Indonesia is a tropical nation characterized by a vast array of terrestrial flora. As many as 22,500 species have been recorded, around 1000 plants can be used as medicine, ¹ such as avocado seeds and Aloe vera, which have long been known as plants believed to have high efficacy and lower side effects. ^{2, 3} Avocado seeds and aloe vera have the potential to serve as raw materials for pharmaceuticals devoid of chemical additives, as well as for food, beverages, and cosmetics. Avocado seeds have analgesic and anti-inflammatory properties in dentistry and may be used as a gel for the treatment of canker sores. Conversely, Aloe vera is currently applied to dentistry to promote wound healing, diminish inflammation, and alleviate discomfort. ³

Avocado seeds and aloe vera possess the same secondary metabolite chemicals, namely tannins, saponins, flavonoids, and alkaloids. ^{2, 4} Tannins possess antioxidant, astringent, antidiarrheal, and antibacterial effects. ⁵ Flavonoids are the predominant antioxidant and anti-inflammatory chemicals. ⁶ The content of different compounds, namely saponins, has the potential to have antibacterial, antioxidant, anticancer, and anti-diabetics properties. ⁷ The constituents of many substances, including saponins, have the potential for antibacterial, antioxidant, anticancer, and anti-diabetic properties. ⁸ Both materials’ secondary metabolite levels were determined using quantitative phytochemical tests. Avocado seed extract is abundant in polyphenols and flavonoids, which have potent antibacterial and antioxidant effects, especially against oral infections. Aloe vera is renowned for its anti-inflammatory and wound-healing properties, rendering it significant for mucosal tissue regeneration. This work tackles the gap by examining a dual-extract formulation that may provide a safer, more accessible alternative to synthetic drugs. This work is essential due to the increasing worry over antibiotic resistance and the desire for biocompatible, plant-based medicines in dental care. ^{3, 5, 6}

Quantitative phytochemical analyses ascertain the quantities of secondary metabolites. ⁹ The ethanol extract of avocado seeds has 0.435% alkaloids, 0.1084% flavonoids, 0.0309% phenols, and 0.2044% tannins, as determined using a spectrophotometer. ¹⁰ A separate investigation employing UV-Vis spectrophotometry determined that avocado seed extract has 56.5063 μg/ml of alkaloids, 245.6875 μg/ml of flavonoids, 15.65 μg/ml of phenols, 27.03 μg/ml of tannins, and 22.73 μg/ml of saponins. ¹¹ Aloe vera extract analyzed via UV-Vis spectrophotometry revealed concentrations of 4.65 ± 0.08 tannins, 1.43 ± 0.031 flavonoids, 60.85 ± 0.61 saponins, and 22.86 ± 0.15 alkaloids. ¹² Aloe vera extract (100 g) had 31.067 g of alkaloids, 25.66 g of tannins, and 10.67 g of saponins. The ethanol extract of avocado seed showed a moderate antioxidant capacity (IC50 77.298 μg/mL). Still, the ethanol extract of Aloe vera displayed 70.7% antioxidant activity as assessed by the DPPH technique using a UV-Vis spectrophotometer. ¹³ These compounds demonstrate considerable antioxidant capabilities, particularly tannins and flavonoids, which correlate with elevated antioxidant levels. ¹⁴ The ethanol extract of avocado seeds had a moderate antioxidant capacity (IC50 77.298 μg/mL), ¹⁵ but the ethanol extract of Aloe vera displayed 70.7% antioxidant activity as assessed by the DPPH technique. ¹⁶

This study will investigate the extraction of avocado and aloe vera seeds by the maceration method utilizing 70% ethanol for 48 hours, distinguishing it from prior studies. This study compares quantitative phytochemical analyses using a UV-VIS spectrophotometer with antioxidant assessments employing the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method, also utilizing a UV-VIS spectrophotometer to ascertain the antioxidant activity and IC50 values in avocado seed extract and Aloe vera extract, thereby evaluating the compound levels and antioxidant activity in both extracts.

Quantitative measurement of saponins was conducted utilizing Quillaja bark standards at a wavelength of 435 nm, with the linear equation Y = 9.44528e-0.44x - 0.00332132 and a correlation coefficient (r ²) of 0.99974 ( Figure 1). The subsequent equation was employed to ascertain the concentrations of saponin components, whereas the r-value indicates the correlation between the concentration of the standard solution and the absorbance. An R value around 1 is considered favorable as it implies a direct proportionality or linearity between the concentration of the standard solution and the absorbance. The overall saponin test findings indicated that the average saponin content in Aloe vera extract surpassed that of avocado seeds. The findings revealed that the mean saponin concentration in the Aloe vera extract sample was 0.74%, whereas that of the avocado seed extract was 0.21%.

The quantitative measurement of alkaloids was conducted utilizing the Quillaja bark standard at a wavelength of 470 nm, with the linear equation Y = 0.00154627x - 0.00434169 and a correlation coefficient (r ²) of 0.99913 ( Figure 2). The overall alkaloid test findings indicated that the average alkaloid level in Aloe vera extract surpassed that of avocado seeds. The findings revealed that the mean concentration in avocado seeds was 0.0232%, whereas that in Aloe vera was 0.0313%.

The quantitative analysis of flavonoids was conducted utilizing the quercetin standard at a wavelength of 510 nm, resulting in a linear equation of Y = 0.00569497 x - 0.00473317, with a correlation coefficient (r ²) of 0.99979 ( Figure 3). The total flavonoid test results indicated that the average flavonoid content in Aloe vera extract was lower than in avocado seeds. The observation results revealed that the average content of avocado seeds was 19.44%, while in Aloe vera, it was 0.99%.

The quantitative analysis of tannin was conducted utilizing the Tannin Acid standard at a wavelength of 760 nm, with a linear equation represented as Y = 0.019469x + 9.88071e-004, and a correlation coefficient (r ²) of 0.99994 ( Figure 4). The total tannin test results on avocado and Aloe vera seeds indicated that the average tannin content in Aloe vera extract was less than that found in avocado seeds. The observation results revealed that the average content of avocado seed extract was 10.66%, while Aloe vera extract was measured at 4.68%.

The test results for Aloe vera extract samples ( Figure 5) indicated an IC50 value of 4614 μg/mL, categorizing it as inactive. Examinations of avocado seeds ( Figure 6) revealed an IC50 value of 135 μg/mL, categorizing it as moderate.

The saponin concentration in A. vera surpasses that of avocado seeds, as the highest levels of saponin in plants are located in the fruit and leaves, particularly in mature leaves ^{17, 18} ; this aligns with prior research indicating that saponin synthesis transpires in the leaves. ¹⁹ Saponin demonstrates foaming properties upon interaction with water. ¹⁹ The composition and concentration of saponins are significantly affected by environmental conditions and extraction methods. ^{20– 22} Saponins work by exhibiting antibacterial action through the denaturation of proteins. The active compound saponin, akin to a detergent, can diminish the surface tension of bacterial cell walls, hence compromising the permeability of the bacterial membrane. ²³

Aloe vera extract contained more alkaloid compounds. Plant type can also influence the difference, and environmental factors such as soil pH approaching neutral (5.79-6.97) can affect alkaloid production. The extraction process also affected the amount of alkaloid compound withdrawal. ²⁴ The condition of the planting and maintenance soil is also thought to affect the quality of the avocado and Aloe vera plants used, so soil that uses nitrogen fertilizer can increase the production of alkaloids. ²⁵ Alkaloids have basic properties and contain one or more nitrogen atoms in a cyclic system combination. This compound is likely to be present in small quantities and must be separated from a complex mixture of compounds. The alkaloid compounds were the lowest compared to the other compounds. ^{26, 27} Alkaloid compounds have non-polar properties; therefore, they are less suitable for extraction with polar compounds, such as 70% ethanol. Alkaloids play a role in plant metabolism and control plant development. Most alkaloid compounds originate from plants, especially Angiosperms. ²⁸

Flavonoid content is higher in plants grown in lowlands, which is closely related to temperature and soil nutrient availability. ^{29, 30} The avocado and Aloe vera seeds used in this study were collected from different areas. The avocado seeds used in this study were obtained from lowland plantations with higher soil calcium content. This can affect flavonoid content. The significant difference in flavonoid content was also caused by the fact that the types and varieties of plants used were not uniform. Flavonoids are primary antioxidants that provide hydrogen atoms to the free radicals. The flavonoid levels in plants affect the plant’s antioxidant activity. Flavonoids are polar compounds that can dissolve in polar solvents, such as ethanol, methanol, butanol, acetone, and dimethylformamide. Water-soluble flavonoids are included in the polyphenol family. Flavonoids are also bound to glycosides. Hence, the mixture of the above solvents with water is a suitable solvent for flavonoid glycosides. In contrast, aglycones such as flavones, flavonols, and flavanones are more easily dissolved in chloroform and ether solvents. ^{30– 32}

The tannin content in avocado seeds was higher than in aloe vera seeds. Tannin compounds can be found in dicotyledonous plants’ stems, skin, flowers, seeds, leaves, and cell walls or vacuoles. Generally, tannin compounds are more commonly found in dicotyledonous plants or flowering plants with dicotyledonous seeds, especially in angiosperm plants, such as plants with closed seeds, such as avocado seeds. During the maturity phase, fruit seeds experience a significant increase in tannin levels. ³² Avocado is a dicotyledonous angiosperm plant that is thought to have a high tannin content, especially in seeds. Simultaneously, Aloe vera is included in monocotyledonous angiosperm plants. ^{33– 35} In addition, tannin has a molecular weight consisting of hydroxyl groups and several other groups, such as carboxyl and complex organic substances, which are difficult to separate and crystallize. Chemically, tannins are divided into condensed and hydrolyzed tannins. The type of tannin commonly found in plants is hydrolyzed tannin, usually marked by a color change from greyish-blue to blackish when given specific reagents. Tannins possess a sour and astringent flavor and create colloids upon dissolution in water. Tannin’s structure comprises two aromatic rings connected by three carbon atoms. ^{35– 37}

The antioxidant activity was evaluated utilizing the DPPH assay. Before assessing the sample concentrations by UV-Vis spectrophotometry, the DPPH solution was analyzed to ascertain the optimal wavelength, ensuring that the sample sensitivity was maximized at the highest absorbance value. A potent antioxidant possesses an IC50 value under 50 μg/mL, a powerful antioxidant has an IC50 value ranging from 50 to 100 μg/mL, a moderate antioxidant exhibits an IC50 value between 101 and 250 μg/mL, a weak antioxidant shows an IC50 value from 250 to 500 μg/mL, and an inactive antioxidant has an IC50 value exceeding 500 μg/mL. ^{37, 38} The analysis of the DPPH solution indicated an optimal wavelength of 515.5 nm for DPPH. This wavelength was employed to assess the antioxidant activity of the samples. Sample testing was conducted by reacting the test solution with the DPPH solution, followed by a 30-minute incubation in a dark environment. The incubation period is ideal for the DPPH technique, facilitating effective binding between antioxidant molecules and DPPH radicals. The comparator employed in this investigation was Vitamin C. Vitamin C comprises powerful natural antioxidant molecules. Vitamin C serves as a reliable comparator with well-defined features; hence, the vitamin C antioxidant test findings can assist in assessing the quality and efficacy of antioxidant components in the extract under examination. ^{38, 39}

The avocado seed extract in this study was tested with three repetitions or taking from the mother liquor, and obtained an average percentage inhibition result of 44.12% with an IC50 value of 135 μg/mL, classified as moderate. Aloe vera extract was tested with three repetitions or taken from the mother liquor, and obtained an average percentage inhibition result of 40.17% with an IC50 value of 4614 μg/mL, classified as inactive, but still has no potential as an antioxidant. The levels or concentrations used in Aloe vera were higher than those in avocado seeds, allowing the IC50 value to be obtained. The requirement for calculating the IC50 value is when there is an intersection between the inhibition value and a level above 50. If both levels are the same, the inhibition value obtained will not be more than 50%; therefore, the IC50 value in Aloe vera cannot be determined. ³⁹

IC50 denotes the concentration of antioxidant chemicals required to neutralize 50% of free radicals. A lower IC50 value indicates greater antioxidant activity. ^{40, 41} The difference in results obtained in A. vera and avocado seed extracts can occur due to several factors, such as plant factors themselves, plant quality, planting methods, the environment around the planting, and contamination by other substances. The difference in results between avocado seeds and Aloe vera can be associated with tannins and flavonoids in both extracts. The levels of flavonoids and tannins obtained in avocado seed extract were much higher, at 10.66% and 19.44%, respectively, while in Aloe vera, the flavonoid and tannin contents were only 4.68% and 0.99%, respectively. The difference in the content of these two compounds can affect the antioxidant activity of a plant. Previous studies stated that the phenolic content, such as flavonoids and tannins, strongly influences a plant’s antioxidant activity. ^{41– 43} The comparison of flavonoid and tannin levels reveals that Aloe vera contains 4.68% tannins and 0.99% flavonoids, whereas avocado seeds exhibit significantly higher concentrations of 10.66% tannins and 19.44% flavonoids. Thus, the levels of both compounds are markedly greater in avocado seeds compared to Aloe vera. Both compounds are significant contributors to antioxidant activity.

This study is limited to identifying the highest antioxidant activity, and further research is needed to optimize dosage and assess in vivo toxicity.

The levels of flavonoids and tannins in the ethanol extract of avocado seeds were higher than those in A. vera. The levels of saponin and alkaloid compounds were higher in Aloe vera.

The antioxidant activity of the ethanol extract from avocado seeds exceeded that of Aloe vera. The inhibition percentage in avocado seeds was 44.12%, corresponding to an IC50 value of 135 μg/mL, indicating moderate activity. In contrast, Aloe vera exhibited an inhibition percentage of 40.17% with an IC50 value of 4164 μg/mL, suggesting inactivity.

Ethical approval and consent were not required.