Chemical features and biological effects of astaxanthin extracted from Haematococcus pluvialis Flotow: focus on gastrointestinal system

The main purpose of this review is to analyze published data concerning the antioxidant properties of a xanthophyll belonging to the group of carotenoids, named astaxanthin, produced by the microalga Haematococcus pluvialis in response to specific conditions of "environmental stress" and characterized by the typical deep red color.

The chemical structure of astaxanthin provides the molecule with marked antiradical properties. Due to its central conjugated double bonds and the presence of hydroxyl and keto groups, astaxanthin exerts a strong antioxidant action, and not the pro-oxidant one.

Natural astaxanthin has the ability to establish effective protection against oxidative stress, neutralizing free radicals in both the inner and outer layer of cell membranes, especially in mitochondria.

The most recent preclinical and clinical studies that have investigated the beneficial properties of this molecule towards the gastrointestinal tract were included. In particular, it was shown that astaxanthin favors gastrointestinal health, thanks to its ability to inhibit inflammation, providing protection against gastric ulcers, reducing Helicobacter pylori infection and decreasing clinical symptoms in patients with dyspepsia. The benefits of astaxanthin concern the whole gastrointestinal tract, from the oral mucosa to the gut, where this molecule helps support a healthy microbiome, promoting the growth of favorable gut bacteria. In addition, astaxanthin's antioxidant and anti-inflammatory properties support immune function, favoring effects promoting overall well-being.

Moreover, the great nutraceutical potentiality of astaxanthin is strictly related to its excellent bioavailability since it presents distinctive amphipathic features. This phytochemical administered at low dosages (typically between 4 and 20 mg/day) reaches, in vivo, concentrations near to those used in in vitro experiments. Therefore, it is reasonable to assume that many of the in vitro experiments are really indicative of the potential effects of this substance also in vivo.