ETHNOBOTANY, PHYTOCHEMISTRY AND PHARMACOLOGY OF OCHNA SCHWEINFURTHIANA: A REVIEW
Yusuf AJ1*, Abdullahi MI1, Muhammad AA2
1Department of Pharmaceutical and Medicinal Chemistry, Usmanu Danfodiyo University, Sokoto, Nigeria.
2Department of Pharmaceutical and Medicinal Chemistry, Ahmadu Bello University, Zaria, Nigeria.
Ochna schweinfurthiana (Os, Family: Ochnaceae) is a small evergreen tree used in ethnomedicine to treat different ailments; it is also used in agri-horticulture and as ornaments, dyes among others. It is a rich source of complex dimers of flavonoids and used for treatment of pain, inflammation, and arthritis. Chemical investigations carried out on the different parts of the plant have been confined to phenolic compounds majorly, bioflavonoids, glycosides, steroids and terpenes. The plant, O. schweinfurthiana have shown a wide spectrum of biological and pharmacological properties which include antimicrobial, cytotoxic/antiproliferative, genotoxicity, antinociceptive, anti-inflammatory, antioxidant and antiplasmodial. This review comprehensively summarizes the potential effects of the plant O. schweinfurthiana, chemically and pharmacologically. However, more researches in the aspect of phytochemical and biological studies are needed to exhaustively isolate bioactive compounds and evaluate their effects on other ailments as claimed by the traditional healers.
Keywords: Anti-microbial, antimalarial, flavonoids, Ochna schweinfurthiana, Ochnaceae, phenolics, pharmacological.
Ochna schweinfurthiana (Os) belonging to the Ochnaceae family is a small tree that was named after a German botanical collector and taxonomist Dr. Georg August Schweinfurth; it is a small tree that measures up to 4 m tall; the plant is commonly known as the brick-red Ochna in English, Jan-taru in Hausa language, Hiéké in Yoruba and Sa’aboule in Foufouldé1, 2. The plant has found use as medicine, for agricultural, social and religious purposes1. This review centered on the ethnobotanical, phytochemical and pharmacological properties of O. schweinfurthiana.
Ochna originated from a Greek word “Ochne” which means wild pear and it was named by Linnaeus in 1951 as Ochna because of the resemblance of their leaves with those of wild pear3. It is an old world genus of mainly trees, shrubs and shrublets which comprises of about 85 species4 and it is widely distributed in tropical Asia, Africa and America5 of which eleven (11) species are found in India6. Ochna’s are usually called Mickey Mouse plants, because of the appearance of the black druplets fruits. The Ochnaceae family is mainly composed of trees and shrubs with an estimated 33 genera and 550 species7 well distributed around the world especially in tropical Africa, Australia, Madagascar Asia, the Mascarene Island and America8. They are notably known for their unusual shiny leaves, with parallel veins that are closely spaced, alongside toothed margins with conspicuous stipules1,7. The largest genera are Ouratea, Ochna, Campylospermum, Sauvagesia and Quiinawith (200, 85, 65, 39 and 34 species) respectively (Table 1).
Figure 1: Leaf and fruits of O. schweinfurthiana
The fruits of O. schweinfurthiana are 1-5 oval appear between August and January, attached at the base are 2-4 black berries when ripe; they are enlarged, borne on brick-red persistent sepals turning cherry to brick-red. The bark is dark grey, thick, and deeply fissured into a grid-like pattern10,11.
Figure 2: Whole plant of O. schweinfurthiana
Kingdom: Plantae Order: Malpighiales
Family: Ochnaceae Genus: Ochna
Species: O. schweinfurthiana9
English: Brick-red Ochna, Hausa: Jan-taru
Yoruba: Hiéké, Fulfulde: Sa’aboule
Habitat, Distribution and Ecology
The plant grows in open deciduous woodland in tropical regions in Africa from Guinea to southern and northern Nigeria and across central Africa to Sudan, Uganda, Zimbabwe, Mozambique, Tanzania and Angola. It has medium water requirement when young and growths fast, flowers from September to November. It required low maintenance and attracts insects and birds4, 10.
Several preparations (powdered and decoctions) of the leaves and/or root of the O. schweinfurthiana have found general use as antimicrobial (wound dressing, eye infection), analgesic, anti-inflammatory and anthelmintic agents1. The leaf is also used as an antiseptic, stimulant, febrifuge, laxative, enemaetc1. In Northern Cameroon, O. schweinfurthiana is used to treat different diseases such as rubella, burns, stomachache and multiple sclerosis12; the root of the plant is also used in the treatment of stomach and eye aches as well as headache, while the leaves are used for toothaches treatment2.
The pulverized bark is used to treat malaria, febrifuges and as anthelminthic, while the decocted root leaves and/or bark is used in wound dressing12. In Northern Nigeria, the O. schweinfurthiana is used to treat typhoid fever, measles and fungal skin infections12. The macerated roots of O. schweinfurthiana has been reportedly used to induce/speed the delivery process and for miscarriage13.
The plant is used in agri-horticulture; the bark and flowers O. schweinfurthiana are cultivated for ornaments, dyes, stains, inks, tattoos and mordent among others. The wood is used for farming, forestry, hunting and fishing apparatus. The leaf has social, religious, superstitious and magic values among others1.
Abdullahi et al.12 reported the presence of flavonoids, steroids/terpenes and saponins in the acetone leaf extract of O. schweinfurthiana and the methanol leaf extract indicated the presence of flavonoids and saponins. However, flavonoids, saponins, glycosides, tannins and steroids/terpenes were reported on the methanol stem extract of O. schweinfurthiana14. A study conducted by Ibrahim et al., reported the presence of carbohydrates, steroids/triterpenes, glycosides, saponins, tannins and flavonoids in the methanol leaf extract of O. schweinfurthiana15.
Chemical constituents isolated from O. schweinfurthiana fall under the following class of secondary metabolites phenolics-flavonoids, and glycosides. O. schweinfurthiana have been reported to contain phenolic derivatives (such as flavonoids, bioflavonoids) which appear as free or in polymerized forms. Isolation and characterization of quercetin-3-O-β-D-glucopyronosyl-(1→6)-α-rhamnoside (quercetin rutinoside) from the n-butanol soluble fraction of methanolic leaf extract of O. schweinfurthiana was reported16. A novel biflavonoid compound, tri-methoxy lophirone was isolated from the chloroform soluble fraction of the methanol root extract of O. schweinfurthiana17.
Ndongo et al.18 reported the isolation of seven flavonoids, hemerocallone, 6,7-dimethoxy-3',4'-dimeth -oxyisoflavone, amentoflavone, agathisflavone, cupressuflavone, robustaflavone, and epicatechin, and three other chemical constituents, lithospermoside, β-D-fructofuranosyl-α-D-glucopyranoside and 3β-O-D-glucopyranosyl-β-stigmasterol from the ethyl acetate the stem bark extract of O. schweinfurthiana.
The roots of O. schweinfurthiana were reported to contain three new compounds viz; 4'''-methoxylophirone A, 4, 4', 4'''–trimethoxylophirone A. In addition, six known compounds were also isolated and characterized, including calodenone, calodenine B, lophirone A, gerontoisoflavone A, and 3β-O-D-glucopyranosyl-β-sitosterol2. Six known compounds were isolated from the powdered bark of O. schweinfurthiana and they include, hemerocallone, 6, 7-dimethoxy-3'-4'-dimethoxyisofla -vone, lithosperm -oside, amentoflavone, agathisflavone and 𝛽-D-fructofuranosyl-𝛼-D-glucopyranoside19.
BIOLOGICAL AND PHARMACOLOGICAL ACTIVITIES
The acetone and methanol leaf extracts of O. schweinfurthiana had a remarkable antibacterial effect against S. aureus, S. typhi, K. pneumoniae and P. aeruginosa with a zone of inhibition ranging from 15 – 21 mm; the extracts had an MIC and MBC values of 10–20 mg/mL and 20–40 mg/mL, respectively12. Quercetin-3-O-β-D-glucopy-ranosyl(1à6)-α-rhamnosi -de from the n-butanol soluble fraction of the methanolic leaf extract of O. schweinfurthiana showed an in vitro inhibitory effect against some bacterial isolates such as S. aureus, MRSA, S. pyogenes, E. coli, K. pneumoniae, S. typhi and P. aeruginosa with an MIC and MBC range between 2.5–5.0 and 5–20 µg/mL, but there was no effect against B. subtilis, C. ulcerans and C. albicans16. Earlier studies showed that tri-methoxy lophirone A from the chloroform soluble fraction of the methanol root extract of O. schweinfurthiana inhibited the growth of some selected human pathogens including S. aureus, S. pyogenes, P. aeruginosa, K. pneumoniae and S. typhi with an MIC and MFC values of 5 µg/mL and 20 µg/mL, respectively17. Crude methanol stem extract of O. schweinfurthiana and its chloroform (CF), ethylacetate (EF) and n-butanol (BF) fractions inhibited the growth of MRSA, S. aureus, S. pyogenes, S. typhi, S. dysenteriae, K. pneumoniae, N. gonnorhea, P. aeruginosa, C. albicans, C. tropicalis; the mean zone of inhibition of extract and fractions ranges from 20–29 mm; moreover, chloroform fraction showed greater antimicrobial activity with an MIC value of 1.25 mg/mL against all the test organisms except P. aeruginosa14.
Cytotoxic and Antiproliferative effect
The methanol and ethylacetate stem bark extracts of O. schweinfurthiana demonstrated cytotoxicity against HeLa cells; amentoflavone and agathisflavone were also active18. Antiproliferative effect of O. schweinfurthiana extract was evaluated against Glioblastoma multiforme (GBM U-1242 MG) cell line and the extract reduced cell count by 20 % with an IC50 value 823.51 µg/mL20. The aqueous stem bark of O. schweinfurthiana did not show any cytotoxic effect on Vero monkey kidney cell line after 48 h incubation with an LC50 value 50±1 µg/mL19.
Djova et al. reported that the extracts of O. schweinfurthiana were non genotoxic in a study they carried out; as none of the plant extracts demonstrated a dose dependent increase or revertent colonies ≥ the number of negative control revertent colonies; thus, the plant O. schweinfurthiana may not contain any genotoxic substances that may lead to mutations either by substitution or by reversion in the genetic material19.
Antinoceptive and anti-inflammatory effect: The methanol leaf extract of O. schweinfurthiana significantly inhibited the writhing response induced by acetic acid in a dose dependent manner; the highest dose exhibited maximum inhibition of pain (84.3 %). In addition, the extract was also able to attenuate pain response in a similar manner though with a slower onset of action in the tail flick model15. The aqueous bark extract of O. schweinfurthiana exhibited good anti-inflammatory effect in both ferrous oxidation-Xylenol Orange (Fox) and BSA denaturation assays; the extract demonstrated good 15-lipoxygenase inhibitory effect with an IC50 value of 32.2±0.36µg/mL, however, an IC50 of 130±5.78µg/mL was recorded by the extract in the inhibition of heat induced albumin denaturation19.
Messiet et al. evaluated the antioxidant activity of some compounds including 4'''-methoxylophirone A, calodenone, calodenine B, lophirone A, gerontoisoflavone A from the roots of O. schweinfurthiana using DPPH radical scavenging and ferric reducing-antioxidant power (FRAP) assays2. In the DPPH radical scavenging assay, calodenine B showed prominent effect with SC50= 0.17±0.04 µM and EC50=4.25 µM, gerontoisoflavone A exhibited weak activity in all the models applied with SC50=19.00 µM and SC50=78.67 µg EAA/mg/dw in DPPH and FRAP respectively.
The antioxidant property of the leaf, stem bark and fraction of O. schweinfurthiana was evaluated21.
An in vivo study showed that the methanol leaf extract of O. schweinfurthiana exerted a suppressive effect against Plasmodium berghei at a lower dose (50 mg/kg); Ibrahim et al., concluded that, the extract possess blood schizonticidal activity as it was able to suppress malaria at the early stage22. Moreso, the extract reduced the level of parasitaemia with 100 % cure at the lowest dose (50 mg/kg); the percentage inhibition of parasitaemia was higher than the chemo suppression which might be due to non-selectivity of the extract to the proliferative process of the parasite22,23.
Antiplasmodial effect of the ethylacetate roots extract of O. schweinfurthiana and some compounds including 4'''-methoxylophirone A,(4E,7Z)-3,8-dicarboxy-1-(O-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl-2,9 dihy-droxyhexeicosa-4,7-diene,calodenine B, lophirone A and gerontoiso -flavone A were investigated in vitro; 4''-methoxylo -phirone A showed good antiplasmodial effect against P. falciparum strain 3D7; this effect as explained by Messi et al.,2 might be related to the presence of a methoxy group on position C-4''' which has been known to enhance lipophilicity thereby enhancing its movement into the cells24; other compounds were found to be inactive2. Cold and hot aqueous leaf extracts of O. schweinfurthiana possess inhibitory effect against P. falciparum in vitro; thus there was significant reduction of parasitaemia.
The high dose (80µg/mL) exhibited 86.42 % (cold extract) and 85.06 % (hot extract) reduction of parasitaemia. On the other hand, no significant difference was observed on the plasmodium lactate dehydrogenase (PLDH) activity of the treated extract when compared with the standard drug25.
Toxicity level of O. schweinfurthiana was assessed in mice both orally and intraperitoneally. The methanol leaf extract of the plant produced an LD50 774.6 mg/kg, i.p. while the oral LD50 value for the extract was about 5000 mg/kg; according to this study, the leaf of O. schweinfurthiana is intraperitoneal toxic and orally safe22.
Table 1: Ochnaceae subfamilies and their estimated number of species
Estimated number of species
Figure 3: Chemical constituents isolated from O. schweinfurthiana