Gliricidia sepium
Gliricidia sepium is a leguminous tree and belongs to the family Fabaceae. Gliricidia, which originated in Central America, is used in many tropical and sub-tropical countries as live fencing. That is, it is planted along the side of fields, and the trunks are used as fence posts. During the dry season, when much of the forage is gone, the tree limbs are cut and the foliage is offered to livestock.
Gliricidia trees are a medium size, with composite leaves. The flowers are reddish and on the end of branches without leaves. The fruit is a pod about 10-15 cm. Typically, it can be found growing in acid soils with low to medium fertility.
There are many compounds in Gliricidia sepium. The ones most researched are the tannins. In one study, Gliricidia was found to contain 40.7g of condensed tannins/kg dry matter. Tannins bind to protein and can make plants with high levels have an astringent dry mouth taste. The exact quantity of tannins varies with the location of the tree. The active medicinal compounds may be the tannins or other compounds such as afrormosin, medicarpin, or some isoflavins. Most of the research with gliricidia and it's compounds have focused on nutritive quality. However, some studies have focused on the ability of the plant and/or roots to decrease soil nematode populations, and control insects or fungi.
Some of the Compounds in Gliricidia sepium(for a more complete list see USDA Phytochemical and Ethnobotanical Databases:
No published studies could be found regarding the toxicity of using gliricidia to repel insects. However, many animals cannot tolerate the consumption of large quantities of gliricidia. The tannins bind proteins and decrease the nutritive value of the plant. Some animals, such as goats, can consume larger quantities of plants with tannins than other animals such as cattle and sheep. Goats, unlike cattle and sheep, have a salivary protein binding factor that binds to the tannins.
Gliricidia is used by farmers in some Latin American countries to repel insects. The leaves are ground up and combined with water. The animal is then bathed with the resulting paste. According to some of the farmers, if this is repeated every 7-14 days, the number of torsalo (tropical warble fly) infections is decreased. No published studies could be found to substantiate this claim. However, when interviewing farmers and checking goats in Honduras, I found that the goats who the farmers claimed to have bathed with gliricidia had only 2-3 torsalos, while others had 10 or more. Also, one study did indicate that the heartwood of gliricidia contains compounds that attract and are toxic to certain insects (e.g., southern army worm, cabbage looper, yellow woolly bear, and Glyptotermes dilatatus, a termite).
In the Philippines, gliricidia is washed and pounded to extract the juice from the leaves. It is then applied to the area affected by external parasites once to twice a day for one week. In Guatemala, the bark and leaves of gliricidia are used to treat human skin diseases.
Research has been conducted on both the antifungal and antimicrobial properties of gliricidia extracts. In a brine shrimp toxicity test, a general screening method indicative of cytotoxicity and pesticidal activity, the LC50 was 454ug.ml (CI 328-608). , medicarpin, one of the compounds in the leaves and heartwood of gliricidia, is supposed to be antifungal. In an antifungal study, gliricidia extracts inhibited the germination of Drechslera oryzae only 6%. However, in another study, 50ug of stem chloroform extracts inhibited the growth of Cladosporium cucumerinum and slightly inhibited the growth of Candida albicans. In contrast, in another study, the antimicrobial properties of extracts from the bark of gliricidia were tested. It was effective against bacteria causing dermatitis. However, it was not effective against enterobacteria or Candida albicans. The discrepancy in the effectiveness against Candida albicans could be because of the quantity of plant extract used or the types of extracts used. In another study, leaf extracts were found to be effective against the dermatophytes Microsporum canis, Trichophyton mentagrophytes var algodonosa, and T. rubrum. It was not effective against Epidermophyton floccosum, M. gypseum or T. mentagrophytes var granulare.
In another study, gliricidia was found to inhibit the growth of various strains of Neisseria gonorrhoea in in vitro tests. Tinctures made from the leaves were used for these tests.
Some Uses in Humans:
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