Bioaksesabilitas Antioksidan Teh Daun Bidara Arab (Ziziphus spina-christi)

Abstract

Tanaman bidara arab (Ziziphus spina-christi) mulai dikenal sebagai tanaman herbal yang memiliki banyak manfaat bagi tubuh manusia serta dikaitkan dengan pengobatan berbagai macam penyakit medis hingga non medis (magis) oleh masyarakat luas. Fitokimia utama yang terkandung dalam daun bidara arab yaitu flavonoid, alkaloid, polifenol, saponin, triterpenoid dan tanin. Namun ketika dikonsumsi dan melewati sistem pencernaan, senyawa ini dapat mengalami perubahan yang memengaruhi bioaksesibilitasnya. Selain itu, proses pengolahan bahan pangan seperti pengeringan dan perebusan juga dapat menyebabkan perubahan struktur senyawa fitokimia dalam pangan, sehingga dapat mengubah kapasitas antioksidannya. Sebelum menyimpulkan efek kesehatan yang potensial, perlu untuk menganalisis bagaimana perbedaan proses pengolahan pada daun bidara arab serta proses pencernaan memengaruhi senyawa bioaktif dan stabilitasnya, karena hal tersebut akan memengaruhi bioaksesibilitasnya atau jumlah yang dapat diserap tubuh. Penelitian ini bertujuan untuk mengidentifikasi karakteristik fitokimia (total fenolik dan flavonoid) dan kapasitas antioksidan (DPPH, ABTS dan FRAP) ekstrak teh daun bidara arab dari hasil penyeduhan dan perebusan, menganalisis perubahan total fenol, flavonoid dan kapasitas antioksidan selama proses pencernaan in vitro serta mengetahui indeks bioaksesibilitas antioksidan ekstrak teh daun bidara arab. Penelitian ini dilakukan dalam tiga tahapan. Tahapan pertama yaitu persiapan sampel teh daun bidara arab meliputi pembuatan teh daun bidara arab dan analisis proksimat teh. Tahap kedua yaitu karakterisasi kimia ekstrak daun bidara arab berdasarkan 2 cara penyajian yang berbeda (perebusan dan penyeduhan) dan 3 waktu ekstraksi (5, 10, dan 15 menit) yang dilanjutkan dengan analisis kapasitas antioksidan sampel. Tahap ketiga yaitu simulasi pencernaan gastrointestinal sampel teh dari berbagai perlakuan dilanjutkan dengan uji kapasitas antioksidan sampel sesudah pencernaan, serta penentuan bioaksesibilitas antioksidan ekstrak teh daun bidara arab. Uji kapasitas antioksidan meliputi uji penghambatan radikal DPPH dan ABTS, kemampuan reduksi ion ferri, total fenolik metode Folin-Ciocalteau, dan total flavonoid metode aluminium klorida. Simulasi pencernaan dilakukan melalui fase lambung dan fase usus halus mengikuti protokol pencernaan in vitro INFOGEST. Komposisi proksimat teh daun bidara arab pada penelitian ini yaitu air (7,85 ± 0,07% bb), abu (5,74 ± 0,15% bk), lemak (2,60 ± 0,29% bk), protein (14,25 ± 0,08% bk), dan karbohidrat (69,56 ± 0,001% bk). Hasil penelitian menunjukkan bahwa teh daun bidara arab hasil perebusan menghasilkan kapasitas antioksidan (DPPH, ABTS dan FRAP), total fenolik, dan flavonoid yang lebih tinggi dibanding perlakuan penyeduhan. Secara lebih lanjut, semakin lama waktu ekstraksi, maka semakin tinggi kapasitas antioksidannya. Kapasitas antioksidan tertinggi sampel sebelum pencernaan yaitu pada perlakuan perebusan 15 menit dengan nilai kapasitas antioksidan 36,02 ± 0,6 mg AEAC/g (bk) (DPPH), 58,55 ± 0,09 µmol FeSO4/g (bk) (FRAP), 7,97 ± 0,00 mg AEAC/g (bk) (ABTS), 43,52 ± 0,63 mg GAE/g (bk) (fenolik), dan 8,69 ± 0,08 mg QE/ mg (bk) (flavonoid). Korelasi sangat kuat ditemukan antara senyawa fenolik dan flavonoid dengan kapasitas antioksidan pada fase sebelum pencernaan ini. Seperti yang dapat diamati pada perlakuan perebusan, perbedaan waktu ekstraksi tidak secara signifikan memengaruhi total fenolik dan flavonoid dalam fase lambung. Kehilangan senyawa fenolik dan flavonoid yang paling signifikan pada fase lambung terjadi pada ekstrak hasil perebusan selama 15 menit. Kondisi biokimia fase usus menyebabkan peningkatan kandungan fenolik dan flavonoid teh daun bidara arab dibanding fase lambung, meskipun jumlah ini secara signifikan (p<0,05) masih lebih rendah daripada yang dihitung pada fase non-cerna, kecuali pada flavonoid teh hasil penyeduhan yang menurun secara ekstrim pada akhir pencernaan. Hasil analisis kapasitas antioksidan dengan metode DPPH dan metode ABTS menunjukkan peningkatan kapasitas antioksidan pada akhir pencernaan teh daun bidara arab hasil perebusan maupun penyeduhan. Sebaliknya pada metode FRAP, kapasitas antioksidan total cenderung mengalami penurunan secara signifikan pada akhir fase pencernaan, baik pada perlakuan perebusan maupun penyeduhan dibandingkan dengan fase sebelumnya yaitu non cerna dan fase lambung. Terjadi penurunan nilai koefisien korelasi antara total fenolik dan flavonoid dengan kapasitas antioksidan setelah pencernaan usus. Secara umum, teh hasil perebusan menunjukkan nilai bioaksesibilitas (BI) dan pemulihan (RI) antioksidan dan flavonoid tertinggi, kecuali BI total fenolik yang tertinggi ditemukan pada sampel penyeduhan. Sementara pengaruh waktu dijelaskan secara berbeda pada masing-masing uji. Perebusan selama 15 menit menunjukkan BI antioksidan metode DPPH, FRAP, ABTS dan flavonoid tertinggi, sementara BI total fenolik tertinggi diperoleh dari hasil penyeduhan 5 menit. Jika dibandingkan dengan larutan standar yang diukur pada masing-masing uji, BI teh daun bidara arab lebih tinggi, bahkan untuk beberapa hasil uji pada perlakuan penyeduhan. Penyajian teh daun bidara arab dengan cara perebusan selama 5-15 menit dianjurkan karena tidak menunjukkan perbedaan yang nyata dan menghasilkan kapasitas antioksidan, total fenolik, dan flavonoid yang tinggi sebelum dan sesudah simulasi pencernaan in vitro.

The bidara plant (Ziziphus spina-christi) was recently known as a herbal plant that had many benefits for humans, it was also associated with the treatment of various kinds of medical to non-medical (magical) diseases by society. The main phytochemical compounds contained in the bidara leaves were flavonoids, alkaloids, polyphenols, saponins, triterpenoids, and tannins. However, when consumed and passed through the digestive system, these compounds could undergo changes that affected their bioaccessibility. Moreover, food processing techniques such as drying and boiling could induce structural modifications in phytochemical compounds present in food, thereby affecting their antioxidant capacity. In this case, the processing effect on the phytochemical characteristics and a more comprehensive understanding of the effect of the digestive process on the antioxidant bidara leaf tea were indispensable. To optimize the utilization of bidara leaf tea, it was crucial to understanding the impact of processing and digestion on its antioxidant properties. This study aimed to identify phytochemical characteristics (total phenolic, flavonoids, and antioxidant capacity using DPPH, ABTS, and FRAP methods) of bidara leaf tea extracts from brewing and boiling methods, to analyze changes in total phenolic content, flavonoid, and antioxidant capacity during vitro digestion, as well as to determine the antioxidant bioaccessibility index of bidara leaf tea extracts. This research was conducted in three stages. The first stage was the preparation of bidara leaf tea samples including the manufacture of bidara leaf tea and proximate analysis of the tea. The second stage was the chemical characterization of bidara leaf extract based on two different ways of serving (boiling and brewing) and three extraction times (5, 10, and 15 minutes), followed by an analysis of the antioxidant capacity of the samples. The third stage was simulating the gastrointestinal digestion of tea samples from various treatments followed by testing the antioxidant capacity of the samples after digestion, as well as determining the bioaccessibility of antioxidants from bidara leaf tea extract. Antioxidant capacity tests included DPPH and ABTS radical scavenging tests, ferric reducing antioxidant power (FRAP), total flavonoids using the Folin-Ciocalteau method, and total flavonoids using the aluminum chloride method. Digestion simulation was carried out through the gastric phase and the small intestine phase following the INFOGEST in vitro digestion protocol. Moisture, ash, fat, protein, and carbohydrate contents of bidara tea leaves were respectively 7.85 ± 0.07% wb, 5.74 ± 0.15% db, 2.60 ± 0.29% db, 14.25 ± 0.08% db, and 69.56 ± 0.00% db. The results of the study showed that boiling bidara leaf tea produced higher antioxidant capacities (DPPH, ABTS, and FRAP), total phenolics, and flavonoids than the brewing treatment. Furthermore, the longer the extraction time, the higher the antioxidant capacity. The highest antioxidant capacity of the samples before digestion was in the 15-minute boiling treatment with antioxidant capacity values of 36.02 ± 0.6 mg AEAC/g (bk) (DPPH), 58.55 ± 0.09 µmol FeSO4/g (bk) (FRAP), 7.97 ± 0.00 mg AEAC/g (bk) (ABTS), 43.52 ± 0.63 mg GAE/g (bk) (phenolic), and 8.69 ± 0.08 mg QE/ mg (bk) (flavonoids). A very strong correlation was found between phenolic and flavonoid compounds with antioxidant capacity in this pre-digestion phase. During the digestive phase, as can be observed in the boiling treatment, the extraction time difference did not significantly affect total phenolic and flavonoids in the gastric phase. The most significant loss of phenolic and flavonoid compounds in the gastric phase occurred in extracts from boiling for 15 minutes. In contrast, the biochemical conditions of the intestinal phase led to an increase in the phenolic and flavonoid content of bidara leaf tea, although this amount was significantly (p<0.05) lower than in the non-digestible phase results, except for the tea flavonoids which decreased significantly at the end of digestion. The results of the analysis of antioxidant capacity using the DPPH method and the ABTS method showed that the digestive process results in increased antioxidant capacity at the end of digestion of bidara leaf tea either in boiling or brewing treatment. Differently, the total antioxidant capacity based on FRAP method tended to decrease significantly at the end of the digestive phase, both in the boiling and brewing treatments compared to the previous phases, i.e. the non-digested and gastric phases. There was a decrease in the value of the correlation coefficient between total phenolics and flavonoids with antioxidant capacity after intestinal digestion. In general, the boiling method for producing bidara leaf tea showed the highest bioaccessibility (BI) and recovery index (RI) values of antioxidants and flavonoids. Meanwhile, the highest BI of total phenolic was found in the brewing samples. The effect of time was explained differently in each test. Boiling for 15 minutes showed the highest BI of antioxidants using the DPPH, FRAP, ABTS, and flavonoid methods, while the highest BI of total phenolics was obtained from the 5-minute brewing. When compared with the standard solution measured in each test, the BI of bidara leaf tea was higher, even for some test results in the brewing treatment. Therefore, it was recommended to prepare bidara leaf tea by boiling it for 5-15 minutes because it did not show a significant difference and produced high antioxidant capacity, total phenolics, and flavonoids before and after in vitro digestion.