A Review on the Ethnobotanical Uses, Phytochemistry and Pharmacology Effect of Luffa cylindrica

Luffa cylindrica , popularly known as sponge gourd is a tropic and sub-tropical fibrous plant with fruits containing black seeds. The fruit is consumed by humans as a vegetable in many parts of Asia, while different parts of the plant are used for cosmetics and as medicine in many parts of the globe. The plant has been used in the treatment of many ailments including nose cancer, snake venom, wound healing, edema, enterobiasis, filaria, whooping cough, stomach upset, stomach pain and malaria. Many health-promoting compounds such as flavonoids (apigenin-7-glucuronide luteolin-7-O- β -D-glucuronide methyl ester, -O-feruloyl- β -D-glucose, luteolin-7-O- β -D-glucuronide methyl ester), phenolics acids (p-Coumaric, gallic, caffeic, chlorogenic), triterpenoids (oleanolic acid and echinocystic acid), saponins (Lucyoside A-M), tannins (catechin), ribosome-inactivating proteins ( α - luffin), carotenoids (9 -cis neoxanthin, all-trans-lutein, all-trans- β -carotene), chlorophylls (chlorophyll a and b, pheophytin), cucurbitacin B and gypsogenin have been detected or isolated from different parts of the plants. Extracts of the plant and isolated compounds have wide spectrum pharmacological activities and have been shown to possess antiemetic, antidiabetic, antiviral, wound healing, anticancer, antipyretic, anti-inflammatory, antifungal, anti-bacteria, anthelmintic, hypoglycemic and antihyperglycemic, anti-inflammatory, antioxidant activity, and hepatoprotective effects in animal models. However, further information is needed on its safety and mechanisms of action. The present article is an updated review of the ethnobotanical uses, pharmacological actions, phytochemistry, safety, and future application of Luffa cylindrica in translational medicine.


Introduction
Luffa cylindrica is an important edible and medicinal plant that belong to the Cucurbitaceae family. It has many common names including smooth luffa, sponge luffa, vegetable sponge gourd, climbing okra, dishcloth gourd, and Chinese okra [1]. Locally in Nigeria, it is commonly referred to as kankan or kankan oyibo in Yoruba, while the Hausas call it soosoo. The Igbos named it Asisa. The plant is a sub-tropical crop which when planted in northern latitudes warrants hot and humid climates as well as prolonged chilly planting conditions. Also, a vast abseiling shrub with such a greenish, scrumptious vine that is slender but very stiff, extending to a length of 30 feet is Luffa cylindrica. It has a fleshy egg -shaped dehiscent fruit with a green papillary dermis, transversely characterized with black crevasses which generally range from 10 to 15 in total. A taut piny filament is discovered under each one of these protrusions [2]. Its leaves are 7-20 cm across and have three lobes. Flowers are bright yellow in color. The fruits which grow to about 60 cm in length are oval-shaped, smooth and, are made up of many seeds. The fruit is brown when matured and dries on the vine to resemble an inedible sponge-like structure. The picture of different parts of the plant is shown in Figure 1.

Distribution
Luffa cylindrica is commonly found in the humid tropics and Asia. Although the plant is of medieval or primitive origin, it is difficult to decide if Africa or Asia is the ancestral home. In West Africa, the plant grows naturally, but this is also presumed to be a consequence of evasion from planting since the crop is known in many cultures in the area as 'white people's sponge.' Proof of Asian ancestry is however scarce. It is also not clear how well the vine has dispersed over the vast coastal area. Many dispute that rising temperatures are a detonation factor, but the likely cause of the extensive distribution of Luffa cylindrica is most often human dispersal. It is documented to have evolved from India but it extensively grows as a weed in Nigeria and many other African countries.

Traditional and medicinal uses
Luffa cylindrica has diverse ethnomedicinal uses especially in Africa and Asia. The thawed fiber is used in Ghana for the filtration of water and palm wine [3]. Leaf

Different parts of Luffa cylindrica (A) leaves with flower (B) matured fruits (C) dried fruits (D) Luffa sponge (E) seeds.
A Review on the Ethnobotanical Uses, Phytochemistry and Pharmacology Effect of Luffa… DOI: http://dx.doi.org /10.5772/intechopen.98405 formulations are used topically for oedemas and for treating malaria in Togo. The fruit is used on tumor and inflammation in Guinea, while the pulp of the fruit is used as a desiccant in Guinea and Nigeria. There are culinary conifers cultivated in Guinea and Côte d'Ivoire. Zulu people in South Africa take a leaf decoction to treat stomach pain. The root formulation and leaf syrup were documented to be ingested in Tanzania to decrease the probability of pregnancy termination. The leaves are used for the stimulation of wound healing and abscess cognitive development. The leaves are grounded with water and the juice is used for stomach upset medication in Rwanda. Leaf decoctions are used to make childbearing smoother in Uganda. Pulverized leaves are anally inserted for enterobiasis therapy in the Central African Republic. Decoction of the leaves is fully viable against filaria and a colloidal solution of fresh leaves is used to combat whooping cough in Congo-Brazaville. Root formulation is used in Gabon as medicine for nose cancer. A root and leaf aqueous extract is documented to be consumed and used as an aborticide in an enema in the Democratic Republic of the Congo. The seed is used in Egypt for managing diabetes. The pulp of the whole crop is often used as a remedy for acid reflux in African  Table 1.
Production of edible forms has taken place in India and the Philippines where the crop is mainly bred. A brand of curry which is produced from the fruit is stripped, chopped and, fried in China and India. The fruit is consumed fresh or diced and processed in Japan for later consumption. The fruit is also employed as a therapy for the treatment of cynocy-tous and flu in Asia. Traditional medicine practitioners in China use the seed and sponge of the old fruits of the plant as stomachic, antipyretic and anthelmintic medicine. In addition, dried fruit is used as therapy for abdominal, chest, muscle, and joint pains [4]. Moreover, the fruits are employed in the treatment of rheumatism, dyspnea, cough and skin inflammation in Chinese folk medicine [5]. The fruit reduces breast swellings and it is combined with other Chinese herbs as a remedy against cancer. The fibrovascular bundle of Luffa cylindrica dried fruit is officially listed as a treatment for paralytic diseases in Chinese pharmacopeia. In Korea, Luffa cylindrica fruit pulp is used to treat fever, induce hemostasis, stimulate menstrual flow, strengthen the network vessels, invigorate blood and clear phlegm [6]. In Japan, the water extract of the vascular bundle of the plant, 'Hechimasui' is used as diuretic, antitussive and skin lotion [7]. In Java-Indonesia, the leaf juice is used for amenorrhea, while it is used for treating snake bites and dysentery in India [8]. The Santals people of Indian, use the plant in treating cramps, convulsion, tetanus, leprosy and syphilis [9]. Oil extracted from the seed is used for treating skin infection, while the fruit or its tincture is used as a therapy against intestinal and biliary colitis, jaundice, hepatomegaly, splenomegaly, dropsy, nephritis, bronchitis, tuberculosis and ascites in Indian herbal medicine practice [9]. The Filipinos used the leaves for orchitis and skin diseases [8].

Other ethnomedicinal uses
Raw or prepared as a vegetable, the new fruit can be consumed, but it must be selected before entrenching the spongy cotyledons and before generating the extinguishing substances. The leaves are also consumed as a vegetable, while the charred seeds contain edible oil that is safe for consumption. The gritty and hazardous seed cake is not ideal for livestock feed but could be used as a compost since the plant is rich in nitrogen and phosphorus [3]. The plant is used for treating bowel and bladder hemorrhage, hemorrhoids, toothache, scarlet fever and smallpox [8]. Luffa cylindrica seeds are used for treating fever and respiratory disorders including sinusitis, bronchitis and asthma [10,11]. The seed oil is used as a lubricant and atopically applied to the skin in the treatment of leprosy, shingles, boils and other skin diseases. The oil also found application in several cosmetic products including sunscreens, anti-aging creams, moisturizers, sunless tanners, facial cleansers and sunscreens. The oil is used in sunscreens because of its toxicity to skin cancer cells.
Goats feed on the fruits and leaves [3], while bees prey on their flowers. The root formulations are also used to relieve of stomach pain and as a muscle relaxant. The leaves are used for stimulation of wound repair and echogenic cognitive development. The fruit sag is consumed as a powerful prophylactic, while the seeds are consumed for their anti-parasitic and relaxing properties. The fruit is also used in the treatment of piles and hematuria [12]. Additionally, the fresh fruit is demulcent, cooling and beneficial to the intestine, stomach and genital organs [8]. The flower of Luffa cylindrica is used as a therapy against migraine [13].

Antioxidant activity
The methanol and chloroform Luffa cylindrica leaves extract exhibited antioxidant property via enhanced scavenging of DPPH and superoxide radicals in a dose-dependent fashion [14]. Similarly, its methanol extract displayed free radical scavenging ability against hydrogen peroxide, hydroxyl and nitric oxide radicals. Ethanol extract of the fruit of Luffa cylindrica was earlier reported to possess strong antioxidant activity against DPPH radical [15]. Methanol extract of Luffa cylindrica vegetable thermally processed by different methods was recently found to show varying degrees of antioxidant properties as measured by thiobarbituric acid, DPPH, ferric thiocyanate and ferric reducing antioxidant power radicals scavenging assays [16]. Similarly, Bulbul et al.

Anti-inflammatory activity
Anti-inflammatory activity was exhibited by chloroform extract of Luffa cylindrica whole plant through marked reduction of carrageenan-induced rat paw edema in experimental animals that received 50 mg/kg body weight of the extract [19]. Ethyl acetate and ethanol extracts of Luffa cylindrica peel and pulp displayed anti-inflammatory action against LPS-induced inflammation in RAW 264.7 cells by modulating NO, IL-6, PGE2, iNOS, pIκβα and p-ERK expression [20]. Moreover, two fractions from the petroleum ether and benzene extracts of the seed exhibited anti-inflammatory activity in the same experimental animal model [9]. Lucyoside B, a triterpenoid saponin extracted from the fruit of Luffa cylindrica also exhibited anti-inflammatory effects through subdual of proinflammatory mediators such as iNOS, IL-6 and MCP-1 at the transcriptional and translational levels coupled with the production of NO [21].

Anti-viral effects
The L. cylindrica vine demonstrated 66.7-80% protection against Japanese B encephalitis virus when given has pre-treatment to mice before viral infection, while the protection diminished when given 210 minutes post-infection to the virus [28]. Luffin P1, a ribosome-inactivating peptide isolated from Luffa cylindrica seeds displayed anti-HIV-1 activity in infected C8166 T-cell lines by binding HIV reverse response element and possibly via charge complementation with cellular or viral proteins [29,30]. Recently, in silico analysis revealed that four saponins namely lucyoside H, lucyoside F, 3-O-β-ᴅ-glucopyranosyl-oleanolic acid and 3-O-β-ᴅglucopyranosyl-spinasterol from air-dried fruits of L. cylindrica showed strong affinity for the substrate-binding pocket of SARS-CoV-2 Mpro with docking energy scores of-7.54, 7.47, −7.29 and − 7.13 kcal/mol, respectively as compared with the binding ability equivalent of N3 protease inhibitor (−7.51 kcal/mol), which is an established inhibitor [31]. Therefore, suggesting that L. cylindrica and these aforementioned compounds could find application in the prevention and treatment of SARS-CoV-2.

Antifungal activity
The ethyl acetate extract of Luffa cylindrica leaves displayed antifungal activity against Candida albicans, Candida tropicalis, Trichophyton rubrum together with four clinical isolates of C. albicans, C. tropicalis, Microsporum canis and Epidermophyton flocossum [32]. Some compounds isolated from the benzene and petroleum ether of Luffa cylindrica seeds also displayed anti-fungal properties against Candida albicans [9]. The petroleum ether crude extract of Luffa cylindrica fruits exhibited anti-fungal property against Candida albicans and Aspergillus niger [33]. The butanol extract displayed profound antifungal action against Trichophyton longifusus and Fusarium solani, while the ethyl acetate fraction of the crude methanol extract markedly inhibited the growth of Microsporum canis [34]. In vivo antifungal activity was also exhibited by crude ethyl acetate extract of Luffa cylindrica leaves in laboratory animals by promoting plodding healing of the infected skin of experimental animals [32].

Anthelmintic activity
Both crude ethanol and methanol extracts of Luffa cylindrica leaves displayed anthelminthic activity against Pheretima posthuma [1,14]. In fact, the anthelminthic activity of the ethanol extract was comparable to the standard drug mebendazole [14].

Anti-pyretic activity
Methanol extract of Luffa cylindrica leaves displayed antipyretic activity by decreasing the rectal temperature of experimental animals at the studied doses and also impeding the compression of abdominal walls in experimental animals, which were induced with agony sensation depending on the dose [35]. The results showed the extract drastically reduced blood glucose level in diabetic rats within three hours of treatment and the efficacy of the extract in reducing blood glucose was similar to a standard anti-diabetic drug, metformin. Tryptic and alcalase protein hydrolysates from the seed have strong inhibitory action against angiotensin-converting enzymes, α-amylase and α-glucosidase [40]. The authors therefore opined that plant holds strong potential in the treatment of hypertension and diabetes.

Hepatoprotective activity
Methanol extract of L.cylindrica leaves displayed hepatoprotective effects through the reduction of serum liver enzymes in a paracetamol model of hepatic injury [41]. The hydroalcoholic extract of Luffa cylindrica leaves also exhibited a similar hepatoprotective property in the erythromycin estolate-induced model of liver damage [42]. Increased serum liver enzyme levels in paracetamol-induced rats reduced drastically on treatment with alcohol and aqueous extracts of Luffa cylindrica fruits coupled with conservation of the structural integrity of liver membrane [43].

Sedative and anti-epileptic effects
The sedative, anti-epileptic and anti-convulsant activities of alcohol extract of L cylindrica fruits were investigated in rats by Sunil et al. [44]. The results showed that the extract at 400 mg/kg body weight lessened the sleep induction time and prolonged the sleeping time in rats exposed to diazepam. At the same dose, the extract lengthened the latency time, but reduced the time of seizure in the pentylenetetrazole-induced model of convulsion, while it decreased total seizure time as well as clonic tonic time in the maximal electroshock model of convulsion. These effects were however lower than that of standard drugs, diazepam and phenytoin.

Skin protection
Umehara et al. [7] investigated the effect of L.cylindrica fruit extract on UVBirradiation-induced mice model of dry skin and demonstrated that the extract and isolated phenylpropanoids inhibited trans-dermal water loss in hairless mice. The extract and p-coumaric acid isolated from the extract stimulated dome formation by MDCK I cells. Additionally, p-coumaric acid increased mRNA expression of water permeability and reabsorption protein, AQP3. The authors, therefore, concluded that p-coumaric was responsible for L. cylindrica related water permeability and that L. cylindrica could contribute to the treatment of disease relating to the inability to retain moisture including dry syndrome. Furthermore, an extract obtained from the fruit pulp prevented the development of atopic dermatitis-like skin lesions in mice exposed to Dermatophagoides farinae [6].

Anti-emetic activity
The ethanol extract of the fruit peel of L.cylindrica showed significant antiemetic activity in young chicks at a dose of 150 mg/kg body weight [45]. The ethanol and hexane extracts of leaves and male flowers of L. cylindrica exhibited anti-emetic effect against chick emesis facsimilia. The anti-emetic effects of hexane extract of male L. cylindrica flowers and leaves were at 71.5% and 43.5% inhibition of reteches respectively, whereas the ethanol extract of leaves and male flowers of L. cylindrica was at 68.66% and 68.46% inhibition of reteches respectively [46].

Wound healing activity
Different parts of L. cylindrica have been reported to possess wound healing capacity. Chloroform extract of the whole plant showed wound healing activity in a rat model by reducing the wound area and time of epithelization [19]. Diethyl ether, n-hexane, chloroform, ethyl acetate, butanol and methanol seed extract also promoted wound healing in rats [47]. Diethyl ether extract showed the highest wound healing activity, while the weakest activity was displayed by chloroform extract [47].

Effects on hematological parameters
Raw and thermally processed Luffa cylindrica seed meal fed to albino rats had no adverse effects on the hematological indices of the experimental animals [48].
However, administration of methanol extract of L.cylindrica leaves to rats produced an elevation in the hematological parameters in experimental animals [49].

Oxytocic activity
Aqueous extract of L.cylindrica leaves increased uterine motility in an isolated rat uterus [50]. Thus suggesting that L.cylindrica is oxytocic and giving credence for its use in Uganda to facilitate labour and treat postpartum issues.

Chemical composition
L.cylindrica is rich in nutrients and phytochemicals. Several recent studies have revealed that L. cylindrica leaves, fruits, and seeds are a rich source of carbohydrates, protein, fiber, fats, amino acids and minerals [48,51] The mineral found in the seeds of Luffa cylindrica plant include sodium, iron, phosphorus, calcium, zinc, potassium, manganese, copper, chromium, magnesium [51]. Moderate amounts of K (13.86 mg/100 g) and Na (8.18 mg/100 g) were found in the seed, but the concentration of Cr (0.25 mg/100 g) was low [50]. L.cylindrica fruit is an excellent source of Vitamins A, B5, B6, C, and dietary fiber.
According to the preliminary phytochemical screening test carried out on different extracts of L.cylindrica leaf and seed extracts, all the extracts were found to contain saponin, alkaloids and cardiac glycosides [52]. Only the seed extracts contained the steroidal rings, while anthraquinones, tannins and phlobatinnins were not detected in any of the extract [52]. Reducing carbohydrates, flavonoids, tannins, saponins and glycosides were also detected in the plant extract [2]. The phytochemical screening carried out on the methanol and ethyl acetate extract of the leaves of L.cylindrica indicated that the extracts of leaves of L.cylindrica contain carbohydrates, sterols, saponins, flavonoids, alkaloid and phenols, while resins, tannins, terpenes, balsams and anthraquinones were not found [32]. Another preliminary phytochemical screening of aqueous methanol extract of L.cylindrica leaves revealed the presence of sugar molecules including glucose, fructose and galactose as well as the presence of amino acids such as phenylalanine, glycine and tyrosine [53]. Moreover, phytate and oxalate were found in the methanol extract of flowers and leaves of L. cylindrica [54]. The L. cylindrica seeds contain high amount of saponins, alkaloids and phlobotannins. The butanol extract of Luffa cylindrica seeds contains alkaloids and deoxy sugars, while the diethyl ether extract contains deoxy sugars, cardiac glycosides, alkaloids and carbohydrates [47]. The chloroform extract contains deoxy sugars and cardiac glycosides [47]. Quantitative analysis of the sponge revealed that it contains 1.2, 0.5, 17.94 and 20.74 mg/g of ascorbic acid, total anthocyanins, flavonoids and phenolics respectively [55]. The total flavonoid and phenol in the aqueous and ethanol extracts of Luffa pulp and peels were reported to range from 0.94-14.02 mg/g GAE and 0.33-18.09 mg/g QE respectively, while olenolic acid, carotenoids, and chlorophylls were in the range 0.01-25.79,0.01-14.87 and 0.04-37.29 mg/g extract respectively [20].
A penotacyclic triterpenoid saponin, lucyoside O was isolated from the leaves of L.cylindrica. Lucyin A, lucyosides G, N, O, Q, P, R, ginsenosides Re and Rg1, 21β-hydroxyoleanoic acid and 3-O-β-D-glucopyranosyl-maslinic acid, were also identified in the leaves of Luffa cylindrica [22]. In addition, Lucyoside K was isolated from the hydro-ethanol extract of the leaf extract, while Lucyoside A-M were identified in the fruit extract of the plant [22]. A peptide with luffacyclin that possessed antifungal activity was also isolated from L. cylindrica seeds. Sapogenins (I & II) were isolated from ethanol extract of the seeds and were both found to exhibit immunomodulatory effects [56]. Some triterpenoids and fibrinolytic saponins were isolated from seeds and fruits of the plant [47].  [15]. A phenylpropanoid glucoside, 4-O-feruloyl-glucose was isolated from a natural source for the first time in L. cylindrica fruit [7]. Other phenylpropanoid glucosides that were isolated from the edible part of Luffa [58].

Conclusion and future perspective
The review provides an up-to-date and comprehensive summary of the traditional uses, pharmacology and phytochemical composition of Luffa cylindrica. Luffa cylindrica has been eaten as food and used in folk medicine for several years especially in Africa and Asia for the treatment of many diseases including malaria, stomach disorders, whooping cough, oedemas, wounds, tumor, filarial, rheumatism, dyspnea, inflammation, leprosy, syphilis, bronchitis, tuberculosis, dysentery and amenorrhea. In the last few decades, the plant has attracted attention due to its potential pharmacological actions including anti-inflammatory, anticancer antioxidant, anti-viral, antimicrobial, anti-diabetic, hepatoprotective, sedative, anthelmintic, anti-pyretic, anti-epileptic, hypoglycemic, skin protection. Anti-emetic and wound healing. The repertoire of beneficial and health-promoting phytochemicals that are present in Luffa cylindrica could be responsible for diverse

Compounds
Pharmacological action Ref.

Volatiles and other compounds
3-hydroxy1methylenetetrahydroxynapthalene-2carbaldehyde Antimicrobial [57] 22, 23-dihydroxy spinasterol Antimicrobial [57] Phenanthrene Antimicrobial, spasmolytic, anti-inflammatory, antiplatelet aggregation, antiallergic activities and phytotoxic effects [130,131] Litchiol B Antioxidant,anti-bacteria [132] Pinoresinol Anti-proliferative, antioxidant [133] Pentanoic acid NRPA Nonanoic acid Bioherbicides [134] 1-Octen-3-ol Pesticides [135] β-linalool Antioxidant, antibacterial [136] α-terpineol Nonanal Antioxidant, insecticidal, anticancer, anti-nociceptive, anticonvulsant, antihypertensive, antiulcer Antifungal, antidiarrheal [137,138] Nonadienal Anti-bacteria [59] Decanal Antimicrobial [139] Eugenol Mosquito repellant, antifungal, antibacterial, antiinflamatory antioxidant [140] Limonene Antitumour, anti-inflammatory, antioxidant, antiviral,antibacterial [141] Trihydroxyoctadecadienoic acid Antifungal and bacteria [141,142] Trihydroxyoctadecenoic acid Antiviral [143] Octadecadienoic acid Antidiabetic [144] NRPA = no reported pharmacological action ethnomedicinal uses and pharmacological activity recorded for the plant. However, like many other medicinal plants, efforts should be made to standardize its usage in different disease models through activity-guided bioassays and isolation of active principle(s). Formulated standardization of Luffa cylindrica extract is needed to have reproducible results that can be integrated into translation medicine. In addition, more mechanistic and comprehensive safety studies on Luffa cylindrica are needed to enhance its pharmaceutical potentials and know the long-term effects of consumption of L. cylindrica as medicine since most of the studies found in literature only addressed its acute toxicity. Moreover, more clinical studies are warranted to confirm the pharmacological activities of Luffa cylindrica extracts and its constituents in order to translate results obtained from animal studies into human. Taken together, Luffa cylindrica holds great potential as a repository of beneficial phytochemicals that can be leveraged on for the betterment of human health. Research efforts should therefore be directed at optimizing the bioactive extracts and/or phytochemicals for health promotion and improving the quality of life.
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