin from EUSD. A response surface experiment was designed based on a single-factor experiment to optimize the extract conditions. The results showed that the best conditions for aucubin extraction were an HBD-HBA ratio of 2.18, a liquid-solid ratio of 46.92 mL/g, a water percentage of 37.95%, a temperature of 321.03 K, and an extraction time of 59.55 min. The maximum amount of aucubin was 156.4 mg/g, which was consistent with the theoretical value (156.8 mg/g). Then, the performance of 12 resins for adsorption and desorption was contrasted. The results revealed that HPD950 resin exhibited the best performance, with an adsorption capacity of 95.2% and a desorption capacity of 94.3%. Additionally, the pseudo-second-order model provided the best match to the kinetics data, the Langmuir model provided the best fit to the isotherm data, and adsorption was a beneficial, spontaneous, exothermic, and physical process. In the recyclability test, the HPD950 resin had great potential and excellent sustainability in aucubin recovery. In the antioxidant activity study, the aucubin extract exerted a strong antioxidant ability with scavenging capabilities for four free radicals. Furthermore, the antifungal activity study found that the aucubin extract exhibited a good antifungal effect against 5 tested pathogens. The research results can provide a theoretical basis for the extraction of high-value components from waste biomass by deep eutectic solvent and a certain application value for the development and utilization of natural aucubin products.

Aucubin protects mouse cochlear hair cells from cisplatin-induced ototoxicity via activation of the PI3K/AKT/STAT3 pathway

Cisplatin is commonly used to treat cancers and is associated with a significant risk of irreversible sensorineural hearing loss. However, no effective preventive strategies are available for cisplatin-induced HL. Therefore, significant efforts have been made to discover new drugs protecting cochlear hair cells from cisplatin-induced damage. We found that a new phytochemical, aucubin, attenuated cisplatin-induced apoptosis, the production of reactive oxygen species, and mitochondrial dysfunction in House Ear Institute Organ of Corti 1 cells and cochlear hair cells. Moreover, aucubin attenuated cisplatin-induced sensorineural hearing loss and hair cells loss in vivo. Furthermore, RNA sequencing analysis revealed that the otoprotective effects of aucubin were mainly mediated by increased STAT3 phosphorylation via the PI3K/AKT pathway. Inhibition of the STAT3 signaling pathway with the inhibitor S3I-201 or siRNA disrupted the protective effects of aucubin on cisplatin-induced apoptosis. In conclusion, we identified an otoprotective effect of aucubin. Therefore, aucubin could be used to prevent cisplatin-induced ototoxicity.

Aucubin Impeded Preosteoclast Fusion and Enhanced CD31hi EMCNhi Vessel Angiogenesis in Ovariectomized Mice

Osteogenesis is tightly correlated with angiogenesis during the process of bone development, regeneration, and remodeling. In addition to providing nutrients and oxygen for bone tissue, blood vessels around bone tissue also secrete some factors to regulate bone formation. Type H vessels which were regulated by platelet-derived growth factor-BB (PDGF-BB) were confirmed to couple angiogenesis and osteogenesis. Recently, preosteoclasts have been identified as the most important source of PDGF-BB. Therefore, inhibiting osteoclast maturation, improving PDGF-BB secretion, stimulating type H angiogenesis, and subsequently accelerating bone regeneration may be potent treatments for bone loss disease. In the present study, aucubin, an iridoid glycoside extracted from Aucuba japonica and Eucommia ulmoides, was found to inhibit bone loss in ovariectomized mice. We further confirmed that aucubin could inhibit the fusion of tartrate-resistant acid phosphatase (TRAP)+ preosteoclasts into mature osteoclasts and indirectly increasing angiogenesis of type H vessel. The underlying mechanism is the aucubin-induced inhibition of MAPK/NF-κB signaling, which increases the preosteoclast number and subsequently promotes angiogenesis via PDGF-BB. These results prompted that aucubin could be an antiosteoporosis drug candidate, which needs further research.

Study on extraction and antibacterial activity of aucubin from Eucommia ulmoides seed-draff waste biomass

Aucubin (AU) is an active ingredient exerting strong antioxidant and anti-inflammatory effects in treating several diseases. This study evaluated the extraction of AU from Eucommia ulmoides seed-draff (EUSD) waste biomass using a series of solvents (methanol, ethanol, i-propanol, n-propanol, n-butanol, n-pentanol and cyclohexane) assisted with microwave and ultrasound, and proposed the optimized method for extraction. Five factors were investigated by Box-Behnken design (BBD) and response surface methodology (RSM). The optimized extraction conditions were as follows: liquid-solid ratio of 46.37 mL/g, methanol percentage of 89.56%, ultrasonic (extraction) time of 59.95 min, microwave power of 306.73 W, and microwave (extraction) time of 18.93 s. To this end, the AU extraction reached the maximum value (149.1 mg/g), which was consistent with the theoretical value (149.3 mg/g). Furthermore, the kinetics of extraction process were investigated by mathematic modeling. The extraction process analysis was also explored by ¹H nuclear magnetic resonance (¹H-NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy and COSMOtherm program. This study found out that methanol provided better extraction efficiency than the conventional solvents (water, ethanol, i-propanol, n-propanol, n-butanol, n-pentanol, cyclohexane) due to possible interactions by the formation of hydrogen bond between AU and methanol, and ultrasound and microwave could significantly enhance mass transfer, which exhibited higher extraction efficiency and lower energy consumptions (149.1 mg/g and 0.102 kW·h vs. 73.4 mg/g and 0.700 kW·h for Soxhlet extraction). In the antibacterial activity study, the AU extract exerted strong antibacterial ability against 4 tested pathogens, and the antibacterial effect followed the order of: Staphylococcus aureus (35.9 ± 1.32 mm) > Escherichia coli (30.7 ± 1.38 mm) > Bacillus subtilis (20.5 ± 1.36 mm) > Salmonella (15.9 ± 1.39 mm) with the AU concentration of 40 mg/mL. Therefore, the development of this study will help to deepen the further understanding of natural product extraction by methanol-based ultrasonic and microwave, and has certain application value for the development and utilization of natural iridoid glycosides product.

Angiogenic footprints in diabetic retinopathy: opportunities for drug development

Diabetic retinopathy is one of the withering disorders that has been making the lives of patients miserable. Arising as a result of chronic high blood sugar levels in diabetes patients, retinopathy has become a major reason causing permanent blindness, retinal detachment, vitreous humor, rage, or glaucoma among patients. Angiogenesis being the major culprit behind the development of this condition is the growth of new blood vessels from the earlier ones existing. The abnormal growth and poor development of blood vessels also lead to aggravation of the conditions, with vascular endothelial growth factor (VEGF) playing a major role in the process. Various anti-angiogenic therapies or anti-VEGF therapies are being explored for the treatment of this condition. 4 widely explored drugs being-Bevacizumab, pegaptanib sodium, ranibizumab, and aflibercept. The review article tries to summarize studies illustrating the efficacy of these drugs in the treatment of diabetic retinopathy along with some of the herbal therapeutic paradigms displaying anti-angiogenic action that is being used to treat this condition.