Dual Inhibitory Activities of Tannins fromHamamelis virginianaand Related Polyphenols on 5-Lipoxygenase and Lyso-PAF: Acetyl-CoA Acetyltransferase¹

Abstract

In the present study, the effects of tannins obtained from various plant sources on the activity of 5-LOX and AT were examined. With IC50 values ranging from 1.0 to 18.7 muM, hamamelitannin and the galloylated proanthocyanidins isolated from Hamamelis virginiana L. were found to be most potent inhibitors of 5-LOX. Unlike the 5-LOX study, hamamelitannin proved to be ineffective in the AT assay. Potent candidates are represented by the group of B-type proanthocyanidins. Structure-activity relationships regarding the in vitro inhibitory potency of the polyphenols in the biological assays are discussed.

Impact of Wines and Wine Constituents on Cyclooxygenase-1, Cyclooxygenase-2, and 5-Lipoxygenase Catalytic Activity

“…Although Leifert and Abeywardena recorded the inhibition of 5-LOX (in enzymatic assay) by grape seed extract (IC 50 = 13  μ g/mL) and commercial perpetration “red wine polyphenolic compounds” (IC 50 = 35  μ g/mL), active constituents responsible for its activity were not identified or suggested in their study [33]. However, as in the case of COX enzymes, galloylated proanthocyanidins were able to inhibit 5-LOX activity with IC 50 ranging from 6.6 to 18.7  μ M [34]. This hypothesis works for red wines, but in white wines the proanthocyanidins concentrations are almost 100 times lower [35].…”

Antiseptic Effect of a Topical Dermatological Formulation That Contains Hamamelis Distillate and Urea

“…Dermatological formulations that contain HM are used mainly for their antiinflammatory activity. Hamamelitannins and proanthocyanidins have been shown to produce in vitro inhibition of 5-lipoxygenase [13], the animal model equivalent of which is inhibition of the carrageenan-and croton oil-induced rat paw edema [14,15]. Inhibition of vascular permeability and a vasoconstrictor effect have been observed in animal studies [16].…”

Synthesis of [2‐13C, 4‐13C]‐(2R,3S)‐catechin and [2‐13C, 4‐13C]‐(2R,3R)‐epicatechin

“…These activities include, but are not limited to inhibiting HIV-1 replication in vitro, 3 reducing the risk of heart disease, 4 suppressing ulcer formation, 5 possessing antimutagenic, 6 neuroprotective, 7 anti-inflammatory, 8 antibacterial, 9 hypertensive 10 properties, and can inhibit the growth of cancer cells. 11 Moreover, flavanols can affect a host of cellular functions in vitro such as signaling pathways, 12 alter cell membrane characteristics 13 and receptor function 14 to imply physiological effects in vivo.…”