Antioxidant effect of ethanol-based sand ginger extract lends promise to anti-ageing applications – Thai study

Commonly known as sand ginger, KG is native to Asian countries including India, China, Indonesia, Malaysia, and Thailand. It has been traditionally used as a food condiment and folk medicine to relieve skin diseases.

Recent studies have shown that different extracts from KG present anti-angiogenic, anti-inflammatory, and antiviral activities.

For instance, key components found in the rhizome extract of KG include cinnamic acid derivatives, such as ethyl p-methoxycinnamate (EPMC) and ethyl cinnamate, as well as flavonoids like kaempferol. In particular, EPMC has a wide range of biological activities, including anti-inflammatory effect.

To explore a novel source of anti-ageing agents, Thai researchers conducted a study whereby KG rhizome was extracted using four solvents of different polarity to investigate their antioxidant, anti-collagenase, and anti-elastase effects on human fibroblast cells.

The KG rhizomes were collected from northern Thailand and extracted via the maceration method. The solvents were namely deionised water, absolute ethanol, ethyl acetate, and hexane.

The highest extraction yield was observed with deionised water (6.43%), followed by absolute ethanol (5.3%), ethyl acetate (4.62%), and hexane (3.68%) respectively.

These findings indicate that solvents with higher polarity (water, absolute ethanol) resulted in greater extraction yield than low polarity solvents (ethyl acetate, hexane).

In addition, absolute ethanol and ethyl acetate were found to be the best solvents for extracting flavonoids and phenolic compounds from KG rhizome.

Particularly, the highest total flavonoid and phenolic contents were achieved through extraction with absolute ethanol and ethyl acetate respectively, while the lowest was obtained by extraction with deionised water and hexane (p < 0.05).

The antioxidant (free radical scavenging) activities of the four KG extracts were evaluated through the DPPH assay and ABTS+ assay, and the ability to reduce iron (III) ion (Fe3+) through the ferric reducing antioxidant power (FRAP) assay.

The results showed that the extract obtained with absolute ethanol exhibited the most potent antioxidant activities on both the DPPH assay and the FRAP assay (p < 0.05), compared to other extracts.

On the other hand, the aqueous extract showed the highest activity in the ABTS+ assay (p < 0.05).

“The high antioxidant activity of the KG extracts are potentially attributed to the high content of flavonoids and phenolic compounds. However, different compound polarities in each of the extraction solvents display various antioxidant mechanisms.​

“The ethanolic extract of KG demonstrated the most effective antioxidant activity, collagenase, and elastase inhibitory effects, with none to low cytotoxicity. Therefore, ethanolic KG extract is suitable for the development of cosmeceutical products geared towards anti-ageing applications,” ​the authors wrote.

Protecting against collagen and elastin breakdown​

Skin ageing is influenced by intrinsic and extrinsic factors, both of which can induce skin cells to generate reactive oxygen species (ROS), which have negative impact on cell functions such as collagen and elastin synthesis.

As collagenase and elastase are responsible for the breakdown of collagen and elastin, the ability to inhibit these enzymes based on spectrophotometric methods are used to assess their anti-ageing effects.

The biggest collagenase inhibitory effect was observed with absolute ethanol used as a solvent (71.83 ± 4.65%), followed by hexane (67.43 ± 1.4%), ethyl acetate (56.08 ± 5.48%), and deionised water (37.61 ± 2.97%).

The KG extract obtained with absolute ethanol exhibited higher anti-elastase activity (66.35 ± 7.21%) than KG extracts obtained with ethyl acetate (43.39 ± 6.75%), hexane (45.07 ± 6.51%), and deionised water (22.7 ± 1.63%).

“The highest collagenase and elastase inhibitory activities, observed in the KG extract obtained with absolute ethanol, may be possibly due to its high total phenolic and total flavonoids content, compared to other solvents. ​

“The results indicated a positive relation between the anti-ageing activity and antioxidant activity of KG extracts. It should be noted that the effect of different extraction solvents on collagenase and elastase inhibitory activity could be dependent on the part of plant, different stages of harvest, phytochemical compound content, concentration of active biological compounds, and their antioxidant activity.” ​

Source: Cosmetics

https://doi.org/10.3390/cosmetics11030097​

“Exploring the In Vitro Antioxidant, Anti-Aging, and Cytotoxic Properties of Kaempferia galanga Linn. Rhizome Extracts for Cosmeceutical Formulations”​

Authors: Panikchar Wichayapreechar, et al