The Neurotherapeutic Attributes of Indian Citrus Pickle: A Tangy Tradition with Neuroprotective Secrets
Sharadendu Bali¹* and Muhammad Arif Khan²
¹ MS (General Surgery), PhD (Biochemistry); Professor, General Surgery, TMMC, TMU, Moradabad, UP, India.
² Department of Pharmacy, Faculty of Biological Sciences, University of Malakand, Dir (L), KPK, Pakistan.
DOI: 10.31080/ASMS.2025.09.2074 | Published: April 15, 2025
Abstract
Review ArticleCitrus limon (C. Limon), commonly known as lemon, represents one of the most significant crops in fruit production. Its unique tangy flavor lends itself to diverse culinary and beverage applications. This review aims to synthesize existing literature on the neuroprotective effects of phytochemicals present in lemon pickle, a traditional condiment made from Citrus limon. We extracted data from published studies examining phytochemicals found in lemon, including nobiletin, hesperidin, hesperetin, naringin, naringenin, rutin, heptamethoxyflavone (HMF), tangeretin (TGN), quercetin, limonene, eriodictyol, isoimperatorin (IMP), apigenin, luteolin, and vitamin C. Phytochemicals found in lemon pickle demonstrate multi-targeted mechanisms to ameliorate neurodegenerative diseases by decreasing oxidative stress, inhibiting neuroinflammation, modulating signaling pathways (cAMP/PKA/ERK/CREB, Nrf2/ARE, BDNF), and protecting against neurotoxicity. Human clinical trials show cognitive improvements with citrus phytochemicals. In conclusion, lemon pickle emerges as a promising dietary inclusion offering a plethora of neuroprotective phytochemicals to reduce neurodegenerative disease risk and enhance brain health.
1. Introduction
Lemon pickle, a traditional fermented Indian relish prepared from Citrus limon, presents a unique food supplement to harness the collective neuroprotective potential inherent in various phytochemicals found in lemons. These phytochemicals, namely nobiletin, hesperidin, hesperetin, naringin, naringenin, rutin, HMF, tangeretin, quercetin, limonene, eriodictyol, isoimperatorin, apigenin, luteolin, and vitamin C, exhibit substantial efficacy in safeguarding against neurodegenerative processes.
Traditional Indian lemon pickle also contains condiments like Carom seeds (ajwain), rock salt (sendha namak), and red chili powder, offering compounds such as quercetin, limonene, capsaicin, and carvacrol. Lemon peel is stratified into outer flavedo (rich in phenolics and flavonoids like hesperidin, diosmin, eriocitrin) and inner albedo (rich in pectin fiber). The pickling fermentation process softens cell walls, boosting bio-accessibility.
2. Phytochemicals in Citrus limon (Table 1)
Citrus limon is a rich repository of diverse phytochemical compounds. Phenolics are predominantly flavonoids classified into flavanones (up to 90% - eriocitrin, hesperidin), flavones (diosmetin 6,8-di-C-glucoside, vicenin-2, diosmin), and flavonols (rutin, myricetin, quercetin, kaempferol).
| Class | Phytochemicals Found |
|---|---|
| Flavanones | Eriocitrin, Hesperidin, Neoeriocitrin, Naringin, Narirutin |
| Flavones | Diosmetin 6,8-di-C-glucoside, Vicenin-2, Diosmin, Nobiletin, Tangeretin |
| Flavonols | Rutin, Myricetin, Quercetin, Kaempferol |
| Hydroxycinnamic Acids | Caffeic Acid, Chlorogenic Acid, Ferulic Acid, Sinapic Acid, p-Coumaric Acid |
| Benzoic Acids | Protocatechuic Acid, p-Hydroxybenzoic Acid, Vanillic Acid |
| Vitamins & Minerals | Vitamin C, Vitamin A, B-complex; Potassium, Calcium, Magnesium, Phosphorus, Copper, Iron, Zinc |
| Essential Oils & Organic Acids | d-Limonene, Beta-Cryptoxanthin, Citric Acid (up to 8% dry weight), Scopoletin, Citropten, Dietary Fiber (Pectin) |
3. Neurodegenerative Diseases (NDDs)
- Alzheimer’s disease (AD): Affecting over 50 million people worldwide (projected to reach 152M by 2050). Characterized by extracellular amyloid-beta (Aβ) plaques and intracellular tau tangles causing progressive cognitive loss.
- Parkinson’s disease (PD): Progressive motor system disorder with limb tremors, muscular rigidity, and dopaminergic neuronal loss.
- Amyotrophic lateral sclerosis (ALS): Targeting motor neurons causing progressive muscle wasting (SOD1 mutations).
4. Neuropharmacological Targets in NDDs
Therapeutic interventions target: 1. Protein Misfolding & Aggregation (α-synuclein, Aβ, tau); 2. Protein Elimination Pathways (ubiquitin-proteasome, autophagy); 3. Unfolded Protein Response (UPR); 4. Mitochondrial Dysfunction & ATP Generation; 5. Ion Homeostasis & Glutamate Excitotoxicity; 6. Neuroinflammation & Oxidative Stress (ROS, NO, microglial activation).
5. In-Vitro Evidence of Lemon Phytochemicals (Table 2)
Nobiletin & DTF: Stimulates cAMP/PKA/ERK/CREB signaling, suppresses BACE1, upregulates neprilysin for Aβ degradation, and prevents toxic calcium overload.
Naringin & Naringenin: Elevates GDNF levels, activates mTORC1 & Nrf2/ARE pathways, and diminishes TNF-α and iNOS expression.
Hesperetin & Hesperidin: Restores mitochondrial ATP generation, reduces Aβ deposition, and inhibits NF-κB & p38 MAPK in microglia.
Rutin & Quercetin: Inhibits amylin and Aβ aggregation, and promotes mitochondrial biogenesis via PGC-1α.
6. Animal Model Evidence (Table 3)
In animal models, Nobiletin preserved cholinergic innervation, restored dopamine levels in 6-OHDA PD models, and reduced ischemic brain damage. Hesperidin improved memory in 5xFAD mice via AMPK/BDNF/TrkB/CREB signaling. Naringin extended lifespan in C. elegans via DAF-16 transcription factor.
7. Human Clinical Trials & Brain Performance (Tables 4 & 5)
- Hashimoto et al. (2022): Perilla seed oil + nobiletin-rich ponkan powder significantly increased cognitive index scores and serum BDNF in healthy elderly.
- Seki et al. (2013): Nobiletin-rich Chinpi prevented 1-year cognitive decline in Alzheimer's patients receiving donepezil.
- De Luca et al. (2022): PEA-Luteolin treatment improved odor identification and reduced brain fog in Long COVID patients.
8. Neuroprotective Benefits of Other Lemon Pickle Ingredients
Figures 1 & 2: Beneficial effects of lemon pickle components on the brain, showing gut-brain axis modulation and prebiotic effects of lemon peel.
9. Discussion & Conclusion
Lemon pickle, a traditional Indian condiment made from Citrus limon, emerges as a promising vehicle for delivering a myriad of neuroprotective phytochemicals. Pickling ferments and softens cell walls, dramatically enhancing bio-accessibility of nobiletin, hesperidin, naringin, rutin, and essential oils. Incorporating lemon pickle into daily meals offers a simple, natural strategy to reduce neuroinflammation, enhance cognition, and protect against neurodegenerative diseases.
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