#Grapefruit seed extract free#
Subjects (5 males and 11 females, 20 to 40 years old) were free of any illness and were not taking medications known to affect immune functions, including nonsteroidal anti-inflammatory agents, histamine receptor antagonists, recreational drugs, or birth control pills. In the present studies, we assessed the effect of a proprietary grape seed extract (GSE) that contains oligomeric procyanidins on Th1 (IFN-γ)- and Th2 (IL-6)-derived cytokine production by normal peripheral blood mononuclear cells (PBMC) to test the above hypothesis.Īfter obtaining informed consent, peripheral blood was drawn from healthy donors into a syringe containing heparin (20 U/ml). We hypothesize that flavonoids exert significant immunomodulatory effects by differentially regulating the production of Th1- and Th2-derived cytokines.
Conversely, the Th2-derived cytokines, such as IL-4, IL-5, and IL-6, exert negative immunoregulatory effects on cell-mediated immunity, while upregulating humoral immunity ( 5, 6, 8). There is general acceptance that the Th1-derived cytokines such as interleukin-2 (IL-2), gamma interferon (IFN-γ), and IL-12 promote cell-mediated immunity ( 4). The molecular mechanisms underlying these biological activities await elucidation. Of these diverse pharmacological actions of the dietary flavonoids, their antitumor and antiviral effects stand out. Documented biological effects of dietary flavonoids include antiallergic, anticarcinogenic, anti-inflammatory, antimicrobial, antineoplastic, antithrombotic, antiviral, cardioprotective, and hepatoprotective effects, among others ( 7). Flavonoids display a remarkable array of pharmacological and biochemical actions. On average, the normal human diet contains 200 mg or more of mixed flavonoids per day. Our results demonstrate that the potentially beneficial immunostimulatory effects of GSE may be mediated through the induction of IFN-γ. The enhancing effect of GSE on IFN-γ expression was further supported by a concomitant increase in the number of cells with intracytoplasmic IFN-γ as well as the synthesis and secretion of IFN-γ.
Our results show that GSE significantly induced the transcription of IFN-γ mRNA as demonstrated by reverse transcription-PCR but had no effect on the Th2-derived cytokine interleukin-6. We hypothesize that the flavonoid constituents of a proprietary grape seed extract (GSE) that contains procyandins exert significant antiviral and antitumor effects, by inducing production of the Th1-derived cytokine gamma interferon (IFN-γ) by peripheral blood mononuclear cells) from healthy donors. Although flavonoids manifest a diverse range of biological activities, including antitumor and antiviral effects, the molecular mechanisms underlying these activities await elucidation.
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