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  • br The value of herbal preparations can be explained in


    The value of herbal preparations can be explained in five major ways. The first is closely related to foodstuffs and the use of plants due to their nutritional value, secondly for manufacturing food supplements or nutraceuticals, thirdly to utilize plants or their products as tradi-tional therapeutic agents, fourthly to use plants or their products such as essential oils in cosmetics and finally the exploration of evidence-based therapeutic uses for plant constituents and manufacturing con-ventional medications from these plants [14–16].
    It has been estimated that about 420,000 plants species exist around the globe. Unfortunately, for most of these species, very limited in-formation about their constituents or their therapeutic or nutritional benefits is available in the literature [17].
    Carlina curetum Heldr. ex Halácsy (family Compositae) is commonly known as carline thistle. It is a perennial edible herb reaching 25–50 cm tall, sparsely cobwebbed to glabrescent, and rarely tomentose. The leaves are leathery, pinnatifid with spiny lobes, while the radical leaves are rosulate, tapering to a petiole; the cauline leaves are distant, narrow-lanceolate, pinnatisect into distant long and strong spiny lobes, canaliculate, spreading to recurved, sessile, with small auricles. C. curetum originated in the Mediterranean basin, especially on the Palestinian plains [10,18–20]. In Palestinian ethnomedicine, the leaves and stems of C. curetum are utilized to decrease blood 4hydroperoxy Cyclophosphamide levels, to burn body fat and for the prophylaxis of cancer [21]. In fact, various species of Carlina plant have been utilized as herbal remedies in Eur-opean traditional medicine. For example, C. acaulis root is still utilized therapeutically as a diaphoretic, diuretic and anthelmintic. Moreover, the decoction of its roots is used for the treatment of toothache, catarrh, skin lesions and rashes [22,23].
    To the best of our knowledge, C. curetum is an unstudied plant species and nothing in the literature is known regarding its chemical constituents or biological/pharmacological uses. However, the current plant species not studied previously its chemical constituents and our study is the first study made phytochemical screenings. Therefore, the present study aimed to qualitatively and quantitatively evaluate the chemical constituents of C. curetum in various fractions and to assess the α-amylase, α-glucosidase and lipase enzyme inhibitory activities and the cytotoxic effects of these fractions against HeLa and Colo-205 cells in order to better understand the anti-obesity, hypoglycemic and an-ticancer effects of this plant.
    2. Material and methods
    2.1. Collection and preparation of plant material
    The selected C. curetum aerial parts were harvested randomly from Nablus region of Palestine in May 2018. Characterization was estab-lished by the Pharmacognosist and Herbal Products Specialist Dr. Nidal Jaradat, in the Laboratory of Pharmacognosy at An-Najah National University and the given code for the voucher̴specimen was Pharm-PCT-521. The plant aerial parts were well cleaned and dried in the shade at ordinary temperature 25 °C and finally, the dried parts were grounded coarsely by the mechanical grinder and then kept in an air-tight container with suitable labeling for future use.
    2.2. Four solvents exhaustive fractionation
    The powder made from the dried aerial parts of C. curetum was exhaustively extracted by a fractionation method by adding solvents in a sequential manner, depending on their polarities, beginning with the totally non-polar solvents hexane and acetone (polar aprotic organic solvents), then methanol (a polar alcohol) and finally distilled water (a  European Journal of Integrative Medicine 30 (2019) 100933
    polar protic solvent). For the preparation of each extract fraction, about 25 g of the ground dried C. curetum plant parts was first placed in 0.5 L of hexane (Loba/Chemie, India) and soaked for 72 h in a shaker at 100 rotations per minute at 25 °C. The hexane was then replaced with 0.5 L of acetone (Alfa-Aesar, UK) in the same manner, then methanol (Loba/ Chemie, India) and finally water. Each organic fraction was filtered and concentrated under vacuum on a rotary evaporator (Heidolph OB 2000-VV2000, Germany), while the aqueous fraction was dried using a freeze dryer (Mill Rock Technology, model BT85, China). Finally, all crude fractions were stored at 4 °C in the refrigerator until further use [24,25].
    The yield of each plant fraction was calculated using the following formula:
    2.3. Preliminary qualitative phytochemical examinations
    A preliminary phytochemical determination of the four plant frac-tions was carried out to reveal the presence of secondary or primary metabolic products in each of the fractions. These examinations were carried out according to the Evans method. The qualitative results are expressed as (+) for the presence and (−) for the absence of these phytochemical classes [26].