A number of scientific researchers have been carried out on medicinal herbs. Herbs have anti-inflammatory and antioxidant activities that may be used in the treatment of AD. Alzheimer’s patients have an acetylcholine deficiency. Anti-inflammatory herbs may reduce inflammation of the brain tissue in Alzheimer’s: German chamomile, Ginseng, licorice, turmeric, and white willow bark. Acetylcholine is a neurotransmitter that plays a key role in cognitive function and reasoning. The brains of those with mild-to-moderate Alzheimer’s disease, a progressive type of dementia, have abnormally low acetylcholine concentrations. This means that any compound that enhances the cholinergic system in the brain may be useful in treating Alzheimer’s disease and similar brain malfunctions. The herbs that inhibit Acetylcholinesterase (AchE) contain natural COX-2 inhibitors, also reported as medicinal herbs, for AD indication. Some ayurvedic herbs like Guduchi, Yashtimadhuk, Padma (Nelumbo nucifera), Vacha, Convolvulus pluricaulis, Shankhpushpi, Pancha-Tikta-Ghruta Gugguli, Amalaki, Musta Arjun, Amalaki, Ashwagandha, Galo Satva, Kutaj, and others are excellent herbs for slowing down the brain cell degeneration caused by Alzheimer’s. They enhance the brain’s ability to function, and therefore, provide stability when used consistently. Curcuma longa L. (Zingiberaceae) Curcuma longa (Turmeric, Harida) has been used as a source of Curcumin (diferuloylmethane), an orange-yellow component of turmeric or curry powder. Studies have proved that Curcumin has anti‑inflammatory and antioxidant activities, and it helps in combating Alzheimer’s disease (AD). Regular consumption of this herb helps in keeping the mind balanced. [11] The dose of curcumin can be reduced by making it to colon targeting.[12] Bacopa monniera Wettst. (Scrophulariaceae) Goswami et al., evaluate the effect of Bacopa monnieri (Brahmi), associated with the Ayurveda system of medicine, on the cognitive functions in Alzheimer’s disease patients, and conclude that it could be beneficial in these patients, but more study is needed. [13] Centella asiatica L. (Umbelliferae) Extract from the leaves of Gotu Kola (Centella asiatica) has been used as an alternative medicine for memory improvement in the Indian Ayurvedic system of medicine for a long time. Ginkgo biloba L. (Ginkgoaceae) Ginkgo Biloba is the best known herb for Alzheimer’s disease and its associated symptoms. In controlled clinical trials, using a placebo and control group, ginkgo biloba extracts showed therapeutic benefits in Alzheimer’s, similar to prescription drugs such as Donepezil or Tactrin, with minimal undesirable side effects. [14] The chief chemical constituent of gingko biloba is gingkolides and it is a pertinent antioxidant, with neuroprotective and cholinergic activities that help in the management of AD. Ginkgo biloba improves protection against Aβ protein-induced oxidative damages (degrading hydrogen peroxide, preventing lipids from oxidation, and trapping the reactive oxygen species). [15] Ginkgo Biloba is best known for its ability to enhance circulation systemically. Its action is directly related to the vasorelaxing activity. Thus, Ginkgo Biloba can lower blood pressure and inhibit platelet aggregation. Scientific studies have shown its promise on cognition-enhancement (booster), if used during the early stages of Alzheimer’s disease. Salvia officinalis (Lamiaceae) Sage as it is more commonly referred for Alzheimer’s disease treatment. It has been reported to assist the brain in the fight against AD. Sage contains the antioxidants carnosic acid and rosmarinic acid. These compounds are thought to protect the brain from oxidative damage. [16] Rosmarinus officinalis (Lamiaceae) Rosemary (Satapatrika) contains the following natural COX-2 inhibitors: Apigenin, carvacrol, eugenol, oleanolic acid, thymol, and ursolic acid. ‘If a synthetic COX-2 inhibitor could prevent Alzheimer’s disease, so could a natural COX-2 inhibitor,’ according to Duke 2007. In addition, Rosemary contains nearly two dozen antioxidants and another dozen anti‑inflammatory compounds. Some of the strongest antioxidant substances in the herb are carnosic acid and ferulic acid, which have even greater reported antioxidant activity than the widely common synthetic antioxidants butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA).[17] Rosemary can be used as a tea, in shampoo, or in bath water, because it can be absorbed through the skin.[18] Matricaria recutita (Asteraceae) German Chamomile is said to stimulate the brain, dispel weariness, calm the nerves, counteract insomnia, aid in digestion, break up mucus in the throat and lungs, and aid the immune system. Chamomile can relieve anxiety, and in higher doses, leads to drowsiness, according to the University of Maryland Medical Center. [19] Melissa officinalis L. (Lamiaceae) Historically, Melissa officinalis (lemon balm) was believed to sharpen memory. Lemon balm can also temporarily improve cognitive decline as well as improve the mood for Alzheimer’s patients. Another study addressing the use of lemon balm for Alzheimer’s disease concluded that Melissa officinalis is one of several plants that may be useful in the prevention and treatment of Alzheimer’s disease due to its ability to inhibit acetylcholinesterase and its antioxidant activity. [19, 20] Glycyrrhiza glabra (Fabaceae) Alzheimer’s disease is characterized by neuronal loss and the presence of extracellular senile plaques, whose major constituent is amyloid-β peptide (Aβ). In this study, we investigated the effects of a water extract of licorice (Yashti-madhuka) on Aβ25-35-induced apoptosis in PC12 cells. Results suggest that GWE exerts a protective effect against apoptotic neuronal cell death induced by Aβ fragments. Extract from the licorice root is reported to treat or even prevent brain cell death in diseases like Alzheimer’s and its associated symptoms.[21] Galanthus nivalis L. (Amaryllidaceae) The chief chemical constituent of the Galanthus nivalis L. (common snowdrop) is Galanthamine, and this is an isoquinoline alkaloid. Acetylcholinesterase (AChE) inhibitors, which are also called ‘anticholinesterase drugs’, have been recently approved as an promising treatment approach for AD. Galanthamine has been found to be the long‑acting and specific inhibitor of the AChE enzyme and to potentiate cholinergic nicotinic neurotransmission by allosterically modulating the nicotinic acetylcholine receptors, which may be of additional value in the treatment of AD.[22,23] Huperzia serrata (Lycopodiaceae) Huperzia serrata (Thunb. ex Murray) is one of the genera in the Huperziaceae family (syn. Lycopodiaceae family). This genus, has been used for its memory-enhancing effect since ages in the Traditional Chinese Medicinal system (TCM), and is known to contain a large group of alkaloids called ‘Lycopodium alkaloids’. Huperzine A, a novel Lycopodium alkaloid extracted from Huperzia serrata, is well known as a reversible, potent, and selective AChE inhibitor. It is also known as ‘Qian Ceng Ta’ in China, and Huperzine A has been used as a therapeutic agent for AD from centuries.[24] As reported by researchers, taking Huperzine-A leads to a significant improvement in memory, concentration, and the learning capacity. Research has also shown that Huperzine-A substantially reduces the abnormally high radical activity both in the brains of elderly animals as well as in the blood of Alzheimer’s patients. An experimental study in monkeys has shown that it reverses scopolamine-induced amnesia, suggesting that it may benefit the cognitive problems in Alzheimer’s patients or those with other cognitive disorders. [25] Commiphora whighitti (Burseraceae) Commiphora whighitti (Guggulu), a plant resin, contains the major constituent of guggulipid, which is guggulsterone. The guggulipid has been seen to be a potential cognitive enhancer for improvement of memory in scopolamine‑induced memory deficits. [26] Commiphora whighitti acts on impairment in learning and memory and decreased choline actyl transferase levels in hippocampus. However, Commiphora whighitti shows maximum effects on memory functions and the potential for dementia disorder. [27] Lipidium Meyenii Walp (Brassicaceae) Lipidium Meyenii (maca), is known as Maca. Maca shows beneficial improvement in memory and learning. Black maca improves experimental memory impairment, induced by ovariectomy, due in part, to its antioxidant and AChE inhibitory activities. Results demonstrated that black maca can enhance learning and memory in OVX (ovariectomized) mice and this effect might be related, at least in part, to its ability to reduce LPO (Lipid peroxidation) and AChE in OVX mice. [28] Panax Ginseng (Araliaceae) Panax Ginseng (Ren-shen) contains saponins protopanaxadiol, protopantriol, and oleanolic acid saponins that are reported to have memory-enhancing action for the learning impairment induced by scopolamine. [26] Ginseng grows in Northeastern Asia. The Ginseng root has been used in folk medicine in countries like China and Korea, for boosting Qi (energy), from ancient time. Ginseng has a history of medicinal use that goes back thousands of years. The ginseng extract has many uses, and claim to achieve and maintain both physical health and mental well-being.[29] Research has also suggested that ginseng is able to enhance the psychomotor and cognitive performance, and can benefit AD by improving the brain cholinergic function, reducing the level of AD, and repairing the damaged neuronal networks.[19] Acorus calamus L. (Araceae) Acorus Calamus (Sweet flag)) (Araceae) possesses a beneficial memory enhancing property for memory impairment, learning performance, and behavior modification. Acorus Calamus inhibits the acetylcholinesterase (AChE). Acorus Calamus contains a majority of α-and β-asarone. [26] In the Ayurveda medicine system, Acorous Calamus has been used for the treatment of memory loss and its related symptoms. Acorus Calamus also shows anti-inflammatory, antioxidant, antispasmodic, cardiovascular hypolipidemic, immunosuppressive, cytoprotective, antidiarrheal, antimicrobial, and anthelmintic activities. Angelica archangelica L.(umbelliferae) Angelica archangelica L., also known as Dudhachoraa (Laghu Coraka), contains several substances that have the same kind of activity as drugs used for Alzheimer’s disease. These substances do not cause the side effects observed with drugs, such as, nausea, stomach ache, insomnia, and so on. The same phytochemicals in Angelica archangelica can also increase blood flow in the brain. A study shows that chloromethane sub-fraction of a methanol extract inhibit AChE in-vitro. [30, 31] Tinospora cordifolia (Menispermaceae) Tinospora Cordifolia (Guduchi) possesses a memory enhancing property for learning and memory in normal and memory-deficits animals. Tinospora Cordifolia’s mechanism for cognitive enhancement is by immunostimulation and synthesis of acetylcholine, this supplementation of choline enhances the cognitive function. [26] Magnolia officinalis (Magnoliaceae) The bark of Magnolia Officinalis (talauma) is used as a traditional memory enhancing agent in Chinese medicine for the treatment of neurosis, anxiety, stroke, and dementia. Magnolia Officinalis inhibits the memory impairment induced by scopolamine through the inhibition of AChE. The ethanolic extracts of M. officinalis, magnolol and honokiol, are reported to have antioxidant activity in vitro and in vivo. [26, 31] Collinsonia canadensis (Lamiaceae) Horsebalm (Monarda) has been reported to prevent the breakdown of acetylcholine. The chief chemical constituents of horsebalm are carvacol and thymol which are used for AD. Normally our body’s protective blood–brain barrier helps prevent harmful substances in the blood from reaching the tissues of the brain. However, it can also prevent helpful medicines from reaching the brain. The horsebalm compounds seem to cross that great divide. Horsebalm is even used as a herbal shampoo by adding a few drops to your normal herbal shampoo. [18] Bertholettia excelsa (Lecythidaceae) although the name is Brazil Nuts, the most significant exporter of Brazil nuts is not Brazil, but Bolivia. In Brazil these nuts are called castanhas-do-Para. [32] It has a high concentration of lecithin, which contains choline. Choline is a building block for acethycholine. These building blocks enhance the concentration of acethylcholine in AD patients. Other plants that contain good amounts of lecithin are dandelion flowers, poppy seeds, soybeans, mung beans, horehound, ginseng, cowpeas, English peas, and lentils. [18] Urtica dioica L. (Clusiaceae) Stinging Nettle has been used for centuries to treat allergy symptoms, particularly hayfever, which is the most common allergy problem. It contains biologically active compounds that reduce inflammation. It contains the mineral boron that is reported to enhance the levels of estrogen, which is a hormone in the body, which can be beneficial in short‑term memory. Stinging nettle has also been shown to elevate the mood in some Alzheimer’s patients.[18,32] Withania somnifera (Solanaceae) Active glycowithanolides of Withania somnifera (Ashawgandha) have a significant antioxidant function, which is accomplished by increasing the activities of superoxide dismutase, catalase, and glutathione peroxidase.[33] Ashwagandha is also reported as a Nervine tonic that rejuvenates the cells and boosts energy. The assessment of cholinesterase inhibition was carried out using a colorimetric method based on Ellman’s reaction and demonstrated that the W. Somnifera extract significantly inhibited AChE in a concentration-dependent manner.
The most common medicinal herbs for the treatment of AD and those reported in literature are Ginkgo biloba L. (Ginkgoceae), Salvia officinalis L., and Huperzia serrata Thunb. (Lycopodiaceae). Some others are medicinal herbs that have a beneficial effect in the reatment of Alzheimer’s disease (AD) and its associated symptoms are: Acorus calamus L. (Araceae), Angelica archangelica L. (Umbelliferae), Bacopa monniera Wettst. (Scrophulariaceae), Biota orientalis L. (Coniferae) Cupressaceae, Celastrus paniculatus Willd. (Celastraceae), Centella asiatica L. (Umbelliferae), Clitoria ternatea L. (Leguminosae), Codonopsis pilosula Franch. (Campanulaceae), Convolvulus pluricaulis Chois. (Convolvulaceae), Coptis chinensis Franch. (Ranunculaceae), Crocus sativus L. (Iridaceae), Curcuma longa L. (Zingeberaceae), Evodia rutaecarpa (Juss.) Benth. (Rutaceae), Ginkgo biloba L. (Ginkgoaceae), Hypericum perforatum L. (Clusiaceae) (Hypericaceae) Magnolia officinalis Rehd. and Wils. (Magnoliaceae), Melissa officinalis L. (Lamiaceae), Piper methysticum Frost. (Piperaceae), Polygala tenuifolia Wild. (Polygalaceae), Rheum spp. L. (Polygonaceae), Salvia lavandulaefolia Vahl. (Lamiaceae), Salvia miltiorrhizia Bung. (Lamiaceae), Salvia officinalis L. (Lamiaceae), Terminalia chebula L. (Combretaceae), Withania somnifera L. (Solonaceae), and so on.