Development of a weight-loss product using Chinese herbal medicine combined with nutritional technologies
Creators: name: LUO, Shiqi
Publisher: name: RMIT University
Year: 2024
Subjects: classificationCode: 420803
subject: Traditional Chinese medicine and treatments

description: Obesity is a worldwide epidemic caused by an imbalance between energy intake and energy expenditure. Globally, more than one-third of the world population is classified as overweight or obese. Obesity has negative impacts on physiological functions, causing a threat to public health. Current anti-obesity pharmacotherapies are either expensive or responsible for developing intolerances. Hence, greater attention has been drawn to herbal supplements, including Chinese herbal medicines, due to their potential for offering novel and cost-effective weight-loss treatments. However, scientific confirmation is required to validate the functional claims for the use of these herbs. Furthermore, health-minded nutritional bars have been employed to facilitate weight management, but the effects are usually small. Therefore, Chinese herbal medicine-enriched nutritional bars that are convenient to consume could be developed to improve weight-loss efficacy and compliance.

This project aims to: 1) investigate the pharmacological actions and safety of a Chinese herbal formula RCM-107 for weight loss; and 2) develop RCM-107-enriched nutritional bars and assess their microbiological safety and acceptability. In order to address these aims, this research was divided into the following two phases.

In phase I, a fluorescence enzyme assay was conducted to investigate the inhibitory effects of RCM-107 and its eight ingredients on porcine pancreatic lipase (PPL). RCM-107 was found to be a potent lipase inhibitor, which could reduce lipid absorption, thus aiding weight loss. The majority of the ingredients in this formula also showed PPL inhibitory activity. Based on the molecular docking and herbal ligand¿target interactions, dehydroeburicoic acid and epigallocatechin gallate (EGCG) were proposed to be the key lipase inhibitors in RCM-107. Moreover, the presence of known weight-loss compounds such as EGCG, epicatechin gallate (ECG), epicatechin (EC), rutin, crocin and caffeine were identified in the RCM-107 and related single herbs using high-performance thin-layer chromatography (HPTLC) profiling approaches.  

Furthermore, both the RCM-107 formula and several individual herbs displayed porcine pancreatic α-amylase (PPA) inhibitory effects in the enzyme assay, indicating they could decrease carbohydrate digestion, thus reducing body weight. According to the molecular docking results, alisol B was predicted as a potential amylase inhibitor, based on its highest binding affinity value among all 149 compounds from RCM-107. Additionally, EGCG and plantagoside were also proposed to be the key compounds responsible for the PPA inhibitory effect of RCM-107 according to the inter-residue contact analysis.

Based on the cell viability test conducted before the enzyme-linked immunosorbent assay (ELISA), Camellia sinensis and RCM-107 exhibited more potent cytotoxic effects on colorectal cancer cells (NCI-H716) compared to the other components in RCM-107. In the ELISA, RCM-107 had no significant effect on stimulating GLP-1 secretion. Gardeniae fructus, one of the ingredients in RCM-107, demonstrated a more significant effect on inducing GLP-1 secretion than the positive control EGCG. Therefore, this herb is likely to reduce body weight by increasing satiety and decreasing appetite. Two Gardeniae fructus compounds, 3-epioleanolic acid and crocin, were predicted to bind to the active form of the GLP-1 receptor at the binding pocket with residues known for receptor activation, suggesting that they could potentially serve as GLP-1 receptor agonists.

In order to establish a safety profile before developing the value-added nutritional bars in phase II, in vitro experiments and in silico studies were performed. RCM-107 was weakly cytotoxic to hepatocellular carcinoma cells (HepG2) based on the results of the cytotoxicity assays. The molecular docking and inter-residue analysis data showed that five compounds, which were previously identified in RCM-107 (namely, EGCG, ECG, EC, rutin and crocin), could inhibit cytochrome P450 (CYP) enzymes, especially CYP2C9, 2C19, 2D6 and 3A4. Thus, there might be a higher risk of developing toxicity or herb-drug interactions if RCM-107 is administered concomitantly with drugs that are metabolised by these CYP isoforms.

Even though caffeine, one of the chemical constituents of RCM-107, is unlikely to be a competitive inhibitor of CYP enzymes, it was predicted to be hepatotoxic at higher concentrations according to the toxicity calculations, which rely on distance-based graph signatures, performed by a comprehensive analysis system pkCSM. However, toxicity cannot be separated from the dosage applied. Therefore, the administration of RCM-107 should follow the safe dosage range approved by the Therapeutic Goods Administration (TGA) to prevent dose-dependent toxicity.

In phase II, six flavours of nutritional bars containing 6% RCM-107 with balanced nutritional profiles were developed in the RMIT food laboratory. Unlike other snack bars or protein bars available on the market, which are usually crunchy or chewy, the developed bars were soft with a slight crispiness. Moreover, the undesirable herbal tastes and smells were masked. The bars were reported to be microbiologically safe as the water activity was less than 0.7. 

In the sensory evaluation test, 45 participants assessed the bar samples in terms of their appearance, aroma, texture, flavour, crispiness and overall liking using 9-point hedonic scales. The majority preferred the dark-chocolate-flavoured bars (DFB) and strawberry-flavoured bars (SFB), and the latter received the highest overall liking rating. The pleasant flavour and aroma of the SFB were found to be the drivers of liking based on principal component analysis (PCA). Further, the texture (hardness), mouthfeel and sweetness level of the DFB and SFB were rated as 'just about right'. However, there was still a small percentage of participants who selected 'too soft' or 'too dry' regarding the texture and mouthfeel of the two most preferred bars.

In conclusion, this project has provided new knowledge of the mechanistic properties of the herbal formula RCM-107 and its respective individual herbal ingredients for weight loss in terms of: reducing lipid absorption by inhibiting pancreatic lipase; decreasing carbohydrate digestion by suppressing pancreatic a-amylase; and enhancing satiety by stimulating GLP-1 secretion. In addition, this project has employed a cross-disciplinary approach that combined Chinese herbal medicine and food technology, and resulted in an innovative product (the RCM-107-enriched nutritional bar). These were microbiologically safe and could be accepted by the participants in the sensory evaluation test.