Isolation, purification, and characterization of auxin from red algae (Eucheuma spinosum) and its application in cayenne pepper (Capsicum frutescens L.) plants

Eucheuma spinosum is a kind of seaweed that belongs to the Rhodophyceae (red algae) class. Red algae itself is a low-level plant that does not have different skeletal arrangements such as roots, stems, and leaves. In red algae, it is believed that besides polysaccharides there is also a plant hormone namely auxin. Auxin is a hormone in plants which have functioned as a regulator of cell enlargement and has the potential to be used as a biostimulant (hormone fertilizer). There are several types of auxins including indole acetic acid (IAA) and indole butyric acid (IBA). This study aims to isolate, purify, and characterize auxin in red algae (E. spinosum) and determine its effect on the growth of chili plants (C. frutescens L.). Isolation and characterization were carried out by thin-layer chromatography, adsorption column chromatography, High Performance Liquid Chromatography (HPLC). Infrared spectrophotometry (IR) and Mass Spectrometry (MS) were used for characterization. Biological test with chili plant as bioindicators with various treatment namely control, ETAC-21/ETAC-12, 1% NPK, IAA isolate, and crude extract from red algae and proximate tests were carried out including protein content, fat content, ash content, water content, and carbohydrate content on the fruit. The total protein pattern was synthesized tested using the Sodium Deodecyl Sulphate Poly Acrylamide Gel Electrophoresis (SDS-PAGE) method to determine the effect of adding IAA isolate to the expressed protein. The results of reversed-phase HPLC analysis stated that the auxin content in red algae was 2.43 mg/g dry weight. The results of IR and MS state that the IAA samples with IAA standards are relatively the same. The results of the biological test on cayenne pepper showed that IAA isolates could stimulate the growth of root length and root dry weight, and increase the number of chilies and chili seeds compared to the control plants. The addition of IAA isolates gave the average protein content, fat content, ash content, moisture content, and carbohydrate content were 6.18, 4.66, 2.96%, 81.46, and 4.73%, respectively. IAA isolate from red algae (E. spinosum) gave a distinctly different pattern of protein synthesis in cayenne pepper (C. frutescens L.) compared to the control plants, as shown on the SDS-PAGE result.