Malaysian Journal of Analytical Sciences Vol 18 No 1 (2014): 43 – 57

 

 

 

KAJIAN AWALAN TERHADAP KINETIK PENGEKSTRAKAN

PEPEJAL-CECAIR DAN ANALISIS KOMPONEN BIO-AKTIF

DAUN Hibiscus rosa-sinensis

 

(Preliminary Study on Kinetic Solid-Liquid Extraction and Bio-Active Components Analysis of Hibiscus rosa-sinensis Leaves)

 

Saiful Irwan Zubairi*, Haizulizam Suradi, Syazwan Aizad Abdul Mutalib, Zetty Shafiqa Othman,

Norshahida Bustaman, Wan Ros Maryana Wan Musa

 

Pusat Pengajian Sains Kimia & Teknologi Makanan, Fakulti Sains & Teknologi,

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

 

*Corresponding author: saiful-z@ukm.my

 

 

Abstrak

Hibiscus rosa-sinensis atau nama tradisinya ‘pokok bunga raya’ adalah sejenis tumbuhan bunga hiasan yang kerap ditanam di negara yang beriklim subtropika. Tumbuhanini kerap digunakan dalam penyediaan perubatan tradisional kerana ia mempunyai ciri-ciri farmakologi yang mampu merawat beberapa masalah kesihatan. Tumbuhan ini mengandungi beberapa bahan bio-aktif dan nutrient penting yang banyak terutama sekali pada bahagian bunga dan daun. Salah satu bahan bio-aktif tersebut adalah β-sitosterol yang banyak terdapat di dalam ekstrak daunnya. Ekstrak air daun bunga raya mengeluarkan lendir atau mukus yang pekat ia banyak digunakan dalam menurukan suhu badan yang tinggi akibat demam panas (antipiretik). Oleh yang demikian, objektif utama kajian ini dijalankan adalah untuk mengenalpasti keberhasilan maksimum dan masa pengekstrakan menyeluruh ekstrak lendir daun segar dan kering menggunakan model matematik Peleq. Di samping itu, beberapa analisis susulan turut dijalankan seperti analisis kualitatif kehadiran bahan bio-aktif menggunakan kaedah kromatografi cecair prestasi tinggi (HPLC) dan penentuan kumpulan berfungsi melalui kaedah tranformasi fourier inframerah (FTIR). Ujikaji sifat fizikal hasil ekstrak dijalankan iaitu analisis tahap keasidan (pH) dan kelikatan bagihasil ekstrak lendir terhadap tegasan ricihan (shear stress). Keputusan kajian mendapati sampel daun kering mempunyai kepekatan hasil ekstrak yang tinggi walaupun masa pengekstrakan menyeluruh yang agak perlahan berbanding daun segar (p<0.05). Berdasarkan kepada analisis HPLC, kehadiran bahan bio-aktif utama β-sitosterol dilihat hanya wujud pada sampel daun segar. Ketiadaan β-sitosterol di dalam sampel pengekstrakan daun kering mungkin disebabkan oleh kehilangan beberapa bahan bio-aktif penting yang bersifat surfaktan (membantu pengeskstrakan β-sitosterol) akibat daripada degradasi termal semasa proses pengeringan atau ianya terdegradasi akibat daripada suhu yang tinggi semasa proses pengeringan pra-rawatan. Pembuktian lanjutan melalui analisis FTIR menunjukkan komposisi puncak penyerapan yang sama bagi kedua-dua jenis sampel daun dengan nilai puncak penyerapan tertinggi iaitu ikatan O-H dikenalpasti. Ini membuktikan bahawa kandungan β-sitosterol di dalam kedua-dua jenis sampel tersebut adalah terlalu sedikit dan komposisi fitosterol yang lain dilihat mendominasi serta mempengaruhi kehadiran β-sitosterol di dalam hasil ekstrak. Sementara itu, ujian sifat fizikal terhadap ekstrak kedua-dua jenis daun turut dijalankan bagi pembuktian kesan pengeringan terhadap komponen bahan bio-aktif penting. Nilai keasidan yang tinggi bagi sampel daun segar dilihat berpunca daripada kebolehdapatan semua komponen bahan bio-aktif manakala bagi ekstrak daun kering, nilai pH yang agak neutral dilihat berpunca daripada penguraian beberapa bahan fitokimia yang bersifat asidik dan sensitif kepada haba.

 

Kata kunci: Hibiscus rosa-sinensis, β-sitosterol, pengekstrakan pepejal-cecair, lendir, kelikatan, FTIR, HPLC

 

Abstract

Hibiscus rosa-sinensis or commonly known as 'Hibiscus' is a kind of decorative flowers which often grown in a subtropical countries. This plant is often used in the preparation of traditional medicine because of its pharmacological properties that are capable of treating number of health problems. The plant contains several essential bio-active substances and nutrients especially in its flowers and leaves. One of the bioactive substances is β-sitosterol which is abundant in the leaf crude extract. Hibiscus leaves water extract yielded mucilage which is widely used in lowering high body temperature due to fever (antipyretic). Therefore, the main objective of this paper was to determine the maximum concentration of mucilage and time of exhaustive extraction from fresh and dried leaves using a Peleq’s mathematical model. Moreover, several analyses were conducted such as qualitative analysis to determine the presence of bioactive substances using high performance liquid chromatography (HPLC) and determination of functional groups by means of fourier transform infrared method (FTIR). Physical properties of the extracts were evaluated to determine its acididity and viscosity of the mucilage with respect to different shear stress. The result show that the extract of dried Hibiscusleaves exhibited high in its concentrations even though the achieved exhaustive extraction was relatively slow as compared to fresh leaves (p<0.05). Based on the HPLC analysis, the main bio-active substances of β-sitosterol was only existed in fresh leaves samples. The absence of β-sitosterol in dried leaves extract was caused by the loss of otherimportant bio-active substances which possess surfactantcapability, due to thermal degradation of drying process or the component itself was deteriorated during the pre-preparation drying process. Furthermore, the FTIR analysis shows that the same composition of theabsorption peaks for both extracts with the highest absorption of O-H bonds was observed. This proves that the content of β-sitosterol in both extracts was too small and the composition of other phytosterols was observed to dominate and influence the availability of β-sitosterol in the crude extract. Meanwhile, physical properties analysis of the both extracts was carried to show the effect of drying process on the observed bio-active components. The high acidity of the fresh leaf extract was attributed to the presence of all bio-active ingredients. Meanwhile for the dried leaf extract, a close neutral pH value was observed due to the bio-active decomposition which is acidic in nature and sensitive to heat.

 

Keywords: Hibiscus rosa-sinensis, β-sitosterol, solid-liquid extraction, mucilage, viscosity, FTIR, HPLC