Bitter melon (Momordica charantia L.), commonly known as bitter gourd, bitter apple, bitter squash or balsam pear, is a medicinal plant belonging to the Cucurbitaceae family. Widely cultivated across tropical and subtropical regions of Asia and Africa, it has been traditionally valued for its diverse medicinal properties. Despite its characteristic bitter taste, which is primarily attributed to pentacyclic triterpenes such as momordicinin, momordicin and momordicilin, the plant has attracted considerable attention for its nutritional and pharmacological potential.
Various parts of the plant, including the fruit, leaves, seeds and roots, have been investigated for their therapeutic properties. Its nutritional composition includes proteins, lipids, dietary fibre, carbohydrates, minerals and vitamins, while its phytochemical profile comprises flavonoids, phenolics, phytosterols, saponins and other bioactive compounds. Traditionally used in several systems of folk medicine, bitter melon has been investigated for its antioxidant, antidiabetic, anti-inflammatory, anticancer and antimicrobial activities, among other biological effects.
Nutritional composition and bioactive constituents1
Bitter melon is recognised as a source of essential nutrients and diverse phytochemicals that may contribute to its biological activities. Its nutritional composition includes calcium, sodium, potassium, iron, manganese, copper and phosphorus, along with vitamins, proteins, carbohydrates, lipids and dietary fibre. Several bioactive constituents, particularly phenolic compounds, flavonoids, saponins, polysaccharides and triterpenoids, have been identified in different plant parts.
The characteristic bitterness has primarily been associated with pentacyclic triterpenes, including momordicinin, momordicin and momordicilin. These constituents, together with other phytochemicals, have been investigated for their potential antioxidant, metabolic and immunomodulatory properties.
Pharmacological properties of bitter melon
Antioxidant and anticancer activities:
Oxidative stress, resulting from an imbalance between free radical production and antioxidant defences, has been implicated in cellular damage, ageing and several chronic disorders, including diabetes and atherosclerosis.
- The antioxidant potential of bitter melon has been attributed to its phenolic compounds, flavonoids, polysaccharides and saponins, which have demonstrated free radical-scavenging activities in experimental studies.
- Ethanolic extracts of M. charantia have demonstrated considerable antioxidant activity, which has been correlated with their phenolic content. Furthermore, increased catalase activity and reduced glutathione levels, alongside inhibition of stress-induced lipid peroxidation, have been reported following bitter melon extract administration.
- Anticancer properties have also been investigated in various experimental models. Bitter melon extracts and their isolated constituents have demonstrated inhibitory effects against several cancer cell types, including those associated with leukaemia, lymphoma, choriocarcinoma, melanoma, breast, skin and prostate cancers. In prostate cancer models, selective induction of apoptosis and suppression of cellular proliferation have been reported. These effects have been associated with modulation of signalling pathways, including the mitogen-activated protein kinase (MAPK) pathway, regulation of cell-cycle proteins and induction of cell-cycle arrest.
- Cucurbitane-type triterpene glycosides have also demonstrated anti-tumour activity in hepatocellular carcinoma-derived cell lines. Additionally, modulation of inflammatory pathways has been proposed as another mechanism underlying its anticancer potential.
Anti-inflammatory activities:
Chronic inflammation is implicated in the development and progression of several disorders, including metabolic syndrome, obesity, cardiovascular diseases, neurodegenerative conditions and cancer.
- The anti-inflammatory properties of bitter melon have been attributed to its ability to modulate inflammatory signalling pathways and reduce the production of pro-inflammatory mediators.
- Additionally, cucurbitane-type triterpene glycosides have demonstrated inhibitory activity against xanthine oxidase, an enzyme involved in uric acid production and associated with hyperuricaemia and gout. Wound-healing, gastroprotective and potential analgesic effects have also been investigated in experimental models.
Antidiabetic and antihyperlipidaemic activities:
The anti-diabetic potential of bitter melon has been widely investigated, particularly because of its traditional use in managing elevated blood glucose levels.
- Several bioactive constituents, including charantin, lectins, triterpenoids and phenolic compounds, have been associated with its hypoglycaemic effects.
- Bitter melon has additionally demonstrated potential antihyperlipidaemic and weight-management effects in experimental studies.
- Reductions in total cholesterol and triglyceride concentrations have been reported, alongside improvements in high-density lipoprotein-associated apolipoprotein A-I (ApoA-I). Increased AMP-activated protein kinase (AMPK) activity has also been proposed to contribute to enhanced glucose uptake and lipid metabolism.
Antimicrobial and antiparasitic activities:
Broad-spectrum antimicrobial properties have been investigated in extracts obtained from different parts of M. charantia.
- Polysaccharides, α-momorcharin, trans-nerolidol and conjugated linolenic acids have been implicated in its antimicrobial activity.
- Antibacterial activity against Pseudomonas aeruginosa and Streptococcus species, along with antifungal effects, has also been investigated. Additionally, activity against Helicobacter pylori, an organism associated with peptic ulcer disease, has been reported.
- Anthelmintic activity has been attributed to constituents such as saponins, momordin, momordicosides and flavonoids. Potential mechanisms include inhibition of acetylcholinesterase, disruption of parasite cell membranes, interference with energy metabolism and inhibition of larval development.
Immunomodulatory and other biological activities:
Immunomodulatory effects have been associated particularly with bitter melon polysaccharides.
- In vitro investigations have demonstrated stimulation of lymphocytes, macrophages, splenocytes and thymocytes, suggesting potential effects on cellular immune responses.
- Other biological activities investigated include antiviral effects, hepatoprotection, neuroprotection and blood pressure regulation.
- Ethanolic extracts from the leaves and stems have demonstrated antiviral activity in experimental investigations, while certain isolated proteins, including momorcharin and lectins, have been studied for their inhibitory effects against HIV.
Safety considerations and potential adverse effects
Despite its traditional use, the safety of bitter melon should be considered, particularly when concentrated extracts or supplements are consumed. Adverse effects may vary according to the dose, preparation method, duration of use and individual susceptibility. Potential renal toxicity associated with prolonged, high-dose consumption requires further clinical evaluation. Individuals with known allergies to plants belonging to the Cucurbitaceae family should exercise caution.
Conclusion
Bitter melon (Momordica charantia) is a phytochemically rich medicinal plant with diverse pharmacological properties. Its bioactive constituents have demonstrated antioxidant, anticancer, anti-inflammatory, antidiabetic, antihyperlipidaemic, antimicrobial and immunomodulatory activities in investigations. Moreover, current evidence suggests that bitter melon may serve as a potential dietary supplement for managing hypercholesterolaemia and its associated complications, with possible benefits for overall health.2,3
References:
- Pehlivan FE. Bitter melon: a multifunctional medicinal plant with powerful bioactive compounds. In: Medicinal Plants. IntechOpen; 2021. doi:10.5772/intechopen.98812 https://www.intechopen.com/chapters/77462
- Saad DY, Soliman MM, Baiomy AA, et al. Effects of Karela (Bitter Melon; Momordica charantia) on genes of lipids and carbohydrates metabolism in experimental hypercholesterolemia: biochemical, molecular and histopathological study. BMC Complement Altern Med. 2017;17(1):319. Published 2017 Jun 17. doi:10.1186/s12906-017-1833-x https://pmc.ncbi.nlm.nih.gov/articles/PMC5474009/
- Bara LV, Budau R, Apahidean AI, et al. Momordica charantia L.: Functional Health Benefits and Uses in the Food Industry. Plants (Basel). 2025;14(17):2642. Published 2025 Aug 25. doi:10.3390/plants14172642 https://pmc.ncbi.nlm.nih.gov/articles/PMC12430404/#_ad93