Xanthohumol: A Metabolite with Promising Anti-Neoplastic Potential

Botanical Flavonoids: Efficacy, Absorption, Metabolism and Advanced Pharmaceutical Technology for Improving Bioavailability

Flavonoids represent a class of natural plant secondary metabolites with multiple activities including antioxidant, antitumor, anti-inflammatory, and antimicrobial properties. However, due to their structural characteristics, they often exhibit low bioavailability in vivo. In this review, we focus on the in vivo study of flavonoids, particularly the effects of gut microbiome on flavonoids, including common modifications such as methylation, acetylation, and dehydroxylation, etc. These modifications aim to change the structural characteristics of the original substances to enhance absorption and bioavailability. In order to improve the bioavailability of flavonoids, we discuss two feasible methods, namely dosage form modification and chemical modification, and hope that these approaches will offer new insights into the application of flavonoids for human health. In this article, we also introduce the types, plant sources, and efficacy of flavonoids. In conclusion, this is a comprehensive review on how to improve the bioavailability of flavonoids.

Antioxidant Potential of Xanthohumol in Disease Prevention: Evidence from Human and Animal Studies

Xanthohumol (XN) is a phenolic compound found in the largest amount in the flowers of the hop plant, but also in the leaves and possibly in the stalks, which is successfully added to dietary supplements and cosmetics. XN is known as a potent antioxidant compound, which, according to current research, has the potential to prevent and inhibit the development of diseases, i.e., cancer and neurodegenerative diseases. The review aims to examine the antioxidant role of XN in disease prevention, with an emphasis on the benefits and risks associated with its supplementation. The regulation by XN of the Nrf2/NF-kB/mTOR/AKT (Nuclear factor erythroid 2-related factor 2/Nuclear factor kappa-light-chain-enhancer of activated B cells/Mammalian target of rapamycin/Protein Kinase B) pathways induce a strong antioxidant and anti-inflammatory effect, among others the acceleration of autophagy through increased synthesis of Bcl-2 (B-cell lymphoma 2) proteins, inhibition of the synthesis of VEGF (Vascular-endothelial growth factor) responsible for angiogenesis and phosphorylation of HKII (Hexokinase II). It is the key function of XN to ameliorate inflammation and to promote the healing process in organs. However, existing data also indicate that XN may have adverse effects in certain diseases, such as advanced prostate cancer, where it activates the AMPK (activated protein kinase) pathway responsible for restoring cellular energy balance. This potential risk may explain why XN has not been classified as a therapeutic drug so far and proves that further research is needed to determine the effectiveness of XN against selected disease entities at a given stage of the disease.

Effect of Xanthohumol from Humulus lupulus L. Against Gouty Bone Damage in Arthritis of Rats Induced by Mono-sodium Urate

Xanthohumol (XAN) is an isoprenyl flavonoid from Humulus lupulus L. known for beer brewing, and an osteoprotective agent due to its active improvement in bone loss of osteoporosis. This study was first time to investigate its effects on anti-gouty bone injury in rats of gouty arthritis (GA) induced by monosodium urate (MSU). Results showed that XAN could significantly exert anti-inflammatory activity by alleviating swelling degree of joints, reducing serum level of inflammatory factors, improving inflammatory injury and degrading the Markin's score in lesion joint. Meanwhile, XAN could also fight against gouty bone damage by improving pathological changes of bone tissue and parameters of bone micro-structure. Moreover, XAN could even promote bone formation by effectively enhancing expression of Runx2 and OPG, while inhibit bone resorption with depressing matrix metalloproteinase-9 (MMP-9), MMP-13 and CTSK expression, reducing RANKL secretion, and abating the ratio of RANKL/OPG. Therefore, it was the first time to reveal the mechanism of XAN against gouty bone injury via inhibiting RANKL/OPG/RANK signaling pathway. Above all, this study provided potential strategy for the treatment of GA, and further contributed to research and resource development for hops.

Prenylated Flavonoids with Selective Toxicity against Human Cancers

The antiproliferative activity of xanthohumol (1), a major prenylated chalcone naturally occurring in hops, and its aurone type derivative (Z)-6,4'-dihydroxy-4-methoxy-7-prenylaurone (2) were investigated. Both flavonoids, as well as cisplatin as a reference anticancer drug, were tested in vivo against ten human cancer cell lines (breast cancer (MCF-7, SK-BR-3, T47D), colon cancer (HT-29, LoVo, LoVo/Dx), prostate cancer (PC-3, Du145), lung cancer (A549) and leukemia (MV-4-11) and two normal cell lines (human lung microvascular endothelial (HLMEC)) and murine embryonic fibroblasts (BALB/3T3). Chalcone 1 and aurone 2 demonstrated potent to moderate anticancer activity against nine tested cancer cell lines (including drug-resistant ones). The antiproliferative activity of all the tested compounds against cancer and the normal cell lines was compared to determine their selectivity of action. Prenylated flavonoids, especially the semisynthetic derivative of xanthohumol (1), aurone 2, were found as selective antiproliferative agents in most of the used cancer cell lines, whereas the reference drug, cisplatin, acted non-selectively. Our findings suggest that the tested flavonoids can be considered strong potential candidates for further studies in the search for effective anticancer drugs.

Oral intake of xanthohumol attenuates lipoteichoic acid-induced inflammatory response in human PBMCs

PURPOSE

The aim of the study was to determine if xanthohumol, a prenylated chalcone found in Hop (Humulus lupulus), has anti-inflammatory effects in healthy humans if applied in low doses achievable through dietary intake.

METHODS

In a placebo-controlled single-blinded cross-over design study, 14 healthy young men and women either consumed a beverage containing 0.125 mg xanthohumol or a placebo. Peripheral blood mononuclear cells (PBMCs) were isolated before and 1 h after the intake of the beverages. Subsequently, PBMCs were stimulated with or without lipoteichoic acid (LTA) for 24 and 48 h. Concentrations of interleukin-1β (IL-1β), interleukin-6 (IL-6) and soluble cluster of differentiation (sCD14) protein were determined in cell culture supernatant. Furthermore, hTLR2 transfected HEK293 cells were stimulated with LTA in the presence or absence of xanthohumol and sCD14.

RESULTS

The stimulation of PBMCs with LTA for 24 and 48 h resulted in a significant induction of IL-1β, IL-6, and sCD14 protein release in PBMCs of both, fasted subjects and subjects after the ingestion of the placebo. In contrast, after ingesting xanthohumol, LTA-dependent induction of IL-1β, IL-6, and sCD14 protein release from PBMCs was not significantly higher than in unstimulated cells after 48 h. In hTLR2 transfected HEK293 cells xanthohumol significantly suppressed the LTA-dependent activation of cells, an effect attenuated when cells were co-incubated with sCD14.

CONCLUSION

The results of our study suggest that an ingestion of low doses of xanthohumol can suppress the LTA-dependent stimulation of PBMCs through mechanisms involving the interaction of CD14 with TLR2. Study registered at ClinicalTrials.gov (NCT04847193, 22.03.2022).

NOTCH signaling: Journey of an evolutionarily conserved pathway in driving tumor progression and its modulation as a therapeutic target

Notch signaling, an evolutionarily conserved signaling cascade, is critical for normal biological processes of cell differentiation, development, and homeostasis. Deregulation of the Notch signaling pathway has been associated with tumor progression. Thus, Notch presents as an interesting target for a variety of cancer subtypes and its signaling mechanisms have been actively explored from the therapeutic viewpoint. However, besides acting as an oncogene, Notch pathway can possess also tumor suppressive functions, being implicated in inhibition of cancer development. Given such interesting dual and dynamic role of Notch, in this review, we discuss how the evolutionarily conserved Notch signaling pathway drives hallmarks of tumor progression and how it could be targeted for a promising treatment and management of cancer. In addition, the up-to-date information on the inhibitors currently under clinical trials for Notch targets is presented along with how NOTCH inhibitors can be used in conjunction with established chemotherapy/radiotherapy regimes.