It has been stated by WHO that the most critical assessment of herbal medicine is safety evaluation. Although Farnsworth indicated that phyto-toxicity is very low, nonetheless, from scientific, professional and moral viewpoints toxicological assessment must be conducted on all herbal medicines intended for either veterinary or human use. Most herbal medicines are obtained from genuine practitioners have been used in ethno-medicine for many centuries. Thus, it can be assumed that only the safe herbal medicines have withstood the test of time. Nonetheless, standard toxicological protocols should be employed for acute, sub-chronic and chronic toxicity tests. Such data is mandatory for the registration of the product with National Health Authorities. It would also enhance the confidence of Health Professionals in the use of herbal medicines (WHO, 1991, 1992).
The basic premise is that toxic effect caused by a drug is similar in man and other animals (Range et al., 1995). If a chemical (or drug material) produces injury to a tissue, the capacity of the tissue to regenerate or recover will largely determine the reversibility of the effect (Curtis, 2001). Toxic effects can range from negligible to so severe as to preclude further development of the compound (Range et al., 1995). However, the target organ of toxicity is not necessarily the site of accumulation of the chemical (Curtis, 2001).
Several studies have shown the relative effect of plant extracts, alcohol, water or acid extracts etc. and therapeutic efficacy. In some of these studies, there has been varying changes in the composition of the animal tissues due to the effect of such extract on it. Some prove to be active on them, while others prove inactive hence making no marked difference.
The Plant Stachytarpheta jamaicensis (Verbanaceae), commonly called
Bastard vervain or Brazilian tea, is an erect or straggling perennial herb about
60-90 cm high. The leaves often covered with flowers, gives it a bluish green
color. The leaves are opposite and whorled; ovate or oblong, elliptic about
4-11 cm long and 2-4.5 cm wide, rounded to broadly acute at the apex, widely
toothed at the margins, smooth on both surfaces with short petioles. In this
study, the effect of powdered leaves of Starchytarpheta jamaicensis
on serum biochemistry and echogenic pattern on some specific organs was investigated
for therapeutic assessment.
MATERIALS AND METHODS
The leaves of Stachytarpheta jamaicensis were collected around the premises of the University of Benin, Benin City, Edo State, Nigeria in October, 2004 and was identified by Mr. Henry Akinnibosun using a Handbook on West African Weeds (Akobundu and Agyukwa, 1998) and authenticated by Prof. MacDonald Idu, both of Botany Department, University of Benin, Benin City, Nigeria. The herbarium specimen (No. B103) has been deposited at Botany Department, University of Benin, Benin City. Nigeria. The leaves were washed and air dried, cleaned off debris and kept in the oven to dry at 40°C for 18 h. The leaves were plucked off the dried branches and pounded in a mortar to obtain the powdered form. Three kilogram of the powdered leaves was weighed and stored in a moisture free airtight container for use.
Twenty Wister rats were randomly sampled and kept one per cage. They were allowed to acclimatize for two weeks, during which they were fed with Pfizer feed mash and water ad libitum before commencement of the experiment. After acclimatization, the rats were divided into three treatment groups and one control group of five rats each. The duration of experiment was six weeks, conducted from October 16 to November 30, 2004. The control group received only feed mash throughout the period. The treatment groups were fed with mash only for the first three weeks and thereafter received mash/leaf powder mixture in the following ratio weight/weight: 75/25, 50/50 and 25/75, respectively.
Methods for serum biochemical assay of Alkaline phosphatase (ALP), serum glutamatate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT), total and conjugated bilirubin were adopted following methods outlined by Idu et al. (2002) and Ataman et al. (2002). Using the Ultrasound machine sonographic assessment of vital organs-Liver, kidney and heart was done for anesthetized rats in the various groups to detect if they are any significant change.
RESULTS AND DISCUSSION
Table 1 shows the results of radiological observations of
the scanned rats. The various results of the ultra sound scan is summarized
in Fig. 1-3.
|| Radiological observations of scanned rats
||C1 and T2 showing sonographic records
of kidney sizes of treated rats with no significant difference in their
measurements between the control and treated group 2 (T2) rats
||T1, T2, T3 and C1
showing sonographic records of the Liver sizes from the various treatment
groups illustrating no significant difference in the two-dimensional measurement
of the Liver compared with control
||C1 and T2 showing the sonographic record
of the heart sizes between the treated and the control group rats with no
The only notable remark from the results of the ultrasound assessment is that
the heart rate seems to increase, with increased dose of the extract. The kidney
size of T1 rats appeared larger than the control, but this cannot
be correlated with the low concentration of the extract.
From ultra sound scan of the rats, there was generally no significant change
in the liver and kidney when compared with the control. In T2, the
liver appeared slightly shrunken with increase in the echogenic pattern. The
heartbeat of the treatment groups was normal with rats in T3 having
a higher value than that of the control group.
|| Effect of S. jamaicensis on biochemistry of rat serum
|Mean±SE (Standard Error)
The rats in T3 showed mild tachycardia with heart rate of 182 beats
per minutes compared with the control with 150 beats per minute. The increase
in heartbeat might probably be due to the high concentration of the powdered
leaves of S. jamaicensis in T3. The difference in heartbeat
rate between the treatment groups and the control group is similar to studies
carried out by Idu et al. (2002). The liver of all the groups were normal,
al1 within the same range with no significant difference between them (p>0.05).
The different serum enzymes assayed (Table 2), revealed Alkaline Phosphatase in T1, T2 and T3 to have high values when compared to the control. Increase in Alkaline phosphatase has been reported to be an indication of bone or liver disease (Price and Stevens, 1993). The indication of the increase in the values of Alkaline Phosphatase in T3 may be due to the dysfunction of the liver as seen in this treatment group. David (1978) reported that ALP increase might be an indication of liver disease.
Though there was increase in ALP of T2, this may be due to possible change in the enzyme metabolism, though the liver of T2 was not affected. The serum glutamate oxaloacetate transaminase values was noticed to be high in T1, T2 and T3 when compared to that of the control. This may be an indication of the involvement of the ducts and the hepatocytes. Earlier studies (Price and Stevens, 1993) had revealed the transaminases (SGOT and SGPT) to be useful in liver disease diagnosis.
The Bilirubin level of all the rats were within normal range though there was slightly marked variation. High value of bilirubin is an indication of red blood cell destruction which may consequently result in jaundice (Table 2). Bilirubin level reduction indicates improvement in health conditions (Beck et al., 1994).
It can be suggested from the results that Starchytarpheta jamaicensis may be relatively safe in the treatment of certain disease conditions.
Further research would be needed to isolate the active ingredients and such possible toxicants that may be present in this plant.