Oligomeric Proanthocyanidins: An Updated Review of Their Natural Sources, Synthesis, and Potentials

Combined treatment with Aronia berry extract and oligomeric proanthocyanidins exhibit a synergistic anticancer efficacy through LMNB1-AKT signaling pathways in colorectal cancer

Colorectal cancer (CRC) is one of the most prevalent and highly recurrent malignancies worldwide and currently ranks as the second leading cause of cancer-related deaths. The high degree of morbidity and mortality associated with CRC is primarily attributed to the limited effectiveness of current therapeutic approaches and the emergence of chemoresistance to standard treatment modalities. Recent research indicates that several natural products, including Aronia berry extracts (ABE) and oligomeric proanthocyanidins (OPCs), might offer a safe, cost-effective, and multitargeted adjunctive role to cancer treatment. Herein, we hypothesized a combined treatment with ABE and OPCs could synergistically modulate multiple oncogenic pathways in CRC, thereby enhancing their anticancer activity. We initially conducted a series of in vitro experiments to assess the synergistic anticancer effects of ABE and OPCs on CRC cell lines. We demonstrate that these two compounds exhibited a superior synergistic anticancer potential versus individual treatments in enhancing the ability to inhibit cell viability, suppress colony formation, and induce apoptosis (p < 0.05). Consistent with our in vitro findings, we validated this combinatorial anticancer effect in tumor-derived 3D organoids (PDOs; p < 0.01). Using genome-wide transcriptomic profiling, we identified that a specific gene, LMNB1, associated with the cell apoptosis pathway, was found to play a crucial role in exhibiting anticancer effects with these two products. Furthermore, the combined treatment of ABE and OPCs significantly impacted the expression of key proteins involved in apoptosis, including suppressed expression levels of LMNB1 in CRC cell lines (p < 0.05), which resulted in inhibiting downstream AKT phosphorylation. In conclusion, our study provides novel evidence of the synergistic anticancer effects of ABE and OPCs in CRC cells, partially mediated through the regulation of apoptosis and the oncogene LMNB1 within the AKT signaling pathway. These findings have the potential to better appreciate the anticancer potential of natural products in CRC and help improve treatment outcomes in this malignancy.

Substantial Differences in Proanthocyanidin Contents among Ginkgo biloba Leaf Extracts in Herbal Medicinal Products Obtained from the German Market

Pharmacologic activity of proanthocyanidins in Ginkgo biloba leaf extract has recently been reported. The objective of the present study was to screen proanthocyanidin contents in herbal medicinal products containing Ginkgo extracts. A recently published HPLC method for quantification of proanthocyanidins in G. biloba leaf extract EGb 761 was adopted to also be suitable for finished herbal medicinal products. The method was applied to 14 products from the German market. For each product, a set of three individual batches was purchased and analyzed. Substantial differences in proanthocyanidins contents were found among distinct products, ranging from 0.30 to 5.86%. The batch-to-batch variability within each product was low. The highest concentrations are in a similar range as, for example, the amount of Ginkgo terpene trilactones specified in the monograph for G. biloba leaf extract in the European Pharmacopeia. Although it has not yet been established whether and to what extent proanthocyanidins contribute to the overall pharmacological or clinical efficacy of Ginkgo extracts, a potential impact on the purported benefits of different contents in proanthocyanidins cannot be ruled out. Quality assessment of different Ginkgo extracts in the future may include proanthocyanidins.

Proanthocyanidin alleviates testicular torsion/detorsion-induced ischemia/reperfusion injury in rats

Testicular torsion is an urological emergency and can lead to ischemia damage and testicular loss if not diagnosed in time. Proanthocyanidin is reported to have anti-inflammatory and antioxidant properties. The current study aimed to examine the possible effects of proanthocyanidin (P) on the testis in torsion/detorsion (T/D)-induced testicular ischemia/reperfusion (I/R) injury in rats. Forty rats were divided into four groups (n=10 for each): sham-operated (sham), I/R, I/R + P100 (100 mg/kg, 30 min before torsion), and I/R + P200 (200 mg/kg, 30 min before torsion). Testicular T/D was performed on the left testicle by 3 hours of torsion at 720° clockwise, followed by 3 hours of detorsion. In the I/R group, an increase in malondialdehyde (MDA) levels and a decrease in glutathione (GSH), vitamin C (Vit C), glutathione peroxidase (GPx), glucose-6-phosphate dehydrogenase (G6PD) values were determined compared to the sham group (p<0.001). Moreover, an increase in the expression of cleaved caspase-3 and Bcl2-associated X protein (Bax), a decrease in the expression of B-cell lymphoma 2 (Bcl-2) and proliferating cell nuclear antigen (PCNA) were detected in the I/R group (p<0.001). Histopathologically, it was determined that the Johnsen and Cosentino scores of the testicles were irregular in the I/R group (p<0.001). Proanthocyanidin treatment caused a decrease in MDA, cleaved caspase-3 and Bax levels and an increase in GSH, Vit C, GPx, G6PD, Bcl-2 and PCNA values. Additionally, Johnsen and Cosentino rearranged the scores. The present findings revealed the protective and curative effects of proanthocyanidin in organ damage due to testicular torsion/detorsion-induced ischemia/reperfusion with their antioxidative and antiapoptotic properties.

Vitis Vinifera Seed Extract Versus Micronized Purified Flavonoid Fraction for Patients with Chronic Venous Disease: A Randomized Noninferiority Trial

BACKGROUND

Venoactive drugs (VADs) based on Vitis vinifera extract are widely used in Korea. However, studies on the clinical effects and head-to-head comparisons with other groups of VADs are limited. This trial aimed to evaluate whether Vitis vinifera seed extract was noninferior to the micronized purified flavonoid fraction (MPFF) in relieving venous symptoms and improving quality of life in patients with chronic venous disease.

METHODS

In this double-blind prospective randomized trial, patients from 13 hospitals, who were diagnosed with venous incompetence by duplex ultrasound and classified as clinical class 1, 2, or 3 in the Clinical, Etiological, Anatomical, and Pathophysiological classifications were enrolled. The primary outcome was the change in the Chronic Venous Disease Quality of Life Questionnaire (CIVIQ-20) score at 8 weeks from baseline. Secondary outcomes included changes in the Aberdeen Varicose Vein Questionnaire, visual analog scale, and Venous Clinical Severity Score at 4 and 8 weeks from baseline. Moreover, the change in leg circumferences was measured at 8 weeks and compared to baseline.

RESULTS

In total, 303 patients were enrolled and randomly assigned to receive either Vitis vinifera seed extract (n = 154) or MPFF (n = 149). The CIVIQ-20 scores at 8 weeks were significantly reduced compared to those at baseline in both groups. No significant intergroup difference in the change of CIVIQ-20 at 8 weeks from baseline was observed (-8.31 ± 14.63 vs. -10.35 ± 14.38, P = 0.29, 95% confidence interval -1.65 to 5.72). The lower limit of the 95% confidence interval was within the predefined noninferiority margin of 6.9. Furthermore, the Aberdeen Varicose Vein Questionnaire, visual analog scale, and Venous Clinical Severity Score scores significantly decreased at 4 and 8 weeks after randomization compared with baseline in both groups. No significant differences were observed in the reduction of each score between groups. The calf circumference measured at 8 weeks was significantly reduced compared to that at baseline in patients receiving Vitis vinifera seed extract.

CONCLUSIONS

Vitis vinifera seed extract was noninferior to MPFF in relieving venous symptoms and improving the quality of life in patients with chronic venous disease.

Seasonal Variation and Mean Degree of Polymerization of Proanthocyanidin in Leaves and Branches of Rabbiteye Blueberry (Vaccinium virgatum Aiton)

The leaves and branches of rabbiteye blueberry are rich in proanthocyanidins, which are thought to have different physiological activities depending on their structure and degree of polymerization. In this study, we analyzed the constituents of the leaves and branches of rabbiteye blueberry to determine the seasonal variations in polyphenol and proanthocyanidin (PAC) contents as well as their mean degrees of polymerization (mDP). Total PAC content was determined using two methods: The p-dimethylaminocinnamaldehyde (DMACA) method, which measures monomeric PAC, showed an increase from spring to summer in both leaves and branches. On the other hand, using the butanol/HCl method, which measures only polymerized PAC, the PAC content of leaves increased from spring to summer but those of branches remained low throughout the year, showing no significant increase or decrease. Furthermore, analysis of the mDP of PAC showed increases from spring to summer in the leaves of 'Kunisato 35 gou'. Although the highest value (8.0) was observed in October, values around 4 remained throughout the year in the branches. Since differences in polymerization degree affect absorption in the body and physiological properties such as antioxidant capacity, selecting the appropriate harvest time and plant organs for each purpose is expected to ensure the quality of processed blueberry foods.

A-type proanthocyanidins: Sources, structure, bioactivity, processing, nutrition, and potential applications

A-type proanthocyanidins (PAs) are a subgroup of PAs that differ from B-type PAs by the presence of an ether bond between two consecutive constitutive units. This additional C-O-C bond gives them a more stable and hydrophobic character. They are of increasing interest due to their potential multiple nutritional effects with low toxicity in food processing and supplement development. They have been identified in several plants. However, the role of A-type PAs, especially their complex polymeric form (degree of polymerization and linkage), has not been specifically discussed and explored. Therefore, recent advances in the physicochemical and structural changes of A-type PAs and their functional properties during extraction, processing, and storing are evaluated. In addition, discussions on the sources, structures, bioactivities, potential applications in the food industry, and future research trends of their derivatives are highlighted. Litchis, cranberries, avocados, and persimmons are all favorable plant sources. Α-type PAs contribute directly or indirectly to human nutrition via the regulation of different degrees of polymerization and bonding types. Thermal processing could have a negative impact on the amount and structure of A-type PAs in the food matrix. More attention should be focused on nonthermal technologies that could better preserve their architecture and structure. The diversity and complexity of these compounds, as well as the difficulty in isolating and purifying natural A-type PAs, remain obstacles to their further applications. A-type PAs have received widespread acceptance and attention in the food industry but have not yet achieved their maximum potential for the future of food. Further research and development are therefore needed.

Bioactive Compounds and Potential Health Benefits through Cosmetic Applications of Cherry Stem Extract

Cherry stems, prized in traditional medicine for their potent antioxidant and anti-inflammatory properties, derive their efficacy from abundant polyphenols and anthocyanins. This makes them an ideal option for addressing skin aging and diseases. This study aimed to assess the antioxidant and anti-inflammatory effects of cherry stem extract for potential skincare use. To this end, the extract was first comprehensively characterized by HPLC-ESI-qTOF-MS. The extract's total phenolic content (TPC), antioxidant capacity, radical scavenging efficiency, and its ability to inhibit enzymes related to skin aging were determined. A total of 146 compounds were annotated in the cherry stem extract. The extract effectively fought against NO· and HOCl radicals with IC50 values of 2.32 and 5.4 mg/L. Additionally, it inhibited HYALase, collagenase, and XOD enzymes with IC50 values of 7.39, 111.92, and 10 mg/L, respectively. Based on the promising results that were obtained, the extract was subsequently gently integrated into a cosmetic gel at different concentrations and subjected to further stability evaluations. The accelerated stability was assessed through temperature ramping, heating-cooling cycles, and centrifugation, while the long-term stability was evaluated by storing the formulations under light and dark conditions for three months. The gel formulation enriched with cherry stem extract exhibited good stability and compatibility for topical application. Cherry stem extract may be a valuable ingredient for creating beneficial skincare cosmeceuticals.

Research progress of procyanidins in repairing cartilage injury after anterior cruciate ligament tear

Anterior cruciate ligament (ACL) tear is a common sports-related injury, and cartilage injury always emerges as a serious complication following ACL tear, significantly impacting the physical and psychological well-being of affected individuals. Over the years, efforts have been directed toward finding strategies to repair cartilage injury after ACL tear. In recent times, procyanidins, known for their anti-inflammatory and antioxidant properties, have emerged as potential key players in addressing this concern. This article focuses on summarizing the research progress of procyanidins in repairing cartilage injury after ACL tear. It covers the roles, mechanisms, and clinical significance of procyanidins in repairing cartilage injury following ACL tear and explores the future prospects of procyanidins in this domain. This review provides novel insights and hope for the repair of cartilage injury following ACL tear.

Grape Seed Proanthocyanidins Protect Pancreatic β Cells Against Ferroptosis via the Nrf2 Pathway in Type 2 Diabetes

Pancreatic β cell damage is the primary contributor to type 2 diabetes mellitus (T2DM); however, the underlying mechanism remains nebulous. This study explored the role of ferroptosis in pancreatic β cell damage and the protective effects of grape seed proanthocyanidin extract (GSPE). In T2DM model rats, the blood glucose, water intake, urine volume, HbA1c, and homeostasis model assessment-insulin resistance were significantly increased, while the body weight and the insulin level were significantly decreased, indicating the successful establishment of the T2DM model. MIN6 mouse insulinoma β cells were cultured in high glucose and sodium palmitate conditions to obtain a glycolipid damage model, which was administered with GSPE, ferrostatin-1 (Fer-1), or nuclear factor erythroid 2-related factor 2 (Nrf2) small interfering (si) RNA. GSPE and Fer-1 treatment significantly improved pancreatic β-cell dysfunction and protected against cell death. Both treatments increased the superoxide dismutase and glutathione activity, reduced the malondialdehyde and reactive oxygen species levels, and improved iron metabolism. Furthermore, the treatments reversed the expression of ferroptosis markers cysteine/glutamate transporter (XCT) and glutathione peroxidase 4 (GPX4) caused by glycolipid toxicity. GSPE treatments activated the expression of Nrf2 and related proteins. These effects were reversed when co-transfected with si-Nrf2. GSPE inhibits ferroptosis by activating the Nrf2 signaling pathway, thus reducing β-cell damage and dysfunction in T2DM. Therefore, GSPE is a potential treatment strategy against T2DM.