Potential biomedical applications of Araucaria araucana as an antispasmodic, bronchodilator, vasodilator, and antiemetic: Involvement of calcium channels.

ETHNOPHARMACOLOGICAL RELEVANCE: Since pre-Columbian era, the resin of Araucaria araucana tree has been used traditionally for the treatment of ulcers and wounds. Araucaria species have also been used to treat inflammation, respiratory problems, viral infections, ulcers, and rheumatoid, cardiovascular, and neurological disorders. AIMS AND OBJECTIVE: Due to its popular use, the authors aimed to scrutinize the potential of this plant as an antispasmodic and an antiemetic agent. Furthermore broncho- and vasodilatory effects of this plant was explored to rationalize its folkloric uses. MATERIALS AND METHODS: Araucaria araucana crude extract (Aa.Cr) was evaluated in isolated preparations of rabbit jejunum, trachea, aorta, and atria to investigate the antispasmodic, bronchodilator, and vasodilator effects. The potential mechanistic approaches were compared with the standard drug 'verapamil'. The antiemetic activity was determined and compared with the standard drug 'domperidone' via chick emesis model. RESULTS: Aa.Cr dose-dependently relaxed both spontaneous and K+-induced contractions in the isolated jejunum preparations of rabbits. In concentration-response curves of calcium (Ca++), Aa.Cr also triggered the rightward shift like verapamil. Applying carbachol and phenylephrine (1 µM) and K+ (80 mM) to the isolated tracheal and aortic tissue preparation, respectively, resulted in broncho- and vasodilatory activities, respectively which may be due to the inhibition of Ca++ channels. Aa.Cr inhibited atrial force and spontaneous contractions in the rabbit's right atria. Aa.Cr exhibited significant antiemetic activity (P < 0.001 vs. saline) in dose-dependent (50-150 mg/kg) manner like domperidone. In silico molecular docking was performed to investigate the biological targets of purified components of Aa.Cr which revealed that cadinol dominantly targets ß2 receptors to cause bronchodilation, however, eudesmin binds non-specifically to all the selected targets, while secoisolariciresinol mediated high hydrogen bonding with muscarinic receptors (M1 and M3) and Ca++ channels, thus shows the suggested mechanistic pathways of targeted activities. CONCLUSIONS: The results of this study indicates that Aa.Cr may exhibit antispasmodic activity, bronchodilation, and vasodilation by inhibiting voltage-dependent Ca++ channels and release of subcellular calcium. This explains its folkloric use in hypertension, bronchospasms, gastrointestinal spasms, and emesis.

Pehuén (Araucaria araucana) seed residues are a valuable source of natural antioxidants with nutraceutical, chemoprotective and metal corrosion-inhibiting properties.

In the last decade, green chemistry has been attracting great interest in many contexts, including, among others, natural antioxidants. However, only a few works deal with natural residue extracts and biowaste, which could be an efficient, economical and environmentally friendly source for the production of useful compounds. In this study, we look for antioxidant activity in Araucaria araucana seeds, an iconic pine species of the Argentine and Chilean Patagonia commonly known as "pehuén". Piñones are the edible pehuén seeds, and it is estimated that approximately 40 tons of piñones are harvested annually in Argentina and Chile. The chemical composition, antioxidants, metal corrosion-inhibiting properties and biological activity of edible and discarded piñón tissues were determined. Acute toxicity was discarded by in vitro testing and double fluorescent staining. Biological activity was evaluated in vivo by determining redox markers in salivary glands from rats treated with Cyclophosphamide (an oncological drug). All piñón tissues had antioxidants and antioxidant activity, with the coats showing the highest levels (up to 404 µg ascorbic acid equivalent per mg). The coats, in particular, had high gallic acid, catechin, quercetin and tannin contents, and more antioxidant activity, polyphenols and flavonoids than berries from the region. Results by X-ray fluorescence spectrometry showed that Na, Mg, P, S, Cl, K, and Ca were majority elements in the coat, embryo and endosperm. Furthermore, coat extract also showed significant anti-corrosion activity and in vivo protection against oxidative damage. The results indicate that piñón biowaste is a low-cost attractive source of natural antioxidants with potential nutraceutical, medical and metal corrosion protection applications.