Biofarmasetikal Tropis (The Tropical Journal of Biopharmaceutica.
2025, 8.
, 24-30 e-ISSN 2685-3167 p-ISSN 2828-6685 Inhibitory Activity of Sea Grapes (Caulerpa racemos.
Against the Growth of Propionibacterium acnes Yessie K.
Lengkey1*.
Indri J.
Kereh1.
Sonny D.
Untu1.
Margaretha S.
Ginting1.
Ferdy A.
Karauwan1.
Selvana S.
Tulandi1.
Adolfina Sumangando1 Department of Biology.
Faculty of Mathematics and Natural Sciences.
Christian University of Indonesia in Tomohon *Corresponding author.
yessiekellylengkey@gmail.
Accepted: 26 September 2025.
Approved : 16 Oktober 2025
ABSTRAK
Penelitian ini bertujuan untuk mengetahui aktivitas daya hambat anggur laut (Caulerpa racemos.
terhadap pertumbuhan bakteri Propionibacterium acnes, yaitu bakteri yang dapat menyebabkan jerawat pada kulit manusia.
Anggur laut merupakan salah satu rumput laut yang mengandung senyawa bioaktif seperti flavonoid dan alkaloid yang berpotensi sebagai antibakteri.
Penelitian ini dilakukan secara eksperimental di laboratorium dengan metode difusi agar menggunakan kertas Sampel anggur laut diekstraksi dengan metode maserasi menggunakan etanol 96%, kemudian diuji pada beberapa konsentrasi yaitu 100, 200, 300, dan 400 AAg/disk.
Aquades digunakan sebagai kontrol negatif.
Hasil penelitian menunjukkan bahwa ekstrak anggur laut mampu menghambat pertumbuhan bakteri Propionibacterium acnes dengan diameter zona hambat antara 33,9Ae41,2 mm.
Zona hambat terbesar diperoleh pada konsentrasi 400 AAg/disk.
Berdasarkan hasil tersebut, dapat disimpulkan bahwa anggur laut (Caulerpa racemos.
memiliki aktivitas antibakteri yang sangat kuat terhadap bakteri Propionibacterium acnes dan berpotensi sebagai bahan antibakteri Kata kunci: Anggur laut.
Caulerpa racemosa, daya hambat.
Propionibacterium acnes, antibakteri ABSTRACT This study aimed to determine the inhibitory activity of sea grapes (Caulerpa racemos.
against the growth of Propionibacterium acnes, a bacterium that can cause acne on human skin.
Sea grapes contain bioactive compounds such as flavonoids and alkaloids which may act as natural antibacterial agents.
This research was conducted experimentally in the laboratory using the agar diffusion method with paper discs.
The sea grape sample was extracted by maceration using 96% ethanol and tested at concentrations of 100, 200, 300, and 400 AAg/disc.
Distilled water was used as a negative control.
The results showed that the extract was able to inhibit the growth of Propionibacterium acnes, with inhibition zone diameters ranging from 33.
9 to 41.
2 mm.
The largest inhibition zone was found at the concentration of 400 AAg/disc.
In conclusion, sea grapes (Caulerpa racemos.
have very strong antibacterial activity against Propionibacterium acnes and have potential as a natural antibacterial source.
Keywords: Sea grapes.
Caulerpa racemosa, inhibition activity.
Propionibacterium acnes.
INTRODUCTION Indonesia, particularly the coastal region of North Sulawesi Province, is endowed with abundant marine biodiversity.
One of the marine resources commonly found in this area is sea Sea grapes are known by various local names, such as Latoh in Java.
Bulung Boni in Bali, and Lawi-lawi in Sulawesi.
Sea grapes (Caulerpa racemos.
are characterized by a green thallus resembling seaweed, consisting of upright branches with small spherical structures at the tips that resemble grapes1.
Sea grapes (Caulerpa racemos.
are widely utilized as a food source, often consumed Biofarmasetikal Tropis (The Tropical Journal of Biopharmaceutica.
2025, 8.
, 24-30 as fresh vegetables, and they also possess potential medicinal properties, including antibacterial activity.
However, particularly in Sulawesi, although C.
racemosa is relatively easy to cultivate, many local communities remain unaware of its beneficial properties and the bioactive compounds contained within this marine algae1.
Propionibacterium acnes is a Grampositive bacterium that constitutes part of the normal flora of human skin, as well as the oral cavity, large intestine, conjunctiva, and external ear canal.
This bacterium predominantly inhabits skin follicles and may contribute to the development of acne when it infects the skin2.
Previous studies have reported that extracts of sea grapes (Caulerpa racemos.
exhibit inhibitory activity against bacterial Research has shown that the active compounds present in C.
racemosa extract are capable of suppressing the growth of Bacillus cereus and Escherichia coli at concentrations of 20 AAg, 40 AAg, and 60 AAg.
Considering this potential, the present study was conducted to evaluate the inhibitory activity of sea grapes (Caulerpa racemos.
against the growth of Propionibacterium acnes.
e-ISSN 2685-3167 p-ISSN 2828-6685 Type and Experimental Design This study was a laboratory experimental research aimed at determining the inhibitory activity of sea grape extract (Caulerpa Antibacterial testing was performed using the agar diffusion method with paper discs .
isc diffusion metho.
, in which the formation of inhibition zones around extract-treated discs was The experimental design employed four extract concentration variations, with each treatment conducted in triplicate.
The concentrations tested were as follows:
K1: Sea grape extract at 100 AAg/disc K2: Sea grape extract at 200 AAg/disc K3: Sea grape extract at 300 AAg/disc K4: Sea grape extract at 400 AAg/disc Sterile distilled water .
AAL/dis.
was used as a negative control.
The antibacterial activity was determined based on the diameter of the inhibition zone formed on the bacterial growth medium.
Research Procedures Collection of Sea Grape Samples (Caulerpa Fresh green sea grape samples (Caulerpa racemos.
were collected from Basaan Beach.
Southeast Minahasa Regency.
North Sulawesi Province.
The samples were washed under running water to remove sand and impurities, drained to reduce moisture content, and cut into smaller pieces to facilitate the extraction of active compounds.
Approximately 2 kg of fresh samples were air-dried to obtain simplicia prior to Preparation of Sea Grape Extract (Caulerpa A total of 450 g of dried sea grape simplicia was extracted using the maceration method with 96% ethanol as the solvent.
The maceration process was conducted for 2 y 24 hours and repeated twice.
After the first immersion, the mixture was filtered using filter paper and a funnel to obtain the first filtrate and residue.
The residue was re-immersed in ethanol and macerated again for 2 y 24 hours until two filtrates were obtained.
All filtrates were combined and concentrated using a rotary evaporator at approximately 40AC to produce a thick extract.
The extract was transferred RESEARCH METHODS Tools and Materials The equipment used in this study included tools for sample collection, extraction, and antibacterial activity testing.
The instruments consisted of a rotary evaporator (IKA RV .
, diving equipment, scissors, knives.
Erlenmeyer flasks, measuring cylinders, beakers, spatulas, forceps, stirring rods, micropipettes, analytical balances, microtubes, test tubes, vials, glass containers, urine pots/tubes, refrigerators, autoclaves, incubators.
Petri dishes .
, inoculating loops, calipers, 8 mm paper discs (Advante.
, gloves, laboratory coats, and a camera for documentation.
The materials used in this research included sea grape samples (Caulerpa Propionibacterium acnes, 95% ethanol as an extraction solvent, 70% alcohol for sterilization.
Nutrient Agar (NA) as bacterial growth medium.
Nutrient Broth (NB) for bacterial rejuvenation, sterile distilled water as a solvent and negative control, and 8 mm paper discs for inhibition Biofarmasetikal Tropis e-ISSN 2685-3167 p-ISSN 2828-6685 (The Tropical Journal of Biopharmaceutica.
2025, 8.
, 24-30 into tubes, weighed, and stored in a refrigerator until further antibacterial testing.
Preparation of Nutrient Broth (NB) for Bacterial Rejuvenation The test bacterium was obtained from the culture stock of the Laboratory of the Faculty of Mathematics and Natural Sciences.
Universitas Kristen Indonesia Tomohon.
Nutrient Broth was prepared by dissolving 8 g of NB powder in 100 mL of sterile distilled water in an Erlenmeyer flask and homogenized thoroughly.
The NB solution was then poured into sterile Stock Propionibacterium acnes were inoculated and incubated for 24 hours.
Bacterial growth was indicated by turbidity in the broth.
Preparation of Nutrient Agar (NA) Nutrient Agar medium was prepared by 9 g of NA powder in 300 mL of sterile distilled water.
The solution was homogenized using a magnetic stirrer and sterilized in an autoclave at 121AC for 15 The sterile NA medium was used for antibacterial testing.
Antibacterial Activity Assay (Disc Diffusion Metho.
Antibacterial activity was evaluated using the agar diffusion method with paper discs.
The rejuvenated bacterial suspension was mixed with sterile NA medium, poured (A50 mL) into Petri dishes, and allowed to solidify.
Paper discs were soaked in sea grape extract solutions at concentrations of 100 AAg, 200 AAg, 300 AAg, and 400 AAg, dissolved in 70% The discs were dried for 24 hours in a desiccator.
The dried discs were placed onto the surface of agar plates inoculated with P.
acnes and incubated at 34Ae37AC for 24 hours.
Antibacterial activity was assessed by measuring the inhibition zone around each Each treatment was performed in Measurement of Inhibition Zone Diameter The inhibition zone was measured using a caliper by determining the clear area surrounding the disc.
The diameter was calculated as the average of three measurements: vertical, horizontal, and Formula:
ya= ya yaA ya Where:
A = vertical diameter B = horizontal diameter C = diagonal diameter D = average inhibition zone diameter Table 1.
Classification of Antibacterial Activity5 Inhibition Zone Diameter .
2Ae5 mm 5Ae10 mm 10Ae20 mm Ou20 mm Data Analysis The inhibition zone diameter data obtained from the antibacterial activity test of sea grape (Caulerpa racemos.
extract against Propionibacterium acnes were statistically If the data were normally distributed and homogeneous, a parametric One-Way ANOVA test was applied.
However, if the data were not normally distributed or not homogeneous, a non-parametric KruskalAeWallis test was used.
All statistical analyses were performed using SPSS software version 22 with a 95% confidence level ( = 0.
Activity Category .
Very weak
Moderate Strong
Very strong
RESULTS AND DISCUSSION
Preparation of Sea Grapes Extract (Caulerpa Sea grapes (Caulerpa racemos.
samples were collected from Basaan Beach.
Southeast Minahasa Regency.
The samples were then transported to the Laboratory of the Faculty of Mathematics and Natural Sciences for the extraction process.
Prior to extraction, the samples were washed under running water, drained, and cut into small pieces to increase the surface area, thereby facilitating the extraction of bioactive compounds.
Biofarmasetikal Tropis e-ISSN 2685-3167 p-ISSN 2828-6685 (The Tropical Journal of Biopharmaceutica.
2025, 8.
, 24-30 A total of 450 g of the sample was macerated using 4 L of 96% ethanol for four days, with two remaceration cycles.
The maceration method was selected because it is simple and can prevent the degradation of heatsensitive active compounds.
Ethanol was used as the solvent due to its ability to dissolve both polar and non-polar compounds.
The maceration filtrate was filtered and concentrated using a rotary evaporator at 40AC until a thick, dark green extract was obtained, weighing 45 g.
Evaporation at low temperature was performed to prevent decomposition of active compounds, as high temperatures may reduce the concentration of bioactive substances in the extract.
A The extraction yield was calculated using the following formula:
%yield = yceycuycycycaycayc ycyceycnyciEayc y 100% ycycnycoycyycoycnycycnyca ycyceycnyciEayc Table 2.
Extraction Yield of Sea Grapes Extract Sample Sample Weight Solvent Extract Weight Yield (%) .
Sea grapes 96% ethanol Antibacterial Inhibitory Activity Against Propionibacterium acnes The antibacterial activity of sea grapes (Caulerpa Propionibacterium acnes was evaluated using the agar disc diffusion method.
Paper discs with a diameter of 8 mm were impregnated with extract solutions at different concentrations and then dried for 24 hours in a vacuum desiccator.
After the Nutrient Agar (NA) medium inoculated with a suspension of P.
solidified in 15 cm Petri dishes, the extractloaded discs were placed on the surface of the The plates were then incubated at 34Ae 37AC for 24 hours.
Antibacterial activity was determined by the formation of a clear inhibition zone surrounding the discs.
In this study, four extract concentrations were tested: 100 AAg/disc, 200 AAg/disc, 300 AAg/disc, and 400 AAg/disc.
Distilled water .
at 50 AAL/disc was used as a negative A Table 3.
Inhibitory Activity of Caulerpa racemosa Extract Against Propionibacterium acnes Extract Concentration .
100 AAg/disc 200 AAg/disc 300 AAg/disc 400 AAg/disc Control (Aquades.
Replicate I .
Replicate II .
Based on Table 3, the ethanol extract of sea grapes (Caulerpa racemos.
exhibited very Propionibacterium acnes.
The smallest inhibition zone was observed at 100 AAg/disc with a mean diameter of 33.
9 mm, while the largest inhibition zone was recorded at 400 AAg/disc with a mean diameter of 41.
2 mm.
Replicate i .
Mean .
These findings indicate that higher extract concentrations resulted in larger inhibition The negative control .
showed no inhibition zone, confirming that the antibacterial effect was derived from active compounds present in the sea grapes extract.
According to antibacterial activity classification, inhibition zones Ou20 mm are categorized as very Biofarmasetikal Tropis e-ISSN 2685-3167 p-ISSN 2828-6685 (The Tropical Journal of Biopharmaceutica.
2025, 8.
, 24-30 Figure 1.
Petri Dish Showing Inhibition Zones of Propionibacterium acnes Treated with Crude Extract Based on the results presented in Table 3 and Figure 1, the sea grapes extract effectively inhibited the growth of Propionibacterium acnes at all tested concentrations.
The mean inhibition zone diameter increased from 33.
9 mm at 100 AAg/disc to 36.
3 mm at 200 AAg/disc, 38.
2 mm at 300 AAg/disc, and reached the highest value of 2 mm at 400 AAg/disc.
Meanwhile, the negative control showed no inhibition zone.
The curve shown in Figure 2 demonstrates corresponded with an increase in inhibition zone This suggests a direct relationship between extract concentration and antibacterial activity against P.
According to the classification criteria, the inhibition zones observed in this study fall within the very strong antibacterial activity category (Ou20 m.
Figure 2.
Inhibition Zone Activity Curve Against Propionibacterium acnes Data Analysis (Propionibacterium acne.
Statistical analysis of the inhibition zone data was preceded by normality and homogeneity tests.
Data are considered normally distributed and homogeneous when the significance value is >0.
However, the results indicated a p-value of 0.
000, suggesting that the data were not normally distributed and not homogeneous .
< 0.
Therefore, further analysis was conducted using the non-parametric KruskalAeWallis test.
Table 4.
Normality Test Results for P.
Test Method Statistic Sig.
KolmogorovAeSmirnov ShapiroAeWilk Biofarmasetikal Tropis e-ISSN 2685-3167 p-ISSN 2828-6685 (The Tropical Journal of Biopharmaceutica.
2025, 8.
, 24-30 The homogeneity test showed that the inhibition zone data were not homogeneous, with a significance value of 0.
< 0.
Consequently, the KruskalAeWallis test was selected as an alternative to ANOVA because it does not require equal variances.
The KruskalAeWallis analysis yielded a significance value of p = 0.
014, indicating a statistically significant difference among treatment groups.
Table 5.
KruskalAeWallis Test Results for P.
Test Statisticsa,b Inhibitory Power of P.
10,607
Chi-Square Asymp.
Sig.
Kruskal Wallis Test
Grouping Variables: Treatment
0,014
Table 6.
MannAeWhitney Post Hoc Test Results Treatment 100 AAg/disc 200 AAg/disc 300 AAg/disc 400 AAg/disc 100 AAg/disc .
Ai 200 AAg/disc .
Ai The MannAeWhitney post hoc test revealed significant differences between all concentration groups .
< 0.
Thus, it can be concluded that the inhibitory activity of C.
racemosa extract against P.
acnes differed significantly across all 300 AAg/disc .
Ai 400 AAg/disc .
Ai (Caulerpa Propionibacterium acnes, it can be concluded Caulerpa racemosa extract exhibited very Propionibacterium acnes at all tested concentrations, with inhibition zone diameters ranging from 33.
9 mm to 41.
2 mm.
A clear correlation was observed between increasing extract concentration and increased inhibition zone diameter.
The highest inhibitory effect was achieved at 400 AAg/disc.
Statistical analysis demonstrated significant differences among concentration treatments.
The KruskalAeWallis test produced p = 0.
< 0.
, and the MannAeWhitney post hoc test confirmed that each concentration differed significantly from the others.
Bioactive Compounds and Antibacterial Mechanism The antibacterial activity of Caulerpa racemosa is attributed to the presence of flavonoids and alkaloids.
Flavonoids inhibit bacterial growth by disrupting nucleic acid synthesis, damaging cytoplasmic membrane function, and interfering with bacterial energy Alkaloids, on the other hand, affect peptidoglycan synthesis, preventing proper cell wall formation and leading to bacterial cell AAeAA The inhibition zones produced at each concentration confirm that Caulerpa racemosa antiPropionibacterium acnes agent.
REFERENCES