Protective Effects of Grape Seed Oligomeric Proanthocyanidins in IPEC-J2–Escherichia coli/Salmonella Typhimurium Co-Culture

Intestinal epithelium provides the largest barrier protecting mammalian species from harmful external factors; however, it can be severely compromised by the presence of bacteria in the gastrointestinal (GI) tract. Antibiotics have been widely used for the prevention and treatment of GI bacterial infections, leading to antimicrobial resistance in human and veterinary medicine alike. In order to decrease antibiotic usage, natural substances, such as flavonoids, are investigated to be used as antibiotic alternatives. Proanthocyanidins (PAs) are potential candidates for this purpose owing to their various beneficial effects in humans and animals. In this study, protective effects of grape seed oligomeric proanthocyanidins (GSOPs) were tested in IPEC-J2 porcine intestinal epithelial cells infected with Escherichia coli and Salmonella enterica ser. Typhimurium of swine origin. GSOPs were able to alleviate oxidative stress, inflammation and barrier integrity disruption inflicted by bacteria in the co-culture. Furthermore, GSOPs could decrease the adhesion of both bacteria to IPEC-J2 cells. Based on these observations, GSOPs seem to be promising candidates for the prevention and treatment of gastrointestinal bacterial infections.

Improvement of the Biosynthesis of Resveratrol in Endophytic Fungus (Alternaria sp. MG1) by the Synergistic Effect of UV Light and Oligomeric Proanthocyanidins

Resveratrol, a natural polyphenol compound with multiple bioactivities, is widely used in food and pharmaceutical industry. Endophytic fungus Alternaria sp. MG1, as a native producer of resveratrol, shows increasing potential application. However, strategies for improvement of the biosynthesis of resveratrol in this species are still scarce. In this study, different elicitors were used to investigate their effect on the biosynthesis of resveratrol in MG1 and the induction mechanism. Ultrasound and sodium butyrate had no effect and slight inhibition on the resveratrol production and related gene expression, respectively. UV radiation and co-culture with Phomopsis sp. XP-8 significantly promoted the biosynthesis of resveratrol with the highest production (240.57μg/l) coming from UV 20min. Co-culture altered the profiles of secondary metabolites in MG1 by promoting and inhibiting the synthesis of stilbene and lignin compounds, respectively, and generating new flavonoids ((+/−)-taxifolin, naringin, and (+)-catechin). Oligomeric proanthocyanidins (OPC) also showed an obviously positive influence, leading to an increase in resveratrol production by 10 to 60%. Two calcium-dependent protein kinases (CDPK) were identified, of which CDPK1 was found to be an important regulatory factor of OPC induction. Synergistic treatment of UV 20min and 100μm OPC increased the production of resveratrol by 70.37% compared to control and finally reached 276.31μg/l.

Elucidation of Interaction between Whey Proteins and Proanthocyanidins and Its Protective Effects on Proanthocyanidins during In-Vitro Digestion and Storage

Whey proteins and oligomeric proanthocyanidins have nutritional value and are widely used in combination as food supplements. However, the effect of the interactions between proanthocyanidins and whey proteins on their stability has not been studied in depth. In this work, we aimed to characterize the interactions between β-Lactoglobulin (β-LG) and α-lactalbumin (α-LA) and oligomeric proanthocyanidins, including A1, A2, B1, B2, B3, and C1, using multi-spectroscopic and molecular docking methods. Fluorescence spectroscopic data revealed that all of the oligomeric proanthocyanidins quenched the intrinsic fluorescence of β-LG or α-LA by binding-related fluorescence quenching. Among the six oligomeric proanthocyanidins, A1 showed the strongest affinity for β-LG (Ka = 2.951 (±0.447) × 104 L∙mol−1) and α-LA (Ka = 1.472 (±0.236) × 105 L∙mol−1) at 297 K. β-LG/α-LA and proanthocyanidins can spontaneously form complexes, which are mainly induced by hydrophobic interactions, hydrogen bonds, and van der Waals forces. Fourier-transform infrared spectroscopy (FTIR) and circular dichroism spectroscopy showed that the secondary structures of the proteins were rearranged after binding to oligomeric proanthocyanidins. During in vitro gastrointestinal digestion, the recovery rate of A1 and A2 increased with the addition of WPI by 11.90% and 38.43%, respectively. The addition of WPI (molar ratio of 1:1) increased the retention rate of proanthocyanidins A1, A2, B1, B2, B3, and C1 during storage at room temperature by 14.01%, 23.14%, 30.09%, 62.67%, 47.92%, and 60.56%, respectively. These results are helpful for the promotion of protein–proanthocyanidin complexes as functional food ingredients in the food industry.

Inhibition Effect of Extract of Psychotria viridiflora Stem on α-Amylase and α-Glucosidase and Its Application in Lowering the Digestibility of Noodles

A collection of tropical medicinal plants from East Malaysia's rainforests are used by indigenous tribes for their curative properties. Despite their purported healing properties, these forest plant species are largely unexplored and hence remain virtually unknown to the outside world. In this study, antidiabetic properties of Psychotria viridiflora, a plant used to treat diabetes by a local community in Sarawak, Malaysia were investigated. Ethyl acetate (EA) extract of P. viridiflora stem was found to exhibit high starch hydrolase inhibition activity with an IC50 value of 15.4 ± 2.1 μg/ml against porcine α-amylase and an IC50 value of 32.4 ± 3.7 μg/ml against rat intestinal α-glucosidase. A complex mixture of A-type oligomeric proanthocyanidins containing (epi)fisetinidol, (epi)afzelechin, (epi)guibourtinidol, and (epi)catechin were found. These compounds may be responsible for the starch hydrolase inhibition activity. Ethyl acetate (EA) extract of P. viridiflora stem was incorporated into wheat and rice flour to reformulate noodles with slow digestibility and was assessed under in vitro simulated gastrointestinal conditions. A dose-dependent effect on digestibility was observed for both noodles upon incorporation of 1-6% (w/w) of EA extract, with noodles containing 6% (w/w) extract exhibiting the greatest reduction in digestibility. As compared to rice noodles containing 6% extract (31.16% inhibition), wheat noodles with the same extract concentration had a smaller decline in digestibility (27.25% inhibition) after 180 min. Overall, our findings highlight the potential of P. viridiflora in the prevention of postprandial hyperglycaemia.

Advanced analysis of oligomeric proanthocyanidins: latest approaches in liquid chromatography and mass spectrometry based analysis

Proanthocyanidins (PAC) are an important and widely spread class of natural products with various bioactivities. The analytical evaluation of oligomeric and polymeric proanthocyanidins in complex extracts is still challenging, due to the complexity of structures. Nevertheless, in the last 20 years analytical techniques especially in the field of chromatography and mass spectrometry have been improved and offer exciting possibilities for a deeper insight into plant secondary metabolism. While classical colorimetric methods and protocols for partial hydrolysis are still valuable tools new chromatographically and mass spectrometric methods provide deep insights into the PAC fine structure, also of polymeric material. The present review focus on recent innovative LC–MS and MALDI-TOF methods, innovative strategies for advanced processing of LC-HRMS data (van Krevelen plots, Kendrick Mass Defect Analysis), MS/MS fragmentation, and newest two-dimensional LC × LC (Offline, Online, Stop-flow-2D) chromatography. Also MALDI-TOF imaging provides exciting inside in PAC distribution within biological samples and functional assays.

Terminalia arjuna: A Potential Ayurvedic Cardio Tonic

Herbal plants have been a significant source of therapeutic agents to cure human diseases. Plants are being in use for treating various kinds of diseases across the world. Terminalia arjuna is a widely used herbal plant since ancient times. The ancient indian practitioners utilized the powdered tree bark of arjuna for the treatment of "hritshool" (angina) and other cardiovascular problems. Terminalia arjuna is regionally called as arjuna which belongs to the combretaceae family. The plant is utilized as a medicine in the various indigenous system like ayurveda, siddha and unani. Arjunic acid, arjunolic acid, arjungenin, arjunone, arjunolone and luteolin, gallic acid, ellagic acid, oligomeric proanthocyanidins (opcs), phytosterols are the major phytoconstituents of Terminalia arjuna that possesses many useful biological properties like anti-microbial, anti-inflammatory, antioxidant, antifeedant, cardio protective, etc. Various clinical evidence of Terminalia arjuna and its beneficial effects on the cardiovascular system. The present review is summarizing the phytomedicinal value of Terminalia arjuna in ayurveda and the folk system of medicine.

Enhanced anti-cancer activity of andrographis with oligomeric proanthocyanidins through activation of metabolic and ferroptosis pathways in colorectal cancer

The high degree of morbidity and mortality in colorectal cancer (CRC) patients is largely due to the development of chemoresistance against conventional chemotherapeutic drugs. In view of the accumulating evidence that various dietary botanicals offer a safe, inexpensive and multi-targeted treatment option, herein, we hypothesized that a combination of Andrographis paniculata and Oligomeric Proanthocyanidins (OPCs) might interact together with regard to anti-tumorigenic activity in CRC. As a result, we demonstrated the enhanced anti-cancer activity between these two botanical extracts in terms of their ability to inhibit cancer cell growth, suppress colony formation and induce apoptosis. Furthermore, we validated these findings in subcutaneous xenograft model and in patient derived primary epithelial 3D organoids. Transcriptomic profiling identified involvement of metabolic pathways and ferroptosis-associated genes, including HMOX1, GCLC and GCLM, that may be responsible for the increased anti-tumorigenic activity by the two compounds. Collectively, our study provides novel evidence in support of the combinatorial use of andrographis and OPCs as a potential therapeutic option, perhaps as an adjunctive treatment to classical drugs, in patients with colorectal cancer.