Recent studies have demonstrated how extracts of avocado, bamboo, Moringa oleifera, lime, lemon, and alligator pepper provide ‘cure’ for viral infections including herpes simplex, dengue fever, hepatitis, polio, yellow fever, measles, chickenpox and Human Immuno-deficiency Virus (HIV) type one (HIV-1).
Until now, several local herbs have been shown to have antibacterial and antiviral properties. Although there are no cures for viral infections, researchers suggest many natural remedies have been shown to provide relief and prevent complications.
The plants include: Bambusa vulgaris (bamboo) and Aframomum melegueta (alligator pepper), Azadirachta indica (neem), Allium cepa (onion), Allium sativum (garlic), rhizomes of Curcuma longa (turmeric), and Aloe vera, Vernonia amygdalina (bitter leaf), Garcinia kola (bitter kola), Citrus medica (lemon), Cymbopogon citratus (lemon grass), Moringa oleifera, Phyllanthus amarus, avocado (Persea americana), and Gardonema mushroom.
Researchers have also identified asthma herb (Euphorbia hirta), pawpaw (Carica papaya), bitter melon (Momordica charantia) and guava (Psidium guajava) extracts as potential ‘cures’ for viral infections.
The latest study published in January 2019 in the journal Scientific Reports showed avocado (Persea americana) fruit extract inhibits dengue virus replication via upregulation of NF-κB–dependent induction of antiviral interferon responses.
Until now, the dengue virus (DENV) caused millions of infections around the world yearly. Co-infection with different serotypes of DENV is associated with dengue haemorrhagic shock syndrome, leading to an estimate of 50 percent death rate. No approved therapies are currently available for the treatment of DENV infection. Hence, novel anti-DENV agents are urgently needed for medical therapy.
However, the researchers have demonstrated that a natural product (2 R,4 R)-1,2,4-trihydroxyheptadec-16-yne (THHY), extracted from the avocado fruit, can inhibit DENV-2 replication in a concentration-dependent manner and efficiently suppresses replication of all DENV serotypes (1–4). “We further reveal that the NF-κB-mediated interferon antiviral response contributes to the inhibitory effect of THHY on DENV replication. Using a DENV-infected ICR suckling mouse model, we found that THHY treatment caused an increased survival rate among mice infected with DENV. Collectively, these findings support THHY as a potential agent to control DENV infection,” they wrote.
Persea americana belongs to the family Lauraceae, which is known as avocado and widely grows in tropical and subtropical regions. The fruit, stem, and leaf of avocado are widely used in ethnomedicine. Particularly, the avocado fruit contains lots of nutrients such as vitamin E, vitamin B, potassium and monosaturated fatty acids, which have been reported to exhibit several bioactive properties such as antibacterial, antiviral, antioxidant, anti-atherosclerotic, hepatoprotective, and other activities. The bioactive components of avocado contain monoterpenoids, sesquiterpenoids, triterpenoids, flavonoids, alkaloids, steroids, carotenoids and long-chain fatty alcohol derivatives.
In the present study, the researchers performed a drug screen of several compounds isolated from the unripe fruit of avocado, including oleic acid (OA), (2 R,4 R)-1,2,4-trihydroxyheptadec-16-ene (THHE), (2 R,4 R)-1,2,4-trihydroxyheptadec-16-yne (THHY), avocadenol A, avocadenol C, and avocadoin, and found that THHY exhibited anti-DENV activity without cytotoxicity. “We next characterised that THHY inhibits DENV infection through induction of NF-κB-mediated antiviral IFN responses. Finally, we assessed the potential of THHY as a dietary supplement used for the prevention of lethal DENV replication using a DENV-infected ICR suckling mouse model,” they wrote.
Also, researchers have demonstrated that avocado is a potential plant extract for the treatment of herpes simplex virus infections either alone or associated with acyclovir.
The study published in the journal Phytomedicine is titled, “In vitro activity of extracts of Persea americana leaves on acyclovir-resistant and phosphonoacetic resistant Herpes simplex virus.”
The researchers explained: “The lyophilized aqueous crude extract (LACE) from leaves of Persea americana species showed a strong inhibitory effect on acyclovir (ACGr4 and dlsp TK mutants) and PAA-resistant (PAAr5 mutant) herpes simplex virus. After exhaustive washing of LACE using methanol, the soluble fraction was chromatographed on a reverse-phase column giving 11 fractions that were revealed by thin-layer chromatography. Analysis of the antiviral effect of the fractions showed the extract-contained compounds that were able to inhibit extracellular virus and the replication of resistant acyclovir HSV. The virucidal effect was concentrated from fraction 4 up to 8. Fraction 7 mainly contains the flavonoid isoquercitrin, and fraction 8 the flavonoid quercitrin. The flavonoid afzelin that is the major substance present in the fraction 9 showed virustatic effect with no virucidal effect.”
Another study published in the journal Antiviral Chemistry & Chemotherapy demonstrated the in-vitro virucidal and virustatic anti HIV-1 effects of extracts from avocado leaves.
The researchers are from Departamento de Virologia, Universidade Federal do Rio de Janeiro, Brazil; and Academic Virology and Retroscreen Limited, The London Hospital Medical College, University of London, UK.
They noted: “Aqueous (PA1) and methanolic extracts (PA2a-d; PA3) from the tropical tree Persea americana, were evaluated for their cellular toxicity and anti-HIV-1 activity both in virustatic and virucidal assays. With the exception of PA3 and PA2d, all extracts showed anti-HIV-1 activity at concentrations, which were not toxic for the H9 indicator cells.
“From the methanol insoluble extract (PA2) four different fractions (PA2a-d) were obtained using reverse-phase column chromatography, and two of the fractions (b and c) showed detectable virucidal effect. One fraction (PA2a) showed virustatic effects inhibiting HIV syncytium formation and viral p24 antigen formation at concentrations, which were not toxic for the indicator cells.
“The results demonstrate for the first time that extracts from P. americana leaves have moderate anti-HIV-1 activity in vitro.”A number of specific antiviral drugs with virustatic activity have been approved for clinical use in patients with Acquired Immunodeficiency Syndrome (AIDS), but the emergence of drug-resistant viruses has imposed limitations on the efficacy of these compounds leading to a renewed interest in virucidal agents.
Virucidal drugs interact directly with viruses and cause virion destruction. In contrast, virustatic drugs normally act intracellularly and inhibit a vital virus-enzyme or virus-coded function. Virucidal compounds against HIV are being investigated widely for use as topically applied virus destructive drugs in the vagina and rectum to inactivate virus before adsorption to susceptible cells.
The Plant Kingdom is an important source of molecules, which have the ability to inhibit the replication of a range of viruses. As part of a project searching for novel virus inhibitors, and particularly those with virucidal activity, which can be isolated, an extract obtained from P. americana leaves was studied. Persea americana leaves have been used in traditional medicine as a diuretic and for removing kidney stones. For the first time in-vitro anti-HIV-1 activity of the extract of leaves of this plant is described.
Yet another study published in the journal Pharmacologia found that bamboo (Bambusa vulgaris), Moringa oleifera and seed of lime (Citrus paridisi) were effective against measles virus and herpes simplex virus. The results obtained showed that n-hexane extracts of B. vulgaris and M. oleifera inhibited measles virus at the concentrations of 0.125 and 0.016 μg μL–1, respectively. Similarly, while aqueous extract of M. oleifera inhibited measles at 0.125 and 0.063 μg μL–1, aqueous extract of C. paridisi inhibited the virus at 0.031 μg μL–1. While none of the extracts of M. oleifera and C. paridisi produced any inhibitory activity against HSV-1, n-hexane extract of B. vulgaris was able to inhibit the virus at 0.125 μg μL–1.
Results of the mechanism of action of the extracts on the replicative cycle of the viruses revealed both adsorption/entry and post infection inhibitors of the viruses. Phytochemical analysis of the extracts revealed the presence of terpenes, alkaloids, flavonoid, tannins, combined and free anthraquinones, cardiac glycosides and saponins.
The researchers concluded: “The extracts of the three plants, Bambusa vulgaris, Citrus paridisi and Moringa oleifera used in this study have shown significant antiviral activities against measles virus which is an enveloped RNA virus as well as HSV-1 which is also enveloped but belongs to the DNA class of viruses. This suggests that the extracts could be said to have a broad spectrum of activity against selected RNA and DNA viruses and so could serve as potential anti-measles virus and anti-HSV-1 agents. Further studies aimed at isolating and characterizing the active antiviral compounds from these three plants is therefore recommended. It is pertinent to suggest that, for the purpose of affordability in developing countries, to formulate these whole plants or their active constituents into drugs that could be used as antiviral agents.”
Also, researchers from Ekiti State University, Ado Ekiti, and Kings University, Osun State have validated antiviral properties of two Nigerian plants- alligator pepper (grains of paradise) and bamboo.
The study was published in African Journal of Plant Science. According to the researchers, ethanolic extracts were prepared from Bambusa vulgaris and Aframomum melegueta. They were analysed for antiviral activities against three human viruses namely: measles, yellow fever and polioviruses by standard laboratory tests.
The researchers wrote: “Both extracts showed antiviral activities against one or two viruses. B. vulgaris resulted in inhibition only on measles virus at Minimum Inhibition Concentration (MIC) of 62.5 µg/ml while A. melegueta inhibited measles and yellow fever viruses at MICs of 125 and 250 µg/ml respectively. Polio virus type 1 was not susceptible to any of these extracts.”
Also, a decoction from the leaves of Neem tops the list of herbal remedies for Chicken pox and other skin diseases. Botanically called Azadirachta indica, Neem also popularly known as Dogonyaro in Nigeria belongs to the Meliceae family. The common tree tops the list of plants that have been scientifically verified to effectively treat chicken pox.
Until now, Neem extracts have been shown to possess anti-bacterial, anti-fungal, potent antiviral and anti-cancerous properties. Neem has been found to be an effective antiseptic for the treatment of viral infection including small pox. Indian researchers in a study published in Journal of Biological Sciences noted that Neem extracts have been shown to possess potent antiviral properties against different viruses including herpes simplex virus type-1 infection and chicken pox. According to a new study published in the International Journal of Clinical Nutrition (IJCN), there are certain compounds in Neem that demonstrate a unique ability to surround viruses, which prevents them from causing infection.
Also, scientists have demonstrated how natural remedies provide cheaper route to prevention and treatment of hepatitis B and C, and indeed liver damage in the country. Top on the list are: bitter leaf, Phyllanthus amarus, avocado, turmeric, garlic, and bitter kola. Phyllanthus amarus belongs to the plant family Euphorbiaceae. To the Efik it is called oyomokeso amanke edem; geeron-tsuntsaayee (birds millet) in Hausa; Ibo (Asaba) buchi oro, Ibo (Umuahia) ngwu; iyeke in Urhobo; and ehin olobe or eyin olobe in Yoruba.
Turmeric is a spice that comes from the root of Curcuma longa, a member of the ginger family, Zingaberaceae. It is called atale pupa in Yoruba; gangamau in Hausa; nwandumo in Ebonyi; ohu boboch in Enugu (Nkanu East); gigir in Tiv; magina in Kaduna; turi in Niger State; onjonigho in Cross River (Meo tribe).
Also, Nigerian researchers have found that water-based extract of bitter leaf (Vernonia amygdalina) could be used as adjuvant in the management of people living with HIV/AIDS. A recent study on the immunological effect of Vernonia amygdalina leaf extract and immunace® (nutritional supplement) on HIV-infected patients taking highly active antiretroviral therapy (HAART) found that it could serve as a nutritional supplement in an HIV-infected or immuno-compromised condition such as cancer or diabetes patients.
The study published in Asian Pacific Journal of Tropical Biomedicine concluded: “The aqueous extract of Vernonia amygdalina (bitter leaf) and immunace or both have the immunological effect on HIV-infected patients. Therefore, we suggest that the V. amygdalina extract or immunace or both could be used as adjuvant in the management of HIV/AIDS clients.”
Also, the World Health Organisation (WHO) and the Food and Agricultural Organisation (FAO) have endorsed some herbs and spices that have shown promise in treating the opportunistic infections associated with the viral infections without side effects.
They have verified the efficacy of garlic, ginger, cloves, thyme, cayenne, basil, Aloe vera, Neem, lemon, lemon grass in the treatment of opportunistic infections associated with the HIV/AIDS. A Neem-based product has received United States (U.S.) patent, “US 20070275085 A1”, as compositions and methods for the cure of HIV/AIDS.
Also, Nigerian researchers led by a professor of pharmacognosy at the University of Nigeria Nsukka (UNN), Chief Executive Officer of Bioresources Development Group (BDG), and former Chairman of the Independent Election Commission (INEC), Prof. Maurice Iwu, have validated local foods such as bitter kola, coconut oil, bitter leaf, Moringa oleifera, Sour sop, the mushroom Garnoderma lucidum, among others as immune boosters and for the treatment of HIV.
Also, another group of researchers have in clinical trials demonstrated how polyherbal preparations made predominantly with bitter leaf provide the cure for the chronic form of hepatitis B and C co-infection, cancer, type 2 diabetes, tuberculosis and HIV. The researchers from Halamin Herbal centre, 10 George Innih Crescent, Apo District, Abuja and Department of Histopathology and Cytology, Jos University Teaching Hospital (JUTH) Jos found that polyherbal preparations with bitter leaf as the active ingredient strengthen the immune system through many cytokines and chemokines regulations.
Other constituents of polyherbal preparations include Sesamum indicatum (sesame), bitter leaf, Aloe barbadensis (popularly known as aloe vera), Saccharum officinarum (sugar cane), garlic and Amaranthus caudatus (green amaranth, inine in Ibo, tete abalaye in Yoruba).
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