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Rhubarb
Published in Mahendra Rai, Shandesh Bhattarai, Chistiane M. Feitosa, Ethnopharmacology of Wild Plants, 2021
Gan B. Bajracharya, Richa K. Gupta
Rhapontigenin (68), 3,5,4′-trimethylpiceatannol (72) and rhaponticin (73) produced potent inhibitory activity against histamines; therefore, they are considered to be a prodrug for anti-allergic actions (Kim et al. 2000, Matsuda et al. 2004).
Inhibiting Insulin Resistance and Accumulation of Triglycerides and Cholesterol in the Liver
Published in Christophe Wiart, Medicinal Plants in Asia for Metabolic Syndrome, 2017
Rhapontigenin from the roots of Rheum rhabarbarum L. given orally at a dose of 1 mg/kg/day for 4 weeks to Sprague–Dawley rats on high-fat diet prevented weight gain, lowered plasma cholesterol, low-density lipoprotein and triglycerides.119 At a dose of 5 mg/kg/day, this stilbene prevented the formation of lipid droplets in the cytoplasm of centrilobular hepatocytes.119 It must be recalled that rhapontigenin is the aglycone of rhaponticin, which is a known inhibitor of fatty acid synthetase as discussed previously.
Inhibition of CYP2C9 by natural products: insight into the potential risk of herb-drug interactions
Published in Drug Metabolism Reviews, 2020
Kai Wang, Qing Gao, Tingting Zhang, Jinqiu Rao, Liqin Ding, Feng Qiu
In addition to the above described common types of naturally occurring compounds, there are some natural products with rare structural characteristics that also act as CYP2C9 inhibitors (Figure 2). Kavalactones, including desmethoxyyangonin (DMY), methysticin (M) and dihydromethysticin (DHM), have been reported to result in significant inhibition of CYP2C9. The most potent inhibitors, M and DHM, have a methylenedioxyphenyl moiety that is usually present in the structures of many of the alkaloids described above and could form metabolic intermediate complexes with a maximum absorption of 455 nm after incubation with HLMs and NADPH (Mathews et al. 2002). Many other types of polyphenolic compounds were also determined to be strong CYP2C9 inhibitors, such as the chalcones xanthohumol and phloretin (Yuan et al. 2014, Kimura et al. 2010). Rhapontigenin, a stilbene, was reported to be a potent inhibitor of CYP2C9 with an IC50 value of 2.7 μM. Rhapontigenin has several phenolic hydroxyl groups in its chemical structure, which is similar to the chemical structures of flavonoids (Cieniak et al. 2013). Another study reported that alkyl phenols isolated from Labisia pumila (Kacip Fatimah) were the material basis for CYP2C9 inhibition, which provided further evidence for the importance of phenolic hydroxyl groups (Manda et al. 2014).
The estrogenic activity of resveratrol: a comprehensive review of in vitro and in vivo evidence and the potential for endocrine disruption
Published in Critical Reviews in Toxicology, 2020
Extensive efforts to identify a molecular target for resveratrol over the past two decades revealed a wide range of cellular effectors that potentially mediate its health benefits. For example, studies showed that resveratrol inhibited the activity of cyclooxygenase 1 and 2 (COX1 and 2), ribonucleotide reductase (RNR), nuclear factor kappa B (NF-κB), signal transducer and activator of transcription 3 (STAT3) and aryl hydrocarbon receptor (AhR). On the other hand, resveratrol was shown to activate AMP activated protein kinase (AMPK), mitogen-activated protein kinase (MAPK), p53 and NAD-dependent deacetylase sirtuin-1 (Sirtuin 1), although the latter was riddled with controversy (Pacholec et al. 2010; Pezzuto 2011). Extensive reviews on the many targets of resveratrol have been published in recent years (Saiko et al. 2008; Athar et al. 2009; Kulkarni and Canto 2015). One early identified biological target of resveratrol has been the estrogen receptor (ER) and the compound has been classified a phytoestrogen by the late 1990s, early 2000s. The primary drive that initiated the investigation of resveratrol’s estrogenic effects was its structural similarity to primary estrogenic compounds such as the natural 17β-estradiol (E2), synthetic diethylstilbestrol (DES; 4-[(E)-4-(4-hydroxyphenyl)hex-3-en-3-yl]phenol) and rhapontigenin, a plant glycoside that has been used in the treatment of estrogen deficiency disorders (Figure 1) (Gehm et al. 1997; Freyberger et al. 2001). Resveratrol shares a stilbene structure with DES and rhapontigenin and the phenolic A ring characteristic of natural estrogens. In addition to these structural similarities, resveratrol also shared in preclinical studies some of the effects of estrogens. For example, preclinical investigation revealed resveratrol produced cardioprotective effects, a long-known biological effect of estrogens (Mendelsohn and Karas 1999). The aim of this review was to collate all experimental and clinical evidence of direct and indirect estrogenic activities of resveratrol. This is followed by a discussion of the potential for endocrine disruption via an estrogenic mode of action.