The potential benefits of aged black garlic on inflammation and prostate cancer

By Dr. Priyom Bose, Ph.D.Reviewed by Benedette Cuffari, M.Sc.Sep 13 2024

Study shows anti-inflammatory effects on prostate cancer cells, but further research needed

Study: The Protective Effects of an Aged Black Garlic Water Extract on the Prostate. Image Credit: kai keisuke / Shutterstock.com

A recent Nutrients study investigates the anti-inflammatory and anti-prostate cancer properties of aged black garlic extract (ABGE).

Inflammation and prostate cancer

Prostate gland inflammation causes acute or chronic prostatitis, which may occur due to bacterial infections, trauma, stress, or immune responses. Animal model studies have shown that acute prostatic inflammation induces epithelial transformation, which increases the risk of developing prostatic intraepithelial neoplasia.

Inflammation is considered to be a potential risk factor for the development of many different types of cancer, including prostate cancer (PCa). Chronic inflammation creates a microenvironment that can induce carcinogenesis through the production of reactive oxygen species (ROS), pro-inflammatory cytokines, and DNA damage.

Nuclear factor (NF)-kB, tumor necrosis factor α (TNF-α), and cyclooxygenase 2 (COX-2) are important biomarkers of inflammation. Increased serum levels of TNF-α is directly linked with a poor prognosis in PCa.

NF-κB plays a vital role in regulating innate and adaptive immune responses, particularly inflammation, by stimulating the production of cytokines and chemokines. In fact, dysregulation of NF-κB can contribute to the development of inflammatory diseases, such as asthma and rheumatic diseases. Several studies have observed that NF-κB activation also modulates PCa malignancy.

What is ABGE?

Fresh garlic is fermented at a controlled high humidity of 80% to 90% at 60-90 °C for several weeks to produce ABG. Fermented garlic is less pungent and sweeter than fresh garlic and contains higher levels of many bioactive compounds, such as flavonoids, S-allyl cysteine, and polyphenols.

The bioactive compounds found in ABG have been shown to suppress cell proliferative activity and apoptosis, as well as modulate the cell cycle. In fact, preclinical studies have revealed that aqueous ABGE possesses anti-inflammatory and antioxidant effects.

About the study

The current study evaluated the effects of 10-1,000 μg/mL ABGE on inflammation and prostate cancer. To this end, the anti-inflammatory properties of ABGE were assessed using an ex-vivo inflammation model that utilizes mouse prostate samples exposed to Escherichia coli lipopolysaccharide (LPS).

Several in vitro assays were also performed using various prostate cancer cell lines to explore the therapeutic potential of ABGE for disease prevention. The role of numerous signaling pathways in the therapeutic effects of ABGE to alleviate inflammation and prostate cancer was also investigated, some of which included like Janus kinases/the signal transducer and activator of transcription proteins (JAK/STAT), mitogen-activated protein kinase (MAPK), transforming growth factor (TGF-β), and protein kinase B.

Study findings

ABGE was found to inhibit gene expression of all studied biomarkers of inflammation, with 1,000 µg/mL ABGE identified as the most effective dose. The anti-inflammatory effects of ABGE may be attributed to the activity of its numerous bioactive compounds, such as catechins, which modulate inflammatory targets like TNF-α, COX-2, and interleukins.

Compared to control cells, ABGE treatment significantly suppressed the proliferation of the androgen-dependent prostate cancer cell line LNCaP in a dose-dependent manner, with maximum inhibition observed at the highest dose and longer exposure times. Inhibitory effects were observed within 24 hours with 100 µg/mL ABGE treatment.

The PC-3 cell line, which was originally obtained from human prostate cancer bone metastases, also exhibited a significant reduction in proliferation following ABGE treatment. Maximum reduction in PC-3 proliferation occurred at the highest treatment dose of 1,000 µg/mL; however, the inhibitory effect was observed at lower doses from 100 µg/mL within 48 hours of the treatment.

The colony-forming ability analysis using LNCaP and PC-3 cell lines revealed that 1,000 µg/mL ABGE can effectively reduce the number of colonies formed as compared to control-treated cells. This finding is indicative of the capacity of ABGE treatment to reduce the long-term proliferative capacity of androgen-dependent cancer cells. The anti-tumor properties of ABGE were confirmed through the reduction in the number of tumor spheroid formations, which has been attributed to its polyphenolic components.

The cell migration assay revealed that 1,000 µg/mL ABGE treatment significantly reduced the cell migration rate as compared to that of the control after 24 hours, thus demonstrating the ability of this treatment to prevent the migration of these cancer cells. Moreover, the phosphorylation assay revealed that, as compared to the studied molecular pathways, the MAPK signaling pathway exhibited maximum alterations in response to 1,000 µg/mL ABGE treatment.

Conclusions

ABGE appears to induce anti-inflammatory and anti-proliferative effects on prostate cancer cell lines, thus suggesting the potential role of this supplement in preventing the development of prostate cancer.