Taheebo (Pau Darco)
Anti-Inflammatory and Antinociceptive Activities of Anthraquinone-2-Carboxylic Acid
Anthraquinone compounds are one of the abundant polyphenols found in fruits, vegetables, and herbs. However, the in vivo anti-inflammatory activity and molecular mechanisms of anthraquinones have not been fully elucidated. We investigated the activity of anthraquinones using acute inflammatory and nociceptive experimental conditions. Anthraquinone-2-carboxylic acid (9,10-dihydro-9,10-dioxo-2-anthracenecarboxylic acid, AQCA), one of the major anthraquinones identified from Brazilian taheebo, ameliorated various inflammatory and algesic symptoms in EtOH/HCl- and acetylsalicylic acid- (ASA-) induced gastritis, arachidonic acid-induced edema, and acetic acid-induced abdominal writhing without displaying toxic profiles in body and organ weight, gastric irritation, or serum parameters. In addition, AQCA suppressed the expression of inflammatory genes such as cyclooxygenase- (COX-) 2 in stomach tissues and lipopolysaccharide- (LPS-) treated RAW264.7 cells. According to reporter gene assay and immunoblotting analyses, AQCA inhibited activation of the nuclear factor- (NF-) κB and activator protein- (AP-) 1 pathways by suppression of upstream signaling involving interleukin-1 receptor-associated kinase 4 (IRAK1), p38, Src, and spleen tyrosine kinase (Syk). Our data strongly suggest that anthraquinones such as AQCA act as potent anti-inflammatory and antinociceptive components in vivo, thus contributing to the immune regulatory role of fruits and herbs.
In summary, the results of this study demonstrate that AQCA is clearly able to inhibit various in vivo inflammatory and nociceptive symptoms without altering acute toxicity parameters such as body and organ weight, gastric irritation, and serum liver toxicity parameters. AQCA is capable of downregulating the levels of inflammatory gene expression by blockade of Src, Syk, p38, JNK, and IRAK1, thus blocking NF-κB and AP-1 activation. Since AQCA is one of the major components of numerous vegetables and fruits, we propose that AQCA or AQCA-rich nutraceuticals be developed as functional foods with anti-inflammatory properties.
Taheebo Polyphenols Attenuate Free Fatty Acid-Induced Inflammation in Murine and Human Macrophage Cell Lines As Inhibitor of Cyclooxygenase-2
Taheebo polyphenols (TP) are water extracts of Tabebuia spp. (Bignoniaceae), taken from the inner bark of the Tabebuia avellanedae tree, used extensively as folk medicine in Central and South America. Some anti-inflammatory drugs act by inhibiting both cyclooxygenase-2 (COX-2) and COX-1 enzymes. COX-2 syntheses prostaglandin (PG) E2, which is a species of endogenous pain-producing substance, whereas COX-1 acts as a house-keeping enzyme. Inhibiting both COX-1 and -2 simultaneously can have side effects such as gastrointestinal bleeding and renal dysfunction. Some polyphenols have been reported for its selective inhibiting activity toward COX-2 expression. Our study aimed to demonstrate the potential and mechanisms of TP as an anti-inflammation action without the side effects of COX-1 inhibition.
Our data suggest that TP is potentially useful in treating lifestyle-related chronic inflammation by attenuating inflammation caused by macrophage infiltration. The useful effects of TP are possibly due to the regulation of macrophages and the targeted inhibition of COX-2 activity, without affecting COX-1. The mechanism of this inhibition is probably due to acteoside, a key compound from TP, binding to the catalytic zone of COX-2, and the downstream catalytic activities thus attenuates PGE2 synthesis. TP are suggested to be one of the new generation of anti-inflammatory substances, exhibiting FFA-induced COX-2-selective inhibitory activities, and other anti-inflammatory actions.
Bioactive Phenylpropanoid Glycosides from Tabebuia avellanedae
Three novel phenylpropanoid glycosides 2, 5, 6 were isolated from water extract of Tabebuia avellanedae, together with three known phenylpropanoid glycosides 1, 3, 4. All compounds were identified on the basis of spectroscopic analysis and chemical methods and, for known compounds, by comparison with published data. All isolated compounds showed strong antioxidant activity in the DPPH assay, and compound 5 give the highest antioxidant activity among all compounds, with an IC50 of 0.12 µM. All compounds exhibited moderate inhibitory effect on cytochrome CYP3A4 enzyme.
The study identified six phenylpropanoid glycosides from the water extract of Taheebo. Phenylpropanoid glycosides displayed strong anti-oxidant activity and moderate inhibitory activity on CYP3A4 enzyme. It is reported that oxidative stress is implicated in a wide array of human diseases, including cancer, neurodegenerative diseases, diabetes, inflammatory joint diseases, cardiovascular dysfunctions, as well as ageing, so the presence of strong anti-oxidant phenylpropanoid glycosides in Taheebo may be a good illustration supporting the many biological activities of Taheebo displays and its use in folk medicine to treat many diseases for thousands of years.