Ulam Herbs of Oenanthe javanica and Cosmos caudatus: An Overview on their Medicinal Properties

Eric Wei Chiang Chan1*, Siu Kuin Wong2, Hung Tuck Chan3 1Faculty of Applied Sciences, UCSI University, Cheras 56000, Kuala Lumpur, Malaysia; chanwc@ucsiuniversity. edu.my, erchan@yahoo.com 2School of Science, Monash University Sunway, Petaling Jaya 46150, Selangor, Malaysia 3International Society for Mangrove Ecosystems, Faculty of Agriculture, University of the Ryukyus, Okinawa 903-0129, Japan


Introduction
In Southeast Asian countries, particularly Malaysia, Thailand and Indonesia, ulam herbs are consumed raw as condiments, and they form an important component of the traditional diet. Dipped in a hot and spicy sauce made from shrimp or fish paste, these herbs would whet the appetite during meals. Ulam herbs are believed to have health-promoting properties, and their regular intake can assist in preventing degenerative diseases, delaying aging and improving overall health 1 . Herbs commonly consumed as ulam include young leaves of Anacardium occidentale (cashew), Barringtonia racemosa (common putat), Centella asiatica (pennywort), Cosmos caudatus (wild cosmos), Oenanthe javanica (water dropwort), Piper sarmentosum (wild pepper) and Persicaria hydropiper (water pepper).
In this review, two ulam herbs of O. javanica (water dropwort) and C. caudatus (wild cosmos) are updated with descriptions of their botany and ethnopharmacological uses. The focus is on their leaves and aerial parts. To date, this is the first review on O. javanica as its information has not been documented. There are two reviews on C. caudatus i.e. Cosmos caudatus Kunth: A traditional medicinal herb 2 and Potential medicinal benefits of Cosmos caudatus (ulam raja): A scoping review 3 .

Botany and Uses
Oenanthe javanica (Blume) DC or water dropwort of the family Apiaceae is an aromatic perennial herb with root tubers 4 . The plant grows up to a metre in height, often forming pure stands. Leaves are variable in shape and resemble those of celery (Fig. 1). The leaf axis branches several times, bearing ovate leaflets that are coarsely dentate or serrate at the terminal. Inflorescences form umbels bearing 5-15 white fragrant florets. In Southeast Asia, the strongly celery-flavoured leaves of O. javanica or selum are consumed raw as ulam during meals. Known as shui qin in China, minari in Korea and seri in Japan, O. javanica is cultivated in early spring, and its aerial parts are consumed for their distinctive aroma and taste. In Korea, O. javanica is consumed as salad or seasoning, and its soup is drunk to clear hangovers from alcohol intoxication 5 . In Chinese and Korean traditional medicine, the herb is used for treating jaundice, hypertension, polydipsia, fever, cold, abscesses, swellings, abdominal pain, leucorrhea, mumps and difficulty in urination 6 .

Antioxidant
Among 10 ulam herbs studied, O. javanica ranked seventh suggesting that its antioxidant properties are moderately low 15 . Total phenolic content, free radical scavenging and ferric reducing power of O. javanica were 3.0, 11 and 5.4 times lower than those of C. caudatus, respectively. However, the contents of carotenoid, lutein and β-carotene of O. javanica were 2.5, 1.9 and 2.8 times higher than those of C. caudatus 16 . The lutein content of O. javanica was the highest among 13 vegetables grown in Thailand 17 . Results of a study on the antioxidant activities of ethanol extract of O. javanica, and its hexane, chloroform, ethyl acetate, butanol and aqueous fractions showed that the ethyl acetate fraction had the highest total phenolic and flavonoid contents, and the strongest free radical scavenging, reducing power and iron-chelating abilities 18  endogenous antioxidant enzymes in the rat kidney has been reported 19 . Immunoreactivities of the enzymes increased two-fold in the group treated with the extract.

Melanogenic
Unlike most plants, O. javanica is one of the few plants that enhances tyrosinase activity and have melanogenic effects. The ethanol extract (50 μg/ml) enhanced tyrosinase activity and melanin synthesis in B16F1 melanoma cells 22 . The study suggested that O. javanica can be used to promote the growth of black hair and to protect the skin from oxidative stress. Other species with similar properties as O. javanica included Piper betle 23 and Salvia miltiorrhiza 24 .

Anti-diabetic
The anti-diabetic effect of O. javanica flavones on alloxaninduced hyperglycaemic mice has been reported 25 . Daily doses of 200 and 400 mg/kg for 10 days decreased blood glucose level in hyperglycaemic mice. The compounds stimulated the secretion of insulin in both normal and diabetic mice, and decreased serum triglyceride and ameliorated the activity of pancreatic amylases in diabetic mice. Oral administration of the O. javanica extract containing falcarindiol (15 mg/kg) significantly decreased the blood glucose level in rats 26 . Falcarindiol was found to inhibit glycogen synthase kinase-3β with an inhibitor constant (Ki) of 87 μM.

Anti-arrhythmic
The anti-arrhythmic activity of O. javanica extract was demonstrated in experimental rats 27 . Intravenous injection of 3.0 ml/kg significantly antagonized arrhythmia induced by aconitine and BaCl 2 , and decreased the rate of ventricular fibrillation induced by CaCl 2 .

Anti-inflammatory
Active compounds isolated from O. javanica have been reported to possess potent anti-inflammatory properties 28,29 . Persicarin and isorhamnetin effectively inhibited the release of High Mobility Group Box 1 (HMGB-1) protein and down-regulated inflammatory responses in human endothelial cells and inhibited hyperpermeability and leukocyte migration in mice.
Studies have been conducted on the anti-inflammatory roles of O. javanica extract and isolated isorhamnetin using lipopolysaccharide (LPS)-activated RAW 264.7 murine cells. Expression of cyclooxygenase (COX)-2, and activation of nuclear factor-kappa B (NF-ĸB) and activator protein-1 were significantly inhibited by the extract at 400 and 600 μg/ml concentration 30 . This suggested that inhibition of LPS-stimulated COX-2 expression by the extract is due to inhibition of NF-ĸB activation. Isorhamnetin has also been reported to inhibit the inflammatory response by blocking NF-ĸB activation 31 .

Neuroprotective
The O. javanica extract and persicarin showed significant neuroprotective activity in glutamate-injured rat cortical cells 10 . Persicarin diminished calcium influx and inhibited over-production of nitric oxide and intracellular peroxide. It also restored the reduced activities of glutathione reductase and glutathione peroxidase, and the content of glutathione. In another related study, the neuroprotective effect of O. javanica extract in the hippocampal region of gerbils subjected to transient cerebral ischemia was investigated 32 . Results showed that the extract can protect neurons from transient ischemic damage and that the neuroprotective effect may be attributed to increased or maintained intracellular antioxidant enzymes.

Neurogenesis
Besides protection against glutamate-induced neurotoxicity, O. javanica has neurogenesis effects based on a study on cell proliferation and neuroblast Journal of Natural Remedies | ISSN: 2320-3358 www.informaticsjournals.com/index.php/jnr | Vol 16 (4) | October 2016 differentiation in the hippocampal dentate gyrus of adolescent rats 33 . Rats with a diet containing the ethanol extract of O. javanica had more immunoreactive cells and neuroblasts, and the immunoreactivity of brainderived neurotrophic factor was enhanced.

Alcohol Detoxification
The ability of O. javanica to detoxify the harmful effects of alcohol has been reported. The methanol plant extract and persicarin enhanced the activities of alcohol dehydrogenase, microsomal ethanol oxidizing system and aldehyde dehydrogenase in the liver of rats intoxicated with ethanol 34 . In another related study, the effects of O. javanica were investigated in ethanolinjected rabbits and ethanol-fed mice 5 . When the extract and ethanol were injected into rabbits, the plasma ethanol level was rapidly reduced from 215 to 50 mg/dL several hours later. When ethanol was orally ingested, the O. javanica extract eliminated up to 44% of the plasma ethanol while the butanol fraction (50-200 mg/ kg) of the extract eliminated up to 70% in mice.

Antitoxic
A study on the antitoxic effects of orally administered O. javanica extract was conducted on mice exposed to methyl mercuric chloride through the drinking water 35 . The control, mercury treated and extract groups did not reveal any significant differences in mean body and organ weights. Examinations of the distribution of mercury in the cerebellum, kidney, liver, and spleen of the mice showed much less staining intensity of mercury in the cerebellum and liver of the extract group.

Anti-coagulant
Persicarin and isorhamnetin isolated from O. javanica displayed anti-coagulant activities 36 . The anti-coagulant and profibrinolytic effects of persicarin were stronger than those of isorhamnetin, suggesting that the sulphonate group of persicarin may be responsible for the anti-coagulatory function. The antithrombotic and profibrinolytic activities of isorhamnetin-3-Ogalactoside (IMG) were found to be stronger than those of hyperoside, indicating that the methoxy group in IMG may be responsible 37 .

Hepatoprotective
The hepatoprotective effects of O. javanica extracts in rats with liver damage have been demonstrated. The extracts enhanced hepatic lipid peroxide content markedly decreased by carbon tetrachloride (CCl 4 ) 38 , bromobenzene 39 and acetaminophen 40 . The extracts also increased the expression of enzymatic antioxidants in the rat liver cells, which decreases oxidative stress in the liver 41 , and protects against liver damage by scavenging free radicals, boosting endogenous antioxidants and inhibiting pro-inflammatory mediators 42 . The hepatoprotective ability of O. javanica extracts have been attributed to chlorogenic acid and caffeic acid 43 . Chlorogenic acid protected against CCl 4 -induced liver damage in rats 44 while caffeic acid protected against H 2 O 2 -induced cell death in HepG2 human liver cancer cells 45 . Isorhamnetin inhibited reactive oxygen species, reduced glutathione levels and maintained mitochondria membrane potential in treated HepG2 cells possibly via the AMP-activated protein kinase pathway 46 , and inhibited fibrosis in rat hepatic stellate cells partly via inhibition of the extracellular signal-regulated kinase signalling pathway 47 . The hepatoprotective effect of persicarin against inflammatory response in type-1 diabetes probably involved hyperglycemia-activated NADPH oxidase activation 48 .

Anti-HBV
The activity of O. javanica flavones (OJF) against hepatitis B virus (HBV) was investigated using human hepatoma HepG2.2.15 cell culture and ducklings 49,50 . In the cell culture, OJF inhibited the production of HBeAg (70%) and HBsAg (73%) on day 9. In HBV-infected ducklings, HBV-DNA levels decreased significantly. At 0.2 g/kg/ day, inhibition was 64% on day 5 and 67% on day 10. Reviews on the role of traditional Chinese medicines and their related compounds on HBV infection 51 and on anti-HBV agents of botanical origin 52 had included O. javanica amongst them. Both reviews acknowledged the need to determine the flavones responsible for the anti-HBV activity and their mechanisms of action.

Patents
In view of the convincing pharmacological properties of O. javanica, scientists in Korea have published several patents. They include three related to alcohol and carcinogen detoxification [55][56][57] , and another three on brain functioning and memory improvement 58-60 .

Botany and Uses
Cosmos caudatus Kunth. or wild cosmos of the family Asteraceae is native to Central America. The species is a short-lived, 1-2 m tall, perennial aromatic herb 61 . Leaves are opposite, pinnate and dissected into five leaflets (Fig.  2). The upper surface of leaf lamina is dark green while the lower surface is light green with minute hairs. The pinkish or violet daisy-like flowers are composite with a cluster of yellow florets at the centre. In Malaysia, C. caudatus or ulam raja is a popular herb that is consumed raw during meals. Its leafy aroma adds diversity and taste to the main dishes. Health benefits include reducing body heat, slowing down aging, improving blood circulation, promoting fresh breath, strengthening bone marrow and treating infections 62 . In Bangladesh, flowers of C. caudatus are used as ornaments during Hindu religious ceremonies 63 . Aerial parts are used to treat skin diseases such as leprosy and are prescribed in herbal bath for patients with skin infections.

Antioxidant
Among the leaves of 10 ulam herbs screened for phenolic contents and antioxidant activities, C. caudatus ranked third suggesting its strong antioxidant properties 15 . Analysis of the antioxidant properties of herbal teas prepared from C. caudatus leaves of different ages showed that teas from young leaves possessed significantly higher phenolic contents and antioxidant activities than teas from mature and old leaves 70 . Another study on the antioxidant properties of C. caudatus leaves reported that the aqueous extract yielded the highest phenolic content while the methanol and ethanol extracts had the strongest antioxidant properties 71

Antimicrobial
Hexane, diethyl ether and ethanol leaf extracts of C. caudatus have been reported to inhibit the growth of Gram-positive bacteria of Bacillus subtilis and Staphylococcus aureus, and Gram-negative bacteria of Escherichia coli and Pseudomonas aeruginosa with MIC values ranging from 6.3-25 mg/ml 72 . The plant has also been reported to possess anti-QS activity against C. violaceum with DIZ of 21 mm and MIC of 31 mg/ ml 20 . Sequential leaf extracts of C. caudatus screened for antifungal activity using the agar cup method showed that the ethyl acetate extract was most effective in inhibiting fungal growth and spore germination 73 .

Anti-inflammatory
The anti-inflammatory activity of C. caudatus against carrageenan-induced paw oedema in mice has been reported 74 . Petroleum ether, chloroform, methanol and aqueous leaf extracts, orally administered at 200 mg/ kg, significantly reduced paw oedema. Methanol and aqueous extracts showed significant anti-inflammatory activity, comparable to diclofenac sodium, the standard drug.

Anti-hypertensive
The aqueous extract of C. caudatus leaves was assessed for anti-hypertensive effect using rats treated with adrenaline and sodium chloride, and results showed that the extract (500 and 1000 mg/kg) lowered the heart beat frequency and stroke volume amplitude 75 . Together with its diuretic activity, the extract can have a synergistic effect in reducing blood pressure.

Hepatoprotective
The aqueous extract of C. caudatus was administered orally to mice at doses of 100, 500 and 1000 mg/kg with control mice given a diet containing 0.5% butylated hydroxyanisole 76 . After 21 days, lactate dehydrogenase levels, which indicated the extent of liver damage caused by oxidative stress, were significantly reduced in all the extract groups.

Detoxification
The effects of C. caudatus extract on detoxifying enzymes in lungs, kidneys and stomachs of mice have been reported 77 . Thirty adult male white mice were fed with 100, 500 and 1000 mg/kg of the aqueous extract for 21 days. In lungs of the treated group, all doses resulted in significant increase in catalase (CAT), superoxide dismutase and glutathione S-transferase activities. The activity of DT-diaphorase (DTD) increased significantly in mice treated with 1000 mg/kg. Lipid peroxidation levels based on malondialdehyde concentration were significantly decreased in mice fed with 100 and 500 mg/kg of the extract but was significantly increased with 1000 mg/kg. In stomachs and kidneys of the treated groups, CAT and DTD activities were significantly increased in mice fed with 1000 mg/kg, respectively.
Results suggested that C. caudatus supplementation in mice could protect extra-hepatic organs from xenobiotic and oxidative injury.

Anti-diabetic
The hexane extract of C. caudatus inhibited α-glucosidase activity, but not the dichloromethane extract, and both extracts inhibited α-amylase activity 78 . The ethanol extract of C. caudatus inhibited α-glucosidase activity with an IC 50 value of 58 ppm 79 . The α-glucosidase inhibitory activity of aqueous and ethanol extracts was attributed to catechin, α-linolenic acid, α-Dglucopyranoside and vitamin E 80 .

Anti-osteoporosis
The effectiveness of C. caudatus in the bone protection of post-menopause osteoporosis has been studied in rats 81 . Four groups of eight female rats were ovariectomized, and treatments of 1% calcium and 500 mg/kg of C. caudatus extract were given six days a week for eight weeks. Results showed that ovariectomy decreased trabecular bone volume and number, and increased trabecular separation. Both 1% calcium and 500 mg/kg of extract reversed structural bone histomorphometry to normal level with C. caudatus showing better effects on trabecular number and separation. The effectiveness of C. caudatus as treatment for post-menopause osteoporosis in rats were further evaluated based on dynamic and cellular parameters of bone histomorphometry 82 . Results showed that the extract increased double-labelled surface, mineral appositional rate, osteoid volume and osteoblast surface, supporting its role in bone protection. It was also reported that supplementation of C. caudatus can prevent the increase of interleukin-1, pyridinoline and bone resorption in ovariectomized rats 83 . In a follow-up study, C. caudatus extract (500 mg/kg) was found to enhance fracture healing in ovariectomized rats with fractured tibia 84 .

Anti-hyperlipidemic
In a recent study, the anti-hyperlipidemic effects of C. caudatus extract on obese rats were evaluated 85 . Rats were given a high-fat diet for three months and those administered with 200 mg/kg of the extract for four weeks showed a significant reduction in plasma triglycerides, total cholesterol, low-density lipoprotein cholesterol and plasma glucose, and significant increase in high density lipoprotein-cholesterol and atherogenic index values. Compared to obese rats, declines in plasma glucose (38%) and total cholesterol (28%) of treated rats were significant at week 17.

Toxicity Studies
An acute toxicity study on C. caudatus extract was conducted in male rats with single doses of 50, 500 and 2000 mg/kg given to the respective groups 86 . Changes in biochemical parameters included increase in the levels of liver enzymes and lower creatinine levels in the 500 and 2000 mg/kg groups, and lower albumin levels in the 2000 mg/kg group. The study showed that the extract may cause acute toxicity at high doses. Concurrently, another toxicity study on C. caudatus appeared to yield contradictory results 62 . Single doses of 2000 and 5000 mg/kg of aqueous extract showed no evidence of toxicity based on behavioural pattern, haematological evaluation and organ weight of rats. Although there was significant weight gain in the 5000 mg/kg group, the organs showed no detectable inflammation. However, the sub-acute toxicity study (single doses of 125, 250 and 500 mg/kg of aqueous extract) yielded variable results indicating that different extract concentrations could have different toxicity effects in rats.

Clinical Trial
In August 2014, the first randomized and controlled clinical trial to assess the effectiveness and safety of C. caudatus in patients with type-2 diabetes (ClinicalTrials. gov ID: NCT 02322268) was conducted in a tertiary hospital in Serdang, Malaysia 87 . In this study, 100 patients with type-2 diabetes and who met the eligibility criteria were divided into two groups (treated and control). Primary and secondary outcomes of serum and urine of the patients were examined at 4, 8 and 12 weeks. The trial was completed in November 2015, and preliminary findings showed that, after eight weeks of supplementation, C. caudatus significantly reduced serum insulin, reduced homeostatic model assessmentinsulin resistance and increased quantitative insulin sensitivity check index in the diabetic treated group 88 .
The study concluded that C. caudatus was safe to consume and that its supplementation significantly improved insulin resistance and sensitivity in patients with type-2 diabetes.

Conclusion
Both ulam herbs reviewed possess a wide array of biological and pharmacological properties, which confer their traditional uses as food and medicine. Properties of water dropwort are anti-diabetic, anti-arrhythmic, antiinflammatory, neuroprotective, alcohol detoxification, antitoxic, anti-coagulant, hepatoprotective, anti-HBV and memory improvement. Wild cosmos possess properties such as antioxidant, antibacterial, antifungal, anti-inflammatory, anti-diabetic, anti-hypertensive, hepatoprotective, detoxification, anti-osteoporosis and anti-hyperlipidemic activities. Some of the pharmacological properties of water dropwort have been patented while a clinical trial has been conducted on the anti-diabetic properties of wild cosmos. Further studies can be conducted on the pharmacological properties of these two ulam herbs. They include isolating and identifying bioactive compounds; assessing the properties and elucidating the mechanisms of action of the isolated compounds; analysing the effects of different processing methods on these herbs; evaluating their toxic effects if any; and exploring their potentials of developing herbal and pharmaceutical products. Notwithstanding, the prospects of studies on additional biological and pharmacological properties of these two ulam herbs are equally promising.