Cellular and Molecular Biology Biological activities and health-promoting effects of Pyracantha genus: a key approach to the phytochemical’s potential

: Pyracantha spp. are commonly called firethorn, and attract human attention due to their colorful berries. These berries are eaten globally as a tra ditional remedy for treating different stomach abnormalities, and as a cooking ingredient for folk diets. The present review aims to provide an overview on Pyracantha genus’ geographical distribution and botanical description, traditional uses, phytochemical composition, biological activities and safety issues. Several biological activities have been reported to Pyracantha species, namely antioxidant, anti-inflammatory, antimicrobial, larvicidal and cytotoxic properties, most of them attributed to the use of their fruits. Pyracantha species phytochemical composition reveal the presence of interesting bioactive molecules, such as pyracrenic acid and fortuneanosides. The currently reported biological activities to these plants derive from in vitro and in vivo studies, so that clinical trials are needed to confirm these preclinical results. Nonetheless, Pyracantha species can be suggested as a safe herb useful to develop future drug formulations and functional foods.


Introduction
Pyracantha genus is an evergreen, thorny shrub belonging to the Rosaceae family, widely used in gardening and landscaping (1). The genus is commonly called as 'firethorn' due to the presence of dense poisonous thorns when pierce the human skin causes severe pain and inflammation. Originally introduced and planted as garden ornamentals, Pyracantha genus appears to house about 10 species (2)(3)(4)(5). However, the exact number of species is unclear as there are many synonyms inconsistently used in the literature. Because of aesthetic values and presence of thorns, these plants are popularly used for making fences and walls.

Traditional uses
Plants of Pyracantha genus are used in traditional cultures in countries where they were originally endemic. They have been used in China for more than 1700 years as a food source, and have also been used as food in the Western Himalayas. At present, fruit juice, fruit wine and preserved fruit from these plants remain popular (11,12).
Pyracantha fortuneana (Maxim.) H. L. Li is used as skin-whitening agent in cosmetics in Japan (13), and Pyracantha crenulata (Roxb. ex D. Don) M. Roem. is a fuel in Himalayan countries (11). Nowadays, plants of Pyracantha genus are popular in countries with a Mediterranean climate as a landscape ornamental (14).
In Ayurvedic medicine, Pyracantha spp. is used in the treatment of a number of disorders, including hepatic, stomach and skin diseases (15).
In traditional herbal medicine in some cultures, 4 species of Pyracantha genus are used. In the traditional medicine of the Indian Himalayas, P. crenulata fruits are often prescribed for the treatment of hypertension, arteriosclerosis, angina, diabetes, pregnant anemia, stomach disorders, including constipation, and externally in the form of juice for the treatment of earache (16)(17)(18)(19). In traditional medicine of Nepal (20) and Indian rural community (21), the fruits of this plant are eaten in cases of dysentery. In Uttarakhand, bark of this plant is recommended for heavy bleeding during menstrual cycles (22). Also leaf paste of P. crenulata is used for burns (23). In Central Himalaya, P. crenulata roots are used in bathing for body pain (24). In traditional Chinese Medicine, P. fortuneana plants are used as a popular remedy. Fruits of this plant are recommended for oral administration for the treatment of dyspepsia and dysentery or for externally for sores relief (13,25). Pyracantha koidzumii (Hayata) Rehder is used in dysmenorrhea (26). In Europe, P. coccinea fruits are taken for medicinal use as heart soother (27). Leaves of this plant are used in diarrhea and urinary diseases in Turkey (27,28). P. coccinea are also used in veterinary medicine for diarrhea (27).

Biological activities
Several bioactive effects have been reported to Pyracantha spp., with the most prominent ones being their antioxidant, antimicrobial, larvicidal, cytotoxic, and anti-inflammatory effects. In the following sections are described the biological activities of the most common Pyracantha spp., summarized in Figure 2.
Pyracantha angustifolia (Franch.) C.K.Schneid. Kim,Park (40) reported that P. angustifolia leaves methanol extract (at 10, 000 ppm) exhibited insecticidal and acaricidal activities against Tetranychus urticae, Aphis gossypii, Myzus persicae, Trialeurodes vaporariorum, and Panonychus citri. The antioxidant activity, total polyphenols and electron donating abilities of methanol extract, methylene chloride, ethyl acetate, and methanol fractions of P. angustifolia were reported by Lee (29). The extract exhibited superoxide radical as well as hydrogen peroxide (H 2 O 2 ) scavenging activity. The highest total polyphenol contents (2007.30±109. 28 μg GAE/mL) were found in 70% methanol extract. Moreover, 70% methanol extract also showed highest electron donating abilities (79.07±7.31) and superoxide radical removal ability (0.018±0.003). Furthermore, the methylene chloride fraction exhibited maximum H 2 O 2 decomposition (0.0027±0.0015) among the extracts/ fractions.  BHT, used as positive control, whereas methanol and ethanol extracts showed higher scavenging activity on DPPH compared to BHT. The extracts also showed better antioxidant activities than α-and δ-tocopherol, vitamins K and D, β-sitosterol, ergosterol, and stigmasterol. Sarikurkcu and Tepe (30) reported that the ethanol and water extracts of P. coccinea inhibited acetylcholinesterase, butyrylcholinesterase, α-amylase, α-glucosidase and tyrosinase effects. It was also observed that the scavenging potential on DPPH radical, ABTS radical cation, superoxide anion and nitric oxide was higher for the ethanol extract than that of water extract. Ethanol extracts also displayed higher activities in antioxidant power (FRAP), cupric ion reducing, ferric reducing, iron (III) to iron (II) reduction, and phosphomolybdenum assays. The work suggested its possible therapeutic use against Alzheimer's disease.
P. coccinea fruits methanolic extract also revealed cytotoxic effectsVahabi, Monajemi (44). In that study, it was reported a weak cytotoxic effect (with highest activity at 800 µg/ml) on Hela cell lines (MTT assay). The antioxidant activity (DPPH assay), and total phenolic contents (Folin-Ciocalteu assay) displayed by the methanol extract were found to be higher when compared to the aqueous extract.
Saklani and Chandra (18) reported that P. crenulata fruit pulp ethanolic extract exhibit antimicrobial activities against Shigella flexneri, Escherichia coli and S. pyogenes. The crude protein, crude fiber and carbohydrates contents in the extract were found to be 5.13%, 7.40% and 24.88%, respectively. The extract was also reported to contain phenolics, saponins and flavonoids at 1.83%, 1.56% and 3.12%, respectively.

Pyracantha fortuneana (Maxim.) H. L. Li
Diverse biological activities have been reported to P. fortuneana. Zhao,Lei (48) reported the antioxidant activity of P. fortuneana fruit water-soluble polymeric polyphenolic fractions on HepG(2) cells. The authors also reported an increase in cell antioxidant activities using peroxyl radical-induced DCFH oxidation method with higher decrement being stated at EC 50 values of 2.91. The in vivo antioxidant benefit of small molecular polyphenols was attributed to the additive effects conferred by the proanthocyanidins present in fractions. In another study, the same group also assessed the total polyphenolic content (TPC), total antioxidant activity (TAA) and chromatographic profiling of the plant extract through response surface methodology (RSM) and solvent optimization, in order to enhance the P. fortuneana fruits applicability as nutraceutical in food industries (49). Wang,Ye (31) with the help of high-pressure liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS/MS) profiling identified 7 flavonoids, 6 phenolic acids, 7 organic acids, 3 tannins, 1 terpene, and 1 alkaloid from P. fortuneana fruit (50% acetone extract) and reported antioxidant and α-glucosidase inhibitory activities. Wei, Chai (50) extracted proanthocyanidins from P. fortuneana fruit and reported α-glucosidase inhibition (IC 50 0.15 µg/mL) in a non-competitive manner. Dai (GLUT2), improved tight junction proteins, modulated bacterial groups linked with gut barrier integrity, such as Actinobacteria, Bacteroidaceae, Corynebacteriaceae, Lactobacillaceae, and S24-7, and inhibited α-amylase, α-glucosidase, and lipase enzymes. Moreover, the same group reported, in rodents, a decrease in body weight, triacylglycerol, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), and malondialdehyde (MDA) levels, and elevation in high-density lipoprotein cholesterol (HDL-c), glutathione peroxidase (GPx), and superoxide dismutase (SOD) (52). These results markedly suggested the P. fortuneana fruit potential against hyperlipidemia, obesity and oxidative stress.

Safety and adverse effects
Pyracantha spp. attracts human attention due to its colorful berries and those are eaten globally as traditional medicine and as a cooking ingredient. However, there is no in-depth report on their safety concerns and adverse effects. P. crenulata fruits are eaten by Indian rural community in several regions, with its powder being also mixed with yoghurt to treat bloody dysentery, thus clarifying its non-toxic properties (21). P. angustifolia leaf extract showed lesser effects while checking its insecticidal activities against A. gossypii, M. persicae, T. vaporariorum, and P. citri, revealing a higher survival rate after 72 h exposure at 10,000 ppm when compared to the control and other plants tested (40). In another study, P. coccinea fruit methanol extract was applied in mosquito larvae (C. pipiens) to determine its larvicidal/insecticidal effects, but no significant mortality was found even at the highest concentration (i.e. 1000 ppm) (43). Pretreatment with P. fortuneana fruit extract on kidney injury in CdCl 2 -injected rats showed that it could significantly reduce CdCl 2 -induced toxicities through increasing Nrf2, HO-1, y-GCS, GSH-Px and NQO-1 expression (56). Thus, it was reported to be beneficial for treating renal toxicity caused by CdCl 2 . This extract was also reported to have ameliorative effects on intestinal barrier dysfunction in high fat dietinduced Sprague Dawley rats without showing toxicity (52). Besides, P. fortuneana polysaccharides were found to enhance immune function and oxidative stress in mice (60). Of them, selenium containing polysaccharides could significantly reduce the tumor growth besides to confer preventive effects against CCl 4 -induce liver injury in mice model without altering body weight (53,54). Peng, Guo (25) reported that selenium containing polysaccharides administered to mice at doses up to 5.4g/kg body weight caused no detectable toxicity and death during the 30-day experiments. Medicinal plant polysaccharides are in general thought to be non toxic, thus making them suitable for therapeutic applications (61), and based on the several previous findings, it is undoubtedly clear that selenium containing polysaccharides from Pyracantha spp. can be used and considered as a safe naturally-derived therapeutic agent.
All previous studies with Pyracantha spp. evidenced its safety and non-toxicity as a traditional medicinal source. However, there are some rumors among rural/ scientific communities on the possible plant toxicities. Thus, Pyracantha spp. can be suggested as a safe herbal source for developing future drug formulations and functional foods for human health promotion.

Conclusions and future perspectives
Pyracantha spp. are used in folk medicine for treating different human medical conditions, such as stomach abnormalities, hepatic and skin diseases. In addition, several biological properties have been attributed to the Pyracantha genus members, viz. antioxidant, anti-inflammatory, antimicrobial, larvicidal and cytotoxic effects. Many reports are available on specific Pyracantha spp. for their pharmacological benefits using various in vitro and in vivo animal models, most of them concentrated on the effects of its fruits. The use of these plants in folk medicine and its reported biological activities (in vitro and in vivo) are closely related to the plants' phytochemical composition. However, a scarce amount of studies is available elucidating some interesting phytochemicals found in Pyracantha spp. (i.e. pyracrenic acid and fortuneanosides). In addition, some Pyracantha spp. extracts and phytochemicals have revealed enzymatic inhibition abilities, and thus may be useful in pathologies such as hyperlipidemia, obesity and oxidative stress-related diseases. Thus, given the current insights, further studies are needed to determine the phytochemical composition of all plant parts of different Pyracantha spp. and to determine the biological activities of plants extracts and purified phytochemicals. Clinical trials should also be conducted to confirm the preclinical studies findings. Anyway, Pyracantha spp. can be viewed as safe plants, useful to develop future drug formulations and functional foods.

Funding
This research received no external funding.