procyanidin-b1 and epigallocatechin-gallate

Proanthocyanidins, also known as condensed tannins and/or oligomeric flavonoids, occur in many edible plants and have various interesting biological activities. Previously, we reported a synthetic method for the preparation of various procyanidins in pure form and described their biological activities. Here, we describe the synthesis of procyanidin B1 acetylated analogs and discuss their inhibition activities against HeLa S3 cell proliferation. Surprisingly, the lower-unit acetylated procyanidin B1 strongly inhibited the proliferation of HeLa S3 cells. This molecule showed much stronger inhibitory activity than did epigallocatechin-3-O-gallate (EGCG), green tea polyphenol, and dimeric compounds that included EGCG as a unit. This result suggests that the phenolic hydroxyl groups of the upper-units in flavan-3-ols are important for their inhibitory activity against cancer cell proliferation and that a hydrophobic lower unit dimer enhances this activity.

Topics: Acetylation; Biflavonoids; Catechin; Cell Proliferation; HeLa Cells; Humans; Neoplasms; Polymers; Proanthocyanidins; Tea

The way specific procyanidins exert their anti-inflammatory effects is not fully understood. This study has investigated the capacity of different procyanidins to modulate lipopolysaccharide (LPS)-induced reactive oxygen species (ROS) production in THP1 human monocytes and their effects on the redox regulated protein kinases activity: IkB kinase beta (IKKb) and the extracellular signal-regulated kinase (ERK). LPS-triggered increase of ROS was prevented by cell pre-incubation with procyanidins. LPS induced ERK1/2 activation through phosphorylation, which was inhibited by all the compounds tested, the most active being epigallocatechin (EG), followed by epigallocatechin gallate (EGCG) and C1. Procyanidins inhibited IKKb activity in vitro. C1 and procyanidin extract (PE) exerted the maximal IKKb inhibition, followed by EGCG and dimer B1. Catechin exerted a slight but significant IKKb inhibition, in contrast to epicatechin, which was ineffective. In conclusion, procyanidins reduce the LPS-induced production of ROS and they exert their anti-inflammatory effects by inhibiting ERK1/2 and IKKb activity.

Topics: Antioxidants; Biflavonoids; Catechin; Cell Line; Extracellular Signal-Regulated MAP Kinases; Flavonoids; Free Radicals; Humans; I-kappa B Kinase; Inflammation; Lipopolysaccharides; MAP Kinase Signaling System; Monocytes; NF-kappa B; Phosphorylation; Proanthocyanidins; Reactive Oxygen Species; Signal Transduction

In a search for possible antitumor agents from natural sources, megastigmane glycosides and polyphenolic constituents isolated from the leaves of Eriobotrya japonica (Rosaceae) were found to inhibit the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced activation of Epstein-Barr virus early antigen in Raji cells. Roseoside and procyanidin B-2 were among the active compounds found in an in vitro assay; these compounds were further assessed for antitumor activity in vivo in a two-stage carcinogenesis assay on mouse skin. Roseoside significantly delayed carcinogenesis induced by peroxynitrite (initiator) and TPA (promoter), and its potency was comparable to that of a green tea polyphenol, (-)-epigallocatechin 3-O-gallate, in the same assay.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Antigens, Viral; Antineoplastic Agents; Biflavonoids; Carcinogens; Catechin; Female; Glucosides; Herpesvirus 4, Human; Humans; Mice; Mice, Inbred ICR; Nasopharyngeal Neoplasms; Norisoprenoids; Peroxynitrous Acid; Plant Leaves; Proanthocyanidins; Rosaceae; Skin Neoplasms; Tea; Tetradecanoylphorbol Acetate; Virus Activation