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Received Jun 25, 2017; Accepted Dec 17, 2017
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1. Introduction
Menopausal women commonly experience symptoms including osteoporosis, hot flash, hyperlipidemia, cardiovascular disease, and fat redistribution, which are associated with decrease in endogenous estrogen level [1, 2]. Estrogen deficiency facilitates osteoporosis by lowering bone mass of trabecular bones, leading to increased fragility, which is due to the imbalance between bone resorption and bone formation [3]. At menopause, there are increases in abdominal fat and cardiovascular disease risk factors associated with a worsening of blood lipid profile, that is, high levels of triglycerides (TG), total cholesterol (TC), and low-density lipoproteins (LDL) [4–6]. Hot flash, related to change in blood circulation, is a quick feeling of heat and sometimes a red, flushed face and sweating due to the disturbances in hypothalamic control of temperature [7]. The characteristic of hot flash is dermal vasodilatation, leading to increased skin blood flow (flushing) and skin temperature, although sometimes there may be a transient decrease in core temperature [8].
Hormone replacement therapy (HRT), composed of estrogen and progesterone, has been used to treat the climacteric complaints [9], but HRT is commonly associated with side effects such as breast cancer and heart disease as long-term effects [10]. Hence, natural selective estrogen receptor modulators have been recommended to reduce those discomforts. The effects of plant-based remedies, such as soy, red clover, flaxseed, black cohosh, and chaste tree berry, are from their constituents known as phytoestrogens. Phytoestrogens are polyphenolic nonsteroidal plant compounds with estrogen-like biological activity. They exert such activity by directly binding to estrogen receptors or by influencing the production, metabolism, and action of natural hormones at the cellular level [11, 12].
Hop (Humulus lupulus L.) in Cannabaceae family has been used as a bitter constituent of beer worldwide. Notably, hop extracts contain diverse phytoestrogen compounds that were the highest in the extracts from female flowers of the hop plant. As active components (phytoestrogens) of hop plant, prenylflavonoids including 8-prenylnaringenin (8-PN), isoxanthohumol (IX), and xanthohumol have been demonstrated, in which 8-PN was the most potent ingredient with binding affinity to estrogen...