Resveratrol is a fat-soluble compound that various plants make to fight off bacteria, fungi, and other microbial attackers, or to withstand drought or lack of nutrients. It occurs naturally in over 70 plant species, most notably in the skin and seeds of red grapes. It has also been found in , cranberries (2.41 mg / 125 g), pinot noir (1.57mg / 150ml), blueberries (0.6 mg / 150 g), red grape juice (1.25 mg / 250 ml), peanuts (0.37 mg / 250 g), purple grapes, mulberries, lingonberries, and pistachios etc. Resveratrol is the most abundant in Polygonum Cuspidatum of 181~350 mg / 100 g (Hu Zhang in Chinese, also known as Japanese knotweed), a plant that has often been used in Chinese medicine.
Resveratrol is a stilbenoid-type polyphenol composed of two phenol rings joined by an ethylene bridge. Resveratrol is also a phytoalexin, a type of antibiotic produced by stressed plants. Phytoalexin is what enables plants to recover from fungal infections, UV light, and other stressors.
Resveratrol is a well-known physiologically active molecule that is produced in plants that have been exposed to viral or ionizing radiation. Renaud and De Lorgeril established the first link between wine polyphenols such as resveratrol and the possible health advantages of moderate wine drinking (the so-called “French Paradox”). Since then, resveratrol has garnered increased scientific attention, resulting in investigations into its biological action and a plethora of publications.
Bioavailability of Resveratrol
Resveratrol is rapidly metabolized upon ingestion, mostly to glucuronide and sulfate derivatives like sulfate, forming resveratrol glucuronides, sulfates, and/or sulfoglucuronides Maximum plasma concentrations of resveratrol metabolites occur roughly 30 minutes after administration; the half-life of total metabolites is approximately 9.2 hours. Humans absorb roughly 75% of resveratrol orally via transepithelial diffusion. From the liver, resveratrol and metabolites enter the systemic circulation and are absorbed by peripheral tissues, such as adipose tissue. The kidneys also participate in the metabolism of resveratrol, leading to the excretion of polar resveratrol metabolites.
Almost all of the positive research on resveratrol has been conducted using cell cultures or laboratory tests including yeast, roundworms, fruit flies, the short-lived turquoise killifish, or mice. The few human studies that have been conducted have examined certain intermediate indicators, such as antioxidant levels, heart rate variability, blood flow to the brain, and cancer protein levels.
Although resveratrol is effectively absorbed by humans when given orally, its bioavailability is poor due to its quick metabolization and elimination. Oral bioavailability is less than 1% due to extensive intestinal and hepatic processing.
Numerous speculative formulations have been proposed to increase resveratrol’s bioavailability, including intake with a variety of meals, micronized powders, combination with other phytochemicals, controlled release devices, and nanotechnological formulations. Laboratory models show that each of these techniques has the potential to increase resveratrol’s bioavailability and maximize its therapeutic value.