A review on the traditional uses, nutritive importance, pharmacognostic features, phytochemicals, and pharmacology of Momordica cymbalaria Hook F

Microscopic characters of tubers

The tubers of M. cymbalaria are reported to contain a periderm in the deeper part of the cortex. The peripheral component of the cortex contains deep narrow fissures. Periderm contains phellem and phelloderm. Phellem is 300 µm broad while the phelloderm is 500 µm broad. Phellem has thin-walled tubular cells and the phelloderm has radial files of thin-walled rectangular cells. The inner portion of the periderm encloses parenchymal cells and starch grains. Nests of vascular strands are present in the midpoint of the tuber consisting of one or two broad xylem materials and a collection of small xylem materials (Koneri, Balaraman & Saraswati, 2006). Phloem is present in the peripheral section of the xylem strand.

Powder characters of tubers

The powder of tubers has been stated to contain cork cells, xylem vessels with pitting, and prisms of calcium oxalate crystals of different sizes (Dhanarajan, Abraham & Isaac, 2006).

Physico-chemical constants

The reported percentages of total ash, acid-insoluble ash, water-soluble ash, and sulfated ash of M. cymbalaria tuber are given in Table S2 (Dhasan, Jegadeesan & Kavimani, 2008). The ash values of the tuber of M. cymbalaria suggest that a certain quantity of inorganic foreign matter and resistant constituents such as sand, soil, and stone particles are present in crude drugs.

Toxicology of M. cymbalaria

It was reported that M. cymbalaria methanolic extract is safe up to 2,000 mg/kg. Furthermore, no symptoms of toxicity were found during either the short-term (48-hour) or long-term (14-day) monitoring periods (Mahesh Kumar et al., 2018).

The diverse pharmacological activities of M. cymbalaria have been evaluated by many investigators. Different parts of M. cymbalaria are shown to possess different pharmacological effects on various preclinical models (Fig. 4). The pharmacological studies of M. cymbalaria reported so far are summarized below:

Analgesic

The ethanolic extract of M. cymbalaria leaves (250 and 500 mg/kg) has been investigated for its analgesic potential on 0.7% v/v glacial acetic acid-induced writhing and radiant heat tail-flickresponse in Swiss albino mice (Ramanath & Burte, 2012). It was noted that the extract (500 mg/kg) significantly decreased the count of writhing in the acetic acid-induced writhing test and increased the mean reaction time in the tail-flick analgesia model. In the acetic acid-induced writhing model, the nociception involves the release of endogenous substances like histamine, serotonin, bradykinin, prostaglandins, and leukotrienes to stimulate the sensory nerve endings, whereas, in the radiant heat tail-flick model, pain is centrally modulated by the central pain pathway. Several complicated processes, viz., opiate, dopaminergic, and serotonergic pathways, are included in the central pain pathway. Therefore, the analgesic activity of M. cymbalaria leaf extract seems to involve both peripheral mechanisms (inhibition of prostaglandin and leukotriene synthesis) and central mechanisms of pain regulation. Furthermore, flavonoids are known to hinder prostaglandin synthesis and cyclooxygenase-2 expressions (Hämäläinen et al., 2011). Thus, the presence of flavonoids in M. cymbalaria may be accountable for its analgesic activity.

Anthelmintic

The anthelmintic activity of petroleum ether, chloroform, ethanolic, and aqueous extracts of the fruits of M. cymbalaria fruits (20 mg/ml) was studied on Indian adult earthworms (Pheretima posthuma). The results showed that chloroform extract took the least time to cause paralysis and death of earthworms, followed by petroleum ether, methanolic, and aqueous extract (Srinivas et al., 2008). The presence of different phytochemicals like tannins, alkaloids, and flavonoids are liable for anthelmintic activity of M. cymbalaria fruits (da Silva, de Carvalho & Borba, 2008; Wang et al., 2010; Athanasiadou et al., 2001). Tannins have been demonstrated to interfere with coupled oxidative phosphorylation causing the blocking of ATP synthesis in these parasites (Martin, 1997). It also binds to the cuticle body surface of the helminth causing paralysis (Williams et al., 2014). Thus, the presence of tannins may be held accountable for the anthelmintic activity of these extracts.

Anticancer and antiangiogenic

The anticancer activity of methanolic extract of aerial parts of M. cymbalaria (100 and 200 mg/kg) was illustrated by the researchers in Ehrlich ascites carcinoma (EAC) bearing Swiss albino mice. The methanolic extract was reported to show a significant decrease in body weight, packed volume, and viable tumor cell count compared to the mice of the EAC control group. The extract also restored the hematological parameters to normal (Jeevanantham et al., 2011a; Jeevanantham et al., 2011b).

The saponin isolated from M. cymbalaria roots was studied on EAC-induced carcinoma in female Swiss albino mice. Treatment with saponin (175 mg/kg) reduced the total cell count and viable cell count. The saponin also significantly increased the survival time of the mice (Koneri et al., 2014).

The antitumor activity of saponin (100 mg/kg) was also evaluated in dimethyl benz[a]anthracene (DMBA) induced breast cancer in female Wistar rats. The isolated saponin reduced tumor size and growth. It also increased the terminal end buds, terminal ducts, alveolar buds, and lobules. The histological improvement was supported by a decrease in necrosis and hemorrhage along with the reduction of focal desmoplastic reaction in the breast of tumor-bearing rats. Moreover, it also reduced the level of lipid peroxidation (LPO) besides enhancing reduced glutathione (GSH) levels and endogenous antioxidant enzymes viz., superoxide dismutase (SOD) and catalase (CAT) (Kaskurthy, Koneri & Samaddar, 2015).

Recently, the saponins of M. cymbalaria roots were studied in diethyl nitrosamine-induced hepatocellular carcinoma in Wistar rats. Oral administration of saponin (175 mg/kg) reduced serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total bilirubin, cholesterol, and triglyceride levels and increased total protein levels. However, there was a significant improvement in SOD and CAT activity and GSH levels in the liver tissue (Nagarathana et al., 2016).

In-vivo antiangiogenic effectiveness of saponins of M. cymbalaria was assessed in air sac angiogenesis in rats and chick chorioallantoic membrane (CAM) angiogenesis models. The air sac model angiogenesis was induced by the administration of carrageenan in the air pouch in Wistar rats. Treatment with saponins (175 mg/kg) significantly reduced the pouch volume, granulation tissue weight, and carmine dye content. In the CAM angiogenesis model, angiogenesis was induced in fertilized chicken eggs by erythropoietin. The experiment was performed between days 8 and 12 of incubation because the implants made from days 8–10 are strongly angiogenic. Saponin (32 µg) was administered into the eggs on the 12th and 13th day after the administration of erythropoietin (30 units) for 4 days from the 8th to 12th day. The saponins were found to reduce vascular formation (Koneri et al., 2014).

In the angiogenesis process, migration of vascular endothelial cells from parental vessels, invasion through the matrix, proliferation, and formation of capillary tubes occurs (Folkman, 2006). Antiangiogenic chemicals generally reduce angiogenesis through the inhibition of proteases or prevention of phosphorylation of receptors resulting in the interruption of endothelial tube formation (Ferrara, 2004). In angiogenesis models, the saponins of M. cymbalaria displayed an antiangiogenic effect (Fig. 5). This finding provides a new explanation for the antitumor effectiveness of M. cymbalaria roots.

Anticonvulsant

A study on the effect of ethanolic extract of M. cymbalaria fruits (250 and 500 mg/kg) on pentylenetetrazole (PTZ) and maximal electric shock (MES)-induced convulsions was carried out in Wistar rats. In the case of PTZ-induced convulsions, treatment with the extract deferred the onset of seizures and effectively reduced the duration of the convulsion. The administration of the extract showed a vital reduction in the duration of tonic-clonic seizures and recovery time in MES-induced convulsions (Vangoori et al., 2013).

Many studies on isolated saponin revealed the anticonvulsant effect via voltage-gated Na⁺channel blockade (Liu et al., 2001) and shortening of open time or prolonging the close time of Ca ²⁺channels (Kim, Nah & Rhim, 2008). Saponins modulate gamma-aminobutyric acid (GABAergic) function by potentiating [³H]-muscimol binding to GABA_A receptors in rat brains (Kim et al., 2001). In addition, saponin also blocks the N-methyl-D-aspartate (NMDA) receptor-mediated excitatory process in rat hippocampal cells (Kim et al., 2004). On the other hand, flavonoids have been reported for their anticonvulsant activity. The mechanisms involved in the anticonvulsant activity of flavonoids are linked to their effect on GABA and NMDA receptors (Citraro et al., 2016). Hence, all these findings support that the anticonvulsant activity of M. cymbalaria fruits might be attributed to the existence of saponin and flavonoids.

Antidepressant

Only one major animal study was conducted to examine the antidepressant activity of M. cymbalaria fruits. The hydroalcoholic extract of M. cymbalaria fruits (at 200, 400, and 600 mg/kg body weight) was evaluated for its antidepressant effect using two behavioral models. viz., forced swim test and tail suspension test in Swiss albino mice. The duration of immobility was acclaimed in both experimental models. Mice treated with hydroalcoholic extract of M. cymbalaria fruits showed a critical lowering in the duration of immobility in both experimental models compared to the mice of the control group (Daripelli et al., 2011). It has been previously reported that flavonoids obtained from medicinal plants like Hypericum perforatum and Glycyrrhiza uralensis show antidepressant activity (Butterweck et al., 2000; Fan et al., 2012). Furthermore, the addition of rutin to Hypericum perforatum extract caused potentiation of antidepressant activity (Nöldner & Schötz, 2002). Interestingly, M. cymbalaria fruits have been reported to contain rutin (Kale & Laddha, 2012). Thus, the antidepressant activity of M. cymbalaria fruits may be possibly attributed to the presence of rutin in M. cymbalaria. However, further investigation is needed to explore the underlying mechanisms behind the antidepressant potential of M. cymbalaria.

Antidiabetic

The most prominent potential pharmacological effect of M. cymbalaria is its antidiabetic activity. The effect of M. cymbalaria fruit powder (500 mg/kg) was studied on the blood glucose level and other biochemical parameters in alloxan-induced diabetes in Wistar rats. Treatment with the powder vitally reduced the blood glucose level and improved the hepatic glycogen level in the powder-treated diabetic rats. The powder also decreased the serum cholesterol and triglyceride levels in diabetic animals (Rao et al., 1999). The aqueous, ethanolic, and n-hexane fractions of M. cymbalaria fruits were studied in both normal and alloxan-induced diabetes in Wistar rats. The blood glucose levels were estimated at 0, 1, 3, 5, and 7 h after the treatment. The aqueous extract of M. cymbalaria at a dose of 500 mg/kg showed a maximal blood-glucose-lowering effect in diabetic rats, whereas the same dose did not exhibit any hypoglycemic activity in normal rats (Rao, Kesavulu & Apparao, 2001). The type 2 antidiabetic activity of saponins of M. cymbalaria roots was studied in streptozotocin-nicotinamide-induced diabetes in Swiss albino mice. Treatment of type 2 diabetic mice with saponin of M. cymbalaria (175 mg/kg) yielded a considerable reduction in blood glucose, cholesterol, and triglyceride levels with an increase in serum insulin level. Moreover, saponin increased the mass of pancreatic β-cells in diabetic mice (Firdous et al., 2009).

In another study, the effect of oleanane-type triterpenoid saponin isolated from the roots of M. cymbalaria on glucose uptake in isolated diaphragms of both diabetics following streptozotocin administration and non-diabetic Swiss albino mice was evaluated. In both models, the diabetic and non-diabetic mice increased glucose uptake in the diaphragm. An increase in β-cells in pancreatic histology was also observed. Besides, the insulin-releasing activity of isolated oleanane-type triterpenoid saponin was investigated in the rat insulinoma cell line (RIN-5F). The release of insulin was elevated in the presence of saponin (1 mg/ml) from RIN-5F pre-exposed to adrenaline (5 µM) and nifedipine (50 µM) (Koneri et al., 2014).

The glucose uptake activity of oleanane-type triterpenoid saponin isolated from the roots of M. cymbalaria was demonstrated in the L6 cell line (mouse skeletal muscle cell line). The saponin (0.01−0.10 mg/ml) did not show cytotoxicity against the L6 cell line and significantly increased the glucose uptake in a concentration-dependent manner. This finding suggests that oleanane-type triterpenoid saponin isolated from the roots of M. cymbalaria can be very effective in treating insulin resistance (Samaddar, Balwanth & Chandrasekhar, 2015). Besides these studies, the effect of “Mcy protein” isolated from the fruits of M. cymbalaria was studied in streptozotocin-induced diabetes in Wistar rats (Marella et al., 2015). The Mcy protein (2.5 mg/kg) significantly lowered the blood glucose level, serum and tissue lipids, and kidney and liver function markers. This protein also showed pancreatic islet regeneration. Therefore, Myc protein can lessen hyperlipidemia and control diabetes by increasing the regeneration of pancreatic islets.

Increased apoptosis and decreased replication of β-cells reduce insulin secretion (Montanya & Téllez, 2009). It has been well documented that the generation of reactive oxygen species (ROS) in diabetes plays a vital role in β-cells apoptosis (Yang et al. 2011). Phytochemicals such as rutin and quercetin are excellent antioxidants. Some triterpenoid saponins have been reported to exhibit antioxidant effects in rats (Kim et al., 2001). The presence of rutin, quercetin, and triterpenoid saponins has been reported in M. cymbalaria (Kale & Laddha, 2013; Koneri, Balaraman & Saraswati, 2006; Dhasan, Jegadeesan & Kavimani, 2008). Moreover, triterpenoid saponins of M. cymbalaria augmented insulin release in the presence of alpha 2 adrenergic agonists, adrenaline. In a study, the antagonism of alpha 2 adrenergic receptors by yohimbine elevated insulin release and β-cells proliferation (Naghadeh, Moghadam & Ibrahimi, 2006). Hence, there remains a need for further examination of the effectiveness of triterpenoid saponins of M. cymbalaria on alpha 2 adrenergic receptors on β-cells to understand the underlying mechanism of its antidiabetic activity.

Antidiarrheal

The effect of the methanolic extract on the fruits of M. cymbalaria (200, 400, and 600 mg/kg) was evaluated against different experimental models of diarrhea in Wistar rats. Administration of the extract showed a critical inhibitory effect against castor oil-induced diarrhea and prostaglandin E₂ (PGE₂)-induced entero-pooling in Wistar rats. In the charcoal meal test, the extract displayed a vital decrease in gastrointestinal motility in rats (Vrushabendra Swamy et al., 2008). Interestingly, different reports in the literature revealed that components like flavonoids, saponins, steroids, tannins, and alkaloids are responsible for antidiarrheal activity through diverse mechanisms (Carlo et al., 1994; Macander, 1986). Flavonoids and tannins are recommended to be accountable for antidiarrheal activity by enhancing water and electrolyte reabsorption. Besides these, other compounds exert anti-diarrheal activity by inhibiting intestinal motility (Daswani et al., 2010). Therefore, the antidiarrheal activity of the fruits of M. cymbalaria could be due to the presence of these phytochemicals. Thus, further investigations are needed to establish the antidiarrheal mechanisms of M. cymbalaria.

Anti-inflammatory and antiarthritic

The antiinflammatory activity of methanolic extract of aerial parts of M. cymbalaria (100 and 200 mg/kg) was assessed using carrageenan-induced hind paw edema in Wistar rats. The extract at doses of 100 and 200 mg/kg was reported to produce 53.11% and 44.43% of inhibition of paw edema, respectively, when measured 4 h after carrageenan administration (Jeevanantham et al., 2011a; Jeevanantham et al., 2011b).

In a study on formaldehyde, Freund’s adjuvant, and collagen-induced arthritis, the ethanolic and aqueous extracts of M. cymbalaria fruits were investigated in Wistar rats. Both extracts (200 and 400 mg/kg) significantly reduced paw edema in all three models. Serum aspartate transaminase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), blood urea nitrogen (BUN), creatinine, cholesterol, and triglyceride levels were significantly reduced by the extracts in both Freund’s adjuvant and collagen-induced arthritic rats. A vital increment in total protein and albumin levels was observed. Moreover, both extracts also attenuated the elevated weight of organs like the liver, kidney, and spleen (Reddy, Rao & Sambasiva-Rao, 2015).

However, flavonoids, for example, rutin and quercetin, have been identified in M. cymbalaria (Dhasan, Jegadeesan & Kavimani, 2008; Kale & Laddha, 2012). Rutin and quercetin are well-known naturally occurring flavonoids. Rutin exerts anti-inflammatory activity by decreasing the expression of cyclooxygenase-2 and inducible nitric oxide (NO) synthase (Choi et al., 2014), whereas quercetin inhibited the expression of inflammatory cytokines, cyclooxygenase, and lipoxygenase (Li et al., 2016). Hence, there remains a need for further examination of the outcome of M. cymbalaria on major inflammatory pathways.

Antimicrobial

The cup plate diffusion and minimal inhibitory concentration (MIC) methods were conducted to determine the antimicrobial activity of petroleum ether, chloroform, aqueous and methanolic extracts of M. cymbalaria fruits against different bacteria (Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Shigella sonnei, Klebsiella pneumonia, Salmonella typhi, Proteus vulgaris, and Pseudomonas aeruginosa), and fungi (Candida albicans and Aspergillus niger). The results indicated that the methanolic extract (2 mg/ml) was more effective against all sets of microorganisms (Vrushabendra Swamy & Jayaveera, 2007).

A study involving the agar well diffusion assay on different microorganisms revealed that the ethanolic and chloroform extracts of M. cymbalaria roots show MIC ranging between 1–5 mg/ml against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Proteus morganii and Salmonella typhimurium. A study on the effect of ethanolic and chloroform extracts on fungi (Candida albicans, Aspergillus niger, Penicillium chrysogenum, Trichophyton rubrum, and Aspergillus flavus) by microtiter plate assay showed MIC ranging between 1–5 mg/ml (Balkhande & Surwase, 2013).

Another study showed that the petroleum ether, chloroform, aqueous and ethanolic extracts of the aerial part of M. cymbalaria display antimicrobial activity against some clinically isolated bacteria viz., Escherichia coli, Staphylococcus aureus, Klebsiella pneumonia, Pseudomonas aeruginosa (clinically isolated) and fungus, Aspergillus niger. The aqueous and ethanolic extracts revealed inhibitory activities on Escherichia coli, Staphylococcus aureus, Klebsiella pneumonia, and Pseudomonas aeruginosa, whereas the chloroform extract showed inhibitory activity on Aspergillus niger (Sajjan et al., 2010).

Several high-quality investigations have demonstrated the relationship between the structures of the compounds obtained from plants and their associated antimicrobial activity, which showed close correlations. Moreover, many research groups have sought to enlighten the antimicrobial mechanisms of natural compounds. Quercetin has been moderately associated with the inhibition of DNA gyrase. It has been proposed that sophoraflavanone G and (-)-epigallocatechin gallate inhibit the functions of the cytoplasmic membrane and licochalcones A and C inhibit energy metabolism (Cushnie & Lamb, 2005). M. cymbalaria contains flavonoids and other phytochemicals, which may represent novel leads, and future investigations may allow the identification of pharmacologically suitable antimicrobial agents from M. cymbalaria.

A recent study concerning the green synthesis of M. cymbalaria extract silver nanoparticles showed an antibacterial effect against multidrug-resistant human pathogens (Gopu et al., 2022).

Antioxidant

The in vitro antioxidant activity screening of the hydroalcoholic extracts of aerial parts, fruits, and roots of M. cymbalaria was carried out by ferric ion reducing, 2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging, NO scavenging, and total antioxidant assays. The extract of the aerial parts showed greater ferric ion-reducing power than the extracts of fruits and roots. The fruit extract was reported to show higher NO and ABTS radical scavenging activity. The total antioxidant activity of the fruit extract was found to be 95.27 mg equivalent of ascorbic acid per gram (Prashanth, Suresh & Maiya, 2013). The methanolic extract of M. cymbalaria fruits showed 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical, superoxide anion, hydroxyl radical, and NO scavenging activities. The extract also exhibited inhibition of in-vitro lipid peroxidation (Vrushabendra Swamy & Jayaveera, 2007). Another study on in vitro antioxidant properties of the hydroalcoholic extract of the tubers of M. cymbalaria has shown potent reducing power, superoxide anion, and hydroxyl radical scavenging activities (Pramod et al., 2008). The total phenolic content of the methanolic extract of M. cymbalaria fruits was investigated by the Folin-Coicalteau phenol reagent test. The total phenolic amount was 272.00 ± 2.20 mg gallic acid equivalent per gram of the plant extract. As flavonoids and phenolic compounds are considered good sources of natural antioxidants, the antioxidant activity of M. cymbalaria can be mainly attributed to the presence of flavonoids and phenolic compounds in this plant.

Antiulcer

The anti-ulcer effect of the petroleum ether, chloroform, and methanolic extracts of M. cymbalaria fruits (100 and 200 mg/kg) against aspirin, alcohol (80% ethanol), and pyloric ligation-induced gastric ulcer models in Wistar rats have been reported previously (Kumar et al., 2011). In the aspirin-induced ulcer model, the methanolic extract of M. cymbalaria fruits indicated a significant defensive effect compared to petroleum ether and chloroform extracts. The methanolic extract significantly abridged ulcer index, the volume of gastric secretion, and free and total acidity of gastric secretion in the pyloric ligation-induced gastric ulcer model. All three extracts significantly lowered the ulcer index in the alcohol-induced ulcer model (Dhasan, Jegadeesan & Kavimani, 2010).

In a study on 80% ethanol-induced ulcers in Wistar rats, the aqueous extract of M. cymbalaria fruits (500 mg/kg) lowered total acidity and ulcer index significantly. The extract restored gastric mucosal structure by reducing gastric erosion and lesions. A vital reduction in the gastric lesion and an increase in non-protein sulfhydryl (NP-SH) level and gastric wall mucus concentration were observed in the extract-treated rats (Dhasan, Jegadeesan & Kavimani, 2010).

Flavonoids, the main compounds of medicinal plants, have been demonstrated to have gastroprotective activity, and several gastroprotective mechanisms of flavonoids have been reported so far. Quercetin has anti-secretory and antihistaminic properties, which decrease histamine release from gastric mast cells and inhibit gastric proton pump. Another important mechanism of flavonoids like quercetin and rutin is their antioxidant properties, which involve the scavenging of free radicals, metal ion chelation, inhibition of oxidizing enzymes, and lowering lipid peroxidation. Besides gastroprotective action, flavonoids also accelerate the healing of gastric ulcers (Mota et al., 2009). Interestingly, flavonoids like rutin and quercetin have been identified in M. cymbalaria (Dhasan, Jegadeesan & Kavimani, 2008; Kale & Laddha, 2012). Thus, the existence of these flavonoids may be held accountable for the antiulcer activity of M. cymbalaria.

Cardioprotective

An animal study has been carried out to demonstrate the attenuating effect of the ethanolic extract of M. cymbalaria roots in preventing isoproterenol (ISO)-induced cardiac injury in Wistar rats. Pretreatment with the ethanolic extract of M. cymbalaria roots (250 and 500 mg/kg) prevented the increase of serum lactate dehydrogenase (LDH), creatine kinase (CK), AST, ALT, ALP and attenuated the alterations of oxidative stress markers like LPO, GSH, CAT, and SOD in cardiac tissues (Raju et al., 2008).

Saponins isolated from the M. cymbalaria roots exerted the cardioprotective effect in ischemic reperfusion-induced myocardial injury in Wistar rats and hypoxia-induced cardiomyocyte cell (H9c2) death in vitro. Pretreatment with saponins (25 mg/kg) reduced myocardial damage by improvement in CK and LDH levels. Moreover, saponins reduced the levels of thiobarbituric acid reactive substances (TBARS) in rats, besides increasing the levels of GSH and the activities of SOD and catalase in cardiac tissues. Saponins also significantly recovered the developed tension and heart rate after myocardial damage induced by ischemia-reperfusion in rats. In H9c2 cells, saponin (20 µg/ml) was found to show a protective role against hypoxia-induced cell death (Mulumba, Koneri & Samaddar, 2015).

Both isoproterenol and ischemia-reperfusion increase oxidative stress in cardiac tissue and promote myocardial cell death (Elahi, Kong & Matata, 2009). In ischemic reperfusion injury, increases in intracellular Na⁺ and Ca²⁺ resulted in irreversible damage to cardiac tissue (Jennings et al., 1985). Saponins of M. cymbalaria roots have been shown to increase endogenous antioxidants in cardiac tissue (Mulumba, Koneri & Samaddar, 2015), but there remains a need for further examination of the effectiveness of saponins on cardiac physiology.

Diabetic neuropathy

Increased oxidative stress in chronic hyperglycemia is a crucial aspect of the progression of neuropathy. The neuroprotective activity of a triterpenoid saponin isolated from the roots of M. cymbalaria (100 mg/kg) was studied in streptozotocin-induced diabetic male Wistar rats. Neuropathic analgesia was estimated by tail-flick and hot-plate models. It was perceived that triterpenoid saponin significantly decreased tail immersion latency time and increased pain sensitivity in diabetic rats. The histopathological study revealed that there was advancement in the myelination and degenerative modifications of dorsal root ganglion neurons and sciatic nerve fibers. Also, treatment with triterpenoid saponin indicated a significant reduction in LPO levels and increased SOD and catalase activities in the sciatic nerve (Citraro et al., 2016).

The protective effect of saponins isolated from roots of M. cymbalaria has been investigated in high glucose-induced neuropathy in mouse neuroblastoma cells (NB-41A3) neuropathy. The results indicated a vital reduction in aldose reductase activity and the accumulation of sorbitol in NB-41A3 cells on saponins treatment. The saponins also improved the Na⁺/ K⁺-ATPase activity and reduced IL-1β, IL-6, and TNF-α production. Moreover, the saponins significantly improved blood glucose levels and lipid profile and decreased glycosylated hemoglobin levels. These results suggest that saponins possess neuroprotective activity in diabetic peripherals (Samaddar, Balwanth & Chandrasekhar, 2015). Moreover, the effect of oleanane-type triterpenoid saponins isolated from the roots of M. cymbalaria was screened in diabetic peripheral neuropathy by in vivo and in vitro methods. In this study, streptozotocin-induced diabetic Wistar rats were employed for various tests of peripheral neuropathy like muscle grip strength, pain sensation test, and nerve conduction velocity measurement. Treatment with oleanane-type triterpenoid saponin (100 mg/kg) increased muscle grip strength, reaction time to pain sensation, and improved nerve conduction velocity. In the in vitro study, saponin significantly decreased the aldose reductase activity and accumulation of sorbitol in sciatic nerve culture (Samaddar, Bhattarai & Chandrasekhar, 2016).

Hyperglycemia increases blood glucose concentration above normal levels and incites glucose-induced neurotoxicity (Tomlinson & Gardiner, 2008). The increase in neuronal glucose level activates the polyol pathway due to the overexpression of aldose reductase, which accumulates sorbitol and promotes neuropathy (Oates, 2002; Tang, Martin & Hwa, 2012). Na⁺/K⁺-ATPase plays a critical role in membrane potential. The increase in neuronal glucose concentration reduces Na⁺/K⁺-ATPase activity via protein kinase activation (Nagilla & Karnati, 2014). Moreover, the development of advanced glycated end products in hyperglycemia stimulates the production of proinflammatory cytokines (Vlassara et al., 2002). These factors together promote the advancement and promotion of diabetic neuropathy. A triterpenoid saponin isolated from M. cymbalaria roots was found to reduce aldose reductase activity, sorbitol accumulation, improved Na⁺/K⁺-ATPase activity, and reduced expression of proinflammatory cytokines (Samaddar, Bhattarai & Chandrasekhar, 2016). Hence, the triterpenoid saponin of M. cymbalaria roots can be attributed to its neuroprotective properties during hyperglycemia.

Effect on fertility

The anti-ovulatory and abortifacient activities of ethanolic extract of M. cymbalaria roots (250 and 500 mg/kg) were studied in female Wistar rats. The extract critically reduced the duration of the estrous cycle and meta-estrous phase and increased the pro-estrous phase, but no change in the diestrus phase was observed. It also possessed a dose-dependent abortifacient activity in pregnant rats during the organogenesis period (Koneri, Balaraman & Saraswati, 2006).

The ethanolic extract of M. cymbalaria roots (250 and 500 mg/kg) was studied at successive stages of embryogenesis in female Wistar rats. The extract displayed highly critical anti-implantation activity. However, an examination of the estrogenic activity of the extract activity did not display any elevation in uterine weight or vaginal cornification. Rats treated with the extract were not found to show any utero-trophic changes, such as the thickness of the endometrium and the height of the endometrial epithelium. However, glucose, cholesterol, and ALP levels in the uterus were not increased compared with the control group (Koneri et al., 2007).

In a study to investigate the progestational and anti-progestational activities, the Sprague Dawley (SD) rats were ovariectomized on the 8th day of pregnancy, and pregnancy was maintained in those rats by administration of estradiol (0.1 µg/rat/day) and progesterone (3 mg/rat/day) for 13 days. The number of viable fetuses on the 20th day was counted, and it was found that the administration of estradiol and ethanolic extracts of M. cymbalaria roots (250 and 500 mg/kg) to the rats did not maintain pregnancy. In the Clauberg assay, the administration of estrogen and ethanolic extract of M. cymbalaria roots (250 and 500 mg/kg) showed ramifications for the uterus. However, the administration of estrogen, norethisterone, and the extract of M. cymbalaria roots did not inhibit the proliferative changes caused by norethisterone (Koneri et al., 2007).

Cucurbitaceae plants have been reported to contain ribosome-inactivating proteins. α- and β-momorcharins are two ribosome-inactivating proteins isolated from the seeds of M. charantia that exhibited abortifacient activity (Ng, Chan & Yeung, 1992). Hence, the abortifacient and anti-implantation effects of the ethanolic extract of M. cymbalaria roots may be because of the existence of the ribosome-inactivating protein. On the contrary, a recent study stated that M. cymbalaria extracts possess a protective effect on diabetes-mediated reproductive toxicity in male Wistar rats (Elangovan et al., 2021). After oral administration of the extracts, the diabetic rats’ reproductive indices, as well as the antioxidant levels of SOD and glutathione-s-transferase (GST), were considerably enhanced (p < 0.05). Besides, the postprandial blood glucose (PBG) and malondialdehyde (MDA) levels were dramatically lowered after the oral administration of M. cymbalaria extracts. It also helped the reproductive organs of diabetic rats to regain their histomorphology. In diabetic rats, peel extract at a dosage of 500 mg/kg was shown to be more effective in raising testosterone levels and sperm count. Accordingly, M. cymbalaria controls not only postprandial blood glucose levels but also improves reproductive health in diabetics (Elangovan et al., 2021).

Hepatoprotective

The hepatoprotective activity of 70% ethanolic extract of tubers of M. cymbalaria was investigated against carbon tetrachloride (CCl₄)-induced liver damage in Wistar rats. Pretreatment with 70% ethanolic extract of M. cymbalaria (40 mg/kg) significantly reversed CCl₄-induced elevation of serum AST, ALT, ALP, and total bilirubin levels along with the reduction of serum cholesterol and triglyceride levels. The extract also enhanced GSH activity and lowered LPO activity in the liver. This study suggests that the probable functioning of hepatoprotective activity may be related to the antioxidant activity of the extract (Pramod et al., 2008). The in-vivo antioxidant and hepatoprotective activities of 70% ethanolic extract of tubers and fruits of M. cymbalaria (20 and 40 mg/kg) against thioacetamide-induced and sodium fluoride-induced hepatotoxicity in Wistar rats displayed significant inhibition of LPO and elevation of GSH activities. The extracts also decreased the levels of serum AST, ALT, ALP, bilirubin, cholesterol, and triglycerides (Mitta et al., 2021; Pramod et al., 2008). The ethanolic extract of roots of M. cymbalaria (500 mg/kg) has also been studied for hepatoprotective activity against CCl₄-induced liver damage in Wistar rats. It was found that the extract elevated the levels of serum AST, ALT, ALP, and total bilirubin. The extract also reduced serum cholesterol and triglyceride levels. In this study, the in-vivo antioxidant activity has been evaluated. The extract reduced LPO, besides improving the level of GSH, CAT, and SOD in rat’s liver (Koneri et al., 2008). In another study, the methanolic extract of M. cymbalaria Hook. (200, 400, and 600 mg/kg) exerted hepatoprotective activity via decreasing the levels of AST, ALT, ALP, and bilirubin, and increasing the level of high-density lipoprotein cholesterol (HDL cholesterol) against CCl₄-induced hepatotoxicity in Wistar rats. The extract also decreased liver tissue LPO levels and improved the GSH level. Moreover, histological observations revealed that the pretreatment of the extract protected the animals from CCl₄-induced liver damage (Vrushabendra Swamy & Jayaveera, 2007). In all these studies, M. cymbalaria improved the levels of endogenous antioxidants. Hence, the hepatoprotective activity of M. cymbalaria may be because of its rich content of flavonoids, tannins, and vitamin C, which possess antioxidative traits (Kumar et al., 2008).

Nephroprotective

The promising nephroprotective activity of 70% ethanolic extract of tubers of M. cymbalaria (20 and 40 mg/kg) has been evidenced against cisplatin, gentamicin, and paracetamol-induced renal injury in Wistar rats. The extract (40 mg/kg) was reported to reduce urea and creatinine levels in serum and increase body weight in all three models. In the paracetamol-induced nephrotoxicity model, the extract (40 mg/kg) has shown an improvement in GSH level and a decline in LPO activity (Pramod et al., 2011). Nitric oxide (NO) plays a pivotal role in cisplatin, gentamicin, and paracetamol-induced renal damage. The renal nitrative stress manifested by an increase in protein nitration and lipid peroxidation promotes renal damage (Abdelmegeed et al., 2013; Dhanarajan, Abraham & Isaac, 2006; Meng et al., 2017). In this study, the extract (100 µg/ml) showed in vitro NO radical scavenging activity. The preliminary phytochemical analysis indicated the presence of triterpenoids, saponins, and cardiac glycosides in the ethanolic extract of M. cymbalaria tubers (Pramod et al., 2011). Saponins have been reported to show antioxidant activity (Kim et al., 2001). Therefore, the antioxidant activity of saponins may be accountable for the nephroprotective activity of M. cymbalaria tubers.

Wound healing

In-vitro evaluation for the wound healing effect of a transdermal patch prepared from M. cymbalaria tuber extract was reported to enhance wound healing. The development of this extract can act as a good candidate to fasten wound healing, especially in diabetic patients (Saundharya et al., 2022).