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.

Comparison of Anti-Inflammatory Activities of Structurally Similar Triterpenoids Isolated from Bitter Melon

Momordica charantia L., or bitter melon, has been suggested to exhibit anti-inflammatory activity. In a previous study, three structurally similar triterpenes, namely 5β,19-epoxy-25-methoxycucurbita-6,23-diene-3β,19-diol (EMCD), 5β,19-epoxy-25-methoxycucurbita-6,23-dien-3β-ol (EMCO), and 5β,19-epoxy-19,25-dimethoxycucurbita-6,23-dien-3β-ol (EDMO), were isolated from bitter melon. EMCD has been shown to exhibit in vitro anti-inflammatory activity. In this study, the anti-inflammatory activities of EMCD, EMCO, and EDMO were compared. All three compounds were toxic to the RAW 264.7 macrophage cell line but not the FL83B cells. EMCD and EMCO inhibited tumor necrosis factor (TNF)-α-induced inducible nitric oxide synthase (iNOS) expression in FL83B cells, and the IC50 values were 19.8 and 25.7 μM, respectively. By contrast, EDMO did not effectively reduce iNOS expression. Furthermore, EMCD and EMCO suppressed other TNF-α-induced proinflammatory signals including the activation of inhibitor kappa B kinase complex, the phosphorylation of inhibitor of nuclear factor-κB, and the activation of c-Jun kinase. EMCD consistently exhibited a higher efficacy than did EMCO in these assays. Hence, the in vivo anti-inflammatory activity of EMCD was tested. EMCD clearly repressed 12- O-tetradecanoylphorbol-13-acetate (TPA)-induced ear edema in mice. In conclusion, differences in the functional group on carbon 19 do affect the anti-inflammatory activities of EMCD, EMCO, and EDMO. EMCD exhibited the highest anti-inflammatory activity among these molecules, and its in vivo anti-inflammatory activity was confirmed.

New Norcucurbitane Triterpenoids from Momordica charantia var. abbreviata

Two new 27-norcucurbitane triterpenoids, 5β,19-epoxy-3β-hydroxy-19( S)-methoxy-27-norcucurbita-6,23( E)-dien-25-one (1) and 3β-hydroxy-25-oxo-27-norcucurbita-6,23( E)-dien-5β,19-olide (2), together with one known cucurbitane triterpene, 5β,19-epoxycucurbita-6,23( E)-diene-3β,25-diol (3), were isolated from the fruits of Momordica charantia var. abbreviata. Their structures were elucidated by spectroscopic methods including EI-MS, 1H, 13C, and 2D NMR data and comparison with the data of known analogues.

Cucurbitane-type Triterpene Glycosides from the Fruits of Momordica charantia

Four new cucurbitane- type triterpene glycosides, charantosides D-G (1–4) were isolated from a methanol extract of Momordica charantia fruits. The structures of these compounds were determined by chemical and spectroscopic methods to be (19 R)-5 β,19-epoxy-25-methoxycucurbita-6,23-diene-3 β,19-diol 3- O-β-D-glucopyranoside, (19 R)-5 β,19-epoxy-25-methoxycucurbita-6,23-diene-3 β,19-diol 3- O-β-D-allopyranoside, 7 β-methoxycucurbita-5,23 E,25-triene-3 β-ol 3- O-β-D-allopyranoside, and 3 β,7 β-dihydroxycucurbita-5,23 E,25-triene-19-al 3- O-β-D-allopyranoside.