A booklet on Costus afer (Opete) by Obasi Kelechi

 The African Gem

Costus afer Ker Gawl

(Opete) by Obasi Kelechi

Abstract

Costus afer Ker Gawl is a plant commonly known as ginger lily, spiral ginger, or bush cane, it is called ''Opete'' by the Igbo's of Nigeria (West Africa).

Costus afer (Opete) is reportedly used in traditional medicine practice to treat and manage many ailments including diabetes mellitus, stomach ache, arthritis, inflammation, and gout. The sap is somewhat rubefacient, and on open wounds its burning, yet it is also anodynal and healing. Sap from a fresh plant or a decoction of the dried plant is used in eye-instillation for various eye-affections and for headache, and in frictions for oedemas and fever. Leaf sap is used as eye drops to treat eye troubles and as nose drops to treat headache with vertigo, and in frictions to treat oedema and fever. Leaf sap or a rhizome decoction is taken to treat malaria.

Stem sap is applied to treat urethral discharges, venereal diseases, jaundice and to prevent miscarriage. Stem sap is acid and rubefacient and burns on open wounds, but it is also anodyne and healing, and is applied to different skin ailments.

A stem decoction is widely taken to treat rheumatoid arthritis. An infusion of the dried aerial parts is taken to treat hypertension. The powdered stems are used as an enema to treat worms and haemorrhoids.

''Opete'' leaf is mixed with those of Aframomum sceptrum (Grains of paradise or Guinea grains) and the expressed sap used in nasal installation for headache with vertigo: the mixed leaves are also applied to the face. A stem-decoction is widely used for treatment of rheumatism and in Casamance (Senegal) and in Gabon crushed stems rubbed on to wounds immediately after their infliction give good results for cleansing and healing. A stem decoction, the mashed or chewed stem or the pounded fruit, sometimes mixed with sugar cane juice, are taken to treat cough, respiratory problems and a sore throat. The smoke of the dried stem is also inhaled to treat cough. In Sierra Leone the stem is mashed or chewed to relieve cough. The pulped-up stems taken in a little water are strongly diuretic. This is used in Ivory Coast-Upper Volta to relieve urethral discharge.

The Ijaw people of Southern Nigeria express the sap which is taken for malaria and to clear urine. The deleafed and debarked stem is used in Nigeria against attacks of nausea and young stems are sucked by the Efik to quench thirst. A cold water extract of the stem is taken to treat small epileptic attacks. Leaf-sap in a root-decoction is drunk in Tanganyika for malaria. The outer layer of the stems is used in Lower Dahomey to weave into small table mats, kola baskets, etc., and the plant is sometimes cultivated for this purpose. The stem has some value as a paper material, and good quality brown and white papers have been produced. Many years ago, children in Southern Nigeria use the stems for cleaning school slates. The sap can be used to coagulate rubber. Nigerian material has been found free of alkaloids.

The root is used in Benue State, Nigeria, for the treatment of cough, and a decoction of roots and epiphytic orchids has been used as a remedy for sleeping-sickness. In Casamance (Senegal), the roots mashed to a thick paste are applied topically to abscesses and ulcers and they are put into a popular medicine for constipation. In Nigeria, a root-infusion is taken for stomach-ache and is considered to be a stimulant and an aphrodisiac.

In Gabon, the root is boiled to a pap and taken for syphilis and a decoction is taken in Tanganyika for leprosy and gonorrhoea. Rhizome pulp is applied to abscesses and ulcers to mature them, applied to teeth to cure toothache, and mixed with water it is taken to treat diarrhoea and amoebic dysentery. A rhizome decoction or the raw rhizome is taken to treat leprosy and venereal diseases.

In Gabon the stem sap is rubbed on the body to treat colic. In Sierra Leone, the canes are laid under bodies of the dead, and when twins are born they are (canes) laid by an anthill.

In Togo, ''Opete'' is sometimes cultivated for the stem bark which is used to make table mats and baskets. Experiments in Uganda to use it for making paper were successful.

In Democratic Republic of Congo, the stems are used in house construction. The sap can be used to coagulate latex and is also used in skin nourishing creams. In West Africa, ''Opete'' is used as a fodder for small ruminants and poultry and the leaves serve as a feed for snails.

In Ghana, the ''Opete'' plant has many superstitious uses. It is placed on a cultivated field, or path, or entrance to a house for protection, and planted in sacred groves. It is used in religious ceremonies. Its smell is regarded as inimical to ghosts and evil influences, and it is offered to a spirit occupying a tree. The stem, seeds and rhizome of ''Opete'' contain several steroidal sapogenins, of which diosgenin is the most important one. The rhizome yields 0.5% diosgenin. Diosgenin is a very important raw material used as a precursor in the synthesis of a number of steroidal drugs, including corticosteroids, sex hormones, oral contraceptives and anabolic agents.

Emotionally and energetically, White Ginger Lily Hydrosol uplifts the spirits and is used in aromatherapy for relieving nervous related issues like anxiety, stress and depression. It is also thought to have natural aphrodisiac properties and widely used for sexual wellness application.

Insight

These purported ethnomedicinal uses have triggered many research studies on the plant to amass scientific evidence. However, these research reports are scattered, and thus, this systematic review seeks to provide a comprehensive update on it covering its traditional uses, phytochemical and nutritional constituents, pharmacological activities, and toxicological effects.

The stem and leaves of the plant contain substantial amounts of micronutrients and macronutrients. The leaves, stem, rhizomes, and roots of ''Opete'' contain several steroidal sapogenins, aferosides, dioscin, and paryphyllin C and flavonoid glycoside kaempferol-3-O-α-L-rhamnopyranoside. Experimental studies on various parts of the plant showed bioactivities such as antihyperglycemic, hepatocellular protection, cardioprotection, nephroprotection, testicular protection, CNS depressant, analgesic, antiarthritis, antibacterial, and antioxidant. Based on these evident data, it is concluded that the plant could be used as an alternative and complementary therapy for many oxidative stress-related diseases, provided further scientific studies on the toxicological and pharmacological aspects are carried out.

The use of herbal medicine to manage or cure diseases dates back to the Stone Age. There has been an advancement in pharmacological discoveries over the years that has resulted in the production of many synthetic drugs. This therefore reiterates the worth of ethnomedicinal plants for drug discovery.

''Opete'' is a rhizomatous herb commonly known as ginger lily or “bush cane”. Almost every part of this plant is endowed with medicinal potential in diseases such as malaria, measles, diabetes mellitus, arthritis, and stomach disorders. In West Africa for instance, the succulent stem is chewed to quench thirst and also to treat cough and its accompanying sore throat. Various solvent extracts of the plant leaves, stem, rhizomes, and roots have been studied and reported to contain chemical compounds that could be useful in the alleviation of oxidative stress-related conditions.

A number of research studies have gone into finding bioactive compounds of plant origin with pharmacological properties to be used in the design of new drugs with lesser side effects. The several medicinal importance of ''Opete'' makes it serve as one of the plants to attract this kind of research. However, information on its bioactivity, safety profile, and active principles is scattered. Implicitly, there is the need to collate these for easy accessibility that could enhance further research. This review therefore tends to provide a comprehensive update on this plant covering the botanical and ecological distribution, phytochemistry, pharmacological actions, and toxicological consequences associated with usage.

''Opete'' is usually an unbranched tropical plant often seen as a herb with a creeping rhizome. It is a relatively small monocot shrub which is commonly found in humid and monstrous forests and riverside. It is a perennial plant which can grow as tall as 4m and bears white and yellow flowers. Its inflorescence is a highly compact, terminal, conical spike of about 2.5 cm to 7.5 cm long, sessile; bracts are oblong, convex, 3.5 cm long, densely imbricate, upper ones usually smaller; apex is truncate to rounded, green with purple markings, each subtending two flowers; bracteoles are boat-shaped, 2.5 cm × 1 cm; and keel is thick and ridged, pale green with pink markings and thin pink papery margin. It has simple leaves, which are arranged spirally. The sheath is lobular, closed, and green with purple blotches. The ligule is about 4 to 8 mm long, which is leathery and glabrous. The leaf blade is elliptic to ovate of about 15 cm to 35 cm  3.5 to 9.5 cm with culminating apex. The margin is sparsely hairy with a bisexual and zygomorphic flower.

''Opete'' is pan tropical with about seventy(70) species, of which forty(40) are found in tropical America, twenty-five(25) in West tropical Africa, and five(5) in South-East Asia.

In Africa, the plant is found in the forest belt from Senegal to Ethiopia and in the East to Tanzania. In tropical West Africa, it is found in the rain forest and riverbanks of countries including Ghana, Sierra Leone, Senegal, Guinea, Togo, Cameroon, and Nigeria.

Nutritional and Phytochemical Composition of ''Opete''.

''Opete'' is used by the local folks, due to its nutritional and medicinal properties. This involves the use of the plant parts such as leaf, stem, and the rhizome in preparation of food. The proximate analysis of different parts of ''Opete'' shows the presence of both macro- and micronutrients. Both the leaves and stem are rich in macronutrients such as carbohydrate, crude protein, fat, ash, moisture, and a good source of fiber. There are also reports of the presence of certain vital nutrients such as vitamins B (1, 2, 3, 6, and 12), E, and C in the leaves. The oil extracted from the plant is made up of 78% saturated fatty acids and 22% unsaturated fatty acids.

The phytochemical analysis of the leaves, stem, and the rhizome of this plant in different solvents shows the presence of alkaloids, phenols, saponins, triterpenes, tannins, and glycosides. These phytochemicals and nutrients may justify the nutraceutical use of the plant. Research on the chemical identification and isolation of bioactive compounds from ''Opete'' has been carried out, and this has led to the elucidation of structures from different parts of the plant. For instance, the rhizome is reported to contain steroidal saponins such as dioxin, deriphyllin C, aferoside B, and aferoside C. Kaempferol-3-O-R-L-rhamnopyranoside, which is a flavonoid glycoside, has also been identified from the aerial part of the plant. Additional aferoside A and aferosides B and C have been isolated from the roots of ''Opete''. The structures of some compounds reported to be found in ''Opete'' leaves, stem, rhizome, and roots are shown in the Figure below.

Pharmacological Activities of ''Opete''

•Pancreatic Protection, Antidiabetic Property, and Hypolipidemic Effect.

Diabetes mellitus is a chronic hormonal and metabolic disorder that is characterized by a persistent increase in blood glucose levels. ''Opete'' leaf and stem extracts are able to reverse histopathological damage of pancreatic β-cells in alloxan-induced diabetes mellitus.

Several studies attest to the fact that ''Opete'' acts as an antidiabetic agent via biochemical mechanisms including restitution of pancreatic β-cell function, amelioration of insulin resistance by sensitizing receptors, inhibition of liver gluconeogenesis, enhanced glucose absorption, and inhibition of G-6-Pase, α-amylase, and α-glucosidase activities. The stem and roots are reported to contain several bioactive compounds with diosgenin and aferosides A, B, and C named as the most likely compounds responsible for the antidiabetic properties of ''Opete''.

Diosgenin ameliorates insulin resistance by increasing glucose usage and intracellular glycogen synthesis.

The concentration of lipids such as triacylglycerol (TAG), total cholesterol (TC), very low-density lipoprotein (VLDL), and low-density lipoprotein (LDL) is highly regulated to avoid certain clinical conditions such as steatosis. This condition occurs when there is abnormal retention of lipids within a cell as a result of impairment in the normal synthesis and degradation of fats. Accumulation of these fats is often associated with disorders and diseases such as diabetes mellitus, obesity, and hepatitis C. When the body is unable to control fat regulation, there is the need for extracellular regulation, which includes the use of a natural product such as ''Opete''.

On the administration of ''Opete'' extract, there was a significant improvement in the lipid profile as indicated by lowering serum TAG, TC, and LDL levels to near normal [39]. Results from these studies indicate that ''Opete'' plant leaves could be explored in the management of diabetes mellitus and its complications such as dyslipidemia.

•Protective Ability against Kidney, Liver, Heart, Testicle, and Mitochondrial Damage.

When the body is exposed to toxins or drugs, it becomes imperative for organs such as the liver and kidney to detoxify such substances. The liver is usually involved in the biotransformation of toxins to less toxic compounds through phase I and II reactions to enhance their elimination by kidneys. In a disease state of the kidney, its detoxifying capacity is impaired. Toxicity of the kidney results in elevated concentrations of sodium and potassium in the serum and enlarged kidney.

The role of the liver is so critical that there is a need to protect it from damage. One of the causes of damage to the liver is oxidative stress and its close proximity to the intestines makes it more prone to a wide spectrum of food-borne toxins. The damaging effect of free radicals to the liver is increased during exposure to xenobiotics such as drugs. A defect in the liver leads to the leakage of certain liver enzymes into the blood. These enzymes include alanine aminotransferase, alkaline phosphatase, and aspartate aminotransferase. These enzymes therefore serve as biomarkers for the detection of liver damage in serum.

''Opete'' contains certain bioactive compounds that chelate calcium ions to help stabilize the membrane, thus inhibiting mitochondrial MPT. This indicates that ''Opete'' leaves could help cure and manage oxidative stress and neurodegenerative diseases such as Alzheimer’s disease.

•Analgesic and Anti-Inflammatory Effects

Analgesic is used as a painkiller without blocking any nerve impulse conduction, altering sensory perception nor affecting consciousness.

Recent studies further identified compounds, which include phytol, coumaran, hexadecanoic acid, octadecatrienoic acid, and cis-vaccenic acid as some key compounds responsible for the anti-inflammatory effects of the plant.

''Opete'' contains phytochemical substances including alkaloids, flavonoids, tannins, phenols, glycosides, and terpenoids, some of which have been implicated in antinociception.

•Inflammation can be defined as the body’s attempt at self-protection with the aim of removing harmful stimuli including damaged cells, irritants, or pathogens and begins the healing process. It is one of the first lines of defense the body adapts to localize and destroy invaded microorganisms or neutralize chemical toxins.

This depicts the fact that ''Opete'' leaf possesses immunomodulation activity against proinflammatory mediators. The hexane fraction of the plant is reported to have high anti denaturation effects on protein, stabilization of HRBS membrane, and antiproteinase with IC50 values of 33.36 μg/mL, 33 μg/mL, and 212.77 μg/mL, .

Reports seen in the analgesic and anti-inflammatory experiments seem to provide some evidence to support the traditional use of ''Opete'' extract for the relief of pain and inflammation in the management of arthritis. Implicitly, the plant could be considered as a drug candidate in pain and inflammatory drug development.

•CNS Depressant Activity.

The use of central nervous depressants such as phenobarbital decreases the transmission of impulse between the receptor organs and the effector organs mediated by the brain. In mechanism, the phenobarbitone inhibits GABA receptors and further inhibits chloride current through the receptor channels. That is, the glutamate-induced depolarization is inhibited by the phenobarbitone, thereby causing hypnosis.

•Antiparasitic and Antibacterial Property.

Aedes aegypti is a mosquito, which is known to spread yellow fever, dengue fever, chikungunya, and zika fever. These mosquitoes are commonly noticed in the tropical and subtropical region including Africa. The conventional agents against these mosquitoes are limited and pose adverse effects on both the individual and the environment. One of the routes to reduce the spread of these diseases by these mosquitoes is through drug agents, which have larvicidal activity against larvae of Aedes aegypti. The eggs of A. aegypti were suspended in water and fed with rabbit pellets until the larvae grew to the 4th instar stage. The leaf and stem extract at a concentration range of 0–5 mg/mL was used to assess the larvicidal activity. It was found that the LC50 values (in both leaf and stem extract) were relatively higher in those exposed to the extract for 28 hours than for 48 hours. The same trend was observed for the reported LC90. This indicates that the long exposure (administration of ''Opete'' extract) augments its larvicidal activity. The LC50 was found to be 8.24 ± 1.15 and 9.00 ± 0.2 at 24 hr and 4.06 ± 0.27 and 3.79 ± 0.05 at 48 hr, respectively.

The antibacterial activity of the ethanol extract of ''Opete'' has also been reported. The data available indicate that extract possesses moderate inhibitory activity against Staphylococcus aureus. leaf extract showed lower inhibition of the Gram-negative organisms (Pseudomonas aeruginosa and Escherichia coli) compared to the reference drug. The data reported in the literature hints of a need for more research on antibacterial properties of ''Opete'' with regard to other pathogenic bacteria.

Toxicological Effects of ''Opete''.

Exogenous substances such as xenobiotics usually pose toxicity to some vital organs in the body even though these organs try to get rid of the toxins. Many drugs are taken to cure and manage diseases and disorders and are seen to be effective at its purpose, but one cannot overlook its side effects.

In a subchronic toxicity study, there was a significant reduction of hemoglobin (HB) and total red blood cell (RBC) count, indicating that long-term use of aqueous leaf extract of ''Opete'' could result in anemia. Further studies need to be done to investigate the bioactive compounds in the plant responsible for the decrease in Hb and total RBC count as well as the type of anemia caused. It was also revealed that aqueous leaf extract of the plant triggered an increase in weight of the liver and other clinical chemistry parameters such as ALT, ALP, AST, and TB but not the kidney. The histological study also showed architectural and vacuolar changes in the hepatic cells, which was concentration-dependent. This was more prominent at a dose of 1125 mg/kg. There was no observed detrimental histological effect/defect on the kidney.

Conclusion

The pharmacological property of the leaf, stem, and rhizome of ''Opete'' compiled in this piece provides some scientific evidence for its use as an antihyperglycemic, hepatoprotective, cardioprotection, nephroprotective, analgesic, anti-inflammatory and antioxidant, and other pharmacological activities. All these findings support its use in the management of various diseases, thus demonstrating its wide-ranging clinical relevance. The compilation of information on ''Opete'' plant parts used for the management of many diseases can serve to promote a more rational medicinal use of the plant. It can also offer evidence-based data for clinical development of the medicinal plant. The presence of high proportions of micro- and macronutrients such as carbohydrates and proteins makes it possible for the plant to be considered a nutraceutical. This and the evidence of abundance of phytochemicals are suggestive of the reasons why local folks use this plant. However, pregnant women must be cautioned about the use of the plant since it has the tendency to induce abortion in the 3rd trimester. The current search has exposed the inadequacy of information on the pharmacokinetics and pharmacodynamics of ''Opete'' extracts and its isolated compounds; thus, a call for more research in that regard is needed.

DISCLAIMER

This post is for enlightenment and should not be used as a replacement for professional medical diagnosis and treatments. Remember to always consult your healthcare provider before making any health-related decisions for any medical condition.

Obasi Kelechi.