African herbal medicines in the treatment of HIV: Hypoxis and Sutherlandia. An overview of evidence and pharmacology. (1/6)

In Africa, herbal medicines are often used as primary treatment for HIV/AIDS and for HIV-related problems. In general, traditional medicines are not well researched, and are poorly regulated. We review the evidence and safety concerns related to the use of two specific African herbals, which are currently recommended by the Ministry of Health in South Africa and member states for use in HIV: African Potato and Sutherlandia. We review the pharmacology, toxicology and pharmacokinetics of these herbal medicines. Despite the popularity of their use and the support of Ministries of Health and NGOs in some African countries, no clinical trials of efficacy exist, and low-level evidence of harm identifies the potential for drug interactions with antiretroviral drugs. Efforts should be made by mainstream health professionals to provide validated information to traditional healers and patients on the judicious use of herbal remedies. This may reduce harm through failed expectations, pharmacologic adverse events including possible drug/herb interactions and unnecessary added therapeutic costs. Efforts should also be directed at evaluating the possible benefits of natural products in HIV/AIDS treatment.  (+info)

Some in vitro and in vivo cardiovascular effects of Hypoxis hemerocallidea Fisch & CA Mey (Hypoxidaceae) corm (African potato) aqueous extract in experimental animal models. (2/6)

This study was undertaken to investigate some cardiovascular effects of Hypoxis hemerocallidea Fisch & CA Mey (Hypoxidaceae) corm (African potato) aqueous extract in experimental animal paradigms. The effect of the corm aqueous extract (APE) on myocardial contractile performance was evaluated on guinea-pig isolated atrial muscle strips in vitro; whereas the antihypertensive (hypotensive) effect of the plant extract was examined in hypertensive Dahl salt-sensitive rats in vivo. APE (25-400 mg/ml) produced concentration-dependent, significant (p < 0.05-0.001) negative inotropic and negative chronotropic effects on guinea-pig isolated electrically driven left, and spontaneously beating right atrial muscle preparations, respectively. Moreover, APE reduced or abolished, in a concentrationdependent manner, the positive inotropic and chronotropic responses of guinea-pig isolated atrial muscle strips induced by noradrenaline (NA, 1-100 microM) and calcium (Ca2+, 5-40 mM). The negative inotropic and chronotropic effects of APE on guinea-pig atrial muscle strips were not modified by exogenous administration of atropine (ATR, 7.5 x 10(-7)-2.5 - 10(-6) M) to the bath fluid. APE also significantly reduced (p < 0.05-0.001) or abolished in a concentration-dependent manner, the rhythmic, spontaneous, myogenic contractions of portal veins isolated from rats. Furthermore, APE caused dose-related transient but significant (p < 0.05-0.001) reductions in the systemic arterial blood pressure and heart rates of the hypertensive rats used. Although the exact mechanisms of the cardiodepressant and the transient hypotensive (antihypertensive) actions of APE could not be established in the present study, we exclude the involvement of the cholinergic system; since the extract's cardiovascular effects were resistant to atropine pretreatment. However, the results of this laboratory animal study indicated that APE caused bradycardia and brief hypotension in the mammalian experimental models used. These observations tend to suggest that the herb may be used as a natural supplementary remedy in some cases of cardiac dysfunctions and in essential hypertension. The findings of this experimental animal study lend pharmacological support to the folkloric, anecdotal uses of the African potato in the management and/or control of certain cardiac dysfunctions and essential hypertension in some rural communities of southern Africa.  (+info)

Development of dissolution tests for the quality control of complementary/alternate and traditional medicines: application to African potato products. (3/6)

PURPOSE: Unlike orthodox medicines, specific guidelines for dissolution testing of complementary/alternate (CAMs) and traditional medicines (TMs) have not been developed nor is dissolution testing a requirement for the quality control of such products. In this report, the dissolution of African Potato (AP) products, an African traditional medicine (ATM) which has been ingested by man for a diversity of ailments, has been investigated. A norlignan glycoside namely hypoxoside and a sterol, beta-sitosterol (BSS) are purported to be the most important phytochemicals in marketed products of AP. Dissolution testing of AP products containing labelled content of sterols and those containing only hypoxoside is proposed whereby BSS and hypoxoside are monitored as markers for the release of the contents of the abovementioned products, respectively. METHODS: The FDA dissolution guidance for industry was used to study the best dissolution condition for several formulations of AP. Buffers in the range of pH 1.2 to 7.5 were used to investigate the dissolution of AP products containing hypoxoside as a marker compound. Similarly, biorelevant dissolution media such as fasted state simulation fluid (FaSSIF) and fed state simulation fluid (FeSSIF) at different pH were used to investigate the release of BSS in AP formulations labelled to contain sterols which exhibited poor water solubility. RESULTS: Dissolution testing of AP products containing hypoxoside, conducted at pH 1.2 using USP Apparatus 1 indicated that more than 75% of hypoxoside was released within 1 hr. Dissolution testing of products containing sterols, conducted in FeSSIF at a pH of 5.0 resulted in a release of at least 75% of BSS after 1 hr for all but one of the products tested. CONCLUSIONS: Dissolution testing conditions have been developed for AP products containing two different marker compounds where one of the components, hypoxoside, is water soluble, whereas another component, BSS is poorly water soluble. This necessitated the use of different dissolution media and pHs in order to monitor the respective release of hypoxoside and BSS from AP products. The results of this study indicate the necessity and possibility of developing appropriate dissolution testing procedures for use in the quality control of CAMs/TMs.  (+info)

Uterolytic effect of Hypoxis hemerocallidea Fisch. & C.A. Mey. (Hypoxidaceae) corm [;African Potato'] aqueous extract. (4/6)

Extracts of Hypoxis hemerocallidea corm (African potato) are commonly used by some traditional health practitioners in KwaZulu-Natal Province of South Africa as natural antenatal remedy to prevent threatening or premature abortion and miscarriage, and to ensure successful confinement. In this study, we investigated the uterolytic activity of H. hemerocallidea corm aqueous extract on spontaneous, rhythmic contractions of uterine horns taken from pregnant rats and guinea-pigs, as well as on spasmogen-provoked contractions of stilboesterol-primed, oestrogen-dominated, non-pregnant rat and guinea-pig isolated uterine horns. Relatively low to high concentrations of H. hemerocallidea corm aqueous extract (APE, 25-400 mg/ml) inhibited the amplitude of the spontaneous, rhythmic contractions of, and relaxed, uterine horns isolated from pregnant rats and guinea-pigs in a concentration-related manner. Furthermore, relatively low to high concentrations of APE (25-400 mg/ml) relaxed basal tones of uterine horns taken from non-pregnant, oestrogen-dominated rats and guinea-pigs in a concentration-dependent manner. The same moderately low to high concentrations of APE (25-400 mg/ml) inhibited acetylcholine-, oxytocin-, bradykinin-, and potassium chloride (K(+))-induced contractions of oestrogen-dominated rat and guinea-pig isolated uterine horns in a concentration-related manner. Although the mechanism of uterolytic action of APE could not be established, the results of the present study lend pharmacological credence to the folkloric, ethnomedical uses of APE as a natural antenatal remedy for threatening or premature abortion, and suggest that the uterolytic action of the corm's extract is unlikely to be mediated via beta(2)-adrenoceptor stimulation, but probably mediated through a non-specific spasmolytic mechanism.  (+info)

Bronchorelaxant property of 'African potato' (Hypoxis hemerocallidea corm) aqueous extract in vitro. (5/6)

This study was undertaken to investigate the bronchorelaxant effect of Hypoxis hemerocallidea corm ('African potato') aqueous extract (APE) on spasmogen-provoked contractions of guinea-pig isolated tracheal smooth muscle preparations. APE (25-400 mg/ml) relaxed spasmogen (histamine-, carbachol- and potassium-)-induced contractions of the isolated tracheal muscle preparations in a concentration-dependent manner. The relaxant effects of APE on spasmogen-evoked contractions of the tracheal muscle preparations were not altered by bath-applied propranolol (0.1-5.0 microg/ml), which markedly inhibited or completely abolished the relaxant effects of isoprenaline (0.1-5.0 microg/ml). Although the precise mechanism of the bronchorelaxant effect of APE could not be established in the present study, it is unlikely that the herb's aqueous extract stimulates the beta(2)-adrenoceptors present on the bronchial smooth muscles to produce its bronchodilatation. The finding that APE significantly relaxed (P<0.05) histamine-, carbachol- and high potassium ion concentration (K(+), 80 mM)-induced contractions of guinea-pig isolated bronchial muscle preparations appears to suggest that the bronchospasmolytic effect of the plant's extract is probably not mediated through a specific receptor, but rather, probably mediated via a non-specific bronchospasmolytic mechanism.  (+info)

Evaluation of the antibacterial and anticancer activities of some South African medicinal plants. (6/6)

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