Emerging Antitumor Activities of the Bitter Melon (Momordica charantia)

The metabolic effect of Momordica charantia cannot be determined based on the available clinical evidence: a systematic review and meta-analysis of randomized clinical trials

Several studies have shown that Momordica charantia L. (Cucurbitaceae, bitter melon) has beneficial effects on metabolic syndrome (MetS) parameters and exerts antidiabetic, anti-hyperlipidemic, and anti-obesity activities. Since the findings of these studies are contradictory, the goal of this systematic review and meta-analysis was to assess the efficacy of bitter melon in the treatment of metabolic syndrome, with special emphasis on the anti-diabetic effect. Embase, Cochrane, PubMed, and Web of Science databases were searched for randomized controlled human trials (RCTs). The meta-analysis was reported according to the PRISMA statement. The primary outcomes of the review are body weight, BMI, fasting blood glucose, glycated hemoglobin A1c, systolic blood pressure, diastolic blood pressure, serum triglyceride, HDL, LDL, and total cholesterol levels. Nine studies were included in the meta-analysis with 414 patients in total and 4-16 weeks of follow-up. In case of the meta-analysis of change scores, no significant effect could be observed for bitter melon treatment over placebo on fasting blood glucose level (MD = -0.03; 95% CI: -0.38 to 0.31; I2 = 34%), HbA1c level (MD = -0.12; 95% CI: -0.35 to 0.11; I2 = 56%), HDL (MD = -0.04; 95% CI: -0.17 to 0.09; I2 = 66%), LDL (MD = -0.10; 95% CI: -0.28 to 0.08; I2 = 37%), total cholesterol (MD = -0.04; 95% CI: -0.17 to 0.09; I2 = 66%,), body weight (MD = -1.00; 95% CI: -2.59-0.59; I2 = 97%), BMI (MD = -0.42; 95% CI: -0.99-0.14; I2 = 95%), systolic blood pressure (MD = 1.01; 95% CI: -1.07-3.09; I2 = 0%) and diastolic blood pressure levels (MD = 0.24; 95% CI: -1.04-1.53; I2 = 0%). Momordica treatment was not associated with a notable change in ALT, AST, and creatinine levels compared to the placebo, which supports the safety of this plant. However, the power was overall low and the meta-analyzed studies were also too short to reliably detect long-term metabolic effects. This highlights the need for additional research into this plant in carefully planned clinical trials of longer duration.

The ribosome-inactivating proteins MAP30 and Momordin inhibit SARS-CoV-2

The continuing emergence of SARS-CoV-2 variants has highlighted the need to identify additional points for viral inhibition. Ribosome inactivating proteins (RIPs), such as MAP30 and Momordin which are derived from bitter melon (Momordica charantia), have been found to inhibit a broad range of viruses. MAP30 has been shown to potently inhibit HIV-1 with minimal cytotoxicity. Here we show that MAP30 and Momordin potently inhibit SARS-CoV-2 replication in A549 human lung cells (IC50 ~ 0.2 μM) with little concomitant cytotoxicity (CC50 ~ 2 μM). Both viral inhibition and cytotoxicity remain unaltered by appending a C-terminal Tat cell-penetration peptide to either protein. Mutation of tyrosine 70, a key residue in the active site of MAP30, to alanine completely abrogates both viral inhibition and cytotoxicity, indicating the involvement of its RNA N-glycosylase activity. Mutation of lysine 171 and lysine 215, residues corresponding to those in Ricin which when mutated prevented ribosome binding and inactivation, to alanine in MAP30 decreased cytotoxicity (CC50 ~ 10 μM) but also the viral inhibition (IC50 ~ 1 μM). Unlike with HIV-1, neither Dexamethasone nor Indomethacin exhibited synergy with MAP30 in the inhibition of SARS-CoV-2. From a structural comparison of the two proteins, one can explain their similar activities despite differences in both their active-sites and ribosome-binding regions. We also note points on the viral genome for potential inhibition by these proteins.

Momordicine I suppresses glioma growth by promoting apoptosis and impairing mitochondrial oxidative phosphorylation

Glioblastoma (GBM) is the most common type of primary brain tumor. Patients with GBM have poor survival outcomes. Isolated components of Momordica charantia have anticancer effects. However, the bioactivity of M. charantia extracts against GBM remains unknown. We tested four major extracts of M. charantia and found that momordicine I reduced glioma cell viability without serious cytotoxic effects on astrocytes. Momordicine I suppressed glioma cell colony formation, proliferation, migration, and invasion. Momordicine I also induced apoptosis, intracellular reactive oxygen species (ROS) production, and senescence in glioma cells. Moreover, momordicine I decreased the oxidative phosphorylation capacity of glioma cells and inhibited tumor sphere formation in temozolomide (TMZ)-resistant GBM cells. We further explored whether the antiglioma effect of momordicine I may be related to cell cycle modulation and DLGPA5 expression. Our results indicate that the cytotoxic effect of momordicine I on glioma cells suggests its potential therapeutic application to GBM treatment. See also Figure 1(Fig. 1).

Immune System and Epidemics: The Role of African Indigenous Bioactive Substances

With over 6 million coronavirus pandemic deaths, the African continent reported the lowest death rate despite having a high disease burden. The African community's resilience to the pandemic has been attributed to climate and weather conditions, herd immunity, repeated exposure to infectious organisms that help stimulate the immune system, and a disproportionately large youth population. In addition, functional foods, herbal remedies, and dietary supplements contain micronutrients and bioactive compounds that can help boost the immune system. This review identified significant traditional fermented foods and herbal remedies available within the African continent with the potential to boost the immune system in epidemics and pandemics. Methodology: Databases, such as PubMed, the Web of Science, and Scopus, were searched using relevant search terms to identify traditional African fermented foods and medicinal plants with immune-boosting or antiviral capabilities. Cereal-based fermented foods, meat-, and fish-based fermented foods, and dairy-based fermented foods containing antioxidants, immunomodulatory effects, probiotics, vitamins, and peptides were identified and discussed. In addition, nine herbal remedies and spices belonging to eight plant families have antioxidant, immunomodulatory, anti-inflammatory, neuroprotective, hepatoprotective, cardioprotective, and antiviral properties. Peptides, flavonoids, alkaloids, sterols, ascorbic acid, minerals, vitamins, and saponins are some of the bioactive compounds in the remedies. Bioactive compounds in food and plants significantly support the immune system and help increase resistance against infectious diseases. The variety of food and medicinal plants found on the African continent could play an essential role in providing community resilience against infectious diseases during epidemics and pandemics. The African continent should investigate nutritional, herbal, and environmental factors that support healthy living and longevity.

Bitter melon derived extracellular vesicles enhance the therapeutic effects and reduce the drug resistance of 5-fluorouracil on oral squamous cell carcinoma

Background

Plant-derived extracellular vesicles (PDEVs) have been exploited for cancer treatment with several benefits. Bitter melon is cultivated as a vegetable and folk medicine with anticancer and anti-inflammatory activities. 5-Fluorouracil (5-FU) is widely used for cancer treatment. However, 5-FU-mediated NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammation activation induced the resistance of oral squamous cell carcinoma (OSCC) cells to 5-FU. In this study, we explored the potential of bitter melon-derived extracellular vesicles (BMEVs) for enhancing the therapeutic efficacy and reduce the resistance of OSCC to 5-FU.

Results

Herein, we demonstrate that bitter melon derived extracellular vesicles (BMEVs), in addition to their antitumor activity against OSCC have intrinsic anti-inflammatory functions. BMEVs induced S phase cell cycle arrest and apoptosis. Apoptosis induction was dependent on reactive oxygen species (ROS) production and JUN protein upregulation, since pretreatment with N-acetyl cysteine or catechin hydrate could prevent apoptosis and JUN accumulation, respectively. Surprisingly, BMEVs significantly downregulated NLRP3 expression, although ROS plays a central role in NLRP3 activation. We further assessed the underlying molecular mechanism and proposed that the RNAs of BMEVs, at least in part, mediate anti-inflammatory bioactivity. In our previous studies, NLRP3 activation contributed to the resistance of OSCC cells to 5-FU. Our data clearly indicate that BMEVs could exert a remarkable synergistic therapeutic effect of 5-FU against OSCC both in vitro and in vivo. Most notably, NLRP3 downregulation reduced the resistance of OSCC to 5-FU.

Conclusions

Together, our findings demonstrate a novel approach to enhance the therapeutic efficacy and reduce the drug resistance of cancer cells to chemotherapeutic agents, which provides proof-of-concept evidence for the future development of PDEVs-enhanced therapy.

Graphic Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00995-1.

Momordicine-I, a Bitter Melon Bioactive Metabolite, Displays Anti-Tumor Activity in Head and Neck Cancer Involving c-Met and Downstream Signaling

Head and neck cancer (HNC) is one of the most aggressive cancers, and treatments are quite challenging due to the difficulty in early diagnosis, lack of effective chemotherapeutic drugs, adverse side effects and therapy resistance. We identified momordicine-I (M-I), a bioactive secondary metabolite in bitter melon (Momordica charantia), by performing liquid chromatography-high resolution electrospray ionization mass spectrometry (LC-HRESIMS) analysis. M-I inhibited human HNC cell (JHU022, JHU029, Cal27) viability in a dose-dependent manner without an apparent toxic effect on normal oral keratinocytes. Mechanistic studies showed that M-I inhibited c-Met and its downstream signaling molecules c-Myc, survivin, and cyclin D1 through the inactivation of STAT3 in HNC cells. We further observed that M-I was non-toxic and stable in mouse (male C57Bl/6) blood, and a favorable pharmacokinetics profile was observed after IP administration. M-I treatment reduced HNC xenograft tumor growth in nude mice and inhibited c-Met and downstream signaling. Thus, M-I has potential therapeutic implications against HNC.

Diverse roles of bitter melon (Momordica charantia) in prevention of oral cancer

Oral squamous cell carcinoma (OSCC) is one of the common lethal malignancies which is increasing rapidly in the world. Increasing risks from alcohol and tobacco habits, lack of early detection markers, lack of effective chemotherapeutic agents, recurrence and distant metastasis make the disease more complicated to manage. Laboratory-based studies and epidemiological studies indicate important roles of nutraceuticals to manage different cancers. The plant bitter melon (Momordica charantia) is a good source of nutrients and bio-active phytochemicals such as triterpenoids, triterpene glycosides, phenolic acids, flavonoids, lectins, sterols and proteins. The plant is widely grown in Asia, Africa, and South America. Bitter melon has traditionally been used as a folk medicine and Ayurvedic medicine in Asian culture to treat diseases such as diabetes, since ancient times. The crude extract and some of the isolated pure compounds of bitter melon show potential anticancer effects against different cancers. In this review, we shed light on its effect on OSCC. Bitter melon extract has been found to inhibit cell proliferation and metabolism, induce cell death and enhance the immune defense system in the prevention of OSCC in vitro and in vivo. Thus, bitter melon may be used as an attractive chemopreventive agent in progression towards OSCC clinical study.

Bitter Melon (Momordica Charantia), a Nutraceutical Approach for Cancer Prevention and Therapy

Cancer is the second leading cause of death worldwide. Many dietary plant products show promising anticancer effects. Bitter melon or bitter gourd (Momordica charantia) is a nutrient-rich medicinal plant cultivated in tropical and subtropical regions of many countries. Traditionally, bitter melon is used as a folk medicine and contains many bioactive components including triterpenoids, triterpene glycoside, phenolic acids, flavonoids, lectins, sterols and proteins that show potential anticancer activity without significant side effects. The preventive and therapeutic effects of crude extract or isolated components are studied in cell line-based models and animal models of multiple types of cancer. In the present review, we summarize recent progress in testing the cancer preventive and therapeutic activity of bitter melon with a focus on underlying molecular mechanisms. The crude extract and its components prevent many types of cancers by enhancing reactive oxygen species generation; inhibiting cancer cell cycle, cell signaling, cancer stem cells, glucose and lipid metabolism, invasion, metastasis, hypoxia, and angiogenesis; inducing apoptosis and autophagy cell death, and enhancing the immune defense. Thus, bitter melon may serve as a promising cancer preventive and therapeutic agent.

Cucurbitane-Type Triterpenoids from the Vines of Momordica charantia and Their Anti-inflammatory Activities

Seven new cucurbitane-type triterpenoids, kuguaovins A-G (1-7), and five known ones were isolated from the rattans of wild Momordica charantia. Their structures were established by spectroscopic data analyses, including 1D and 2D NMR, IR, and MS techniques. The absolute configurations of the cucurbitanes were determined from NOESY data and partially by X-ray crystallographic analysis. In pharmacological studies, compounds 1-7 and 9-12 exhibited weak anti-inflammatory effects (IC50 = 15-35 μM), based on an anti-NO production assay.