(By Temitope Obayendo)
The use of medicinal plants as foods and medicines is becoming more popular, as the campaign for consumption of natural, rather than processed foods, continues to spread. Consequently, efforts are already being made to tap into the health benefits of certain plants, in a bid to reduce the disease burden of Africa, as a whole, and Nigeria, in particular.
Tithonia diversifolia (commonly called wild sunflower or tree marigold), a member of the Asteraceae family, is one of the medicinal plants under consideration. Locally known as Jogbo or Agbale among the Yorubas and Izondiri in some eastern parts of the country, researchers have found it to be effective in the treatment and prevention of malaria.
According to a study conducted by Dr. Taiwo O. Elufioye and J. M. Agbedahunsi of the Drug Research and Production Unit, Faculty of Pharmacy, Obafemi Awolowo University, Ile Ife, Nigeria, ethanolic extracts of Tithonia diversifolia and the stem bark of Crossopteryx febrifuga gave some level of suppression of parasitaemia in the early and established infection stages. Titled, “Antimalarial activities of Tithonia diversifolia (Asteraceae) and Crossopteryx febrifuga (Rubiaceae) on mice in vivo”, the study was published in the Journal of Ethnopharmacology.
Another study, published in the Journal of Medicinal Plants Research and titled “Anti-malarial and repellent activities of Tithonia diversifolia (Hemsl.) leaf extracts”, also corroborated the effectiveness of the plant extracts in curing malaria and other domestic ailments.
According to the researchers, extracts from the leaf of Tithonia diversifolia used in folk medicine for treatment of various ailments were tested, under laboratory conditions, for antimalaria and mosquito repellency properties in experimental animals and human volunteers. Comparison of the effectiveness of Chloroquine with the aqueous and methanolic extracts from the plant (T. diversifolia) showed that Chloroquine was 100 per cent effective in clearing the parasite, while the aqueous and methanolic extracts were 50 and 74 per cent effective in clearing the parasites respectively.
They reported that both aqueous and methanolic extracts were more effective when administered before the onset of the infection, probably indicating the time-dependency of the antimalaria effects. Earlier application of the extracts at the onset of the malaria symptoms was more effective in reducing the parasitemia within a few days. The administration of the plant extracts during the malaria episode was also effective with longer period of administration.
The LC50 of the aqueous extract in mice was 1.2ml/100g body weight while the Maximum Tolerated Dose (MTD) was found to be 1.0ml/g. The repellent activity of volatile oil at different concentrations was measured by protection period against the bites of Anopheles gambiae, Aedes aegypti and Culex quinquefasciatus. The volatile oil extract showed higher repellent effect on A. gambiae at higher concentrations. However, its repellent and protective effects at various concentrations on all other species of mosquito tested cannot be underestimated.
Other Health Benefits of the Sunflower
• Analgesic/Anti-Inflammatory: A study of methanol extract of dried leaves of TD (Tithonia diversifolia) produced dose-related inhibition of carrageenan-induced paw edema and cotton pellet-induced granuloma in rats. The analgesic effect was observed with hot plate latency assays. Results confirm the traditional use of TD for the treatment of painful inflammatory conditions.
• Sesquiterpene Lactones/Anti-Inflammatory/Antibacterial: The main sesquiterpene lactones of species growing in Costa Rica – diversifolin, diversifolin methyl ester and tirotundin – were studied for their anti-inflammatory activity. Results showed inhibitory activity of the 3 compounds, attributed to aklation of cysteine residues. Diversifolin was also found to have antibacterial activity, moderately active against B subtilis.
• Antimicrobial: Chemical analysis of the leaf of Tithonia yielded sesquiterpene lactones, e.g. Tagitinin, which possess insecticidal properties. Study showed it possessed antimicrobial activity, active against both gram-positive and gram-negative bacteria, with activity against S aureus, E coli and P aeruginosa, suggesting they can be used in treating gastrointestinal infections, skin diseases and urinary tract infections in man.
• Anti-Diabetic: Study on an 80 per cent ethanol extract of TD showed reduction of blood glucose in KK-ay mice 3 weeks after a single oral dose, also significantly lowering plasma insulin, decreasing blood glucose in an insulin tolerance test. Results suggest it may be useful for the treatment of type2 diabetes.
• Potential Cancer Chemopreventive: Study isolated three new sesquiterpenoids – 2a-hydroxytirotundin, tithofolinolide, and 3a-acetoxy-8b-isobutyryloxyreynosin along with 8 known sesquiterpene lactones. Among the isolates, 2 compounds showed significant antiproliferative activity, 3 compounds induced HL-60 cellular differentiation, one significantly inhibited lesion formation in the mouse mammary organ culture assay.
• Antimicrobial/Germacranolide-type Sesquiterpene Lactone: Results indicate the non-polar leaf extract of T diversifolia could be useful in the treatment of some disease conditions and the sesquiterpene lactone is a potential candidate as a phytotherapeutic agent against some bacterial infections.
• Anti-Inflammatory/Hepatoprotective: Results indicate that treatment with a water extract of the aerial part of T diversifolia decreased paw edema induced by carrageenan, with reduction of the elevated liver enzymes, and improvement in the pathologic hepatic changes caused by carbon tetrachloride.
Tithonia diversifolia is 2–3 m (6.6–9.8 ft) in height with upright and sometimes ligneous stalks in the form of woody shrubs. The large, showy flowers are yellow to orange coloured and 5 – 15 cm wide and 10 – 30 cm long. Leaves are sub-ovate, serrate, acute, 10 to 40 cm long, simply or mostly 3 – 7 lobed, somewhat glandular and slightly grayish beneath. The seeds are achenes, 4-angled, and 5mm long. The seeds are spread by wind.
Journal of Ethnopharmacology, 2004
Journal of Medicinal Plants Research, 2008