Contents lists available at ScienceDirect Journal of Functional Foods journal homepage: www.elsevier.com/locate/jff Small black bean (Rhynchosia volubilis) extract ameliorates gut microbial and metabolic perturbation in ovariectomized mice Kwang Hyun Cha a , Kyung-A Kim b , Suk Woo Kang b , Seemi Tasnim Alam a,d , Jong Beom Jin a , Gyhye Yoo c , Sang Hoon Jung b,d , Cheol-Ho Pan a,d , Kyungsu Kang a,d, ⁎ a Natural Product Informatics Research Center, Korea Institute of Science and Technology, Gangneung, Gangwon-do 25451, Republic of Korea b Natural Products Research Center, Korea Institute of Science and Technology, Gangneung, Gangwon-do 25451, Republic of Korea c Smart Farm Research Center, Korea Institute of Science and Technology, Gangneung, Gangwon-do 25451, Republic of Korea d Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology (UST), Republic of Korea ARTICLE INFO Keywords: Gut microbiome Intestinal metabolite Ovariectomy Phytoestrogen Rhynchosia volubilis ABSTRACT Phytoestrogen is considered a promising natural remedy for various postmenopausal symptoms. However, most studies have focused on common soybean, Glycine max. Here, for the first time, we evaluated the in vivo effect of a distinct species, small black bean (Rhynchosia volubilis), on ovariectomized mice and investigated its impact on the intestinal microbiota and metabolic status. Ovariectomized mice exhibited significant body weight gain, a typical postmenopausal symptom, and microbial changes, such as decreased α-diversity; changes in microbial composition, especially abundances of the families Desulfovibrionaceae and Mogibacteriaceae and genus Dorea; and decreased amino acid and short-chain fatty acid levels. Administration of small black bean extract restores body weight and gut microbial perturbation to levels similar to those observed under normal conditions. Our data suggest that small black bean extract is a potential candidate functional food for treating postmenopausal symptoms via remodeling of the intestinal microbiome. 1. Introduction Menopause is a normal phenomenon in women’s lives and occurs when the regular menstruation cycle ends permanently at ages ranging from approximately 40–55, resulting from a loss of ovarian follicles (Valera et al., 2017). The importance of menopause and its symptoms has received significant attention because there have been a large number of clinical reports regarding this phenomenon, and women experience problems caused by menopause (Agarwal, Alzahrani, & Ahmed, 2018). Hot flashes, night sweats, vaginal dryness, osteoporosis, depression, and body weight gain are representative symptoms that are observed in postmenopausal women (Agarwal et al., 2018; Davis et al., 2015; Duffy, Iversen, & Hannaford, 2013). Some therapies have been introduced to address these problems, including hormone replacement therapy (Agarwal et al., 2018; Ellis, Hendrick, Williams, & Komm, 2015). However, synthetic hormone-based or chemical drug-based treatments have undesirable side effects, including increasing the risk of endometrial and breast cancer (Beck, Rohr, & Jungbauer, 2005). Therefore, natural remedies, such as soy-based foods, can be the first choice for treatment, providing a healthy lifestyle for postmenopausal women (Beck et al., 2005; Messina, 2016). More than 15 years of emerging research has revealed that the gut microbiota and the associated metabolic activity are crucial regulators of human health and many diseases, such as inflammatory bowel dis- eases, autoimmune diseases, obesity and diabetes, cardiovascular dis- eases, and mental disorders (Durack & Lynch, 2019). The gut micro- biome plays a pivotal role in the alteration of estrogen levels in women during development, maturation, and menopause (Baker, Al-Nakkash, & Herbst-Kralovetz, 2017; Vieira, Castelo, Ribeiro, & Ferreira, 2017). The relationship between pre- and postmenopause is associated with a wide range of changes in gut microbial composition (Santos-Marcos et al., 2018). Postmenopausal women lack many important bacterial classes compared to premenopausal women, leading to an imbalance in the conditions and hampering the continued production of necessary metabolites for daily life (Baker et al., 2017; Vieira et al., 2017). The imbalance in gut microbial composition can affect and lead to many postmenopausal symptoms, including metabolic and immunological disorders. Therefore, remodeling of the gut microbiome can be a major influential factor for improvement of postmenopausal symptoms (Baker et al., 2017; Vieira et al., 2017). In a previous study, the overall gut https://doi.org/10.1016/j.jff.2019.103415 Received 12 April 2019; Received in revised form 11 June 2019; Accepted 11 June 2019 ⁎ Corresponding author at: Natural Product Informatics Research Center, Korea Institute of Science and Technology, 679 Saimdang-ro, Gangneung, Gangwon-do 25451, Republic of Korea. E-mail address: kskang@kist.re.kr (K. Kang). Journal of Functional Foods 60 (2019) 103415 1756-4646/ © 2019 Elsevier Ltd. All rights reserved. T