Aqueous extract of Arbutus unedo inhibits STAT1 activation in human breast cancer cell line MDA-MB-231 and human fibroblasts through SHP2 activation

Use of Strawberry Tree (Arbutus unedo) as a Source of Functional Fractions with Biological Activities

Arbutus unedo, commonly named 'strawberry tree' (ST), is a Mediterranean native plant that represents a relevant source of biologically active fractions and compounds. ST fruits, traditionally used with culinary and medicinal purposes, along with other components (leaves, roots, honeys, etc.), have been subjected to varied extraction procedures to obtain enriched and bioactive products. This work reviewed the scientific literature, searching for studies that evaluated the potential health implications of ST fractions and attending to the tested biological activities (antioxidant, antiproliferative, hypoglycemic, immune-modulatory, antihypertensive, antimicrobial, etc.), the part of the tree, the experimental model, the specific bioactive compounds and the selected extraction protocol. Furthermore, the strengths and weaknesses of the current state of the published evidence were critically analysed. Although in vitro results demonstrated the potential of ST fractions, further research is encouraged in order to obtain in vivo evidence (animal and clinical studies), assess additional activities (hypocholesterolemic, microbiome-modulatory), maximize the use of advanced extraction technologies, purify and isolate specific bioactive compounds and broaden the analysis investigating phenolic and non-phenolic molecules and their bioavailability.

An Insight into Phytochemical, Pharmacological, and Nutritional Properties of Arbutus unedo L. from Morocco

Arbutus unedo L. (Ericaceae) is an evergreen shrub widely distributed in the Mediterranean region, particularly through the Moroccan forests. It is an important medicinal plant of great scientific interest due to its nutritional, pharmacological, and chemical properties. The objective of this review is to provide insights into traditional medicinal uses and phytochemical and pharmacological properties of A. unedo from Morocco. In Morocco, the plant has been used as a traditional medicine to treat several pathological conditions. Many phytochemical compounds have been reported in the plant, of which vitamins, carotenoids, flavonoids, polyphenols, tannins, and their derivatives are the most prevalent. Leaves and fruits of A. unedo contain the most significant number of phytochemicals among the species. Furthermore, researchers have demonstrated that A. unedo exhibited antioxidant, anticancer, antibacterial, antidiabetic, antiaggregant, and antihypertensive activities due to the presence of many biochemical compounds with health-promoting properties. According to different toxicity tests, the use of A. unedo is devoid of any significant side effects and/or toxicity. Despite its nutraceutical and health-promoting properties, Moroccan A. unedo remains underexploited mainly, and most of its traditional uses have not yet undergone scientific evidence-based research; therefore, improved knowledge about the potential value of the plant would allow understanding of its biological activity based on its phytochemical compounds that may contribute to the species preservation and valorization.

Contribution of Flavonoids and Iridoids to the Hypoglycaemic, Antioxidant, and Nitric Oxide (NO) Inhibitory Activities of Arbutus unedo L

This study aims at investigating the contribution of two classes of compounds, flavonoids and iridoids, to the bioactivity of Arbutus unedo L. leaves and fruits. The impact of different extraction procedures on phytochemicals content and hypoglycemic, antioxidant, and nitric oxide (NO) inhibitory activities of A. unedo fresh and dried plant materials was investigated. Ellagic acid 4-O-β-D-glucopyranoside, kaempferol 3-O-glucoside, and norbergenin were identified for the first time in this genus by using liquid chromatography-electrospray ionization-quadrupole-time of flight-mass spectrometry (LC-ESI-QTOF-MS). Three iridoids (gardenoside, geniposide, unedoside) are specifically identified in the leaves. Interestingly, asperuloside was extracted only from dried fruits by ethanol with Soxhlet apparatus. Extracts were screened for their potential antioxidant activities by using the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), Ferric Reducing Activity Power (FRAP), and β-carotene bleaching tests. Based on the Global Antioxidant Score (GAS) calculation, the most promising antioxidant extract was obtained by hydroalcoholic maceration of dried leaves that showed half maximal inhibitory concentration (IC₅₀) of 0.42 and 0.98 μg/mL in ABTS and DPPH assays, respectively. The hypoglycaemic activity was investigated by α-amylase and α-glucosidase inhibition tests. Extracts obtained by ethanol ultrasound extraction of fresh leaves and hydroalcoholic maceration of fresh fruits (IC₅₀ of 19.56 and 28.42 μg/mL, respectively) are more active against α-glucosidase than the positive control acarbose (IC₅₀ of 35.50 μg/mL). Fruit extracts exhibited the highest anti-inflammatory activity.

Arbutus unedo L., (Ericaceae) inhibits intestinal glucose absorption and improves glucose tolerance in rodents

ETHNOPHARMACOLOGICAL RELEVANCE

Arbutus unedo L., (Ericaceae) is one of the most traditional plants commonly used to treat diabetes in people living in Eastern Morocco region particularly in Taza and Beni Mellal.

AIM OF THE STUDY

The aim of the study was to find if there is a scientific support to the ethnopharmacological relevance use of Arbutus unedo L., roots bark (AU) to treat diabetes.

MATERIALS AND METHODS

We studied the effects of crude aqueous extract of AU on intestinal glucose absorption using short-circuit current technique in vitro and oral glucose tolerance test in vivo.

RESULTS

The aqueous extract of AU (10 µg/mL to 1 mg/mL) induced concentration-dependent inhibition of sodium-dependent glucose transport across isolated mouse jejunum. The maximal inhibition was obtained with 1 mg/mL, which exhibited more than 80% of the Phloridzin inhibition with an IC₅₀ close to 216 µg/mL. A 6-week AU ingestion (2 g/(kg day)), improved oral glucose tolerance as efficiently as metformin (300 mg/(kg day)). Arbutus unedo L. and metformin also reduced body weight.

CONCLUSIONS

Arbutus unedo L. roots bark aqueous extract directly inhibited the electrogenic intestinal absorption of glucose in vitro. In addition it improved oral glucose tolerance and lowered body weight in rats after chronic oral administration in vivo. These results add a scientific support to the ethnopharmacological relevance use of Arbutus unedo L. roots bark to treat diabetes.

Arbutus unedo L.: From traditional medicine to potential uses in modern pharmacotherapy

ETHNOPHARMACOLOGICAL RELEVANCE

Arbutus unedo L., the strawberry tree (Ericaceae family) is of increasing interest because of its common traditional, industrial, chemical and pharmaceutical uses. The plant is a typical evergreen plant of the Mediterranean basin, as well as of other regions with hot summers and mild rainy winters. This review covers the studies relevant to Arbutus unedo L. utilization in the current pharmacological therapy.

MATERIALS AND METHODS

The available information on traditional uses, phytochemistry and biological activities of Arbutus unedo L. was collected from scientific databases through a search using the keywords 'Arbutus unedo L.' and/or 'strawberry tree' in 'Google Scholar', 'Pubmed', 'Sciencedirect', 'SpringerLink', 'Web of Science - Clarivate Analytics' and 'Wiley'. Unpublished Ph.D. and M.Sc. dissertations were also consulted for chemical composition, biological activities and traditional uses of Arbutus unedo L. and for manual search of additional references.

RESULTS

The fruits of the plant have been traditionally used as antiseptics, diuretics and laxatives in folk medicine, while the leaves have been used due to their diuretic, urinary antiseptic, antidiarrheal, astringent, depurative and antihypertensive properties. According to the scientific literature survey, different extracts obtained from Arbutus unedo L. have demonstrated a high pharmacological potential due to their in vitro and preclinical antibiotic, antifungal, antiparasitic, antiaggregant, antidiabetic, antihypertensive, anti-inflammatory, antitumoral, antioxidant, and spasmolytic properties.

CONCLUSION

This review suggests that A. unedo is a promising source of phytopharmaceutical products. The potential advantages of Arbutus unedo are related with the presence of polyphenolic compounds in its composition. However, further studies are needed to ascertain some profitable effects in humans. The beneficial effects associated with this shrub suggest that Arbutus unedo can be used for the development of new drugs to treat diseases such diabetes, hypertension, among others. Nonetheless, the safety of the Arbutus unedo compounds should also be examined.

(Poly)phenol-digested metabolites modulate alpha-synuclein toxicity by regulating proteostasis

Parkinson’s disease (PD) is an age-related neurodegenerative disease associated with the misfolding and aggregation of alpha-synuclein (aSyn). The molecular underpinnings of PD are still obscure, but nutrition may play an important role in the prevention, onset, and disease progression. Dietary (poly)phenols revert and prevent age-related cognitive decline and neurodegeneration in model systems. However, only limited attempts were made to evaluate the impact of digestion on the bioactivities of (poly)phenols and determine their mechanisms of action. This constitutes a challenge for the development of (poly)phenol-based nutritional therapies. Here, we subjected (poly)phenols from Arbutus unedo to in vitro digestion and tested the products in cell models of PD based on the cytotoxicity of aSyn. The (poly)phenol-digested metabolites from A. unedo leaves (LPDMs) effectively counteracted aSyn and H₂O₂ toxicity in yeast and human cells, improving viability by reducing aSyn aggregation and inducing its clearance. In addition, LPDMs modulated pathways associated with aSyn toxicity, such as oxidative stress, endoplasmic reticulum (ER) stress, mitochondrial impairment, and SIR2 expression. Overall, LPDMs reduced aSyn toxicity, enhanced the efficiency of ER-associated protein degradation by the proteasome and autophagy, and reduced oxidative stress. In total, our study opens novel avenues for the exploitation of (poly)phenols in nutrition and health.

Functions of Shp2 in cancer

Diagnostics and therapies have shown evident advances. Tumour surgery, chemotherapy and radiotherapy are the main techniques in treat cancers. Targeted therapy and drug resistance are the main focus in cancer research, but many molecular intracellular mechanisms remain unknown. Src homology region 2-containing protein tyrosine phosphatase 2 (Shp2) is associated with breast cancer, leukaemia, lung cancer, liver cancer, gastric cancer, laryngeal cancer, oral cancer and other cancer types. Signalling pathways involving Shp2 have also been discovered. Shp2 is related to many diseases. Mutations in the ptpn11 gene cause Noonan syndrome, LEOPARD syndrome and childhood leukaemia. Shp2 is also involved in several cancer-related processes, including cancer cell invasion and metastasis, apoptosis, DNA damage, cell proliferation, cell cycle and drug resistance. Based on the structure and function of Shp2, scientists have investigated specific mechanisms involved in cancer. Shp2 may be a potential therapeutic target because this phosphatase is implicated in many aspects. Furthermore, Shp2 inhibitors have been used in experiments to develop treatment strategies. However, conflicting results related to Shp2 functions have been presented in the literature, and such results should be resolved in future studies.

Arbutus unedo L.: chemical and biological properties

Arbutus unedo L. (strawberry tree) has a circum-Mediterranean distribution, being found in western, central and southern Europe, north-eastern Africa (excluding Egypt and Libya) and the Canary Islands and western Asia. Fruits of the strawberry tree are generally used for preparing alcoholic drinks (wines, liqueurs and brandies), jams, jellies and marmalades, and less frequently eaten as fresh fruit, despite their pleasing appearance. An overview of the chemical composition of different parts of the plant, strawberry tree honey and strawberry tree brandy will be presented. The biological properties of the different parts of A. unedo and strawberry tree honey will be also overviewed.