Centella asiatica extract prevents visual impairment by promoting the production of rhodopsin in the retina

Natural products for the treatment of age-related macular degeneration

BACKGROUND

Age-related macular degeneration (AMD) is a chronic retinal disease that significantly influences the vision of the elderly.

PURPOSE

There is no effective treatment and prevention method. The pathogenic process behind AMD is complex, including oxidative stress, inflammation, and neovascularization. It has been demonstrated that several natural products can be used to manage AMD, but systematic summaries are lacking.

STUDY DESIGN AND METHODS

PubMed, Web of Science, and ClinicalTrials.gov were searched using the keywords "Biological Products" AND "Macular Degeneration" for studies published within the last decade until May 2023 to summarize the latest findings on the prevention and treatment of age-related macular degeneration through the herbal medicines and functional foods.

RESULTS

The eligible studies were screened, and the relevant information about the therapeutic action and mechanism of natural products used to treat AMD was extracted. Our findings demonstrate that natural substances, including retinol, phenols, and other natural products, prevent the development of new blood vessels and protect the retina from oxidative stress in cells and animal models. However, they have barely been examined in clinical studies.

CONCLUSION

Natural products could be highly prospective candidate drugs used to treat AMD, and further preclinical and clinical research is required to validate it to control the disease.

Assessment of tear film parameters post-treatment with commercial eyelid cleaning wipes: a pilot study

AIM

To investigate the short-term effects of commercially available eyelid-cleaning wipes on film parameters.

METHODS

This study enrolled 48 healthy participants aged 20-35y (both males and females). Clinical assessment included the Ocular Surface Disease Index (OSDI) questionnaire, non-invasive tear break-up time (NITBUT), tear meniscus height (TMH), and lipid layer pattern (LLP). Based on these initial results, participants were categorized as either non-dry eye or dry eye. Participants in each group were randomly allocated to either Blephaclean® or Systane® treatments. Changes in NITBUT, TMH, and LLP levels before and after lid wipe treatment were assessed.

RESULTS

The dry eye group exhibited significantly higher OSDI scores and lower NITBUT and TMH levels than in the non-dry eye group (P<0.001). Following the application of eyelid wipes (Systane® wipes), dry eye subjects experienced a significant improvement in NITBUT levels (P=0.0014) compared to the non-dry eye individuals. Although the remaining participants showed a marginal increase in TMH and NITBUT levels, these changes did not achieve statistical significance (P>0.05). Similarly, the LLP levels were significantly improved with Systane® (P<0.001) post-treatment compared to individuals in the non-dry eye group. However, the dry eye subjects showed higher post-treatment LLP levels than the untreated group (P<0.02).

CONCLUSION

The short-term effects of Systane® eyelid wipes on tear film parameters suggest their effectiveness in dry eye disease. Nonetheless, further exploration of their long-term impact is essential to justify their cost effectiveness and efficacy in treating both aqueous deficiency and evaporative dryness.

Cosmeceutical Therapy: Engaging the Repercussions of UVR Photoaging on the Skin's Circadian Rhythm

Sunlight is an important factor in regulating the central circadian rhythm, including the modulation of our sleep/wake cycles. Sunlight had also been discovered to have a prominent influence on our skin’s circadian rhythm. Overexposure or prolonged exposure to the sun can cause skin photodamage, such as the formation of irregular pigmentation, collagen degradation, DNA damage, and even skin cancer. Hence, this review will be looking into the detrimental effects of sunlight on our skin, not only at the aspect of photoaging but also at its impact on the skin’s circadian rhythm. The growing market trend of natural-product-based cosmeceuticals as also caused us to question their potential to modulate the skin’s circadian rhythm. Questions about how the skin’s circadian rhythm could counteract photodamage and how best to maximize its biopotential will be discussed in this article. These discoveries regarding the skin’s circadian rhythm have opened up a completely new level of understanding of our skin’s molecular mechanism and may very well aid cosmeceutical companies, in the near future, to develop better products that not only suppress photoaging but remain effective and relevant throughout the day.

Preventive Effects against Retinal Degeneration by Centella asiatica Extract (CA-HE50) and Asiaticoside through Apoptosis Suppression by the Nrf2/HO-1 Signaling Pathway

Age-related macular degeneration (AMD) is caused by the chronic and gradual oxidative degeneration of the retina. Unfortunately, the general purpose of current treatments is to slow AMD progression, as the retina cannot be restored to its pre-AMD condition. We aimed to identify natural products that can be potential treatments that prevent AMD and can delay the development of late-AMD and selected Centella asiatica extract (CA-HE50), which shows excellent efficacy in cytoprotection. In animal experiments using N-methyl-N-nitrosourea (MNU), CA-HE50 dramatically increased the thickness of photoreceptors and the outer nuclear layer (ONL) and the number of nuclei in the ONL (p < 0.05). Using retinal epithelial ARPE-19 cells showed that CA-HE50 inhibited apoptosis through inhibition of the intrinsic apoptosis signaling pathway and cell cycle regulation (p < 0.05). The anti-apoptotic efficacy was confirmed to be due to activation of the Nrf2/HO-1 antioxidation pathway (p < 0.05). These results were also observed with asiaticoside, a functional substance of CA-HE50. In addition, the accumulation of oxidized-N-retinylidene-N-retinylethanolamine (A2E), which induces AMD, was inhibited by CA-HE50, resulting in increased ARPE-19 cell viability (p < 0.05). This study demonstrates that CA-HE50 is worth further research and human application tests, to develop it as a raw material for treatment or dietary supplement for the prevention of AMD.

Hepatoprotective effect of Centella asiatica 50% ethanol extract against acetaminophen-induced acute liver injury in BALB/c mice

N-acetyl-p-aminophenol (acetaminophen, APAP) is a well-known component of analgesic and antipyretic monotherapy products. However, exceeding the recommended dose can lead to serious injury to the liver. We conducted this study to determine the potential of Centella asiatica as a natural substance to protect against APAP-induced liver injury. When acute hepatotoxicity was induced in mice by APAP overdose, their liver weight decreased significantly (p < 0.05). However, mice treated with C. asiatica 50% ethanol extract (CA-HE50, 200 mg/kg) for a week before induction of hepatotoxicity by APAP had similar liver weights to those of mice in which hepatotoxicity was not induced. In particular, levels of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase, which are biomarkers of liver injury, were significantly increased by APAP and dose-dependently decreased by CA-HE50 (p < 0.05). Glutathione and malondialdehyde, indicators of oxidative stress, were significantly changed by APAP and CA-HE50 (p < 0.05). In addition, hepatic necrosis and expression of genes encoding pro-inflammatory cytokines (tumor necrosis factor-α, interleukin (IL)-1β, and IL-4) induced by APAP were inhibited by CA-HE50, and these results were dose-dependent. Through our in vivo studies, we found that CA-HE50 can help prevent APAP-induced hepatic tissue injury in BALB/c mice. Furthermore, CA-HE50 was effective at protecting RAW 264.7 cells from lipopolysaccharide-induced cytotoxicity and inhibiting the release of nitric oxide from these cells; in particular, asiaticoside was found to be a key component of CA-HE50 responsible for these effects. Therefore, we suggest that CA-HE50 has potential applications in functional health foods and drugs.